Wireless communication system, terminal, and base station apparatus

The present invention relates to a wireless communication system using OFDM for downlink communication and FH for uplink communication.

Most of the conventional wireless communication systems that perform two-way communication between a base station and a terminal use a vertically symmetric wireless link having the same vertical communication bandwidth and the same vertical communication modulation method. (See, for example, Patent Document 1).

OFDM is one of the modulation methods that realizes high-speed data transmission. The signal modulated by OFDM contains a plurality of subcarriers, has a large dynamic range of the signal as a time waveform, and requires linearity in the transmission power amplifier. That is, when transmitting a signal using OFDM, it is indispensable to increase the power consumption. Therefore, when the above OFDM is applied to a conventional wireless communication system to realize a high-speed downlink (from a base station to a terminal), the same bandwidth and modulation method (from the terminal to the base station) are also applied to the uplink (from the terminal to the base station). Since OFDM) is used, there is a problem that the power consumption of the terminal becomes large.

There is a conventional wireless communication system that performs two-way communication between a base station and a terminal, and has a different bandwidth for vertical communication and a different radio frequency band for uplink communication and downlink communication (there is a wireless communication system). For example, see Patent Document 2). In a wireless communication system using such a vertically asymmetric wireless link, since the radio frequencies used for uplink communication and downlink communication are different, it is not possible to accurately estimate the characteristics of the transmission line. Therefore, technologies such as transmission power control, directivity control, and adaptive modulation cannot be effectively used, resulting in deterioration of wireless line quality.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2000-299681</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 7-176791</text></patcit>

<p> In this way, in the conventional wireless communication system using a vertically asymmetric wireless link, it is possible to increase the speed of downlink communication and reduce the power consumption of the terminal, but the radio frequencies used for uplink communication and downlink communication are different. Therefore, it is not possible to accurately estimate the characteristics of the transmission line, and there is a problem that the communication quality of the vertical communication is low.</p><p> Therefore, in view of the above problems, the present invention provides a wireless communication system, a terminal device, and a base station device using a vertically asymmetric wireless link that enables high-quality communication between a base station and a terminal. With the goal.</p>

<p> The wireless communication system of the present invention uses an OFDM (Orthogonal Frequency Division Multiplexing) signal including a plurality of subcarriers for downlink communication from a base station to a terminal, and the frequency of the OFDM signal for uplink communication from a terminal to a base station. It is a wireless communication system that performs bidirectional communication by TDD (Time Division Duplex) using an FH (Frequency Hopping) signal in the same frequency band as the band, and the terminal is a plurality of the above based on the received OFDM signal. An estimation means for estimating transmission line characteristics (at least one of power, power ratio, and phase / amplitude distortion) for the subcarriers of the above, and a transmission means for transmitting the estimation result by the estimation means to the base station. Based on the estimation result transmitted from the terminal, the base station has a subcarrier used in the downlink communication among the plurality of subcarriers and a hopping pattern used in the uplink communication with respect to the terminal. It is provided with an allocation means for allocating at least one of them.</p><p> In downlink communication, transmission is performed using the entire band of the plurality of subcarriers, so that the terminal side can accurately measure the state of the transmission line between the terminal and the base station. Based on this measurement result, the most suitable subcarrier for the terminal is preferentially selected for the terminal, and the hopping pattern used for uplink communication and the subcarrier used for downlink communication are assigned to the base station and the terminal. Enables high quality communication between.</p><p> The wireless communication system of the present invention uses an OFDM (Orthogonal Frequency Division Multiplexing) signal including a plurality of subcarriers for downlink communication from a base station to a terminal, and the frequency of the OFDM signal for uplink communication from a terminal to a base station. It is a wireless communication system that performs bidirectional communication by TDD (Time Division Duplex) using an FH (Frequency Hopping) signal in the same frequency band as the band, and the base station transmits from a terminal in the uplink communication time slot. An estimation means for estimating the transmission line characteristics between the terminal and the base station based on the signal to be generated, and based on the estimation result by the estimation means, for each of the terminals, the plurality of subcarriers of the plurality of subcarriers Of these, an allocation means for allocating at least one of the subcarrier used in the downlink communication and the hopping pattern used in the uplink communication is provided.</p><p> When the base station receives an FH signal or an OFDM signal using the entire band of the plurality of subcarriers transmitted from the terminal in uplink communication, the base station accurately determines the state of the transmission line between the terminal and the base station. Can be measured. Based on this measurement result, the most suitable subcarrier for the terminal is preferentially selected for the terminal, and the hopping pattern used for uplink communication and the subcarrier used for downlink communication are assigned to the base station and the terminal. Enables high quality communication between.</p>

<p> According to the present invention, it is possible to easily construct a wireless communication system using a vertically asymmetric wireless link that enables high-quality communication between a base station and a terminal.</p>

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the outline of the communication system according to the present embodiment will be described.

FIG. 1 schematically shows a schematic configuration example of the entire wireless communication system. In FIG. 1, the terminal TE1 and the base station (or wireless access point) BS1 perform two-way communication. The average data rate of downlink (DL) is faster than that of uplink (UL) in order to easily download images and files. In order to realize this, in the system of the present embodiment, the downlink is a modulation method based on OFDM (Orthogonal Frequency Division Multiplexing) using a multi-carrier signal composed of a plurality of subcarrier signals, and the uplink is a modulation method. , FH (Frequency Hopping) is used for communication (see Fig. 4 and Fig. 8).

With such a configuration, it is possible to realize an uplink with a narrow signal bandwidth and dynamic range while ensuring a high-speed data rate, and it is possible to reduce the power consumption of the terminal.

In order to realize bidirectional communication between downlink OFDM communication and uplink FH communication, TDD (Time Division Duplex) may be used or FDD (Frequency division Duplex) may be used. First, the former case will be described.

Figure 4 shows the case where the same frequency band is used for the downlink and uplink and is accommodated by TDD. Since the OFDM signal used in the downlink is transmitted using the entire radio band, the receiving side estimates (measures) distortion (for example, amplitude, phase distortion) and power in the transmission line for each subcarrier. By doing so, it is possible to accurately estimate the characteristics of the wireless transmission line. On the other hand, in FH, since carrier frequency hopping is performed (because the radio frequency used fluctuates frequently), it is difficult to accurately measure the characteristics of the radio transmission line for each subcarrier signal.

However, by combining OFDM and FH with TDD, information representing the state of each radio transmission line recognized through each subcarrier of OFDM (by estimating the transmission line characteristics for the subcarrier signal) is transmitted by FH. Can be used for. For example, while measuring the transmission line characteristics of each OFDM subcarrier signal on the downlink, transmission power control and antenna directivity control are performed on the uplink, and high-quality frequencies are preferentially assigned to the FH hopping pattern. Etc. can be easily realized.

As described above, according to the wireless communication system, it is possible to transmit data at a high data rate and to reduce the power consumption of the terminal. In addition, system control can be facilitated and high communication quality can be realized.

In the above wireless communication system, as shown in FIG. 2, by applying a multiplexing method such as TDMA or CDMA to the downlink OFDM signal and a multiplexing method using the FH hopping pattern to the uplink, a plurality of users can be used. It can be accommodated. By adopting such a method, it becomes easy to control the interference even in a system in which communication areas are overlapped and developed in a cellular shape as shown in FIG. FIG. 5 shows a case where signals of a plurality of users are accommodated in the downlink.

Next, a case where bidirectional communication is realized by using different frequencies for the downlink of OFDM and the uplink of FH, that is, the case of FDD (Frequency division Duplex) will be described with reference to FIG. In this case, since the transmission timings of the base station and the terminal can be designed independently, the synchronization control in the wireless communication system can be simplified. Further, as in the case of bidirectional communication with the TDD, it is possible to transmit data at a high data rate and reduce the power consumption of the terminal. In addition, system control can be facilitated and high communication quality can be realized.

Hereinafter, a wireless communication system that realizes bidirectional communication between downlink OFDM communication and uplink FH communication by TDD will be described.

(First Embodiment) First, each configuration of a base station and a terminal applicable to a wireless communication system that realizes bidirectional communication between downlink OFDM communication and uplink FH communication by TDD will be described.

(Configuration of base station) Fig. 18 shows a configuration example of a base station.

The data transmitted from the base station to each user # 1 to #N, the FH pattern information output from the uplink FH user allocation unit 8, and the user allocation information output from the downlink OFDM user allocation unit 7 are the user allocation unit 1. Is sorted using the order of transmission to each user and the user allocation information. The sorted (divided into subcarriers) signals destined for each user are modulated by the FDM transmitter 2 as shown in FIG. That is, in the OFDM transmission unit 2, after each subcarrier signal is modulated by the subcarrier modulation unit 2a, the IFFT unit 2b generates a multicarrier signal by IFFT (inverse Fourier transform), and the guard interval addition unit 2c adds a guard interval. Then, the symbol shaping unit 2d shapes the waveform. The baseband signal thus obtained is passed to the radio unit 11. In the radio unit 11, the baseband signal is converted from a digital signal to an analog signal by the D / A conversion unit 11a, and then converted into an intermediate frequency (IF) and then to a radio frequency (RF) by the frequency conversion unit 11b via an antenna. And send.

The FH signal transmitted from each terminal is received by the radio unit 12. As shown in FIG. 61, the radio unit 12 corrects the level of the received signal by AGC (Automatic Gain Control) in the AGC unit 12a, and then performs frequency conversion of the received signal in the frequency conversion unit 12b to perform A / D conversion. The unit 12c converts an analog signal into a digital signal and outputs the received signal to the FH receiving unit 9.

The FH receiving unit 9 detects each subcarrier signal from the received signal output from the radio unit 12 by the subcarrier detecting unit 9a. Each subcarrier signal is output to the transmission line estimation unit 6 and the user signal extraction unit 10.

The transmission line estimation unit 6 estimates the transmission line characteristics of the uplink from each terminal to the base station based on the received power values of each subcarrier signal and the FH signal measured for the above AGC by the radio unit 12. To do. That is, for each terminal, transmission line characteristics such as transmission line distortion, power value, and power ratio are obtained for each subcarrier signal. The uplink transmission line characteristics from each terminal to the base station estimated by the transmission line estimation unit 6 are output to the downlink OFDM user allocation unit 7 and the uplink FH user allocation unit 8, respectively, and are similar to the transmission line status information. It is used as a judgment material when allocating a channel to each terminal on the downlink and uplink.

When the downlink OFDM user allocation unit 7 and the uplink FH user allocation unit 8 allocate channels to each terminal on the downlink and uplink, the transmission line characteristics estimated by the transmission line estimation unit 6 and the transmission line characteristics estimated by each terminal are used. It suffices to use one of the transmitted transmission line state information.

By the way, the subcarrier signal output from the FH receiving unit 9 is also input to the user signal extraction unit 10. The user signal extraction unit 10 extracts each user's signal from each subcarrier signal by using the FH pattern information of each terminal used for the FH signal received this time, and outputs the user signal corresponding to each terminal. ..

The signal separation unit 5 decodes each user signal output from the user signal extraction unit 10 and separates the transmission path state information and the user data from each decoded user signal. Then, the transmission line status information is output to the downlink OFDM allocation unit 7 and the uplink FH user allocation unit 8.

Based on the transmission line estimation result, the downlink OFDM user allocation unit 7 allocates channels (subcarriers, symbols, etc.) in the next downlink slot to each terminal, and outputs user allocation information indicating the result. The uplink FH user allocation unit 8 determines the FH pattern of each user in the next uplink slot based on the transmission line estimation result, and outputs the FH pattern information of each user representing the result.

(Terminal configuration) Fig. 19 shows an example of terminal configuration.

The data transmitted from each user to the base station is input to the FH transmission unit 51. As shown in FIG. 60, the FH transmission unit 51 multiplexes the transmission data to the base station input by the multiplexing unit 51a and the transmission line state information output from the transmission line estimation unit 52, and also modulates the modulation unit 51. At 51b, modulation is performed using the FH pattern information notified from the base station (obtained by the signal separator 55). The resulting baseband signal is converted from a digital signal to an analog signal by the D / A conversion unit 58a in the radio unit 58, then frequency-converted by the frequency conversion unit 58b, and transmitted via the antenna.

The OFDM signal transmitted from the base station is received by the radio unit 57. As shown in FIG. 59, the radio unit 57 corrects the level of the received signal by the AGC (Automatic Gain Control) in the AGC unit 57b, then performs frequency conversion of the received signal in the frequency conversion unit 57b, and further, the said The A / D converter 57c converts the received signal from an analog signal to a digital signal and outputs it to the OFDM receiver 53.

The OFDM reception unit 53 uses the known signals (preamble signal, pilot signal) for establishing synchronization included in the reception signal with respect to the reception signal output from the radio unit 53, and the AFC unit 53a synchronizes the carrier frequency (transmission / reception). (Synchronize by adjusting the carrier frequency error between machines) processing, symbol timing synchronization (timing synchronization of OFDM symbol and demodulation processing) processing is performed by the timing detection unit 53b, and guard interval is performed by the guard interval removal unit 53c. Is removed. After that, the FFT unit 53d performs demultiplexing processing of the multicarrier signal by FFT (Fourier transform), and each subcarrier signal obtained is output to the channel equivalent processing unit 53e and the transmission path estimation unit 52. Channel equivalence processing based on the distortion of the transmission line (for example, the distortion of the phase and amplitude of each subcarrier signal) estimated from each subcarrier (for example, estimated by the channel estimation circuit included in the transmission line estimation unit 52). In part 53e, processing (synchronous detection) for obtaining a data signal from each subcarrier signal is performed. It is generally practiced to use a channel equivalent circuit in order to perform synchronous detection using the estimated distortion of the transmission line. Then, the subcarrier demodulation unit 53f decodes each subcarrier signal and outputs it to the user signal extraction unit 54.

