Transmitter/receiver for base station

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a transmission / reception device of a base station that repeats a transmission mode and a reception mode, transmits a signal in the transmission mode, and receives a signal in the reception mode. In particular, TDD (Time Divisional Duplex) is used in a PHS (Personal Handyphone system) or the like. Related to the transmitter / receiver of the mobile communication base station used.

【0002】

[Conventional technology]

In order to reduce the load on the hardware on the terminal side and realize small size, light weight, and long standby time, PHS realizes bidirectional information transmission by TDD. TDD alternates transmission and reception in time division. For example, in the case of PHS, the transmission / reception timing of the 4-channel multiplex TDMA-TDD method is shown in Fig. 23, and transmission 4 (CH1 TX to CH4 TX) and reception 4 (CH1 RX to CH4 RX) are each in 1 frame 5ms. Exchange 625 μs slots. In FIG. 23, CS (Cell Station) is a base station, PS1 to PS4 (PS: Personal Station) are slave stations that are mobile stations, TS is a transmission mode period of a base station, and RS is a reception mode period of a base station. Information is transmitted from the base station CS to the four slave stations PS1 to PS4 at the timing shown as a burst signal of 625 μs in 5 ms. In addition, each slave station PS1 to PS4 transmits the transmission information of its own station in a burst of 625 μs 2.5 ms after receiving the signal from the base station CS.

【0003】

When multiple PHS operators have recently placed base stations densely in the same area, transmission / reception interference becomes a problem. This is because the frames are not synchronized between the PHS operators, so when the base station is started independently, the transmission slot of the base station of the operator A overlaps with the reception slot of the base station of the adjacent operator B. This is because it interferes with the reception of radio waves from the slave station of the operator B.

【0004】

The simplest way to solve this problem is to transmit a frame synchronization signal between base stations via a cable and switch the transmission / reception timing according to the frame synchronization signal received by each station. However, each base station is usually installed independently, and even in the building next to it, it is not easy and unrealistic to connect the base stations with each other with a cable. Moreover, if an attempt is made to send a frame synchronization signal using a general line, a network for synchronization will be constructed by itself, which is not economical. As one of the means for avoiding the above problems due to cable transmission, a method called air synchronization is used. This air synchronization method is a method in which a base station that will be put into operation later receives radio waves from a base station that has already started operation, and starts up in synchronization with the radio waves.

【0005】

[Problems to be Solved by the Invention]

In the process of establishing synchronization of transmission / reception timing by the air synchronization method, it is necessary for a base station to perform an unusual operation of receiving radio waves emitted by another base station. Therefore, excessive input to the receiver of the base station becomes a problem. Since a base station has a larger transmission output than a slave station, radio waves emitted at a short distance become an excessive input for the base station that receives the radio wave, which causes deterioration of the characteristics of the front-end low noise amplifier or damage in the worst case. Configuring a low-noise amplifier using a device with a large input resistance is not an effective solution because it causes an increase in noise characteristics and a decrease in reception sensitivity. When base stations of different PHS operators are installed in adjacent buildings, or when multiple base station devices are installed in one place to increase the number of subscribers for applications such as WLL (Wireless Local Loop). In particular, they often face the above problems.

【0006】

From the above, it is an object of the present invention that the synchronization of transmission / reception timing between base stations can be established by using the air synchronization method, the characteristics of the low noise amplifier are not deteriorated or damaged, and the reception sensitivity is lowered. It is to provide a transmitter / receiver of a base station that never happens. Another object of the present invention is to provide a base station transmitter / receiver capable of effectively installing a base station by removing restrictions on the installation location of the base station.

【0007】

[Means for solving problems]

(a) First solution FIG. 1 is a configuration diagram of a base station transmitter / receiver for explaining the first solution of the present invention. The TPA is turned on during the transmission mode period TS (see Fig. 23) and turned off during the reception mode period RS, the FE is the front end that amplifies and frequency-converts the received signal, and the DM is provided behind the front end for reception. A demodulator that demodulates data from a signal, ANT is an antenna, ANT-SW is an antenna switch that connects the antenna to the transmitting side and receiving side as appropriate, and AT is provided between the front end and the antenna switch to pass / attenuate the input signal. Attenuation means, TRMG is a signal generator that generates a transmission / reception identification signal TRS indicating whether it is a transmission mode period or a reception mode period, and SYCC is the first and second reception modes (normal reception mode, synchronous control reception mode). Signal V instructing to switch_CONTIs a synchronous control unit that generates. The first reception mode is a normal reception mode, and the second reception mode is a synchronization control reception mode for synchronizing the transmission / reception timing of the own station with the transmission / reception timing of another base station, and is a strong input signal from another station. Is attenuated and received, and the own station is synchronized with another station by using the synchronization information included in the received signal. The attenuation means AT attenuates the input signal during the transmission mode period, passes the reception signal in the first reception mode (normal reception mode) at the time of reception, and attenuates the reception signal in the second reception mode (synchronous control reception mode). ..

