Radio terminal, radio base station and radio communication system

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a wireless communication system, and can be applied to, for example, a case where a wireless signal transmitted from a wireless terminal such as a mobile telephone or a fixed wireless terminal to a wireless base station is multiplexed by CDMA (code division multiple access).

【0002】

The present invention also relates to a wireless terminal as a component of such a wireless communication system.

【0003】

Furthermore, the present invention relates to a radio base station as a component of such a radio communication system.

【0004】

[Conventional technology]

There is a case as shown in FIG. 3 in which two wireless terminals 102 and 103 communicate with a common base station 101. It is assumed that the terminal (A) 102 and the terminal (B) 103 simultaneously transmit to the base station 101.

【0005】

In FIG. 4, which shows the internal configuration of the base station 101, the CPU 501 outputs the transmission data to the transmission line encoder 502. The transmission line coder 502 outputs the data as a transmission symbol with redundancy by a method such as convolutional coding.

【0006】

The encoded information symbol is spread by the spreader 505 using the spreading code (diffusion code for downlink channel) output from the transmission spreading code generator 504, and is transmitted as transmission modulation data. At this time, the spread code length is set so that the output data is N times the information symbol rate.

【0007】

On the other hand, the reception modulation data received by the base station 101 is symbol demodulated by the despreader 507. The spreading code used for despreading is generated by the receiving spreading code generator 506, but is the same spreading code (uplink channel spreading code) used by the terminal for transmission.

【0008】

Since the timing of the reception diffusion code (phase of the diffusion code) differs for each terminal and is unknown to the base station 101, the optimum reception is performed by the CPU 501 and the reception timing adjuster (circuit including synchronous acquisition and synchronization tracking circuit) 508. The timing of the reception diffusion code generator 506 is adjusted at the timing.

【0009】

If there is an error in the despreaded reception symbol in the wireless transmission line, the transmission line decoder 509 corrects the error and outputs it to the CPU 501 as received data.

【0010】

The receiver 510 is composed of these circuits 506 to 509.

【0011】

The timing here is the timing of the generation of the diffusion code, and as shown in FIG. 6, the temporal LP of the pulse TP in FIG. 6 (B), which indicates the leading LP of the diffusion code in FIG. 6 (A). Position.

【0012】

The receiver of the base station 101 includes a plurality of receivers having the same internal configuration as the receiver 510 in order to simultaneously demodulate data from a plurality of terminals (for example, terminals 102 and 103) that transmit data at the same time. That is, it has M receivers of 510 to 512 receivers.

【0013】

On the other hand, on the terminal 102 or 103 side, the transmission / reception method is the same as that of the base station 101.

【0014】

In FIG. 5, which shows the internal configuration of the terminal 102 (or 103), the reception spreading code generator 604 generates the same code as the transmission spreading code (downlink channel spreading code) of the base station 101, and the transmission spreading of the terminal 102. The code generator 608 generates the same code as the reception diffusion code of the base station 101.

【0015】

When the CPU601 and the reception timing regulator 603 set the optimum reception timing for the transmission wave from the base station 101 to the reception spread code generator 604, the transmission timing regulator 610 has the same timing as the reception spread code generator 604. The signal is output to the transmission diffusion code generator 608 so as to generate the transmission diffusion code (diffusion code for uplink channels).

【0016】

In this way, if the transmission timing of each terminal 102, 103 is matched with the reception timing, the propagation delay from the base station 101 to the terminals 102, 103 is different, so that the signal timing from the terminals 102 and 103 received by the base station 101 is different. It will not match.

【0017】

That is, assuming that the transmission timing of the base station 101 is the timing T1 in FIG. 2 (A), the reception / transmission timing of the terminal A (102) is, for example, the timing T2 (delay ΔtA) in FIG. 2 (B), and the terminal B ( The reception / transmission timing of 103) is, for example, the timing T3 (delay ΔtB) of FIG. 2 (C), and the timing at which the base station 101 receives the transmission wave of the terminal A is the timing T4 (delay ΔtA with respect to the terminal A) of FIG. 2 (D). The timing of receiving the transmitted wave of the terminal B is the timing t5 (twice the delay ΔtB with respect to the terminal B).

【0018】

[Problems to be Solved by the Invention]

Now, as shown in FIG. 7, it is assumed that terminals 1 to M (302 to 304) of M station simultaneously transmit to a common base station 301.