The AGC unit 57a of the radio unit 57 measures the received power of the received OFDM signal for the above AGC. The received power value of this measured OFDM signal is output to the transmission line estimation unit 52. Further, the OFDM receiving unit 53 also outputs each subcarrier signal (including a pilot signal (known signal) included in each subcarrier signal) obtained by the FFT to the transmission line estimation unit 52.

The transmission line estimation unit 52 has a channel estimation circuit for estimating the phase and amplitude distortion of each subcarrier signal from each input subcarrier signal. This channel estimation circuit estimates the distortion of the transmission line estimated from each subcarrier signal. The estimated distortion of the transmission line is also used in the above-mentioned synchronous detection processing. The transmission line estimation unit 52 further measures the power of each input subcarrier signal. Further, the power ratio (S / N (signal to noise ratio) ratio) for each subcarrier signal is calculated from the power value of each subcarrier signal and the received power value of the OFDM signal measured for AGC.

The transmission line estimation unit 52 uses the transmission line characteristics such as the transmission line distortion, power value, and power ratio estimated for each subcarrier to obtain a subcarrier signal with a poor transmission line condition (for example, transmission line distortion and power value). And a subcarrier signal whose power ratio is lower than a predetermined threshold) is detected, and transmission line state information including an identifier (for example, a number in this case) of the subcarrier signal is generated. In addition, transmission line state information including the estimated transmission line distortion amount (phase, amplitude distortion amount), power value, and power ratio for each subcarrier is generated. In addition, transmission including the estimated transmission line distortion amount (phase, amplitude distortion amount), power value, and power ratio for each subcarrier, as well as the identifier of the subcarrier signal with poor transmission line condition determined based on these. Generate road condition information.

The transmission line estimation unit 52 uses a subcarrier signal having a good transmission line condition (for example, a transmission line distortion or a subcarrier signal whose power value or power ratio is equal to or higher than a predetermined threshold value) based on the estimated transmission line characteristics. The hopping pattern may be determined. In this case, the hopping pattern may be included in the transmission line state information.

The transmission line state information is transmitted to the base station via the FH transmission unit 51.

When the transmission line state information is received by the base station, it is used in the uplink FH user allocation unit 8 to determine the hopping pattern for each user, and in the downlink OFDM user allocation unit 7, as described above. It is used when assigning a subcarrier or the like to each user.

The user signal extraction unit 54 extracts a signal addressed to its own device from each subcarrier signal output from the OFDM reception unit 53. At that time, the user allocation information received in advance and stored in the storage unit 55a is referred to. The user signal extraction unit 54 decodes the extracted signal addressed to the own device and outputs it to the signal separation unit 55.

The signal separation unit 55 separates the user allocation information included in the user signal, the FH pattern, and the received data addressed to the own device from the user signal output from the user signal extraction unit 54. The user allocation information is temporarily stored in the storage unit 55a for use when extracting a signal addressed to the own device (by the user signal extraction unit 54) from the OFDM signal to be received next time. Further, the FH pattern information is output to the FH transmission unit 51 and used for frequency hopping in the next uplink slot.

(Operation of base station and terminal) Fig. 6 shows transmission power control, FH hopping pattern control, etc. using information representing the characteristics of the transmission line estimated by each terminal that receives the OFDM signal transmitted on the downlink. It is a figure for demonstrating the case of performing. Further, FIG. 7 is a flowchart for explaining the operation at that time. Hereinafter, description will be made with reference to FIGS. 6 and 7.

In the above wireless communication system, the fact that the downlink is OFDM is used, and on the terminal side, the transmission line characteristics are transmitted from the downlink OFDM signal (for example, information symbol, pilot signal, etc.) transmitted in the first time slot. (For example, subcarrier power, transmission line distortion (phase, amplitude), delay profile, transmission line frequency response, etc.) are estimated (measured) (steps S1 and S2 in FIG. 7). At least one of the resulting information (for example, a subcarrier number indicating a low power subcarrier, a received power value / S / N ratio (signal to noise ratio) of each subcarrier, a hopping pattern candidate, etc.) The including transmission line state information) is transmitted to the base station side using the uplink of the second time slot immediately after (step S3 in FIG. 7). Then, the base station performs transmission power control (TPC) on the downlink in the next third time slot based on the transmission line state information, and FH hopping on the uplink in the next fourth time slot. Determine the pattern (step S4 in Figure 7).

For example, in FIG. 6, since the transmission line characteristic (for example, the received power value) of the frequency band of the subcarrier #n is lower than the predetermined threshold value, in the third time slot, the OFDM signal in which the transmission power of the subcarrier #n is increased is increased. (Step S5 in Figure 7). Alternatively, in the fourth time slot, a pattern is determined so as not to perform hopping in the frequency band of subcarrier #n, and the determined hopping pattern is notified to the terminal side. On the terminal side, transmission is performed using the notified hopping pattern (step S6 in FIG. 7).

By controlling the system by such a method, it is possible to realize a wireless communication system that maintains good communication quality regardless of the wireless propagation condition.

In addition to the transmission power control and FH hopping pattern control shown in FIG. 6, the control target is antenna directivity in the base station based on various information included in the transmission line state information transmitted from each terminal. Control, adaptive modulation, etc. can be performed.

Next, the arrangement of the channels of each terminal assigned to each of the uplink / downlink time slots by the downlink OFDM user allocation unit 7 and the uplink FH user allocation unit 8 of the base station will be described.

(First slot configuration) Fig. 9 shows an example of the first slot configuration. The downlink communication from the base station to each terminal and the uplink communication from each terminal to the base station are time-multiplexed and performed using the same frequency band. Further, here, the minimum unit of the hopping frequency in the uplink FH is the same as the frequency interval ΔF of the subcarriers in the downlink OFDM signal.

The base station transmits an OFDM signal of the N_DL symbol (N_DL is an integer of 1 or more) to each user (each terminal) using the frequency and time domain 101. That is, the N_DL symbol is transmitted by one downlink slot. Note that one symbol corresponds to the waveform of the signal that can be transmitted per unit time. In FIG. 9, subcarriers # 1 to # 8 are used in one downlink slot to transmit data of four symbols in one downlink slot.

After the base station finishes transmitting the OFDM signal and after the interval time 102, each terminal uses the frequency band specified by the base station in advance, and the N_UL symbol (N_UL is an integer of 1 or more) is continuous in one uplink slot. And send. That is, one uplink slot corresponds to the time width of the N_UL symbol length.

In FIG. 9, the terminal of user # 1 uses subcarrier # 8 to continuously transmit eight symbols in one uplink slot. In addition, the terminal of user # 2 uses subcarrier # 3 to continuously transmit 8 symbols in one uplink slot.

Each terminal ends transmission, and after an interval time of 105, the base station again transmits a downlink OFDM signal to each terminal using the time and frequency domain 106. Further, after the interval time 107, each terminal transmits to the base station using the frequency band designated. At this time, the frequency band used does not have to be the frequency band used in the previous uplink slot. In FIG. 9, the terminal of user # 1 transmits using subcarrier # 5, and user # 2 transmits using subcarrier # 8. In this way, in uplink communication, communication is performed by hopping the frequency for each uplink slot. In other words, the hopping cycle is the N_UL symbol long time.

According to the first slot configuration described above, the frequency band (subcarrier) having good characteristics is preferentially selected and the uplink hopping pattern is selected by using the transmission line characteristics of each subcarrier estimated (measured) on the terminal side. By making a decision, the transmission efficiency of uplink communication can be improved.

(Second slot configuration) Fig. 10 shows an example of the second slot configuration. The downlink communication from the base station to each terminal and the uplink communication from each terminal to the base station are time-multiplexed and performed using the same frequency band. Further, here, the minimum unit of the hopping frequency in the uplink FH is the same as the frequency interval ΔF of the subcarriers in the downlink OFDM signal.

The base station transmits an OFDM signal of the N_DL symbol (N_DL is an integer of 1 or more) to each user using the frequency and time domain 201. That is, the N_DL symbol is transmitted by one downlink slot. In FIG. 10, data of 4 symbols (1 downlink slot) is transmitted using subcarriers # 1 to # 8.

After the base station finishes transmitting the OFDM signal and the interval time 202, each terminal has a hopping period (1 / M (M is an integer of 1 or more) specified in advance by the base station from the frequency and time domain 203. Using the hopping pattern of (symbol long time), the N_UL symbol (N_UL is an integer of 1 or more) is transmitted in one uplink slot.

In FIG. 10, user # 1 transmits data of one symbol using subcarriers # 12 and # 10 at time 6. Similarly, from time "7" to time "11", subcarriers # 8, # 11, # 2, # 4, # 6, # 7, # 9, # 5, # 3, # 1 are used in order. A total of 6 symbols of data are transmitted in one uplink slot. In addition, user # 2 has subcarriers # 3, # 6, # 11, # 9, # 7, # 5, # 12, # 1, # 8, # 10, # 2 from time "6" to time "11". , # 4 are used in order to transmit 6 symbols of data in 1 uplink slot. In such a slot configuration, the value of N_UL is "6" and the value of M is "2".

Each terminal ends transmission, and after the interval time 204, the base station again transmits a downlink OFDM signal to each terminal using the time and frequency domain 205. Then, after the interval time 206, each terminal transmits to the base station using the hopping pattern specified. At this time, the hopping pattern used does not have to be the hopping pattern used in the previous ascending slot.

According to the second slot configuration described above, the base station can perform highly accurate control such as adaptive modulation for each subcarrier in the downlink OFDM signal from the highly accurate transmission line characteristics of a wide frequency band notified from the terminal. This can be done, and the transmission efficiency of downlink communication can be improved.

(Third slot configuration) Fig. 11 shows an example of the third slot configuration. The downlink communication from the base station to each terminal and the uplink communication from each terminal to the base station are time-multiplexed and performed using the same frequency band. Further, here, the minimum unit of the hopping frequency in the uplink FH is the same as the frequency interval ΔF of the subcarrier of the downlink OFDM.

The base station transmits an OFDM signal of the N_DL symbol (N_DL is an integer of 1 or more) to each user in one downlink slot using the frequency and time domain 301. In FIG. 11, subcarriers # 1 to # 8 are used to transmit data of 4 symbols in one downlink slot.

After the base station finishes transmitting the OFDM signal and after the interval time 302, each terminal uses the frequency specified in advance from the base station from the frequency and time domain 303, and the N_UL symbol (N_UL is) in one uplink slot. Send data of 1 or more). At the same time, the data of the N_UL symbol is transmitted using the hopping pattern of the 1 / M symbol long period specified by the base station. Therefore, each terminal transmits a signal with a total of 2 × N_UL symbols.

In FIG. 11, user # 1 transmits data of 6 symbols using subcarrier # 5 (frequency and time domain 304), and at the same time, subcarriers # 12 and # 10 are transmitted from time "6" to "11". , # 8, # 12, # 2, # 4, # 6, # 7, # 9, # 6, # 3, # 1 are used in order to transmit data of 4 symbols. Therefore, user # 1 transmits data of a total of 12 symbols in one uplink slot. Similarly, user # 2 uses subcarrier # 11 (frequency and time domain 305) to transmit 6 symbols of data, and at the same time, subcarriers # 3, # 6, # 12, # from time 6 to 11. Data of 4 symbols are transmitted using 9, # 7, # 6, # 12, # 1, # 8, # 10, # 2, and # 4 in order. Therefore, user # 2 is transmitting data of a total of 12 symbols.

Each terminal ends transmission, and after an interval time of 306, the base station again transmits a downlink OFDM signal to each terminal using the time and frequency domain 307. Further, after the interval time 308, each terminal transmits to the base station using the frequency and hopping pattern specified. At this time, the frequency and hopping pattern used do not have to be the hopping pattern used in the previous uplink slot.

According to the above-mentioned third slot configuration, in one uplink slot, each terminal has a first hopping pattern having a hopping cycle of D_UL symbol length and a hopping cycle of 1 / M (M is an arbitrary positive integer) symbol length. The signal is transmitted using the second hopping pattern of.

Using the transmission line characteristics of each subcarrier estimated (measured) on the terminal side, the frequency band (subcarrier) with good characteristics is preferentially selected to determine the frequency for uplink transmission, thereby performing uplink communication. Transmission efficiency can be improved. In addition, the base station can perform control such as adaptive modulation for each subcarrier in the downlink OFDM signal with high accuracy from the highly accurate transmission line characteristics of a wide frequency band notified from each terminal, and can be used for downlink communication. Transmission efficiency can be improved.

(Fourth slot configuration) Fig. 12 shows an example of the fourth slot configuration. The downlink communication from the base station to each terminal and the uplink communication from each terminal to the base station are time-multiplexed and performed using the same frequency band. Further, here, the minimum unit of the hopping frequency in the uplink FH is the same as the frequency interval ΔF of the subcarrier of the downlink OFDM.

The base station transmits an OFDM signal to each user in one downlink slot using the frequency and time domain 401 (N_DL is an integer of 1 or more). In FIG. 12, four symbols are transmitted in one downlink slot using subcarriers # 1 to # 8.

After the base station finishes transmitting the OFDM signal and after the interval time 402, each terminal has a hopping period of 1 / M (M is an integer of 1 or more) specified in advance by the base station from the frequency and time domain 403. ) Using the symbol length hopping pattern, send the data of the N_UL symbol (N_UL is an integer of 1 or more) in one uplink slot. The frequency band used in this hopping pattern is limited to a part of the frequency domains of subcarriers # 1 to # 8.

In FIG. 12, user # 1 hops frequencies using the frequency domains of subcarriers # 1, # 2, # 3, and # 4. At time "6", data of one symbol is transmitted using subcarriers # 3 and # 2. Similarly, from time "8" to time "11", subcarriers # 1, # 4, # 2, # 3, # 4, # 1, # 2, # 4, # 3, # 1 are used in order. A total of 6 symbols of data are transmitted in one uplink slot. In addition, user # 2 hops the frequency using the frequency domains of subcarriers # 6, # 7, and # 8. Using subcarriers # 7, # 6, # 8, # 6, # 8, # 7, # 8, # 6, # 8, # 7, # 6, # 7 from time "6" to time "11" Data of 6 symbols is transmitted in 1 uplink slot. In this case, the value of N_UL is "6" and the value of M is "2".