【0008】

When the transmission / reception timing cannot be synchronized with other stations in the same location or nearby, or when synchronization is required, the synchronization control unit SYCC uses the reception mode switching signal V._CONTIs output to set the second reception mode. As a result, the attenuation means AT attenuates the strong input signal from another station, inputs it to the demodulation unit DM via the front end FE, and the demodulation unit demodulates the received data. The synchronization control unit SYCC detects synchronization information from the received data, synchronizes it, and returns the reception mode to the first reception mode. The attenuating means can be composed of an attenuator or a switch. By doing so, the synchronization of transmission / reception timing between base stations can be established by using the air synchronization method, and the strong input signal from other stations is attenuated and received, so that the characteristics of the low noise amplifier are deteriorated or damaged. And does not reduce the reception sensitivity. Further, since the transmission / reception timing of the own station can be synchronized with the transmission / reception timing of another station, restrictions on the installation location of the base station can be eliminated, which enables effective installation of the base station.

【0009】

(b) Second solution FIG. 2 is a configuration diagram of a base station transmitter / receiver for explaining the second solution of the present invention, and the same parts as those in FIG. 1 are designated by the same reference numerals. The difference from FIG. 1 is the method of attenuating the received signal in the second reception mode (synchronous control reception mode). In Fig. 1, the received signal was attenuated by the attenuator (attenuator or switch) AT in the second reception mode, but in Fig. 2, the antenna ANT is not connected to the receiving side but connected to the transmitting side in the second receiving mode. This attenuates the received signal. That is, the received signal is attenuated by inputting the leak signal in the switch to the front end. The attenuation means AT does not perform the attenuation operation in the first and second reception modes, passes through the input signal, and performs the attenuation operation only at the time of transmission.

【0010】

When the transmission / reception timing cannot be synchronized with other stations in the same location or nearby, or when synchronization is required, the synchronization control unit SYCC uses the reception mode switching signal V._CONTIs output to set the second reception mode. As a result, the antenna switch ANT-SW connects the antenna ANT to the transmitting circuit side and not to the receiving side. Therefore, the strong input signal from another station is attenuated as a leak in the switch, input to the demodulation unit DM via the front end FE, and the demodulation unit demodulates the received data. The synchronization control unit SYCC detects synchronization information from the received data, synchronizes it, and returns the reception mode to the first reception mode. By doing so, the synchronization of transmission / reception timing between base stations can be established by using the air synchronization method, and the strong input signals from other stations are attenuated in the switch, so that the characteristics of the low noise amplifier are deteriorated or damaged. And does not reduce the reception sensitivity. Further, since the transmission / reception timing of the own station can be synchronized with the transmission / reception timing of another station, restrictions on the installation location of the base station can be eliminated, which enables effective installation of the base station.

【0011】

BEST MODE FOR CARRYING OUT THE INVENTION

(A) First Example (a) Overall configuration FIG. 3 is a configuration diagram of the base station transmitter / receiver according to the first embodiment of the present invention, and shows an example in which the receiving system has two branches. In the figure, 1 and 2 are antennas for both transmission and reception, and two antennas are provided for diversity reception. 3 is an antenna switch that connects the antennas 1 and 2 shared for transmission and reception by switching between the transmission system and the reception system in a time-division manner. During the transmission mode period, the antenna 1 or antenna 2 is connected to the transmission system and the reception mode period. Connect antennas 1 and 2 to the 1st and 2nd receiving systems, respectively. Reference numeral 4 denotes a transmission / reception control unit, which receives a timing signal and outputs a transmission / reception identification signal TRS that has a low level in the transmission mode period TS (see FIG. 23) and a high level in the reception mode period RS. 5 is a demodulation unit that demodulates received data by QPSK demodulation processing, 6 is the first reception system, 7 is the second reception system, 8 is the transmission system, and 9 synchronizes the transmission / reception timing of the own station with the transmission / reception timing of other stations. , Receive mode switching signal V_CONT10 is an attenuator control signal generator that generates an attenuator control signal Vc.