【0019】

At this time, if the power received from the base station 301 is Pow1, the power from the terminal 2 is Pow2, ..., and the power from the terminal M is PowM, the total power received by the base station 301 is Pow1. + Pow2 ... + PowM.

【0020】

When the data from the terminal 1 is demodulated, all the power from other than the terminal 1 is interference noise, so the signal-to-noise ratio at the base station 301 when the incoming wave from the terminal 1 is the desired wave is Pow1 /. (Pow2 + Pow3 + ... PowM).

【0021】

For the sake of simplicity, assuming that the power from all terminals is the same (Pow1 = Pow2 = Pow3 ... = PowM), the signal-to-noise ratio can be expressed as 1 / (M-1). .. This means that as the number of terminals (M) transmitting at the same time increases, the S / N decreases and the communication quality deteriorates.

【0022】

On the other hand, in order to reduce interference from other terminals, it is effective to use an orthogonal code as the diffusion code. Assuming that Σ means the sum from n = 1 to n = M, the Walsh-Hadamard sign is when i = j. (ΣPi [n] * Pj [n]) / M = 1 ... Next, When i j (ΣPi [n] * Pj [n]) / M = 0 ... ("*" Means the product; the same applies below).

【0023】

That is, when the diffusion code of i j is assigned to each terminal, the signal after despreading is a component of only the desired wave, and the incoming wave component (power) from other terminals becomes zero.

【0024】

As an example, the case where two terminals transmit at the same time is shown below.

【0025】

Assuming that the transmission wave of terminal 1 has A1 as the amplitude and the transmission symbol of terminal 1 is Dm1, S1 [n] = A1 * Dm1 * P1 [n] ... Therefore, if the transmission wave of terminal 2 has A2 as the amplitude and the transmission symbol of terminal 2 is Dm2, S2 [n] = A2 * Dm2 * P2 [n] ... Will be.

【0026】

On the other hand, assuming that the propagation delay difference between the transmitted wave of terminal 1 and the transmitted wave of terminal 2 is Φ, the received wave of base station 301 is r [n] = S1 [n] + S2 [n + Φ] ... Therefore, the signal after despreading of terminal 1 is d1 = (Σr [n] * P1 [n]) / M = A1 * Dm1 + A2 * D2 (ΣP2 [n]) + Φ] * P1 [n]) / M ... Will be.

【0027】

However, since the second term on the right side of the equation is 0 from the equation when Φ = 0, the reception symbol d1 at this time includes only the transmission signal component from the terminal 1.

【0028】

However, this is a property that can be obtained only when Φ = 0, that is, when the transmission waves from the terminal 1 and the terminal 2 received by the base station 301 are synchronized. Therefore, as shown in FIG. 2, each terminal is obtained. In the conventional system in which the incoming wave from is asynchronous, there is a problem that the orthogonality is not ensured at the time of reception by the base station 301 and the S / N is not improved.

【0029】

[Means for solving problems]

In order to solve such a problem, the present invention provides a terminal-side transmission diffusion code generating means for generating (1) an uplink spread code for transmission in a wireless terminal which is code-division multiple access to a common wireless base station. , (2) Terminal-side transmission phase control means that controls the generation phase of the uplink spread code, (3) Terminal-side reception spread code generation means that generates the downlink spread code for reception, and (4) The terminal-side transmission phase is based on the terminal-side reception phase control means that controls the generation phase of the downlink channel diffusion code and (5) delay information corresponding to the propagation delay between the relevant radio terminal and the radio base station. It is equipped with a transmission timing control means that controls the control means to change the generation phase of the uplink spread code, and (6) is transmitted from a plurality of wireless terminals and is assigned to each wireless terminal by the uplink spread code. It is characterized in that the correlation between the spread-modulated transmission waves is controlled by paying attention to the reception time point by the radio base station.

【0030】

Further, according to the present invention, in a radio base station in which a plurality of wireless terminals are connected by code division and multiple elements, (1) a base station-side reception spreading code generating means for generating an uplink spreading code for reception, and the uplink spreading. A plurality of reception processing means including a base station side reception phase control means for controlling the code generation phase are provided, and (2) a base station side transmission spread code generation means for generating a downlink channel spread code for transmission, and (3) ) A base station-side transmission phase control means for controlling the generation phase of the downlink spread code is provided, and (4) the generation phase of the uplink spread code in the radio terminal is set between the radio base station and the radio terminal. By changing based on the delay information corresponding to the propagation delay between, the correlation between the transmission waves spread-modulated by the uplink spread code assigned to each of the plurality of wireless terminals can be determined by the plurality of radio terminals. It is characterized in that it is controlled by paying attention to the reception time point by the reception processing means.