Each terminal ends transmission, and after an interval time of 404, the base station again transmits a downlink OFDM signal to each terminal using the time and frequency domain 405. Further, after the interval time 406, each terminal transmits to the base station using the hopping pattern in the frequency domain designated. At this time, the hopping pattern used does not have to be the hopping pattern used in the previous ascending slot.

According to the fourth slot configuration, the frequency band (subcarrier) having good characteristics is preferentially selected and the uplink hopping pattern is determined by using the transmission line characteristics for each subcarrier estimated on the terminal side. As a result, the transmission efficiency of uplink communication can be improved.

(Fifth slot configuration) Fig. 13 shows an example of the fifth slot configuration. The downlink communication from the base station to each terminal and the uplink communication from each terminal to the base station are time-multiplexed and performed using the same frequency band.

Each terminal transmits an FH signal of the N_UL symbol (N_UL is an integer of 1 or more) to the base station using the frequency and time domain 501 in one uplink slot.

After the terminal finishes transmitting the FH signal and the interval time is 502, the base station uses the time and frequency domain 503 for one user terminal to record the OFDM of the N_DL symbol (N_DL is an integer greater than or equal to 1) in one downlink slot. Send a signal. In FIG. 13, the base station transmits data of 4 symbols to user # 1 in one downlink slot from time 6 to time 9.

The base station ends transmission to one user, and after the interval time 504, each terminal again transmits an uplink FH signal to the base station using the time and frequency domain 505. Also, after the interval time 506, the base station transmits an OFDM signal to one user using the time and frequency domain 507 as an N_DL symbol. In FIG. 13, the base station transmits the data of 4 symbols to the user # 2 from the time 16 to 19.

By having such a slot configuration, the terminal does not need to perform the reception process when there is no data to be received, so that the power consumption of the terminal can be reduced. Further, since the user terminal to be received is switched for each downlink slot, the transmission power control for each user terminal can be performed with a margin of time.

(Sixth Slot Configuration) Fig. 14 shows an example of the sixth slot configuration. The downlink communication from the base station to each terminal and the uplink communication from each terminal to the base station are time-multiplexed and performed using the same frequency band. Further, here, the minimum unit of the hopping frequency in the uplink FH is the same as the frequency interval ΔF of the subcarrier of the downlink OFDM.

Each user terminal transmits an FH signal of the N_UL symbol (N_UL is an integer of 1 or more) to the base station using the frequency and time domain 601 in one uplink slot. Here, the hopping pattern of the upstream FH signal uses all the subcarrier signals at least once.

After each user finishes transmitting the FH signal and after the interval time 602, the base station assigns each user's data to each subcarrier and outputs the OFDM signal of the N_DL symbol (N_DL is an integer of 1 or more) in one downlink slot. Send.

In FIG. 14, the base station transmits data of 4 symbols to user # 1 from time 8 to time 11 using subcarriers # 10, # 11, and # 12 in one downlink slot. ing. In addition, subcarriers # 3, # 4, # 5, and # 6 are used to transmit data of 4 symbols to user # 2 in one downlink slot.

The base station ends transmission to each user, and after an interval time of 605, each terminal again transmits an FH signal to the base station using the time and frequency domain 606. Also, after the interval time 607, the base station transmits an OFDM signal of the N_DL symbol to each user. At this time, the subcarrier assigned to each user does not have to be the same as the subcarrier assigned in the previous downlink slot. That is, the base station changes the subcarrier assigned to each terminal each time the OFDM signal of the N_DL symbol is transmitted to each terminal.

According to the sixth slot configuration described above, the base station uses the transmission line identification for each subcarrier estimated (measured) on the terminal side to prioritize the frequency band (subcarrier) having good characteristics for each terminal. Can be selected to assign a subcarrier in the downlink slot to the terminal. Therefore, the transmission efficiency of downlink communication can be improved.

(7th slot configuration) Fig. 15 shows an example of the 7th slot configuration. The downlink communication from the base station to each terminal and the uplink communication from each terminal to the base station are time-multiplexed and performed using the same frequency band. Further, here, the minimum unit of the hopping frequency in the uplink FH is the same as the frequency interval ΔF of the subcarrier of the downlink OFDM.

Each user transmits an FH signal of the N_UL symbol (N_UL is an integer of 1 or more) to the base station using the frequency and time domain 701 in one uplink slot. Here, it is assumed that the hopping pattern of the FH signal is a hopping pattern in which the frequency domain assigned to each uplink slot changes. In this example, user # 1 uses subcarrier # 9 and user 2 uses subcarrier # 4, and 6 symbols of data are transmitted in one uplink slot.

Each user finishes transmitting the FH signal, and after the interval time 702, the base station assigns each user's data to each symbol and transmits an OFDM signal of the N_DL symbol (N_DL is an integer of 1 or more) in one downlink slot. .. Here, the base station assigns user # 1 to time "8" and "10", user # 2 to time "9", and "11", and transmits data of two symbols to each user's terminal. ..

In this way, the base station allocates the downlink slot through which the OFDM signal is transmitted to each terminal in units of one symbol length. That is, in the downlink slot, signals addressed to each terminal are multiplexed by TDMA (Time Division Multiple Access).

The base station ends transmission to each user, and after the interval time 704, each terminal again transmits an uplink FH signal to the base station using the time and frequency domain 705. Also, after the interval time 706, the base station transmits an OFDM signal of the N_DL symbol to each user. At this time, the symbol assigned to each user does not have to be the symbol assigned in the previous downlink slot.

According to the seventh slot configuration, since the terminal receives data in the entire frequency domain (here, subcarriers # 1 to # 12), it is possible to accurately estimate the transmission line characteristics of each subcarrier. it can. In the base station, using the transmission line characteristics estimated by each terminal, a frequency band having good characteristics for each terminal is preferentially selected, and an uplink hopping pattern is determined for each terminal, thereby performing uplink communication. Transmission efficiency can be improved.

(8th slot configuration) Fig. 16 shows an example of the 8th slot configuration. The downlink communication from the base station to each terminal and the uplink communication from each terminal to the base station are time-multiplexed and performed using the same frequency band. Further, here, the minimum unit of the hopping frequency in the uplink FH is the same as the frequency interval ΔF of the subcarrier of the downlink OFDM.

Each user transmits an FH signal of the N_UL symbol (N_UL is an integer of 1 or more) to the base station using the frequency and time domain 801 in one uplink slot. In one uplink slot, each terminal uses a first hopping pattern with a hopping cycle of D_UL symbol length and a second hopping pattern with a hopping cycle of 1 / M (M is any positive integer) symbol length. , Send a signal. That is, here, the first hopping pattern is a hopping pattern in which the frequency domain assigned to each uplink slot changes, and the second hopping pattern uses all subcarriers in one uplink slot. It is a hopping pattern.

In FIG. 16, the terminal of user # 1 uses subcarrier # 9, and the terminal of user # 2 uses subcarrier # 4, respectively, to transmit data of 6 symbols in one uplink slot. In addition, each terminal transmits 6 symbols of data using a hopping pattern that uses all subcarriers. Therefore, each terminal transmits data of a total of 12 symbols in one uplink slot.

After each user finishes transmitting the FH signal and after interval time 802, the base station uses frequency and time domain 803 to allocate each user's data in 1 symbol length units and 1 carrier unit, in one downlink slot. , Sends the OFDM signal of the N_DL symbol (N_DL is an integer greater than or equal to 1). In the frequency and time domain 803 of FIG. 16, by alternately arranging the signals for the user # 1 and the user # 2, each user receives the data in all the subcarriers.

The base station ends transmission to each user, and after the interval time 804, each terminal again transmits an uplink FH signal to the base station using the time and frequency domain 805. Also, after the interval time 806, the base station transmits an OFDM signal of the N_DL symbol to each user. At this time, the carrier and symbol assigned to each user do not have to be the carrier and symbol assigned in the previous uplink slot. That is, the base station changes the symbol and subcarrier assigned to each user in the downlink slot each time the OFDM signal of the N_DL symbol is transmitted.

In the uplink slot 805 and the downlink slot 807 of FIG. 16, it is a case where it is determined between the user # 1 and the base station that the transmission line condition is good in the frequency domain of the subcarrier # 6. Data communication is efficiently performed between user # 1 and the base station by mainly performing data communication using the frequency domain of subcarrier # 6. At the same time, by communicating data using other subcarriers, it is possible to constantly monitor the transmission path status of other subcarriers.

According to the eighth slot configuration described above, when a request is made in the base station and the terminal to measure the transmission line state or to improve the transmission efficiency, the frequency domain is adapted to the request. Can be assigned.

(9th slot configuration) Fig. 17 shows an example of the 9th slot configuration. The downlink communication from the base station to each terminal and the uplink communication from each terminal to the base station are time-multiplexed and performed using the same frequency band. Further, here, the minimum unit of the hopping frequency in the uplink FH is the same as the frequency interval ΔF of the subcarrier of the downlink OFDM.

Each user transmits an FH signal of the N_UL symbol (N_UL is an integer of 1 or more) to the base station using the frequency and time domain 901 in one uplink slot. In one uplink slot, each terminal uses a first hopping pattern with a hopping cycle of D_UL symbol length and a second hopping pattern with a hopping cycle of 1 / M (M is any positive integer) symbol length. , Send a signal. That is, the first hopping pattern is a hopping pattern in which the frequency domain assigned to each uplink slot changes, and the second hopping pattern is a hopping pattern in which all subcarriers are used in one uplink slot. Is.

In FIG. 17, the terminal of user # 1 uses subcarrier # 9, and the terminal of user # 2 uses subcarrier # 4, and 6 symbols of data are transmitted in one uplink slot. In addition, each terminal transmits 6 symbols of data using a hopping pattern that uses all subcarriers. Therefore, the terminals of user # 1 and user # 2 transmit data of a total of 12 symbols in one uplink slot, respectively.

After each user terminal finishes transmitting the FH signal and after the interval time 902, the base station uses the frequency and time domain 903 to multiplex each user's data with an orthogonal code OFDM-CDMA (Code Division Multiple Access). Send a signal. In FIG. 17, the signal from the base station to user # 1 and the signal to user # 2 are multiplexed using the spread code assigned to each user, and the OFDM of the N_DL symbol (N_DL is an integer of 1 or more) in one download slot- Send a CDMA signal.

The base station ends transmission to each user, and after the interval time 904, each terminal again transmits an uplink FH signal to the base station using the time and frequency domain 905. Also, after the interval time 906, using the time and frequency domain 907, the base station transmits an OFDM signal to each user as an N_DL symbol. At this time, the spreading code assigned to each user does not have to be the spreading code assigned in the previous uplink slot. Since each user receives data from all subcarriers, the transmission line characteristics of each subcarrier can be measured accurately.

The uplink slot 905 of FIG. 17 is a case where it is judged that the transmission line condition is good in the frequency domain of the subcarrier # 6 between the user # 1 and the base station, and the uplink slot 905 is between the user # 1 and the base station. Efficient data communication is performed by performing data communication mainly using the frequency domain of subcarrier # 6. At the same time, by communicating data using other subcarriers, it is possible to constantly monitor the transmission path status of the other subcarriers.

By having the ninth slot configuration, since the terminal side receives signals in the entire frequency domain, it is possible to accurately estimate the transmission line characteristics of each subcarrier. In the base station, the transmission line characteristics of each subcarrier estimated by each terminal are used to preferentially select a frequency band having good characteristics for each terminal, and an uplink hopping pattern is determined for each terminal. The transmission efficiency of uplink communication can be improved.

As described above, according to the first embodiment, there are the following effects. (1) High-speed data transmission is possible by using OFDM for the downlink, and line interference can be suppressed by using FH for the uplink. Further, it becomes possible to use a highly efficient terminal transmission power amplifier, and it is possible to prolong the communication time of the terminal. (2) Since the same frequency is used for the upper and lower links and the entire band is used for the downlink, the terminal side accurately measures the condition of the transmission line between the terminal and the base station. be able to. This measurement result can also be used for transmission power control in the vertical link, directivity control, equalization control, etc., and is particularly effective for FH in which the carrier frequency changes periodically. (3) Based on the transmission line characteristics measured by the terminal that receives the downlink OFDM signal, the uplink hopping pattern is determined, and the subcarrier used for downlink communication is determined from among multiple subcarriers. For each terminal, high-quality wireless communication is realized by performing communication using only the band in which the transmission line is in good condition. (4) In the downlink communication time slot, TDM (Time Division) By multiplexing the signal addressed to each terminal by Multiplex), transmission is performed using the entire band in the downlink communication time slot, so that the state of the transmission line for each user can be accurately measured. This measurement result can be used for transmission power control, directivity control, equalization control, etc. in the vertical link for each user.

Hereinafter, a variation of the wireless communication system according to the first embodiment, which realizes bidirectional communication between downlink OFDM communication and uplink FH communication by TDD, will be described.

(Second Embodiment) A schematic configuration of the entire wireless communication system according to the second embodiment will be described with reference to FIG. The base station BS1 transmits downlink OFDM signals DL1 and DL2 toward terminals TE1 and TE2 for a certain period of time. When the base station BS1 finishes transmitting the downlink OFDM signal, the terminals TE1 and TE2 transmit the uplink FH signals UL1 and UL2 to the base station BS1 using the same frequency band as the downlink OFDM signal. In this way, the downlink OFDM signal and the uplink FH signal are temporally multiplexed.

The base station BS1 uses a frequency band other than the frequency band used by the downlink OFDM signal and the uplink FH signal toward the terminals TE1 and TE2, such as a time synchronization signal and a paging signal (a signal for notifying the terminal of an incoming call). To send.