【0012】

In the first and second receiving systems 6 and 7, 11 and 21 are attenuators with variable attenuation, attenuate the transmission signal leaked from the antenna switch 3 at the time of transmission, and receive the reception received by the antennas 1 and 2 at the time of reception. Pass the signal. In the attenuators 11 and 21, the transmission / reception identification signal TRS has the maximum attenuation at the low level (transmission mode period) and the minimum attenuation at the high level (reception mode period). This prevents leakage of the transmitted wave from the antenna switch 3 during transmission as an excessive input to the front end of the next stage, causing deterioration or damage. 12 and 22 are front ends having a low noise RF amplifier and frequency converter, and after amplifying the received signal in the 1.9 GHz band, the frequency is converted into the first intermediate frequency signal in the 250 MHz band. 13,23 are bandpass filters that pass the first intermediate frequency signal, 14 and 24 are amplifiers that amplify the first intermediate frequency signal, and 15,25 are the first intermediate frequency signal in the 250MHz band and the second at 10MHz. Frequency converter that down-converts to the frequency signal of, 16 and 26 are bandpass filters, 17 and 27 amplify the second intermediate frequency signal and signal RSSI (Received Signal) proportional to the received electric field strength of antennas 1 and 2, respectively. It is a limiter amplifier that outputs (Strength Indicator).

【0013】

The demodulation unit 5 synthesizes the second intermediate frequency signals output from the limiter amplifiers 17 and 27 by the maximum-ratio combining method, and then demodulates QPSK to demodulate and output the received data. The synchronization control circuit 9 detects the synchronization word UW from the received data output from the demodulation unit 5, and synchronizes the transmission / reception timing of its own station with the transmission / reception timing of another station based on the detection result. In the transmission system, 31 is an orthogonal modulator that QPSK orthogonally modulates the carrier signal with the transmitted data, 32 is a frequency converter that upconverts the orthogonally modulated signal to the 1.9 GHz band, and 33 is a band path that passes through the 1.9 GHz band radio signal. The filter, 34, is a transmission high-power amplifier (transmission power amplifier), which amplifies the radio signal and radiates it into the air from the antenna 1 or the antenna 2 via the antenna switch 3.

【0014】

(b) Attenuator FIG. 4 shows an example of a circuit of the attenuators 11 and 21, and as shown in FIG. 5, the attenuation amount decreases as the control signal Vc increases. That is, when the control signal Vc is increased, the DC path shown by the dotted line is formed, and the diode D1 is forward biased. Therefore, the signal V input to the input terminal_INIs V from the output terminal via the diode D1_OUTIs sent as. On the other hand, when the control signal Vc becomes smaller, the DC path indicated by the alternate long and short dash line is formed, and the input signal V_INIs output to the output terminal via capacitor C diode D2 resistor R diode D3 capacitor C, so the degree of attenuation increases. Therefore, the degree of attenuation of the attenuator can be controlled to two values by setting the control voltage Vc to high level H or low level L.

【0015】

Figure 6 shows another example of the attenuator circuit, which is a switch-like input signal V._INIt passes / attenuates. As shown in FIG. 7, the first control signal V is used to make the pass state._CO_NT1Is set to high level (= Vcc), and the second control signal V_CONT2To low level (= 0). In this way, the first and second control signals V_CONT1, V_CONT2When biased, a DC path is formed in the direction of the dotted arrow, the diode D1 becomes conductive, and the diode D2 becomes non-conducting. Therefore, the input signal V_INIs V from the output terminal via diode D1_OUTIs sent as. On the other hand, in order to put it in the attenuated state, the first control signal V_CONT1Is set to low level (= 0), and the second control signal V_CONT2To high level (= Vcc). In this way, the first and second control signals V_CONT1, V_CONT2When biased, a DC path is formed in the direction of the alternate long and short dash arrow, the diode D2 becomes conductive, and the diode D1 becomes non-conducting. Therefore, the input signal V_INDoes not appear at the output terminal and is attenuated.