【0031】

Further, the wireless communication system of the present invention is characterized by including a plurality of wireless terminals according to any one of claims 1 to 3 and a wireless base station according to any one of claims 4 or 5.

【0032】

BEST MODE FOR CARRYING OUT THE INVENTION

(A) Embodiment Hereinafter, embodiments of the present invention will be described by exemplifying a case where the wireless terminal, wireless base station, and wireless communication system according to the present invention are applied to a CDMA wireless communication system.

【0033】

A feature common to the first to fifth embodiments is that in the uplink channel from the terminal to the base station, incoming waves from a plurality of terminals are controlled to be synchronized at the time of reception in a single base station. The point is to ensure orthogonality and reduce interference between terminals.

【0034】

(A-1) Configuration of First Embodiment FIG. 1 shows the configuration of the terminal of the fixed station radio system of the present embodiment, that is, the fixed radio station 11. The terminal 11 may communicate with the same base station as the base station 101 shown in FIG. 4, for example.

【0035】

In FIG. 1, the terminal 11 is a CPU 701, a reference clock generator 702, a reception timing regulator 703, a reception diffusion code generator 704, a despreader 705, a transmission line decoder 706, a transmission line encoder 707, and a transmission diffusion code. In addition to the generator 708 and diffuser 709, it is equipped with a transmission timing adjuster 710 and memory 711.

【0036】

Of these, the components other than the transmission timing regulator 710 and the memory 711 correspond to each component shown in FIG. 5, and therefore detailed description thereof will be omitted.

【0037】

That is, the CPU 701 corresponds to the CPU 601, the reference clock generator 702 corresponds to the reference clock generator 602, the reception timing regulator 703 corresponds to the reception timing regulator 603, and the reception spread code generator 704 corresponds to the said. The receive spreading code generator 604 corresponds, the despreader 705 corresponds to the despreader 605, the transmission line decoder 706 corresponds to the transmission line decoder 606, and the transmission line encoder 707 corresponds to the transmission line. Corresponding to the encoder 606, the transmission spreading code generator 708 corresponds to the transmission channel spreading code generator 608, and the diffuser 709 corresponds to the diffuser 609.

【0038】

The memory 711 connected to the CPU 701 is a portion that stores a transmission timing offset value used for transmission timing control.

【0039】

This transmission timing offset value is usually substantially determined by the distance between the terminal 11 and the base station 101, and corresponds to the amount of propagation delay between the two.

【0040】

Further, the transmission timing adjuster 710 connected to the CPU 701 by the CPU interface is a circuit that adjusts the transmission timing according to the transmission timing offset value supplied from the CPU 701.

【0041】

In order to adjust the transmission timing, the transmission timing regulator 710 receives an input from the reception diffusion code generator 704 and supplies an output to the transmission diffusion code generator 708.

【0042】

Hereinafter, the operation of the first embodiment having the above configuration will be described.

【0043】

(A-2) Operation of the first embodiment The operation on the base station 101 side is exactly the same as before.

【0044】

The basic operation on the terminal 11 side is almost the same as the conventional one, but an operation for adjusting the transmission timing, which has not been done in the past, is performed.

【0045】

As described above, the transmission timing offset value is a value that is almost determined according to the distance between the base station 101 and the terminal 11, but the CPU 701 writes the transmission timing offset stored in advance in the memory 711 to the transmission timing adjuster 710. After that, transmission is started.

【0046】

Assuming that the terminal 11 of the present embodiment corresponds to the terminal A, the operation of the transmission timing adjuster 610 sets the transmission timing of the terminal A, which is originally the timing T2, to DS (transmission timing offset) in FIG. 2 (B). It corresponds to the operation of delaying by (value) and making it TS. As a result, the transmission wave of the other terminal B and the transmission wave of the terminal A are received by the base station 101 at the same timing T5.

【0047】

Therefore, the transmission timing offset value DS can be obtained as a value obtained by subtracting twice the propagation delay time of the corresponding terminal from a sufficiently large constant value.