Figure 20 shows an example of slot configuration. Base station BS1 transmits data to each terminal using the OFDM method using the frequency and time domain 201 (subcarriers # 1 to # 12 and time "1" to "4"). After the base station BS1 finishes transmitting the downlink OFDM signal and the guard time 202, each terminal is preliminarily in the frequency and time domain 203 (subcarriers # 1 to # 12 and time "6" to time "11"). The FH signal is transmitted using the hopping pattern determined with the base station. Here, it is desirable to use a hopping pattern that spans all frequencies (subcarriers # 1 to # 12) in one uplink slot.

After each terminal finishes transmitting the uplink FH signal and the guard time 204, the base station transmits the OFDM signal again using the frequency and time domain 205. In this way, the downlink OFDM signal and the uplink FH signal are used by time-multiplexing the same frequency band.

Further, the base station uses a frequency band (control-only frequency band) 208 different from the frequency band used by the downlink OFDM signal and the uplink FH signal, and is a signal including at least one of the time synchronization signal and the paging signal ( Control signal) is being transmitted.

FIG. 21 shows a configuration example of the base station BS1. In FIG. 21, the same parts as those in FIG. 18 are designated by the same reference numerals, and characteristic parts of the present embodiment will be described. The data to be transmitted to each user is multiplexed and sorted by the user allocation unit 1 using the user allocation information, and output to the OFDM transmission unit 2. The signal addressed to each user is converted into an OFDM signal by the OFDM transmission unit 2, band-limited by the band-passing filter (BPS) 14, and then output to the radio unit 11.

When the transmission of the downlink OFDM signal is completed, the FH signal from the terminal is received by the radio unit 12. The signal output from the radio unit 12 passes through the bandpass filter (BPF) 13 to become a band limiting signal and is input to the FH receiver unit 9.

The FH receiving unit 9 detects each subcarrier signal from the received signal output from the radio unit 12. Each subcarrier signal is output to the transmission line estimation unit 6 and the user signal extraction unit 10.

In the transmission line estimation unit 6, based on the received power value of each subcarrier signal and the FH signal measured for the above AGC by the radio unit 12, the distortion and power of the transmission line for each subcarrier signal for each terminal. Obtain transmission line characteristics such as value and power ratio. The uplink transmission line characteristics from each terminal to the base station estimated by the transmission line estimation unit 6 are output to the downlink OFDM user allocation unit 7 and the uplink FH user allocation unit 8, respectively, and are output to the downlink and uplink, respectively. It is used as a judgment material when allocating a channel to a terminal.

The base station BS1 uses a control-only frequency band 208 to perform a common pilot signal (a signal known between the base station and the terminal and a time synchronization signal) and a paging signal (a time synchronization signal) for synchronization processing between the base station and the terminal. Common pilot channel, paging channel) is transmitted. The control signal is multiplexed by the channel multiplexing unit 3. In FIG. 21, the multiplexed control signal is input to the CDMA transmission unit 4, where the spreading and modulation processing of the CDMA (Code Division Multiple Access) method is performed. The modulated control signal is band-limited through a band-pass filter (BPF) 15 and then input to the radio unit 16. The radio unit 16 converts the digital signal output from the BPF 15 into an analog signal, then performs frequency conversion, and transmits the signal in a frequency band 208 different from the downlink OFDM signal and the uplink FH signal.

FIG. 22 shows a configuration example of terminals TE1 and TE2. In FIG. 22, the same parts as those in FIG. 19 are designated by the same reference numerals, and characteristic parts of the present embodiment will be described. The transmission data from the terminal to the base station is converted into an FH signal by the FH transmission unit 51. The hopping pattern at this time is based on the FH pattern information received in the immediately preceding downlink slot. Further, the FH transmission unit 51 performs modulation at a timing based on the synchronization signal output from the CDMA reception unit 63. The FH signal output from the FH transmission unit 51 is band-limited by the bandpass filter (BPF) 60, and then transmitted to the base station BS1 through the radio unit 58.

When the transmission of the FH signal is completed, the reception of the OFDM signal from the base station BS1 transmitted using the downlink slot is started. The OFDM signal is received by the radio unit 57, converted into a digital signal, and then passed through a bandpass filter (BPF) 59 to become a band-limited received signal. The OFDM receiver 53 modulates the band-limited reception signal and outputs each subcarrier signal. At this time, the OFDM receiving unit 53 performs the modulation processing at the timing based on the synchronization signal output from the CDMA receiving unit 63.

In the terminal, the radio unit 61 further receives the control signal transmitted on the downlink of the control signal dedicated frequency band 208. The radio unit 61 performs frequency conversion and A / D conversion on the received signal and outputs the received signal to the bandpass filter (BPF) 62. In the BPF 62, the signal corresponding to the control dedicated frequency band 208 is extracted from the received signal and output to the CDMA receiver 63. The CDMA receiver 63 demodulates the input signal using a predetermined spreading code to obtain a synchronization signal and a paging signal in standby.

According to the wireless communication system that realizes bidirectional communication between downlink OFDM communication and uplink FH communication by TDD according to the second embodiment, high-speed communication on downlink is possible and a terminal for uplink communication. Since the peak power on the side is suppressed, low power consumption of the terminal can be realized. In addition, by performing bidirectional communication between the OFDM signal and the FH signal by time multiplexing, the base station estimates the transmission path characteristics of each subcarrier for each terminal from the FH signal transmitted from each terminal in the uplink slot. It becomes possible to improve the transmission efficiency. Further, in the second embodiment, a low-speed control signal is transmitted using the downlink control signal band 208 from the base station to the terminal, in addition to the frequency band used for the two-way communication. Therefore, since the terminal can perform synchronization and paging processing without performing OFDM signal reception processing, it is possible to realize low power consumption during standby and the like.

(Third Embodiment) The schematic configuration of the entire wireless communication system according to the third embodiment is the same as that of the second embodiment.

FIG. 23 shows an example of a slot configuration of the wireless communication system according to the third embodiment. Base station BS1 transmits data to each terminal using the OFDM method using the frequency and time domain 201 (subcarriers # 1 to # 12 and time "1" to "4"). After the base station BS1 finishes transmitting the downlink OFDM signal and the guard time 202, each terminal is preliminarily in the frequency and time domain 203 (subcarriers # 1 to # 12 and time "6" to time "11"). The FH signal is transmitted using the hopping pattern determined with the base station. Here, it is desirable to use a hopping pattern that spans all frequencies (subcarriers # 1 to # 12) in one uplink slot.

After each terminal finishes transmitting the uplink FH signal and the guard time 204, the base station transmits the OFDM signal again using the frequency and time domain 205. In this way, the downlink OFDM signal and the uplink FH signal are used by time-multiplexing the same frequency band.

The terminals TE1 and TE2 use a frequency band (control-only frequency band) 209 different from the frequency band used by the downlink OFDM signal and the uplink FH signal, and are used for transmission power control and position registration of each terminal (signals used for transmission power control and position registration of each terminal). Control signal) is being transmitted.

FIG. 24 shows a configuration example of the base station BS1. In FIG. 24, the same parts as those in FIGS. 18 and 21 are designated by the same reference numerals, and characteristic parts of the present embodiment will be described. The data, FH pattern information, and user allocation information to be transmitted to each user are multiplexed and rearranged in the user allocation unit 1 using the user allocation information, and output to the OFDM transmission unit 2. The signal addressed to each user is converted into an FDM signal by the OFDM transmission unit 2, band-limited by the band-passing filter (BPS) 14, and output from the radio unit 11.

At this time, the OFDM transmission unit 2 adjusts the transmission power of each subcarrier signal using the transmission power control information output from the transmission power control unit 20.

When the transmission of the downlink OFDM signal is completed, the FH signal from the terminal is received by the radio unit 12. The signal output from the radio unit 12 passes through the bandpass filter (BPF) 13 to become a band limiting signal and is input to the FH receiver unit 9.

The FH receiving unit 9 detects each subcarrier signal from the received signal output from the radio unit 12. Each subcarrier signal is output to the transmission line estimation unit 6 and the user signal extraction unit 10.

In the transmission line estimation unit 6, based on the received power value of each subcarrier signal and the FH signal measured for the above AGC by the radio unit 12, the distortion and power of the transmission line for each subcarrier signal for each terminal. Obtain transmission line characteristics such as value and power ratio. The uplink transmission line characteristics from each terminal to the base station estimated by the transmission line estimation unit 6 are output to the downlink OFDM user allocation unit 7 and the uplink FH user allocation unit 8, respectively, and are output to the downlink and uplink, respectively. It is used as a judgment material when allocating a channel to a terminal.

In the base station BS1, the radio unit 17 receives the control signal transmitted on the uplink of the control signal dedicated frequency band 209. The radio unit 17 performs frequency conversion and A / D conversion on the received signal and outputs the received signal to the bandpass filter (BPF) 18. In BPF18, the signal corresponding to the control signal dedicated frequency band 209 is extracted from the received signal and output to the CDMA receiver 19. The CDMA receiving unit 19 demodulates the input signal using a predetermined diffusion code, and outputs the demodulated control signal to the transmission power control unit 20 and the terminal position information registration unit 21.

The transmission power control unit 20 uses the power value and power ratio of each subcarrier included in the control signal obtained by decoding the control signal transmitted from each terminal to transmit power to the next downlink slot. The transmission power control information is output to the radio unit 11 in order to control. For example, when the power value (power ratio) of each subcarrier is smaller than the predetermined first threshold value, the transmission power is increased by a predetermined value from the current transmission power, and the power value (power ratio) of each subcarrier is predetermined. When the transmission power is smaller than the current transmission power by a predetermined value, and the power value (power ratio) of each subcarrier is equal to or more than the predetermined first threshold value and less than the second threshold value. , Control the transmission power so that the transmission power does not change.

The terminal position information registration unit 21 notifies the upper layer to use the position registration information included in the control signal obtained by decoding the control signal transmitted from each terminal for processing such as handover.

FIG. 25 shows a configuration example of terminals TE1 and TE2. In FIG. 25, the same parts as those in FIGS. 19 and 22 are designated by the same reference numerals, and the characteristic name parts of the present embodiment will be described. The transmission data from the terminal to the base station is converted into an FH signal by the FH transmission unit 51. The hopping pattern at this time is based on the FH pattern information received in the immediately preceding downlink slot. The FH signal output from the FH transmission unit 51 is band-limited by the bandpass filter (BPF) 60, and then transmitted to the base station BS1 through the radio unit 58.

When the transmission of the FH signal is completed, the reception of the OFDM signal from the base station BS1 transmitted using the downlink slot is started. The OFDM signal is received by the radio unit 57, converted into a digital signal, and then passed through a bandpass filter (BPF) 59 to become a band-limited received signal. The OFDM receiver 53 modulates the band-limited reception signal and outputs each subcarrier signal.

The terminal further transmits the control signal on the uplink of the control signal dedicated frequency band 209. In FIG. 25, the information for location registration from the upper layer (location registration information) and the power and power ratio of each subcarrier obtained by the transmission line estimation unit 52 are modulated and diffused by the CDMA transmission unit 64. Modulates and outputs a CDMA signal. The CDMA signal is output to the radio unit 66 through a bandpass filter (BPF) 65 corresponding to the control dedicated frequency band 209. D / A conversion, frequency conversion, etc. are performed on the CDMA signal input to the radio unit 66, and the CDMA signal is transmitted via the antenna.

According to the wireless communication system according to the third embodiment, high-speed communication on the downlink is possible, and peak power on the terminal side in uplink communication is suppressed, so that low power consumption of the terminal can be realized. Further, by performing bidirectional communication between the OFDM signal and the FH signal by time multiplexing, it becomes possible to estimate the transmission line characteristics from each other's data signals, and it becomes possible to improve the transmission efficiency. Further, in the third embodiment, the control signal is transmitted using the frequency band 209 dedicated to the uplink control signal from the terminal to the base station, in addition to the frequency band used for the bidirectional communication. Therefore, control information such as transmission power control and location registration information can be transmitted to the base station without performing frequency hopping pattern negotiation processing between the base station and the terminal, thus reducing the amount of processing at the base station. Will be possible.

(Fourth Embodiment) The schematic configuration of the entire wireless communication system according to the fourth embodiment is the same as that of the second embodiment.

FIG. 26 shows an example of a slot configuration of the wireless communication system according to the fourth embodiment. In FIG. 26, the same parts as those in FIG. 23 of the third embodiment are designated by the same reference numerals, and only different parts will be described. That is, in FIG. 26, in addition to the control-only frequency band 209 described in the third embodiment, the control-only frequency band 208 described in the second embodiment is further provided. Then, a second control signal including at least one of the signals used for transmission power control and position registration of each terminal is transmitted from each terminal to the base station using the control dedicated frequency band 209, and the base is transmitted. A second control signal including either a time synchronization signal or a paging signal is transmitted from the station to each terminal by using the control-dedicated frequency band 208, which is a frequency band different from the control-dedicated frequency band 209. There is.

FIG. 27 shows a configuration example of the base station BS1 according to the fourth embodiment. The same parts as those in FIGS. 21 and 24 are designated by the same reference numerals, and only the parts different from these will be described.

As described in the second embodiment, the base station according to the fourth embodiment uses the control dedicated frequency band 208 to transmit the first control signal (common pilot channel, paging channel). It has a channel multiplexing unit 3, a CDMA transmission unit 4, a BPF15, and a radio unit 16.

Further, as described in the third embodiment, the radio unit 17, BPF18, CDMA receiver 19, transmission power for receiving the second control signal transmitted on the uplink of the control signal dedicated frequency band 209. It has a control unit 20 and a terminal position information registration unit 21.

Then, the OFDM transmission unit 2 adjusts the transmission power of each subcarrier for each terminal based on the transmission power control information output from the transmission power control unit 20.

FIG. 28 shows a configuration example of terminals TE1 and TE2. In FIG. 28, the same parts as those in FIGS. 22 and 25 are designated by the same reference numerals, and only the parts different from these will be described.

As described in the second embodiment, the terminal according to the fourth embodiment uses the control dedicated frequency band 208 to transmit the first control signal (common pilot channel, paging channel) transmitted from the base station. It has a radio unit 61, a BPF 62, and a CDMA receiver 63 for receiving. The FH transmission unit 51 modulates at a timing based on the synchronization signal output from the CDMA reception unit 63. Further, the OFDM receiving unit 53 performs the modulation processing at the timing based on the synchronization signal output from the CDMA receiving unit 63.