【0016】

(c) Antenna switch FIG. 8 is a configuration diagram of the antenna switch 3, which is provided with three switches 3a to 3c inside, and the antenna 1 or the antenna 2 is connected to the transmission system 8 as appropriate, or the antennas 1 and 2 are connected to the first and second. It is designed to connect to receiving systems 6 and 7. Each switch 3a to 3c has a C terminal into which a signal is input, an A terminal and a B terminal for selectively outputting a signal, and a control terminal for controlling which of the A and B terminals the signal is output.

【0017】

Figure 9 shows an example of a switch circuit, where IC1 is an inverter and IC2 is an IC circuit. IC circuit IC2 outputs a low level signal to the a terminal and a high level signal to the b terminal when the control signal SWC is high level, and high level to the a terminal and low to the b terminal when the control signal SWC is low level. Output the level signal. Therefore, if the control signal SWC is at a high level, the diode D1 has a forward bias and the diode D2 has a reverse bias, and the signal V input from the C terminal._INIs output from the A terminal. Conversely, if the control signal SWC is low level, diode D1 is reverse biased, diode D2 is forward biased, and signal V._INIs output from the B terminal.

【0018】

(d) Normal control FIG. 10 is an operation explanatory diagram of the transmission power amplifier 34, the antenna switch 3, and the attenuators 11 and 21 during the normal transmission mode period and the reception mode period. That is, the transmission power amplifier 34 performs the amplification operation at the time of transmission (transmission / reception identification signal TRS = low level), and stops the amplification operation at the time of reception (TRS = high level). Further, the antenna switch 3 connects the antenna 1 or the antenna 2 to the transmission system 8 at the time of transmission, and connects the antennas 1 and 2 to the first and second reception systems 6 and 7 at the time of reception, respectively. In addition, the attenuators 11 and 21 perform an attenuation operation during transmission, thereby attenuating the transmission signal leaked to the first and second receiving systems via the antenna switch 3, and receiving by the antenna 1 and antenna 2 during reception. The received signal is input to the front ends 12 and 22 without being attenuated.

【0019】

The reason why the attenuators 11 and 21 are attenuated during transmission is that the transmission signal amplified by the transmission power amplifier 34 leaks from the antenna switch 3 to the receiving side, and this leakage of the transmission signal prevents deterioration and destruction of the front ends 12 and 22. To do. For example, the transmission output has an average of about +29 dBm in the burst, and even if it is attenuated by 30 dB due to the isolation of the antenna switch 3, it is added to the receiving system at about 0 dBm. On the other hand, the maximum input resistance level of the front ends 12 and 22 is often around -20 dBm. Therefore, attenuators 11 and 21 are inserted on the input side of the front end to perform an attenuation operation at the time of transmission, and the leakage of the transmitted wave is attenuated to protect the front end.

【0020】

When the transmission / reception identification signal TRS becomes low level during transmission, the transmission power amplifier (PA) 34 performs amplification operation, the antenna switch 3 connects between the transmission system 8 and antenna 1, and the attenuators 11 and 21 operate in attenuation. .. As a result, the radio signal power amplified by the transmission power amplifier 34 is radiated into space from the antenna 1, and the leakage of the transmission signal is attenuated by the attenuators 11 and 21. When the transmission / reception identification signal TRS becomes high level during reception, the transmission power amplifier (PA) 34 stops the amplification operation, and the antenna switch 3 connects the antennas 1 and 2 to the first and second reception systems 6 and 7, respectively. , Antennas 11 and 21 are in the passing state. As a result, the received signals received by the antennas 1 and 2 are amplified and frequency-converted and input to the demodulation unit 5, and the demodulation unit 5 synthesizes the signals input from the first and second reception systems at the maximum ratio. After synthesizing by the method, QPSK demodulates and the received data is demodulated and output.

【0021】

(e) Synchronous control When multiple base stations are installed at one location (for example, on both sides of one pillar) using WLL (Wireless Local Loop), etc., the maximum transmission wave of the base station device CS that has been put into operation is -5 dBm. It is calculated that it reaches another base station CS in a certain degree, and the base station CS that starts up later in a state of being out of synchronization will be exposed to excessive input at the time of reception. According to the present invention, the attenuators 11 and 21 are controlled at the start-up of the base station control device CS to protect the front ends 12 and 22 from being over-input until air synchronization is established.