【0048】

In a wireless communication system in which the antennas of the terminal and the base station are within the line-of-sight (positional relationship in which the line-of-sight can be obtained), the transmission timing delay from the terminal (for example, ΔtA, ΔtB in FIG. 2) with respect to the base station transmission timing (for example, T1 in FIG. ) Depends almost only on the distance between the two, so it is considered that the transmission timing delay is almost constant as long as the distance does not change.

【0049】

For example, if the propagation delay time of the terminal having the longest distance from the base station among all the terminals communicating with the common base station is Δtm, this Δtm can be set to the constant value.

【0050】

Such a relationship holds even when the number of terminals communicating with the common base station 101 is 3 or more, and the transmitted waves from all the terminals arrive (synchronize) at the same timing, so that the spreading code is an orthogonal code. In a system using the above, the received power from a terminal other than the terminal to be received does not become noise. Therefore, the signal-to-noise ratio of the received data is not affected by the terminals transmitting at the same time, and it is possible to maintain a good state.

【0051】

In an actual device, the transmission timing offset value with respect to the memory 711 may be stored by measuring the distance from the terminal to the base station 101 when each terminal is installed.

【0052】

(A-3) Effect of the first embodiment According to this embodiment, since the received waves arriving from each terminal can be synchronized, Φ can be set to zero in the above equation, the signal-to-noise ratio (communication quality) between each terminal, and It is possible to improve the number of terminals (system capacity) that can be transmitted at the same time.

【0053】

(B) Second embodiment (B-1) Configuration of Second Embodiment FIG. 8 shows the configuration of the base station 12 of the fixed station wireless system of the present embodiment. The configuration of the terminal that communicates with the base station 12 may be the same as that of the terminal 11 of FIG. 1 described above, but from the functional aspect, as will be described later, the terminal 11 has in the description of the first embodiment. It is necessary to equip the functions that were not available.

【0054】

In the present embodiment, the terminal having such a function is referred to as a terminal 11.

【0055】

In FIG. 8, the base station 12 includes M receivers (810 to 812) 1 to M, and the internal configuration of each receiver is the reception spread code generator 806, the despreader 807, and the reception timing. It consists of a regulator 808, a transmission line decoder 809, and a timing comparator 820.

【0056】

The base station 12 includes a CPU 801 and a transmission line encoder 802, a reference clock generator 803, a transmission spreading code generator 804, and a spreader 805 outside the receivers 1 to M.

【0057】

Since the components of the base station 12 other than the timing comparator 820 correspond to the components of the base station 101 shown in FIG. 4, detailed description thereof will be omitted.

【0058】

That is, the CPU 801 corresponds to the CPU 501, the transmission line encoder 802 corresponds to the transmission line encoder 502, the reference clock generator 803 corresponds to the reference clock generator 503, and the transmission diffusion code generator 804. Corresponds to the transmit diffuse code generator 504, the diffuser 805 corresponds to the diffuser 505, the receive diffuse code generator 806 corresponds to the receive diffuse code generator 506, and the despreader 807 corresponds to the despread. The reception timing regulator 808 corresponds to the reception timing regulator 508, and the transmission line decoder 809 corresponds to the transmission line decoder 509.

【0059】

The timing comparator 820 is a circuit that counts the difference between the transmission timing and the reception timing with a reference clock and supplies the result to the CPU 801.

【0060】

The terminal 11 diffuses and transmits the transmitted wave at the transmission timing that matches the received reception timing of the transmitted wave of the base station 12. Therefore, in the base station 12, the substantial distance between the base station 12 and the corresponding terminal can be obtained by obtaining the difference between the transmission timing and the reception timing in the base station 12.

【0061】

The timing comparator 820 receives inputs from the transmission spreading code generator 804 to detect the transmission timing and from the reception spreading code generator 806 to obtain the reception timing, and further obtains the reference clock to obtain the reference clock. The input is also obtained from the generator 803, and the obtained output is supplied to the CPU 801.

【0062】

Hereinafter, the operation of the second embodiment having the above configuration will be described with reference to FIG.

【0063】

(B-2) Operation of the second embodiment In FIG. 9, which shows the state transition of the terminal 11, when the terminal 11 is newly installed (901), the base station 12 makes a test transmission request to the terminal 11.

【0064】

Upon receiving this request, the newly installed terminal 11 starts transmitting to the base station 12 (902). The transmission timing at this time matches the reception timing by the terminal 11 as in the conventional case.