Further, as described in the third embodiment, it has a CDMA transmission unit 64, a BPF 65, and a radio unit 66 for transmitting a second control signal on the uplink of the control signal dedicated frequency band 209.

According to the wireless communication system according to the fourth embodiment, high-speed communication on the downlink is possible, and peak power on the terminal side in uplink communication is suppressed, so that low power consumption of the terminal can be realized. Further, by performing bidirectional communication between the OFDM signal and the FH signal by time multiplexing, it becomes possible to estimate the transmission line characteristics from each other's data signals, and it becomes possible to improve the transmission efficiency. Further, in the fourth embodiment, the second control signal is transmitted using the uplink control signal band 209 from the terminal to the base station, in addition to the frequency band used for the two-way communication. Therefore, control information such as transmission power control and location registration information can be transmitted to the base station without performing frequency hopping pattern negotiation processing between the base station and the terminal, thus reducing the amount of processing at the base station. Will be possible. Further, in the fourth embodiment, a low-speed first control signal is transmitted using the downlink control signal band 208 from the base station to the terminal, in addition to the frequency band used for the two-way communication. Therefore, since the terminal can perform time synchronization processing, paging processing, and the like without performing OFDM signal reception processing, it is possible to realize low power consumption during standby. As described above, by providing the control signal dedicated bands 209 and 208 on the uplink and downlink, there is an effect of reducing the power consumption during standby of the terminal and reducing the processing amount of the base station.

(Fifth Embodiment) In the fifth and sixth embodiments, the uplink wireless link and the downlink wireless link are based on the amount of data to be transmitted from the terminal to the base station and the amount of data to be transmitted from the base station to the terminal. A case of changing the communication speed ratio with and is described.

The schematic configuration of the entire wireless communication system according to the fifth embodiment will be described with reference to FIG. The base station BS1 transmits downlink OFDM signals DL1 and DL2 toward terminals TE1 and TE2 for a certain period of time. When the base station BS1 finishes transmitting the downlink OFDM signal, the terminals TE1 and TE2 transmit the uplink FH signals UL1 and UL2 to the base station BS1 using the same frequency band as the downlink OFDM signal. In this way, the downlink OFDM signal and the uplink FH signal are temporally multiplexed. Then, in the wireless communication system according to the fifth embodiment, the communication speed ratio of the downlink OFDM signal and the uplink FH signal can be dynamically changed by changing the format of the time slot.

FIG. 29 is a flowchart showing a processing procedure for changing the communication speed ratio between the base station and the terminal. The base station knows the amount of data to be transmitted from the base station to the terminal at regular intervals (step S11). In addition, each terminal also notifies the amount of data to be transmitted from each terminal to the base station at regular intervals (step S12). The notification from the terminal to the base station is sent, for example, by using an FH signal on the uplink.

The base station should use this information to change the balance between the amount of data transmitted on the uplink and the amount of data transmitted on the downlink if it is determined that the balance is significantly different from the current communication speed ratio. The communication speed ratio is determined (step S13). For example, suppose that the ratio of the current uplink communication speed to the downlink communication speed is 1:10. However, since the amount of downlink data is large, in FIG. 29, the uplink communication speed and the downlink communication speed are to be changed to 1:20.

The base station transmits slot format change information to each terminal (step S14). The terminal receives the slot format change information and starts preparing for it. When the terminal is ready to change the slot format, it returns a response signal to the slot format change information to the base station (step S15).

At the base station, when all the communicating terminals return a response signal to the slot format change, a slot format change start signal is transmitted, and at the same time, the communication speed ratio is changed by changing the slot format (step S17). ..

In this way, the base station determines whether or not to change the communication speed ratio by constantly grasping the amount of downlink data and the amount of uplink data.

In a wireless communication system that realizes bidirectional communication between downlink OFDM communication and uplink FH communication with TDD, it becomes possible for the terminal to estimate the transmission line state in all bands used for bidirectional communication. Further, by using the FH communication method for the uplink, it is possible to reduce the peak average power, so that the low power consumption of the terminal can be realized. Furthermore, by temporally multiplexing the uplink communication and the downlink communication, it is possible to use each other's transmission line characteristic estimates, and the negotiation between the base station and the terminal can be relatively performed with a time margin. It can be easily determined. In addition, system resources can be effectively utilized by changing the slot format using negotiation.

Next, with reference to FIG. 30, how the slot format is changed will be described more specifically. In FIG. 30, the downlink OFDM signal from the base station to each terminal is transmitted using the time 1, 3, 5 .... In addition, the upstream FH signal from the terminal to the base station is transmitted using the time "2", "4", "6" .... Here, in the uplink FH signal at time "4", the amount of data to be transmitted by the terminal is transmitted. It is assumed that the base station decides to change the communication speed ratio in consideration of the amount of data received from each terminal and the amount of downlink data to be transmitted to each terminal.

In the downlink at time "5", the base station transmits the slot format change information to each terminal, and in the uplink communication at time "6", each terminal transmits a response signal to the slot format change information. The base station confirms that all the terminals currently communicating have transmitted the response signal, and transmits the slot format change start signal to each terminal in the downlink communication at time "7".

In FIG. 30, before the slot format was changed, one uplink slot and one downlink slot were transmitted alternately to perform time multiplexing. From time "8", the uplink communication speed is improved by alternately transmitting 3 uplink slots and 1 downlink slot. On the contrary, in the time "17" to "19", the downlink communication speed is improved by transmitting the downlink communication continuously for 3 slots.

FIG. 31 shows a configuration example of the base station according to the fifth embodiment. In FIG. 31, the same parts as those in FIG. 18 are designated by the same reference numerals, and only different parts will be described. That is, in FIG. 31, the transmission / reception timing control unit 22 is newly added.

From each terminal, the transmitted uplink data amount information is sent by the FH signal. This uplink data amount information is passed from the signal separation unit 5 to the upper layer.

In the upper layer, if it is determined that the communication speed ratio should be changed from the amount of uplink data sent from each terminal on a regular basis and the amount of data to be transmitted from the base station to the terminal, each terminal Generates slot format change information for notifying the timing at which the communication speed ratio should be changed and the communication speed ratio, and transmits it to each terminal as an OFDM signal. Since the slot format change response is transmitted from each terminal by the FH signal, it is received in the upper layer. In the upper layer, when the slot format change response from all the terminals during communication is obtained, the slot format change start signal to be transmitted to each terminal is given to the user allocation unit 1 so as to be transmitted as an OFDM signal. At the same time, the transmission / reception timing control unit 22 is given the timing to be changed and the communication speed ratio.

The transmission / reception timing control unit 21 calculates the slot format so as to have the desired communication speed ratio, and outputs the transmission timing control signal and the reception timing control signal to the OFDM transmission unit so that the transmission / reception timing corresponds to the slot format. Output to 2 and FH receiver 9, respectively.

For the timing at which the OFDM signal is output by the OFDM transmission unit 2, the transmission timing control signal output from the transmission / reception timing control unit 22 is referred to. Further, the reception timing control signal output from the transmission / reception timing control unit 22 is used as the timing for performing the reception processing in the FH reception unit 9.

FIG. 32 shows a configuration example of the terminal according to the fifth embodiment. In FIG. 32, the same parts as those in FIG. 19 are designated by the same reference numerals, and only different parts will be described. That is, in FIG. 32, the transmission / reception timing control unit 67 is newly added.

The upper layer periodically gives the uplink data amount information to the FH transmission unit 51 in order to transmit the uplink data amount information to the base station. The FH transmission unit 51 modulates the uplink data amount information into an FH signal in the same manner as described above and transmits the information to the base station. The OFDM signal transmitted from the base station in the downlink slot is processed by the OFDM receiving unit 53, the user signal extracting unit 54, and the signal separating unit 55 as described above, and only the received data addressed to the own device is passed to the upper layer. Is done. When the received data includes slot format change information, the upper layer gives the slot format change response information to be transmitted to the base station to the FH transmission unit 51 so as to transmit the slot format change response information as an FH signal. At the same time, the upper layer gives the transmission / reception timing control unit 67 the timing to be changed and the communication speed ratio included in the slot format change information.

The transmission / reception timing control unit 67 calculates the slot format so as to have the desired communication speed ratio, and outputs the transmission timing control signal and the reception timing control signal to the FH transmission unit so that the transmission / reception timing corresponds to the slot format. Output to 51 and OFDM receiver 53, respectively.

The transmission timing in the FH transmission unit 51 refers to the transmission timing control signal output from the transmission / reception timing control unit 67. Further, the timing at which the OFDM reception unit 53 receives the OFDM signal refers to the reception timing control signal output from the transmission / reception timing control unit 67.

As described above, according to the fifth embodiment, the effective utilization of system resources can be achieved by changing the slot format (changing the transmission time width of the OFDM signal and the transmission time width of the FH signal). You can do it. In addition, the communication speed ratio can be changed without making major changes to the existing system configuration.

(Sixth Embodiment) In the fifth embodiment, the communication speed ratio between the uplink wireless link and the downlink wireless link is changed by changing the transmission time width of the OFDM signal and the transmission time width of the FH signal. Was there. That is, the slot format was changed from 1 time slot assigned to each of OFDM signal transmission and FH signal transmission to 2 or 3 consecutive time slots for OFDM signal transmission and 1 time slot for FH signal transmission. By doing so, the uplink / downlink communication speed ratio was changed.

In the sixth embodiment, another method for changing the uplink / downlink communication speed ratio will be described. That is, a case where the transmission of a part of the OFDM signal subcarriers is stopped and the FH signal is transmitted using the frequency band and time at which the transmission is stopped to change the uplink / downlink communication speed ratio will be described. .. Here, a case where the uplink / downlink communication speed ratio is changed by combining this method with the above-mentioned fifth embodiment will be described, but even if only one of them is used, the uplink / downlink can be used. It is possible to change the communication speed ratio.

FIG. 33 shows an example of a slot configuration used in the wireless communication system according to the sixth embodiment. The base station transmits data to each terminal using the OFDM method using the frequency and time domain 201 (subcarriers # 1 to # 12 and time "1" to "4"). After the base station finishes transmitting the downlink OFDM signal and the guard time 202, each terminal pre-bases in the frequency and time domain 203 (subcarriers # 1 to # 12 and time "6" to time "11"). The FH signal is transmitted using the hopping pattern defined with the station.

After this, in the downlink OFDM slot from time "13" to time "16", the base station stops data transmission from subcarrier # 1 to subcarrier # 6 and uses the frequency domain from subcarriers # 7 to # 12. And send the data. At this time, the terminal transmits an FH signal to the base station using the frequency and time domain 209 (subcarriers # 1 to # 5 and time 11 to 17). Therefore, from the time "13" to the time "16", the base station transmits while receiving the data. Further, in the terminal, the terminal configuration can be simplified by only transmitting or receiving data.

As described above, in the wireless communication system according to the sixth embodiment, the downlink communication is performed by limiting the band allocated to the user in the downlink (by forming the transmission stop frequency and the time domain 209 in the downlink communication). Uplink OFDM communication is performed using the frequency band and time domain of the subcarrier that is not used for.

FIG. 34 shows a configuration example of the base station according to the sixth embodiment. In FIG. 34, the same parts as those in FIG. 31, which shows the configuration of the base station according to the fifth embodiment described above, are designated by the same reference numerals, and only different parts will be described. That is, in FIG. 34, the bandpass filter (BPF) 14 is connected between the OFDM transmission unit 2 and the radio unit 11, and the bandpass filter (BPF) 13 is connected between the radio unit 12 and the FH reception unit 9. Has been done.

In the upper layer, if it is determined that the communication speed ratio should be changed from the amount of uplink data sent from each terminal on a regular basis and the amount of data to be transmitted from the base station to the terminal, each terminal The timing and communication speed ratio at which the communication speed ratio should be changed and the frequency band and time when the reception of the OFDM signal is stopped (or used for receiving the OFDM signal), or the timing and communication speed ratio at which the communication speed ratio should be changed. And the slot format change information for notifying the frequency band and time used for transmitting the FH signal is generated, and it is transmitted to each terminal as an OFDM signal. Since the slot format change response is transmitted from each terminal by the FH signal, it is received in the upper layer. In the upper layer, when the slot format change response from all the terminals during communication is obtained, the slot format change start signal to be transmitted to each terminal is given to the user allocation unit 1 so as to be transmitted as an OFDM signal. At the same time, the transmission / reception timing control unit 22 is notified of the timing and communication speed ratio to be changed, the frequency band and time for stopping the reception of the OFDM signal (or used for receiving the OFDM signal), and the frequency used for transmitting the FH signal. Notify the band and time.

When the transmission / reception timing control unit 22 can give the timing to change the communication speed ratio and the communication speed ratio to be changed from the upper layer, the transmission / reception timing control unit 22 calculates the slot format so as to obtain the desired communication speed ratio, and performs the said. The transmission timing control signal and the reception timing control signal are output to the OFDM transmission unit 2 and the FH reception unit 9, respectively, so that the transmission / reception timing corresponds to the slot format. In addition, the transmission band control signal and the reception band control signal for notifying the frequency band and time for stopping the transmission of the OFDM signal notified from the upper layer (or used for transmitting the OFDM signal) are output to BPF14 and BPF13, respectively. To do.

The timing at which the OFDM signal is output by the OFDM transmission unit 2 is determined by the transmission timing control signal output from the transmission / reception timing control unit 22, and the frequency band at which transmission is stopped (or the frequency band used for transmission) is transmission / reception timing control. The BPF 11 is notified by the transmission band control signal output from the unit 22, and the BPF 14 refers to the transmission band control signal to limit the band of the OFDM signal output from the OFDM transmission unit 2.