【0022】

(e-1) Establish synchronization The transmission slot includes a control slot for transmitting notification information, simultaneous call information, control information required for call connection, and a communication slot for transmitting traffic. The base station CS transmits control information to the slave station in the predetermined slot in the format shown in FIG. 11 (a), and transmits the control information to the slave station in the predetermined slot (communication slot) in the format shown in FIG. 11 (b). In the formats shown in FIGS. 11 (a) and 11 (b), R is the 4-bit transient response lamp time (burst transient response time) to guarantee the rise time, and SS is the start symbol (fixed to 10) indicating the start of the signal. , PR is a preamble for regenerating the clock from the received signal and establishing bit synchronization between the base station / slave station, and UW is a synchronization word for taking frame synchronization, as shown in FIG. 11 (c). Different patterns are specified for control uplink / downlink and communication uplink / downlink. CI is the channel identifier indicating what control channel (notification channel, simultaneous call channel, individual cell channel, information channel, etc.) is being sent in the corresponding slot, I is the information part such as control information and voice data, and CRC is incorrect. It is an inspection bit.

【0023】

The synchronization word UW is generated after different times from the beginning of the control slot and the communication slot. Therefore, as shown in FIG. 11A, a window WID having a time width corresponding to UW and CI is set after a time Tw after detecting the rising edge of the input, and the UW bit of the downlink control channel is set in the window WID. If the pattern is detected, it can be determined that the rise time is the start of the transmission time slot. In the case of 4 multiplex TDMA-TDD, since the downlink control channel is located in the first slot, the above rise time is the rise time of the transmission period of another base station. From the above, if a transmission signal from another base station is received and the rise time of the transmission slot is detected by the above method, it is possible to synchronize the transmission / reception timing of the own station with the transmission / reception timing of the transmission / reception device of the other base station. ..

【0024】

(e-2) Synchronous control of the first embodiment In addition to the normal reception mode, a reception mode (synchronous control reception mode) for synchronizing the transmission / reception timing of the own station with the transmission / reception timing of another station is provided. Then, in the transmission mode / normal reception mode / synchronous control reception mode, the transmission power amplifier 34, the antenna switch 3, and the attenuators 11 and 21 are controlled according to the operation explanatory chart shown in FIG. That is, during transmission and normal reception, the transmission power amplifier 34, the antenna switch 3, and the attenuators 11 and 21 are controlled in the same manner as in the operation explanatory chart of FIG. However, in the synchronous control reception mode, the strong input signals from other base stations are attenuated and controlled so that the synchronous control circuit 9 can detect the UW bit pattern. Therefore, in the synchronous control reception mode, the antennas 1 and 2 are connected to the first and second reception systems 6 and 7, and the attenuators 11 and 21 are attenuated. However, the amplification operation of the transmission power amplifier 34 is stopped.

【0025】

In the synchronous control reception mode, the attenuation operation of the attenuators 11 and 21 can attenuate the excessive input to the front ends 12 and 22 by 20 to 30 dB, preventing deterioration and damage of the characteristics of the low noise amplifier that constitutes the front end. it can. From the above, a strong signal transmitted from another station is received, attenuated, frequency-converted, amplified and input to the demodulation unit 5, and the demodulation unit demodulates and outputs the received data. The synchronization control circuit 9 detects the synchronization word UW from the received data and synchronizes the transmission / reception timing of its own station with the transmission / reception timing of another station.

【0026】

(e-3) Attenuator attenuation / passage control FIG. 13 is a configuration diagram of the attenuator control signal generation unit 10 that passes / attenuates the attenuators 11 and 21 according to the operation explanatory chart of FIG. In the figure, 4 is a transmission / reception control unit that outputs a transmission / reception identification signal TRS that is low level in the transmission mode period and high level in the reception mode period, and 9 is a mode switching signal V that switches between normal reception mode / synchronous control reception mode._CONT10 is an attenuator control signal generator that generates an attenuator control signal Vc, and 11 is an attenuator having the configuration shown in FIG. The attenuator control signal generator 10 is a transmission / reception identification signal TRS and a reception mode switching signal V._CONTIt has an and gate 10a that calculates the logical product of and outputs the attenuator control signal Vc.