【0065】

When the base station 12 detects the test transmission wave from the terminal 11, the base station 12 transmits the transmission timing (pulse indicating the beginning of the transmission code) from the transmission diffusion code generator 804 to the timing comparator 820 from the reception diffusion code generator 806. The reception timing (pulse indicating the beginning of the reception code) is sent.

【0066】

The timing comparator 820 counts the difference between the transmission timing and the reception timing with the reference clock, and sends the result to the CPU 801. The CPU 801 generates a timing difference counted by the timing comparator 820 as a message and transmits it to the terminal 11.

【0067】

Upon receiving the timing difference information, the terminal 11 stops the test transmission and stores the timing difference information in the memory 711. After setting this value in the transmission timing adjuster 710, the terminal 11 is in a state where normal information transmission (data transmission) can be performed (903).

【0068】

After that, the state of the terminal 11 transitions between the idle / standby state (904) and the data transmission state (905).

【0069】

When the fluctuation range of the timing difference information is large, such as when the mobility of the terminal 11 is high, the processing in the terminal 11 continues data transmission after receiving the timing difference information, and applies the timing difference indicated by the timing difference information. It is advisable to make corrections slowly so that the base station 12 can follow during data transmission.

【0070】

Then, after the correction is completed, the base station 12 can count the timing difference again, and after confirming that the transmission timing and the reception timing difference have become zero, the transmission of the terminal 11 can be stopped.

【0071】

(B-3) Effect of the second embodiment According to the present embodiment, unlike the first embodiment, it is not necessary to measure the distance from the terminal to the base station 101 and obtain the transmission timing offset value each time each terminal is installed, which is efficient. Is.

【0072】

Further, when the base station and the terminal are out of sight, the radio wave is reflected and propagated to a plurality of buildings, and it is extremely difficult to measure the distance of the propagation path. However, according to the present embodiment, the actual received wave at the base station. Since accurate timing adjustment is possible by measuring the timing, it is possible to minimize interference between terminals regardless of whether or not a line of sight is obtained, and improvement in communication quality can be expected.

【0073】

Further, in this way, when the line-of-sight cannot be obtained, the propagation delay amount can fluctuate even if the terminal does not move, so that the efficiency of the measurement of the propagation delay amount according to the present embodiment works more effectively. ..

【0074】

(C) Third embodiment (C-1) Configuration of Third Embodiment Since the configuration of the terminal used in the present embodiment is exactly the same as that of the terminal 11 shown in FIG. 1 and the configuration of the base station is exactly the same as that of the base station 12 shown in FIG. 8, these explanations will be omitted.

【0075】

However, in terms of functionality, as will be described later, both the terminal 11 and the base station 12 of the present embodiment are equipped with functions different from those of the terminal 11 and the base station 12 described above.

【0076】

Hereinafter, the operation of the third embodiment having the above configuration will be described with reference to FIG.

【0077】

(C-2) Operation of the third embodiment In FIG. 10 showing the state transition of the terminal 11 of the present embodiment, the terminal 11 is characterized in that the timing is corrected every time before starting the data transmission.

【0078】

In FIG. 10, when the terminal 11 is installed (1001), the terminal 11 immediately enters the idle / standby state (1002) and makes a communication request (access request) to the base station 12 (1003).

【0079】

When the base station 12 receives a communication request from the terminal 11, the difference between the transmission timing of the base station 12 and the transmission timing from the terminal 11 is measured by using the timing comparator 820, and the correction value of the timing is transmitted to the terminal 11. ..

【0080】

The terminal 11 that receives this corrects the transmission timing (1004). The transmission timing is corrected little by little so that the base station 12 can follow the timing fluctuation (for example, 1/8 clock or less in 80 msec).

【0081】

When the base station 12 confirms that the transmission timing of the terminal 11 has been corrected, the base station 12 transmits the permission to start communication to the terminal 11.

【0082】

The terminal 11 that has received the communication start permission performs data communication (message communication) (1005) with the base station 12, and then transitions to the idle / standby state (1002) again.

【0083】

(C-3) Effect of the third embodiment According to the present embodiment, even when the propagation characteristics between the base station and the terminal change from the time of installation, for example, when a building is constructed after the terminal is installed, the transmission timing from the terminal is set every time the terminal starts transmitting. Since the base station measures and issues a timing adjustment instruction to the terminal, the signal from the terminal is received by the base station at the same timing even when the propagation characteristics change.