Further, the timing of receiving processing by the FH receiving unit 9 is determined by the receiving timing control signal output from the transmitting / receiving timing control unit 22, and the receiving frequency band (or the frequency band not receiving) is determined by the transmitting / receiving timing control unit 22. The reception band control signal output from is notified to BPF13. The BPF 13 refers to this reception band control signal to limit the band of the FH signal received by the FH reception unit 9.

With such a configuration, the OFDM transmitter 2 stops data transmission from subcarrier # 1 to subcarrier # 6 in the downlink OFDM slot at time 13 to time 16 in FIG. 33, and subcarrier # 7 Transmit the OFDM signal using the frequency domain from to # 12. Further, the FH receiving unit 9 receives the FH signal transmitted from the terminal using the subcarriers # 1 to # 5 at the time 11 to 17 in FIG. 33.

FIG. 35 shows a configuration example of the terminal according to the sixth embodiment. In FIG. 35, the same parts as those in FIG. 32 showing the configuration of the terminal according to the fifth embodiment described above are designated by the same reference numerals, and only different parts will be described. That is, in FIG. 35, the bandpass filter (BPF) 60 is connected between the FH transmitter 51 and the radio 58, and the bandpass filter (BPF) 59 is connected between the radio 57 and the OFDM receiver 53. ing.

When the upper layer receives the slot format change information, the reception of the timing for changing the communication speed ratio, the changed communication speed ratio, and the OFDM signal contained in the slot format change information is stopped (or the OFDM signal). The frequency band and time (used for reception), or the timing at which the communication speed ratio should be changed, the changed communication speed ratio, and the frequency band and time used for transmitting the FH signal are given to the transmission / reception timing control unit 67.

The transmission / reception timing control unit 67 determines the timing at which the communication speed ratio should be changed from the upper layer, and the transmission / reception timing corresponding to the slot format such that the desired communication speed ratio is obtained when the communication speed ratio to be changed is given. The transmission timing control signal and the reception timing control signal are output to the FH transmission unit 51 and the OFDM reception unit 53, respectively. Also, a transmission for notifying the frequency band and time of stopping the reception of the OFDM signal (or used for receiving the OFDM signal) or the frequency band and time used for transmitting the FH signal given from the upper layer. The band control signal and the reception band control signal are output to BPF60 and BPF59, respectively.

The timing at which the FH signal is output by the FH transmission unit 51 is determined by the transmission timing control signal output from the transmission / reception timing control unit 67, and the frequency band at which transmission is stopped (or the frequency band used for transmission) is transmission / reception timing control. The BPF60 is notified by the transmission band control signal output from the unit 67, and the BPF60 limits the band of the FH signal output from the FH transmission unit 51 with reference to this transmission band control signal.

Further, the timing of receiving processing by the OFDM reception unit 53 is determined by the reception timing control signal output from the transmission / reception timing control unit 67, and the reception frequency band (or the non-reception frequency band) is determined by the transmission / reception timing control unit 67. The reception band control signal output from is notified to BPF59. The BPF59 refers to this reception band control signal to limit the band of the OFDM signal received by the OFDM receiving unit 53.

With such a configuration, in the terminal, the FH signal is transmitted to the base station by the FH transmission unit 51 using the subcarriers # 1 to # 5 at the time 11 to 17 in FIG. 33. Alternatively, during this time period, the OFDM signal including subcarriers # 1 to subcarriers # 6 transmitted from the base station from the time "13" to the time "16" is transmitted to the OFDM receiver without transmitting the FH signal. Receive at 53.

As described above, according to the sixth embodiment, the transmission speed of uplink communication is improved, and the communication speed ratio can be changed in more detail. In addition, more detailed changes in the communication speed ratio can be realized without making major changes to the existing system configuration.

Although FIG. 33 shows the case where the transmission stop frequency and the time domain are formed on the downlink, it is also possible to form the transmission stop frequency and the time domain on the uplink as shown in FIG. 36. The configurations of the base station and the terminal in this case are the same as those in FIGS. 34 and 35.

In FIG. 36, the base station transmits data to each terminal using the OFDM method using the frequency and time domain 201 (subcarriers # 1 to # 12 and time 1 to 4). After the base station finishes transmitting the downlink OFDM signal and guard time 202, each terminal pre-bases in the frequency and time domain 210 (subcarriers # 7 to # 12 and time "6" to time "11"). The FH signal is transmitted using the hopping pattern defined with the station. Here, the frequency and time domain 211 (subcarriers # 1 to # 6 and time "5" to "12") are the regions for transmitting the downlink OFDM signal. Therefore, each terminal uses a hopping pattern in which transmission is not performed for this area 211.

The base station uses the frequency and time domain 211 to transmit the downlink OFDM signal to the terminal while receiving the uplink signal from each terminal in the frequency and time domain 210. Further, the terminal can simplify the terminal configuration by only transmitting or receiving data. Each terminal ends uplink communication at time "11", and after guard time 204, the base station again transmits data using all subcarriers.

In FIG. 36, by using a hopping pattern that limits the band in the uplink (by forming a transmission stop frequency and a time domain in the uplink communication), the downlink uses a frequency and a time domain that are not used in the uplink. It is designed to perform OFDM communication. By adopting such a slot configuration, it is possible to improve the transmission speed of downlink communication and change the communication speed ratio in more detail.

(7th Embodiment) The schematic configuration of the entire wireless communication system according to the 7th embodiment is the same as that in FIG. That is, the base station BS1 transmits downlink OFDM signals DL1 and DL2 toward the terminals TE1 and TE2 for a certain period of time. When the base station BS1 finishes transmitting the downlink OFDM signal, the terminals TE1 and TE2 transmit the uplink FH signals UL1 and UL2 to the base station BS1 using the same frequency band as the downlink OFDM signal. In this way, the downlink OFDM signal and the uplink FH signal are temporally multiplexed.

FIG. 37 shows an example of a slot configuration used in the wireless communication system according to the seventh embodiment. Base station BS1 continuously transmits N_DL symbol data to each terminal using the OFDM method using the frequency and time domain 201 (subcarriers # 1 to # 12 and time "1" to "4"). .. At this time, a pilot symbol whose base station and terminal are known to each other is assigned to the first symbol 213 and the last symbol 214 among the consecutive symbols of one downlink slot.

In FIG. 37, the data of the user # 1 is assigned to the subcarriers # 10 and # 11, and the data of the user # 2 is assigned to the subcarriers # 4 and # 5, respectively. The base station BS1 selects a subcarrier whose transmission line condition is good for each user from the transmission line estimation result using the pilot symbol of the downlink slot (transmitted from the terminal), and channels for each user in the downlink slot. Allocation is being made.

After the base station finishes transmitting the downlink OFDM signal and the guard time 202, each terminal pre-bases in the frequency and time domain 203 (subcarriers # 1 to # 12 and time "6" to time "11"). The FH signal of the N_UL symbol is continuously transmitted using the hopping pattern notified by the station.

In FIG. 37, since the user # 1 has a good transmission line condition in the subcarriers # 10 and # 11, a hopping pattern in which the subcarriers # 10 and # 11 are mainly used is used. Further, since user # 2 has a good transmission line condition in subcarriers # 4 and # 5, he uses a hopping pattern mainly using subcarriers # 4 and # 5.

When each terminal finishes transmitting data, after the guard time 204, the base station starts transmitting the downlink OFDM signal to each terminal again.

FIG. 38 shows a configuration example of the base station according to the seventh embodiment. In FIG. 38, the same parts as those in FIG. 18 are designated by the same reference numerals, and only different parts will be described. That is, the user allocation unit 1 in FIG. 38 multiplexes the pilot signal with the signal addressed to each user. Then, the OFDM transmitter 2 converts the OFDM signal into an OFDM signal to which a pilot signal is added at the beginning and the end.

In addition, the downlink OFDM user allocation unit 7 and the uplink FH user allocation unit 8 use the transmission path status information transmitted from each terminal included in the FH signal received by the FH reception unit 9 to provide user allocation information and each. Generate user FH pattern information.

The configuration example of the terminal according to the seventh embodiment is the same as that in FIG. The difference is that what is used when the transmission line state estimation unit 52 estimates the transmission line state is the first pilot signal and the last pilot signal of each subcarrier signal received by the OFDM receiving unit 53. .. The transmission line state estimation unit 52 estimates the transmission path state for all subcarriers by using at least one of the leading and terminal pilot signals output from the OFDM receiving unit 53. For example, the transmission line state information representing the estimation result of the transmission line state using the pilot signal at the end is output to the FH transmission unit 51.

Further, the OFDM receiving unit 53 decodes the received signal based on at least one of the pilot signals at the beginning and the end of the received OFDM signal. For example, the received signal is decoded based on at least one of the first pilot signals of the received OFDM signal.

The FH transmission unit 51 multiplexes the transmission data to the base station and the transmission line state information output from the transmission line estimation unit 52, and is notified from the base station (obtained from the reception signal in the OFDM reception unit 53). It is converted into an FH signal using the FH pattern information () and transmitted.

The control process between the base station and the terminal using the start and end symbols (pilot signals known to the base station and the terminal) in the downlink slot of FIG. 37 will be described with reference to the flowchart shown in FIG. 39. To do.

In the downlink slot 201, the base station transmits a signal of the N_DL symbol to the terminal using the OFDM signal (step S21). Of these signals, the first symbol and the last symbol are pilot signals known to the base station and the terminal. When the terminal receives the downlink OFDM signal, the transmission line estimation unit 52 estimates the transmission line state using the leading pilot signal (step S22), and the OFDM reception unit 53 decodes the received data. The estimation result of the transmission line state (transmission line state information) using the terminal pilot signal is fed back to the base station using the FH signal in the uplink slot 203 (step S23).

The base station can recognize a frequency band having a good transmission line condition for each terminal from the transmission line state information of each terminal received from each terminal. Then, when allocating the subcarriers in the downlink slot 205 to each terminal, the subcarriers having a frequency having a good transmission path condition for each terminal are preferentially assigned to generate user allocation information. Further, when determining the hopping pattern of the FH signal in the uplink slot 207 for each terminal, the hopping pattern mainly using the frequency band in which the transmission path condition is good for each terminal is determined, and the FH pattern information of each user is determined. Is generated (step S24).

After determining the user assignment in this way, the base station adds a start and end pilot signal to the OFDM signal containing the subcarriers assigned to each terminal for transmitting data addressed to each terminal to each terminal. Then, it is transmitted to each terminal using the downlink slot 205 (step S25).

According to the seventh embodiment, the peak average power can be reduced by using the FH communication method for the uplink, so that the low power consumption of the terminal can be realized. Further, by using the OFDM communication method for the downlink, it is possible to increase the speed of the downlink communication. By temporally multiplexing the uplink communication and the downlink communication, it is possible to use each other's transmission line characteristic estimates. Therefore, negotiation between the base station and the terminal can be performed relatively easily with a time margin.

Further, according to the seventh embodiment, for example, the transmission line state is estimated using the pilot signal at the end of the OFDM signal transmitted in the downlink slot 201. The estimation result of the transmission line state is used in the base station when allocating the time and frequency band in the downlink slot 205 and the uplink slot 203 immediately after that to the user. Therefore, it is possible to preferentially assign the optimum frequency band (with good transmission line condition) to each terminal based on the transmission line state at a time close to the time when the data is transmitted between the base station and the terminal. The error rate can be reduced and the transmission efficiency can be improved.

(8th Embodiment) Similarly to the 7th Embodiment above, the wireless communication system according to the 8th embodiment also has a signal at the beginning and end of the OFDM signal transmitted in the downlink slot (a signal known to the base station and the terminal). The pilot signal is included. In the terminal of the wireless communication system according to the eighth embodiment, the OFDM signal is demodulated using the pilot signal at the beginning of the OFDM signal, and the reception state of the pilot signal is indexed using the pilot signal at the end.

For example, a table common to the base station and each terminal representing the phase shift and amplitude information of the terminal pilot signal is stored in the base station and the terminal, respectively. The terminal selects the information closest to the state of the currently received pilot signal from the information in the table. Then, the value for identifying the address of the selected information in the table is set as an index value corresponding to the reception state of the pilot signal. The index value (reception state index value) is fed back to the base station using the uplink FH signal.

The base station estimates the transmission line state using the index value of the reception state in each terminal received from each terminal. Using the estimated transmission line condition, the base station preferentially assigns subcarriers of frequencies with good transmission line conditions to each terminal, and determines a hopping pattern mainly using the frequency band with good transmission line conditions. To do.

The configuration of the base station according to the eighth embodiment is almost the same as that in FIG. 18, and only the different parts will be described. That is, the OFDM transmission unit 2 includes the data addressed to each user output from the user allocation unit 1, the FH pattern information generated by the uplink FH user allocation unit 8, and the user allocation information generated by the downlink OFDM user allocation unit 7. Are multiplexed, and pilot signals are added to the beginning and end to convert them into FDM signals.

Further, the transmission line estimation unit 6 stores a table for associating the phase shift and amplitude information of the terminal pilot signal with the index value (reception state index value). Then, the transmission path state of each subcarrier in each terminal is estimated using the reception state index value transmitted from each terminal included in the FH signal received by the FH receiving unit 9. That is, the phase and amplitude information of the terminal pilot signal corresponding to the reception state index value is obtained from the table, and the transmission line estimation result based on these is output to the downlink OFDM user allocation unit 7 and the uplink FH user allocation unit 8. The downlink OFDM user allocation unit 7 determines the user allocation in the next downlink slot based on the transmission line estimation result, and outputs the user allocation information representing the result. The uplink FH user allocation unit 8 determines the FH pattern of each user in the next uplink slot based on the transmission line estimation result, and outputs the FH pattern information of each user representing the result.

The configuration example of the terminal according to the eighth embodiment is the same as that in FIG. The difference is that the transmission line state estimation unit 52 stores a table for associating the phase shift and amplitude information of the terminal pilot signal with the index value (reception state index value). Then, using the table, the index value corresponding to the phase shift and amplitude information of the terminal pilot signal obtained by the OFDM receiving unit 53 is obtained. This reception status index value is output to the FH transmission unit 51. The FH transmission unit 51 multiplexes the transmission data to the base station and the reception status index value output from the transmission path estimation unit 52, and is notified from the base station (obtained from the reception signal in the OFDM reception unit 53). FH pattern information is used to convert to an FH signal for transmission.