【0027】

As is clear from FIG. 4, the attenuator 11 passes through when the attenuator control signal Vc is high level H, and attenuates when the attenuator control signal Vc is low level L. Therefore, in order to control the attenuator 11 according to the operation explanation chart of FIG. 12, (1) Vc = low level L in the transmission mode, (2) Vc = high level H in the normal reception mode, and (3) in the synchronous control reception mode. Vc = low level L needs to be set. Therefore, as shown in FIG. 14, the synchronous control circuit 9 has (1) a mode switching signal V in the normal reception mode._CONTIs set to high level H, and (2) in the synchronous control reception mode, the mode switching signal V_CONTTo low level L. However, in the transmission mode, the mode switching signal V_CONTCan be either H or L. As a result, the attenuator control signal generator 10 uses the transmission / reception identification signal TRS and the mode switching signal V._CO_NTAnd is calculated, an attenuator control signal Vc is generated in each mode as shown in FIG. 14, and the attenuators 11 and 21 are attenuated / passed controlled by the control signal Vc as shown in the operation explanatory chart of FIG.

【0028】

(B) Second Example (a) Overall configuration FIG. 15 is a configuration diagram of a base station transmitter / receiver according to a second embodiment of the present invention, and the same parts as those of the first embodiment of FIG. 3 are designated by the same reference numerals. In the second embodiment, the differences from the first embodiment of FIG. 3 are that (1) the attenuator control signal generation unit 10 is deleted and the antenna switch control unit 50 is provided in its place, and (2) the operation of FIG. The point that each part of the transmitter / receiver is controlled according to the explanatory chart, and the point that the received signal is attenuated by connecting the antenna to the transmitting system instead of connecting the antenna to the receiving system in the synchronous control receiving mode.

【0029】

(b) Synchronous control In the second embodiment, in the transmission mode / normal reception mode / synchronous control reception mode, the transmission power amplifier 34, the antenna switch 3, and the attenuators 11 and 21 are controlled according to the operation explanatory chart shown in FIG. That is, during transmission and normal reception, the transmission power amplifier 34, the antenna switch 3, and the attenuators 11 and 21 are controlled in the same manner as in the operation explanatory chart of FIG. However, in the synchronous control reception mode, the strong input signals from other base stations are attenuated and controlled so that the synchronous control circuit 9 can detect the UW bit pattern. Therefore, in the synchronous control reception mode, the antennas 1 and 2 are not connected to the first and second reception systems 6 and 7, but are connected to the transmission system 8. In this way, even if a strong input signal is received from another base station, the signal can be prevented from being directly input to the receiving system. That is, the leakage signal from the antenna switch 3 becomes the input of the first and second receiving systems 6 and 7, and the strong input signal from the other base station is attenuated even if it is not attenuated by the attenuators 11 and 21. By such an attenuation operation, the excessive input to the front ends 12 and 22 can be attenuated by 20 to 30 dB, and the characteristics deterioration and damage of the low noise amplifier constituting the front end can be prevented. From the above, the signals transmitted from other stations are attenuated by the antenna switch, then frequency-converted and amplified and input to the demodulation unit 5, and the demodulation unit demodulates the received data and outputs it. The synchronization control circuit 9 detects the synchronization word UW from the received data and synchronizes the transmission / reception timing of its own station with the transmission / reception timing of another station.

【0030】

(c) Antenna switch switching control FIG. 17 is a chart showing the signal output terminals and control signal logic (H, L) of the three switches 3a to 3c constituting the antenna switch 3 (see FIG. 8) according to the operation explanatory chart of FIG. It is necessary to connect antenna 1 or antenna 2 to transmission system 8 at the time of transmission. Therefore, the signal output terminals of the switches 3a, 3b, 3c are set to A, A, *. Note that * means that the output terminal may be either A or B. During normal reception, it is necessary to connect antennas 1 and 2 to the first and second receiving systems 6 and 7. Therefore, the signal output terminals of the switches 3a, 3b, 3c are set to B, B, *. At the time of synchronous control reception, antennas 1 and 2 must not be connected to the first and second receiving systems 6 and 7. Therefore, the signal output terminals of the switches 3a, 3b, 3c are set to A, A, *.