【0084】

That is, it can be expected to maintain synchronization between terminals even in urban areas where the propagation characteristics are liable to fluctuate and where buildings are densely packed, and to suppress deterioration of communication quality and system capacity.

【0085】

(D) Fourth Embodiment (D-1) Configuration of Fourth Embodiment Since the configuration of the terminal used in the present embodiment is exactly the same as that of the terminal 11 shown in FIG. 1 and the configuration of the base station is exactly the same as that of the base station 12 shown in FIG. 8, these explanations will be omitted.

【0086】

However, in terms of functionality, as will be described later, both the terminal 11 and the base station 12 of the present embodiment are equipped with functions different from those of the terminal 11 and the base station 12 described above.

【0087】

Hereinafter, the operation of the fourth embodiment having the above configuration will be described with reference to FIG.

【0088】

(D-2) Operation of the fourth embodiment FIG. 11 shows the state transition of the terminal 11 of the present embodiment. The present embodiment is characterized in that the transmission timing of the terminal 11 is periodically corrected during data communication.

【0089】

In FIG. 11, the terminal 11 that has been in the idle / standby state (1102) after installation can transition between the access request state (1003), the timing adjustment state (1004), and the message transmission state (1105). ..

【0090】

On the other hand, the base station 12 always measures the difference between the transmission timing of the base station 12 and the transmission timing of the terminal 11 during data communication with the terminal 11. Then, the CPU 801 of the base station 12 determines that the transmission timing of the terminal 11 has shifted when the measured timing difference exceeds a certain threshold value (1/2 clock).

【0091】

At this time, the base station 12 transmits a timing correction value in addition to the communication data to be transmitted to the terminal 11, and instructs the terminal 11 to adjust the transmission timing.

【0092】

On the terminal 11 side, communication data and timing correction data are identified by the CPU 701 from the received data, and if there is timing correction data, the transmission timing is adjusted according to the correction value (1104).

【0093】

The adjustment of the transmission timing is controlled by the CPU 701 so that it is within 1/8 clock in 80 msec as shown in the third embodiment.

【0094】

Although the operation during communication between the base station 12 and the terminal 11 has been described here, the above processing may be performed after adjusting the timing before the start of communication shown in the third embodiment.

【0095】

The reception timing of the signal from the terminal 11 received by the base station 12 varies depending on the distance between the base station 12 and the terminal 11. Therefore, when the terminal 11 moves during communication as in a mobile phone system, it is necessary to correct the transmission timing of the terminal 11 according to the movement of the terminal 11.

【0096】

In the present embodiment, the base station 12 constantly monitors the reception timing during communication and informs the terminal 11 of the transmission timing correction value of the terminal 11. Therefore, even when the terminal 11 moves, the signal from the terminal 11 is the base station. At 12, it will be received at the same timing.

【0097】

(D-3) Effect of Fourth Embodiment According to the present embodiment, even when the terminal 11 moves, it is possible to maintain synchronization between radio waves arriving from a plurality of terminals at the same time, and it is possible to suppress deterioration of communication quality and system capacity.

【0098】

(E) Fifth embodiment (E-1) Configuration of Fifth Embodiment FIG. 13 shows the configuration of the terminal 14 which is the terminal of the present embodiment.

【0099】

In FIG. 13, the terminal 14 is a CPU 1301, a reference clock generator 1302, a reception timing regulator 1303, a reception spread code generator 1304, a despreader 1305, a transmission line decoder 1306, a transmission line encoder 1307, and a transmission spreading code. It is equipped with a generator 1308, a diffuser 1309, a transmission timing adjuster 1310, a memory 711, and a timing control information extractor 1312.

【0100】

Of these, the components other than the timing control information extractor 1312 correspond to each component shown in FIG. 1, and therefore detailed description thereof will be omitted.

【0101】

That is, the CPU 1301 corresponds to the CPU 701, the reference clock generator 1302 corresponds to the reference clock generator 702, the reception timing regulator 1303 corresponds to the reception timing regulator 703, and the reception spreading code generator 1304 corresponds to the above. Corresponding to the receive spreading code generator 704, the despreader 1305 corresponds to the despreader 705, the transmission line decoder 1306 corresponds to the transmission line decoder 706, and the transmission line encoder 1307 corresponds to the transmission line. Corresponding to the encoder 707, the transmission diffusion code generator 1308 corresponds to the transmission diffusion code generator 708, the diffuser 1309 corresponds to the diffuser 709, and the transmission timing regulator 1310 corresponds to the transmission timing regulator 710. The memory 1311 corresponds to the memory 711.