The processing operation between the base station and the terminal using the terminal symbol (pilot signal known in the base station and the terminal) in the downlink slot of FIG. 37 will be described with reference to the flowchart shown in FIG. 40.

In the downlink slot 201, the base station transmits a signal of the N_DL symbol to the terminal using the OFDM signal (step S31). Of these signals, the first symbol and the last symbol are pilot signals known to the base station and the terminal. When the terminal receives the downlink OFDM signal, the transmission line estimation unit 52 obtains an index value corresponding to the phase shift and amplitude information of the received terminal pilot signal (step S32). This index value is fed back to the base station using the FH signal in the uplink slot 203 (step S33).

The base station estimates the transmission path state of each subcarrier at each terminal from the reception state index value received from each terminal (step S34). Then, based on the transmission line estimation result, the user allocation in the next downlink slot is determined, and the user allocation information representing the result is generated. Further, based on the transmission line estimation result, the FH pattern of each user in the next uplink slot is determined, and the FH pattern information of each user representing the result is generated (step S35).

After determining the user assignment in this way, the base station adds a start and end pilot signal to the OFDM signal containing the subcarriers assigned to each terminal for transmitting data addressed to each terminal to each terminal. Then, it is transmitted to each terminal using the downlink slot 205 (step S36).

According to the eighth embodiment, the peak average power can be reduced by using the FH communication method for the uplink, so that the low power consumption of the terminal can be realized. Further, by using the OFDM communication method for the downlink, it is possible to increase the speed of the downlink communication. By temporally multiplexing the uplink communication and the downlink communication, it is possible to use each other's transmission line characteristic estimates. Therefore, negotiation between the base station and the terminal can be performed relatively easily with a time margin.

Further, according to the eighth embodiment, when the terminal receives the OFDM signal transmitted in, for example, the downlink slot 201, the terminal obtains an index value indicating the reception state of the terminal pilot signal included in the OFDM signal. This index value is transmitted to the base station in the uplink slot 203, and is used in the base station when estimating the transmission line state for each terminal. The base station allocates the time and frequency bands in the downlink slot 205 and the uplink slot 203 immediately after the estimation result of the transmission line state to the user. Therefore, it is possible to preferentially assign the optimum frequency band (with good transmission line condition) to each terminal based on the transmission line state at a time close to the time when the data is transmitted between the base station and the terminal. The error rate can be reduced and the transmission efficiency can be improved.

(9th Embodiment) In the wireless communication system according to the 9th embodiment, as shown in FIG. 41, the base station BS1 and the terminals TE1 and TE2 are transferred from the base station to the terminal in the cell in the cellular communication network. OFDM communication using multiple subcarriers is performed on the downlink, communication is performed by the frequency hopping method and OFDM method on the uplink from the terminal to the base station, and bidirectional communication between downlink and uplink is performed by TDD. It has become.

As shown in FIG. 42, in the 1-down slot 201 of the TDD, communication is performed by the OFDM method using a plurality of subcarriers. On the other hand, in the uplink slot of TDD, as shown in FIG. 43, communication is performed by the frequency hopping method and the OFDM method. However, the transmission slot (communication time) of the OFDM signal in the uplink slot is shorter than the transmission slot (communication time) of the frequency hopping (FH) signal, and each terminal shall transmit one symbol of the OFDM signal. .. Further, since the OFDM signal transmitted by the terminal in the uplink slot is used as a pilot signal for measuring reception quality, it is a symbol sequence known to the base stations BS1 and the terminals TE1 and TE2. In the following description, the OFDM signal transmitted by the terminal in the uplink slot may be referred to as a known signal.

In the uplink slot, the known signal transmitted by the terminal by the OFDM method is used when the base station side measures (estimates) the transmission quality of each subcarrier. The transmission quality measurement result is used as a guideline for selecting the subcarrier to be used in the downlink slot.

FIG. 44 is a flowchart for explaining a processing operation using the known signal between the base station and the terminal of the communication system according to the ninth embodiment.

The terminal transmits a known OFDM signal in the uplink slot, as shown in FIG. 43 (step S51). After transmitting the known signal, the terminal transmits the FH signal (step S52). On the other hand, the base station can estimate the reception quality of each subcarrier at each terminal by demodulating the received OFDM signal and measuring the received power for all subcarriers from the series of known signals (step). S53).

After measuring the received power of each subcarrier, the base station selects the subcarrier to be used for communication with each terminal in the subsequent downlink slot (step S54). For example, a subcarrier having a high received power value is preferentially selected from among subcarriers whose received power value is equal to or higher than a predetermined threshold value. Then, the subcarrier whose received power value does not reach the threshold value is not used for communication with the terminal.

The base station transmits a signal for notifying each terminal of the selected subcarrier (step S56), and then transmits transmission data addressed to the terminal using the selected subcarrier (step S57). ..

Here, a method of allocating the frequency band / time domain (user channel) in each of the uplink slot and the downlink slot to each terminal will be described.

FIGS. 45 and 46 show the first allocation method. Each terminal has a predetermined OFDM signal slot (time slot) in the uplink and downlink slots. For each terminal, the base station determines a frequency hopping pattern in the transmission slot of the FH signal in the uplink slot (for example, by selecting a frequency band having good reception quality in the terminal). This frequency hopping pattern shall be notified in advance from the base station to each terminal.

In step S54, as shown in FIG. 46, it is determined from the known signal transmitted from the terminal of user # 1 that the reception quality in the frequency domain 251 in the time slot assigned to user # 1 in the downlink slot is low. After that, the subcarrier of the frequency domain 251 is not assigned to the user # 1. Similarly, if it is determined from the known signal transmitted from the terminal of user # 2 that the reception quality in the frequency domain 252 in the time slot assigned to the user # 2 in the downlink slot is low, the frequency domain 252 Subcarriers are not assigned to user # 2.

In FIG. 46, it is assumed that the subcarrier used for communication is notified to each terminal by the first symbol of the OFDM signal transmitted from the base station in each slot assigned to each terminal in the downlink slot.

In this way, by using the wideband signal transmitted from the terminal in the uplink slot, the known station can estimate the reception quality of all subcarriers. In the base station, the communication quality between the base station and the terminal can be expected to be improved by preferentially using the subcarrier with good reception quality in the downlink slot based on the reception quality of each subcarrier obtained.

FIGS. 47 and 48 show the second allocation method. In the OFDM signal slot in the uplink and downlink slots, a case where user multiplexing is performed using a diffusion code assigned to each terminal in advance (OFCDM: Orthogonal Frequency and code division multiplexing) is shown. Each terminal communicates using the spreading code specified by the base station. For each terminal, the base station determines a frequency hopping pattern in the transmission slot of the FH signal in the uplink slot (for example, by selecting a frequency band having good reception quality in the terminal). This frequency hopping pattern shall be notified in advance from the base station to each terminal.

In step S54, as shown in FIG. 48, it is determined from the known signal transmitted from the terminal of user # 1 that the reception quality in the frequency domain 253 in the time slot assigned to user # 1 in the downlink slot is low. After that, the subcarrier of the frequency domain 253 is not assigned to the user # 1. Similarly, if it is determined from the known signal transmitted from the terminal of user # 2 that the reception quality in the frequency domain 254 in the time slot assigned to the user # 2 in the downlink slot is low, the frequency domain 254 is determined. Subcarriers are not assigned to user # 2.

In this way, by using the wideband signal transmitted from the terminal in the uplink slot, the known station can estimate the reception quality of all subcarriers. In the base station, the communication quality between the base station and the terminal can be expected to be improved by preferentially using the subcarrier with good reception quality in the downlink slot based on the reception quality of each subcarrier obtained.

FIG. 49 shows a configuration example of the transmission system of the terminal of the wireless communication system according to the ninth embodiment, the same parts as those in FIG. 19 are designated by the same reference numerals, and only different parts will be described. That is, in FIG. 49, an OFDM transmission unit 88 for transmitting a known signal and a storage unit 87 for storing a bit sequence of the known signal (a pattern of the known signal) are newly added. Further, the configuration of the radio unit 58 is different from that in FIG. Note that FIG. 49 shows the configuration of the wireless unit 58 in more detail than in FIG. Further, the configuration of the terminal according to the ninth embodiment is the same as that of FIG. 19 except for the configuration of the transmission system shown in FIG. 49.

D / A conversion unit 82 for converting the FH signal output from the FH transmission unit 51 from a digital signal to an analog signal, frequency conversion unit 84 for frequency conversion, and a power amplifier for transmitting a radio signal from the antenna. (PA) 86 is also included in the radio section 58 of the terminal of FIG. Further, the radio unit 58 of FIG. 49 includes a D / A conversion unit 81 for converting an OFDM signal output from the OFDM transmission unit 88 from a digital signal to an analog signal, and a frequency conversion unit 83 for performing frequency conversion. A switching unit 85 for outputting only one of the FH signal output from the frequency conversion unit 84 and the OFDM signal output from the frequency conversion unit 83 to the PA86 is included.

Generally, in OFDM communication, a signal having a flat frequency spectrum is transmitted over a wide band, so that the difference between the peak power and the average power of the transmission time waveform becomes large, and the power amplifier (PA) of the transmission system is consumed. Power is a problem.

However, the OFDM signal transmitted on the uplink is a known bit sequence for channel estimation. Therefore, a series in which the difference between the peak power and the average power is (most) small is investigated in advance, and this is stored in the storage unit 87 in advance. Then, when transmitting a known signal, the bit sequence stored in the storage unit 87 is read out, and the OFDM transmission unit 88 performs coding, subcarrier modulation, IFFT, etc. on the bit sequence to perform the radio unit. Transmit from the antenna via 83. According to the configuration shown in FIG. 49, it is possible to process with one PA86 without using two PAs for OFDM and frequency hopping.

FIG. 50 shows another configuration example of the transmission system of the terminal of the wireless communication system according to the ninth embodiment, the same parts as those in FIG. 49 are designated by the same reference numerals, and only different parts will be described. To do. That is, in FIG. 50, there is no OFDM transmitter 88 for transmitting a known signal, and the storage unit 87 has a small difference between peak power and average power (PAPR (ratio of maximum power to average power). The time waveform after IFFT of the bit series is stored, not the bit series itself. The configuration of the terminal according to the ninth embodiment is the same as that of FIG. 19 except for the configuration of the transmission system shown in FIG. 50.

In the case of the configuration shown in FIG. 50, when transmitting a known signal via the uplink, the waveform stored in the storage unit 87 is read out, and the radio unit 83 performs D / A conversion and frequency conversion. There is.

With such a configuration, the OFDM transmitter 88 for converting the bit sequence into the OFDM signal becomes unnecessary, and the terminal can be miniaturized and the power consumption can be reduced.

When the frequency hopping method is used for the uplink, it may not be possible to grasp the frequency characteristics of the entire band to be used depending on the selected hopping pattern. Further, when the subcarrier used for the uplink communication is selected according to the reception status of the downlink communication, the signal is not transmitted to the subcarrier that is not used, and the reception status of the subcarrier cannot be grasped.

However, according to the ninth embodiment, each terminal transmits a wide band signal over the entire band used in the downlink time slot by using a part of the time interval of the uplink time slot. By receiving this wideband signal, the base station can measure the frequency characteristics in the entire band. By using the wideband signal transmitted by the terminal in the uplink time slot, the base station can measure the frequency characteristics of the entire communication band regardless of the selected frequency hopping pattern. Further, using this result, it becomes possible to perform processing such as selecting a subcarrier having good frequency characteristics on the downlink and performing communication. This makes it possible to improve the reception quality of the terminal.

The frequency hopping pattern used in uplink communication is selected so as to be orthogonal to each terminal. However, if each terminal transmits a wideband signal transmitted by the terminal using a part of the uplink time slot at the same timing, the base station cannot correctly receive the signal due to interference. Therefore, by multiplexing the wideband signal by either TDMA (Time Division Multiple Access) or CDMA (Code Division Multiple Access), interference when receiving the wideband signal at the base station is eliminated.

In the OFDM method, there is a problem that the ratio of peak signal power to average signal power (PAPR) becomes large depending on the signal sequence to be transmitted. However, since the series transmitted by the terminal for frequency characteristic measurement on the uplink may be a known series, by selecting a series in which the PAPR is small in advance, the non-linearity in the power amplifier resulting from the large PAPR. The effect of distortion can be reduced.

Since the signal transmitted by the terminal using the OFDM method is a known series, the terminal can be set to the OFDM method by storing the time waveform of the signal obtained as a result of processing the series by the OFDM method transmission circuit in advance. The transmission circuit becomes unnecessary, and the signal processing and circuit scale of the terminal can be reduced.

(10th Embodiment) In the 10th embodiment, in the wireless communication system according to the first embodiment, a hopping pattern for a terminal to communicate with a base station in an uplink slot and a base station downlink with the terminal. An example of the processing procedure for determining the channel for communication in the slot will be described by taking the wireless communication system shown in FIG. 41 as an example.

As shown in FIG. 41, the base station BS1 and the terminals TE1 and TE2 perform OFDM communication using a plurality of subcarriers on the downlink from the base station to the terminal in the cell in the cellular communication network, and the terminal to the base station. In the uplink, communication is performed by the frequency hopping method and the OFDM method, and bidirectional communication between downlink communication and uplink communication is performed by TDD.

The base station BS1 transmits information for notifying the hopping pattern that can be used on the uplink to the terminal newly entering the coverage area on the common channel of the downlink.

The common channel is a channel for transmitting common information that the base station should notify all terminals in its own area. Basically, even when multiplexed, the terminal can retrieve information immediately by using a known channel.