【0031】

As is clear from FIG. 9, the switches 3a to 3c appear at the terminal A when the control signal SWC is high level H and at the terminal B when the control signal SWC is low level L. Therefore, assuming that each switch 3a to 3c selects output terminals A and B as shown on the left side of FIG. 17, the antenna switch control unit 50 sets the control signals SWC1 to SWC3 at a level as shown on the right side of FIG. Should occur in. Transmission / reception identification signal RTS and reception mode switching signal V during transmission / normal reception / synchronous control reception_CONTAre as shown in FIG. Therefore, the antenna switch control unit 50 receives the transmission / reception identification signal RTS and the reception mode switching signal V._CONTBased on the combination of logics of, the switch control signals SWC1 to SWC3 at the time of transmission / normal reception / synchronous control reception are controlled to be output.

【0032】

That is, the antenna switch control unit 50 sets SWC1 and SWC2 to a high level and SWC3 to an arbitrary level when transmitting RTS = L. Also, RTS = H, V_CONTDuring normal reception of = H, SWC1 and SWC2 are set to low level, and SWC3 is set to arbitrary level. In addition, V_CONTIn the synchronous control reception mode of = L, SWC1 and SWC2 are set to a high level (SWC3 is an arbitrary level), and the received signal is attenuated so that it can be input to the first and second receiving systems.

【0033】

(C) Synchronous control when starting up the base station FIG. 19 shows a synchronous control processing flow from the start-up of the base station to the start of normal operation according to the first embodiment or the second embodiment. When the base station is started up, the synchronous control reception mode is set (step 101). That is, the mode switching signal V from the synchronous control circuit 9_CONTSet to = L. As a result, the received signal is attenuated by the attenuators 11 and 21 (first embodiment) or by the antenna switch 3 (second embodiment) regardless of the level of the transmission / reception identification signal TRS. In addition, the mode switching signal V so that reception operation can be performed continuously._CONTIs controlled so that the antennas 1 and 2 are connected to the first and second receiving systems (first embodiment) or the antennas 1 and 2 are not connected to the first and second receiving systems while the level L is low. (2nd example). (Step 102).

【0034】

Then, the synchronization control circuit 9 checks whether the synchronization word UW can be detected (step 103), and if it detects it, determines the transmission / reception timing of its own station based on the detection timing, and shifts to the TDD operation (step 104). Next, the synchronous control circuit 9 has a mode switching signal V._CONTIs set to a high level, and thereafter, the reception mode is set to the normal reception mode (step 105). On the other hand, if the synchronization word UW cannot be detected in step 103, it is checked whether the set time T1 has elapsed from the rise of the base station (step 106), and if not, the processing after step 103 is continued. If the synchronization word UW cannot be detected even after the set time T1 has elapsed, the synchronization control circuit 9 has the mode switching signal V._CONTIs set to high level and the reception mode is set to the normal reception mode (step 107).

【0035】

After that, the synchronization control circuit 9 checks whether the synchronization word UW can be detected without attenuating the received signal (step 108), and if it can detect it, determines the transmission / reception timing of its own station based on the detection timing, and shifts to the TDD operation. (Step 109). On the other hand, if the synchronization word UW cannot be detected in step 108, it is checked whether the set time T2 has elapsed after shifting to the normal reception mode (step 110), and if not, the processing after step 108 is continued. If the synchronization word UW cannot be detected even after the set time T2 has elapsed, the TDD operation is started at the timing of the own station (step 111).

【0036】

(C) Third Example In the third embodiment, when an input larger than a certain value is detected in the reception slot of the normal reception mode, it is determined that the same location or other stations in the vicinity are not synchronized, and the mode shifts to the synchronization control reception mode for synchronization. It controls. FIG. 20 is a configuration diagram of the base station transmitter / receiver of the third embodiment, and the same parts as those of the first embodiment of FIG. 3 are designated by the same reference numerals. The differences from the first embodiment are that (1) the received signal strengths RSSI1 and RSSI2 of the antennas 1 and 2 detected by the limiter amplifiers 17 and 27 are input to the synchronous control circuit 9, and (2) the synchronous control circuit 9 is constant. When an input larger than the value is detected, the normal reception mode is automatically switched to the synchronous control reception mode. (3) The synchronous control circuit 9 automatically switches from the synchronous control reception mode to the normal reception mode after the synchronization control is completed. It is a point to restore.