【0102】

The transmission timing extractor 1310 is a circuit for extracting timing control information periodically inserted in the received signal. The input is obtained from the transmission line decoder 1306, and the output is the CPU 1301 and the transmission timing adjuster. Supply to 1310.

【0103】

On the other hand, the configuration of the base station 13 of the present embodiment that communicates with such a terminal 14 is as shown in FIG.

【0104】

In FIG. 12, the base station 13 includes M receivers (1210 to 1212) 1 to M, and the internal configuration of each receiver is as follows: reception spread code generator 1206, reverse spreader 1207, reception timing. It consists of a regulator 1208, a transmission line decoder 1209, and a timing comparator 1220.

【0105】

Then, the base station 13 is outside the receivers 1 to M, in addition to the CPU 1201, the transmission line encoder 1202, the reference clock generator 1203, the transmission spreading code generator 1204, the spreader 1205, the timing comparator 1220, and the multiplexer 1221. It has.

【0106】

Since the components of the base station 13 other than the multiplexer 1221 correspond to the components of the base station 12 shown in FIG. 8, detailed description thereof will be omitted.

【0107】

That is, the CPU 1201 corresponds to the CPU 801, the transmission line encoder 1202 corresponds to the transmission line encoder 802, the reference clock generator 1203 corresponds to the reference clock generator 803, and the transmission diffusion code generator 1204 Corresponds to the transmit diffuser code generator 804, the diffuser 1205 corresponds to the diffuser 805, the receive diffuser code generator 1206 corresponds to the receive diffuser code generator 806, and the despreader 1207 corresponds to the reverse spreader. Corresponding to the device 807, the reception timing regulator 1208 corresponds to the reception timing regulator 808, the transmission line decoder 1209 corresponds to the transmission line decoder 809, and the timing comparator 1220 corresponds to the timing comparator 820. To do.

【0108】

The multiplexer 1221 is a circuit that periodically switches the selection of two inputs obtained from the transmission line encoder 1202 and the timing comparator 1220, and the timing control value obtained by the timing comparator 1220 can be obtained by this selection switching, for example. It will be periodically inserted into the information symbol once every 80 msec.

【0109】

Hereinafter, the operation of the fifth embodiment having the above configuration will be described.

【0110】

(E-2) Operation of the fifth embodiment The base station 13 measures the transmission timing difference between the base station 13 and the terminal 14 with the timing comparator 1220.

【0111】

The timing comparator 1220 quantizes the measured timing difference and outputs it once every 80 msec.

【0112】

For example, the quantization method is 1 if the transmission timing of the terminal 14 is to be advanced, and 0 if the transmission timing is to be delayed. The quantized timing control value is input to the multiplexer 1221 and added to the transmission line coded transmission symbol. As a result, the timing control value is periodically inserted into the information symbol string once every 80 msec described above.

【0113】

The transmission symbol to which the timing control value is added is spread-modulated and transmitted by the diffuser 1205.

【0114】

The terminal 14 inputs the symbol obtained by demodulating the received signal by the despreader 1305 to the timing control information extractor 1312. The timing control information extractor 1312 extracts the timing information inserted periodically and outputs it to the transmission timing adjuster 1310.

【0115】

In the transmission timing adjuster 1310, if the input from the timing information extractor 1312 is 1, the transmission timing is advanced by, for example, 1/8 clock, and if it is 0, the transmission timing is delayed by 1/8 clock to adjust the timing. Do.

【0116】

(E-3) Effect of the fifth embodiment According to this embodiment, since the timing correction value obtained by the timing comparator 1220 is inserted without passing through the CPU 1201, it is possible to transmit and receive the correction value at high speed up to the limit of the hardware. It becomes.

【0117】

The fact that the transmission / reception of the timing correction value can be performed at high speed means that the transmission timing control of the terminal 14 can be performed at high speed, and the transmission timing of the terminal 14 is followed by the fluctuation of the propagation characteristics at high speed and the movement of the terminal 14. It means that it is possible to make it.