The hopping pattern is information indicating the order and timing at which the frequencies of the transmitting carriers change in the FH method, and here, a pattern in which all subcarriers are used is used. As a hopping pattern, for example, as shown in FIG. 51, there is a pattern (sequential hopping) in which each OFDM symbol is switched to an adjacent subcarrier. Further, as shown in FIG. 52, a pattern (random hopping) is also possible in which hopping is performed randomly, but the subcarriers once transmitted are not transmitted until all the subcarriers are transmitted once. Further, as shown in FIG. 53, a pattern (slide hopping) in which adjacent subcarriers are skipped and hopping is also possible.

The configurations of the base station and the terminal according to the tenth embodiment are the same as those in FIGS. 18 and 9.

Next, with reference to FIG. 54, a processing operation for allocating a user channel on the downlink by the base station using the FH signal transmitted from the terminal will be described.

The base station transmits the information of the hopping pattern available on the uplink on the predetermined common channel of the downlink (step S61). The terminal selects an arbitrary hopping pattern from the empty hopping patterns notified on the common channel and transmits an FH signal to the base station (step S62). The base station (for example, the transmission line estimation unit 6) constantly receives and monitors an empty hopping pattern, and when a certain amount of power or more is detected, it is considered that there is a transmission from the terminal. The terminal transmits an FH signal with a hopping pattern so that all subcarriers are used at least once within a certain period of time.

Until the transmission of the FH signal using all the subcarriers is completed from each terminal, the transmission line estimation unit 6 of the base station that has detected the transmission performs transmission line estimation using the signal transmitted in the hopping pattern. .. The transmission line estimated value is stored in, for example, a predetermined storage area in the transmission line estimation unit 6 (step S63). The transmission line estimated value is obtained by receiving the pilot signal inserted in the symbol as a known signal when the terminal / base station transmits, dividing by the pilot signal component, and averaging the transmission line. It is a value extracted as an amplitude / phase distortion.

In addition to the terminal that has newly started FH transmission, the base station also stores the transmission line estimated value measured for the FH transmission signal of the terminal being communicated in a predetermined storage area in the transmission line estimation unit 9. .. The base station (downstream OFDM user allocation unit 7) updates the channel allocation of the downlink OFDM signal based on the transmission line estimation value of each terminal (step S64).

The channel assigned to each terminal (here, for example, one subcarrier) is notified to each terminal using, for example, a predetermined common channel of the downlink (step S65).

Upon receiving the above notification, each terminal receives the data transmitted from the base station through the downlink channel assigned to each terminal (step S66).

Here, the channel allocation process in the downlink OFDM user allocation unit 7 of the base station in step S64 will be described with reference to FIG. 55. The channel allocation process shall be performed in units of subcarriers, and one subcarrier shall be one user's channel.

Select one of all subcarriers (total number of subcarriers is N). This is referred to as subcarrier i. Based on the transmission line estimation value stored in the storage area in the transmission line estimation unit 6, the terminal having the best transmission line condition of the subcarrier i is selected from the terminal group to which the subcarrier is not assigned (step). S71). If only one terminal is selected, subcarrier i is assigned to that terminal (step S72, step S73). When a plurality of terminals are selected (step S72), the subcarrier i is assigned to the terminal having the largest transmission line estimated value among the plurality of terminals (step S74). The above steps S71 to S74 are repeated until subcarriers are assigned to all terminals in the area.

FIG. 56 shows the process of allocating a downlink channel to each terminal using the FH signal transmitted from each terminal.

According to the tenth embodiment, efficient channel allocation can be performed with a small number of processing procedures.

(11th Embodiment) In the 11th embodiment, in the wireless communication system according to the 10th embodiment, a case where a plurality of user channels are multiplexed on one subcarrier in the downlink will be described. When CDMA or TDMA is used as a method for multiplexing a plurality of channels in one subcarrier, CDMA and TDMA may be used in combination. Hereinafter, parts different from the tenth embodiment will be described.

The configuration example of the terminal according to the eleventh embodiment is substantially the same as that in FIG. What is different is the processing operation of the user signal extraction unit 54. That is, the user signal extraction unit 52 extracts only the symbols addressed to the own device from the wideband signals (plurality of subcarrier signals) output from the OFDM reception unit 53 and outputs them to the signal separation unit 55. For example, in the case of multiplexing by CDMA, the user allocation information includes a spreading code assigned to the own device or information for identifying the spreading code. Then, the user signal extraction unit 54 performs the reverse diffusion process using the diffusion code. Other operations are the same as those in the first embodiment.

The configuration example of the base station according to the eleventh embodiment is almost the same as that in FIG. The difference is the processing operation of the user allocation unit 1. That is, the user allocation unit 1 multiplexes a plurality of user channels in one subcarrier. For example, when CDMA is used, the spreading process is performed using a spreading code predetermined for each shelf MT U.

Multiplexing is performed with the OFDM symbol as the minimum unit. When CDMA is used to multiplex multiple user channels on one subcarrier, a chip in which one data is spread by a spreading code is transmitted as an OFDM symbol. The chips can be arranged in the frequency axis direction and the time axis direction, and on the receiving side, decoding is possible by collecting the chips in the user signal extraction unit 10 and back-diffusing them.

In this way, by allocating a plurality of channels to one subcarrier, it is possible to accommodate more user channels in the downlink OFDM signal.

Actually, when an OFDM symbol is assigned as a channel to each terminal, the number of OFDM symbols required for one downlink slot (the number of OFDM symbols included in one user channel) is calculated from the transmission rate required by the terminal.

Therefore, in the eleventh embodiment, in step S64 of FIG. 54, the following processing operation is performed to allocate channels.

Of the transmission line estimates for each subcarrier of each terminal belonging to the area of the base station, 1 OFDM symbols are assigned to the terminals in order from the subcarrier with the highest transmission line estimate. At this time, the channel is not assigned to the subcarrier whose transmission line estimated value does not reach the predetermined threshold value (the transmission line condition is bad). In this way, the required number of OFDM symbols are assigned to each user channel while preferentially selecting the subcarrier having the highest transmission line estimation value for each subcarrier of the terminal.

FIG. 57 shows the process of allocating a downlink channel to each terminal using the FH signal transmitted from each terminal.

According to the eleventh embodiment, channel allocation can be performed more efficiently than in the case of the tenth embodiment.

The present invention is not limited to the above-described embodiment as it is, and at the implementation stage, the components can be modified and embodied within a range that does not deviate from the gist thereof. In addition, various inventions can be formed by an appropriate combination of the plurality of components disclosed in the above-described embodiment. For example, some components may be removed from all the components shown in the embodiments. In addition, components across different embodiments may be combined as appropriate.

<figref num="1">The figure which schematically showed the schematic configuration example of the whole wireless communication system which concerns on 1st Embodiment of this invention.</figref><figref num="2">The figure which schematically showed the schematic configuration example of the whole wireless communication system which concerns on 1st Embodiment of this invention.</figref><figref num="3">The figure which schematically showed the schematic configuration example of the whole wireless communication system which concerns on 1st Embodiment of this invention.</figref><figref num="4">The figure for demonstrating the case where the same frequency band is used for the downlink and the uplink, and it is accommodated by TDD.</figref><figref num="5">The figure for demonstrating the case of multiplexing the signal of a plurality of users on a downlink.</figref><figref num="6">The figure for demonstrating the case of performing transmission power control, FH hopping pattern control, etc. by utilizing the characteristic of the transmission line estimated in each terminal which receives an OFDM signal transmitted by a downlink.</figref><figref num="7">To explain the processing operation of terminals and base stations when performing transmission power control, FH hopping pattern control, etc. using the characteristics of the transmission line estimated by each terminal that receives the OFDM signal transmitted on the downlink. Flow chart.</figref><figref num="8">The figure for demonstrating the case of realizing bidirectional communication by using different frequencies for the downlink of OFDM and the uplink of FH (FDD).</figref><figref num="9">The figure which shows the 1st slot configuration.</figref><figref num="10">The figure which shows the 2nd slot configuration.</figref><figref num="11">The figure which shows the 3rd slot configuration.</figref><figref num="12">The figure which shows the 4th slot configuration.</figref><figref num="13">The figure which shows the 5th slot configuration.</figref><figref num="14">The figure which shows the 6th slot configuration.</figref><figref num="15">The figure which shows the 7th slot configuration.</figref><figref num="16">The figure which shows the 8th slot configuration.</figref><figref num="17">The figure which shows the 9th slot configuration.</figref><figref num="18">The figure which shows the configuration example of a base station.</figref><figref num="19">The figure which shows the configuration example of a terminal.</figref><figref num="20">The figure which shows the slot structure applied to the wireless communication system which concerns on 2nd Embodiment.</figref><figref num="21">The figure which shows the configuration example of the base station which concerns on 2nd Embodiment.</figref><figref num="22">The figure which shows the configuration example of the terminal which concerns on 2nd Embodiment.</figref><figref num="23">The figure which shows the slot structure applied to the wireless communication system which concerns on 3rd Embodiment.</figref><figref num="24">The figure which shows the configuration example of the base station which concerns on 3rd Embodiment.</figref><figref num="25">The figure which shows the configuration example of the terminal which concerns on 3rd Embodiment.</figref><figref num="26">The figure which shows the slot structure applied to the wireless communication system which concerns on 4th Embodiment.</figref><figref num="27">The figure which shows the configuration example of the base station which concerns on 4th Embodiment.</figref><figref num="28">The figure which shows the configuration example of the terminal which concerns on 4th Embodiment.</figref><figref num="29">A flowchart for explaining a processing procedure for changing a communication speed ratio between a base station and a terminal in the wireless communication system according to the fifth embodiment.</figref><figref num="30">The figure for demonstrating how the slot format changes.</figref><figref num="31">The figure which shows the configuration example of the base station which concerns on 5th Embodiment.</figref><figref num="32">The figure which shows the configuration example of the terminal which concerns on 5th Embodiment.</figref><figref num="33">The figure which shows the slot structure applied to the wireless communication system which concerns on 6th Embodiment.</figref><figref num="34">The figure which shows the configuration example of the base station which concerns on 6th Embodiment.</figref><figref num="35">The figure which shows the configuration example of the terminal which concerns on 6th Embodiment.</figref><figref num="36">The figure which shows the other slot configuration applied to the wireless communication system which concerns on 6th Embodiment.</figref><figref num="37">The figure which shows the slot structure applied to the wireless communication system which concerns on 7th Embodiment.</figref><figref num="38">The figure which shows the configuration example of the base station which concerns on 7th Embodiment.</figref><figref num="39">A flowchart for explaining a control process between a base station and a terminal using the start and end symbols (pilot signals known in the base station and the terminal) in the downlink slot.</figref><figref num="40">In the wireless communication system according to the eighth embodiment, the control process between the base station and the terminal using the start and end symbols (pilot signals known in the base station and the terminal) in the downlink slot will be described. Flowchart to do.</figref><figref num="41">The figure which schematically showed the schematic configuration example of the whole wireless communication system which concerns on 9th Embodiment.</figref><figref num="42">The figure which shows the arrangement of a signal in a time / frequency axis in a downlink slot.</figref><figref num="43">The figure which shows the arrangement of the signal in the time / frequency axis in an uplink slot.</figref><figref num="44">The flowchart for demonstrating the processing operation using the known signal between the base station and the terminal of the communication system which concerns on 9th Embodiment.</figref><figref num="45">The figure which shows an example of the allocation method to each terminal of the frequency band / time domain (user channel) in each of an uplink slot and a downlink slot.</figref><figref num="46">The figure which shows an example of the allocation method to each terminal of the frequency band / time domain (user channel) in each of an uplink slot and a downlink slot.</figref><figref num="47">The figure which shows another example of the allocation method to each terminal of the frequency band / time domain (user channel) in each of an uplink slot and a downlink slot.</figref><figref num="48">The figure which shows another example of the allocation method to each terminal of the frequency band / time domain (user channel) in each of an uplink slot and a downlink slot.</figref><figref num="49">The figure which showed the configuration example of the transmission system of the terminal of the wireless communication system which concerns on 9th Embodiment.</figref><figref num="50">The figure which showed the other configuration example of the transmission system of the terminal of the wireless communication system which concerns on 9th Embodiment.</figref><figref num="51">The figure for demonstrating the hopping pattern of sequential hopping.</figref><figref num="52">The figure for demonstrating the hopping pattern of random hopping.</figref><figref num="53">The figure for demonstrating the hopping pattern of slide hopping.</figref><figref num="54">In the wireless communication system according to the tenth embodiment, a flowchart for explaining a processing operation for allocating a user channel on a downlink by a base station using an FH signal transmitted from a terminal.</figref><figref num="55">A flowchart for explaining a channel allocation processing operation of a base station.</figref><figref num="56">The figure which shows the process until the channel by the downlink is assigned to each terminal using the FH signal transmitted from each terminal.</figref><figref num="57">FIG. 5 is a diagram showing a process of allocating a downlink channel to each terminal using an FH signal transmitted from each terminal in the wireless communication system according to the eleventh embodiment.</figref><figref num="58">The figure which shows the basic configuration example of the main part (OFDM transmission part and radio part) of the transmission system of a base station.</figref><figref num="59">The figure which shows the basic configuration example of the main part (wireless part and OFDM receiving part) of the receiving system of a terminal.</figref><figref num="60">The figure which shows the basic configuration example of the main part (FH transmission part and wireless part) of the transmission system of a terminal.</figref><figref num="61">The figure which shows the basic configuration example of the main part (radio part and FH receiving part) of the receiving system of a base station.</figref>

Code description

1 ... user allocation unit, 2 ... OFDM transmission unit, 5 ... signal separation unit, 6 ... transmission line estimation unit, 7 ... downlink OFDM user allocation unit, 8 ... uplink FH user Assignment section, 9 ... FH receiver section, 10 ... user signal extraction section, 11, 12 ... radio section, 51 ... FH transmitter section, 52 ... transmission line estimation section, 53 ... OFDM receiver, 54 ... user signal extraction unit, 55 ... signal separation unit, 55a ... storage unit, 57, 58 ... radio unit.