【0118】

In addition, since high-speed control is performed, the time for which the incoming waves arriving from a plurality of terminals at the same time is out of synchronization is shortened, and it can be expected that deterioration of communication quality and deterioration of system capacity can be suppressed.

【0119】

Further, since the timing adjustment value to be periodically transmitted is suppressed to the width that the base station 13 can follow, it is not necessary to consider the speed of the timing correction on the terminal 14 side, and the processing load of the terminal 14 is reduced.

【0120】

(F) Other embodiments Due to the nature of each of the above embodiments, it is preferable that the terminals of the first and second embodiments are fixedly installed as described above, and the terminals of the third to fifth embodiments are highly mobile. However, since the mobility of the terminal is a relative concept, it is not always necessary to set such a limitation in applying the present invention.

【0121】

For example, when the present invention is applied to a mobile communication system or the like, the terminal installation shown in FIGS. 9 and 10 can be omitted.

【0122】

Further, fixedly installed terminals and highly mobile terminals may coexist in one wireless communication system.

【0123】

Since the first to fifth embodiments are not essentially inconsistent with each other, they can be appropriately combined and used in the same terminal and the same base station.

【0124】

Further, in the above, although the base station has M receivers, it has only one transmission component (for example, circuits 502 to 505 in FIG. 4) (one set). There are no such structural restrictions. For example, it may be equipped with the same number of M transmission components as the receiver.

【0125】

Further, in the above, the timing comparator for measuring the distance is mounted on the base station side, but the timing comparator may be mounted on the terminal side so that the terminal measures the distance. In this case, regarding the distance measurement, the operation of the base station and the operation of the terminal are interchanged with each other.

【0126】

Further, although hardware is used in the above embodiment, the present invention can also be realized by using software.

【0127】

Further, in the above embodiment, the orthogonal code is used as the diffusion code, but the present invention can be expected to exert an effect also on the diffusion code to which the orthogonality is not imparted.

【0128】

This is because, in general, it is considered that there is a preferable phase relationship between a plurality of diffusion code sequences in which the value of the cross-correlation is the lowest (or relatively) and the influence of interference is reduced when the base station receives the signal. This is because the present invention can ensure the realization of the phase relationship.

【0129】

That is, the present invention can be widely applied to wireless terminals, wireless base stations, and wireless communication systems in which a plurality of wireless terminals are code-division multiple access to a common wireless base station.

【0130】

[Effect of the invention]

As described above, according to the present invention, when the transmission wave spread-modulated using the uplink code for the uplink assigned to each wireless terminal is received by a common wireless base station, a preferable correlation is established. Since it can be controlled as shown, it is possible to improve the signal-to-noise ratio (communication quality) between each wireless terminal in the wireless base station and the number of wireless terminals capable of simultaneous transmission (system capacity).

[Simple explanation of drawings]

[Figure 1]

It is a block diagram which shows the structure of the terminal which concerns on embodiment.

[Figure 2]

It is a time chart regarding a conventional technique and an embodiment.

[Fig. 3]

It is a schematic diagram which shows the structure of the wireless communication system which concerns on a prior art.

[Fig. 4]

It is a block diagram which shows the structure of the base station which concerns on the prior art and embodiment.

[Fig. 5]

It is a block diagram which shows the structure of the terminal with respect to the prior art, and embodiment.

[Fig. 6]

It is a time chart regarding a conventional technique and an embodiment.

[Fig. 7]

It is the schematic for demonstrating the problem which the invention tries to solve.

[Fig. 8]

It is a block diagram which shows the structure of the base station which concerns on embodiment.

[Fig. 9]

It is a state transition diagram of the terminal which concerns on embodiment.

[Fig. 10]

It is a state transition diagram of the terminal which concerns on embodiment.

[Fig. 11]

It is a state transition diagram of the terminal which concerns on embodiment.

[Fig. 12]

It is a block diagram which shows the structure of the base station which concerns on embodiment.

[Fig. 13]

It is a block diagram which shows the structure of the terminal which concerns on embodiment.

[Explanation of symbols]

11,14 ... Terminal, 12,13 ... Base station, 703 ... Receive timing adjuster, 704 ... Receive spread code generator, 708 ... Transmission spread code generator, 710 ... Transmission timing regulator, 711 ... memory, 810 ~ 812 ... receiver, 820 ... timing comparer, 1221 ... multiplexer.