【0037】

FIG. 21 is a configuration diagram of the synchronization control circuit 9 in the third embodiment, 9a is a controller, controls for detecting the synchronization word UW from the demodulated data, and generates a timing signal based on the detection of the synchronization word UW. It executes control to synchronize the transmission / reception timing of a station with the transmission / reception timing of another station, and controls to generate a reset signal B when synchronization control is completed to return from the synchronization control reception mode to the normal reception mode. 9b is a reference voltage generator that generates a reference voltage Vr, and 9c and 9d are comparators that compare the reference voltage with the received signal strength RSSI1 and RSSI2 output from the limiter amplifiers 17 and 27. Outputs a high level signal when is greater than the reference voltage Vr. 9e is an orgate, and when one of the received signal strength RSSI1 and RSSI2 exceeds the reference voltage Vr, that is, when a strong signal is detected in the receiving slot, the transmission / reception timing of the other station and the own station is not synchronized. Is determined and a high level signal A is output. 9f is a flip-flop, (1) Initially reset and high level signal V_CONTIs output to the normal reception mode, and (2) When one of the received signal strength RSSI1 and RSSI2 exceeds the reference voltage (when a high level signal A is generated), the low level mode switching signal V_CONTIs output to enter the synchronous control reception mode, and (3) is reset by the reset signal B output from the controller 9a when the synchronization control is completed, and is returned to the normal reception mode.

【0038】

FIG. 22 is an operation time chart of the synchronous control circuit of the third embodiment. In normal receive mode (V_CONT= High level), reception signal strength When one of RSSI1 and RSSI2 exceeds the reference voltage Vr and signal A is generated, flip-flop 9f is set and synchronous control reception mode (V)._CONT= Low level). In the synchronous control reception mode, the attenuators 11 and 21 (Fig. 20) are in the attenuation operation state. As a result, the strong input signal from another station is attenuated and input to the demodulation unit 5, and the demodulation unit 5 demodulates the received data and inputs it to the controller 9a of the synchronous control circuit 9. The controller 9a controls the detection of the synchronization word UW, and if the synchronization word UW is detected, outputs a transmission / reception timing signal based on the detection timing to synchronize the transmission / reception timing of the own station and another station. In addition, the controller 9a generates a reset signal B, resets the flip-flop 9f, and performs the normal reception mode (V)._CONT= High level).

【0039】

In the above, the received signal intensities RSSI1 and RSSI2 are input to the synchronous control circuit 9 of the first embodiment to configure the third embodiment, but the received signal is input to the synchronous control circuit 9 of the second embodiment (see FIG. 15). It is also possible to input the intensities RSSI1 and RSSI2 to configure the third embodiment. Although the present invention has been described above by way of examples, the present invention can be modified in various ways according to the gist of the present invention described in the claims, and the present invention does not exclude these.

【0040】

[Effect of the invention]

As described above, according to the present invention, synchronization of transmission / reception timing between base stations can be established by using the air synchronization method, and strong input signals from other stations are attenuated and received, so that the characteristics of the low noise amplifier are deteriorated or damaged. And does not reduce the reception sensitivity. Further, according to the present invention, since the transmission / reception timing of the own station can be synchronized with the transmission / reception timing of another station, restrictions on the installation location of the base station can be eliminated, which enables effective installation of the base station. Become. Further, according to the invention, when a strong transmission wave of a base station already in operation is received at the same location or adjacent to the base station, the own station can be started up while synchronizing the transmission and reception between the own station and another station. As a result, it becomes easy for a plurality of PHS companies to increase the number of base stations in the same area, or to install a plurality of base station devices in one installation location such as WLL to accommodate a large number of subscribers.

[Simple explanation of drawings]

[Figure 1]

It is 1st principle explanatory drawing of this invention.

[Figure 2]

It is the 2nd principle explanatory drawing of this invention.

[Fig. 3]

It is a block diagram of the base station transmission / reception device of 1st Example.

[Fig. 4]

This is the circuit configuration of the attenuator.

[Fig. 5]

It is a relationship diagram of the control voltage Vc of the attenuator and the amount of attenuation.

[Fig. 6]

It is another circuit configuration of the attenuator.

[Fig. 7]

It is an operation explanatory chart of FIG.

[Fig. 8]

It is a block diagram of an antenna switch.

[Fig. 9]

This is the circuit configuration of the switch.

[Fig. 10]

It is operation explanatory chart of each part of the transmission / reception part at the time of normal control.

[Fig. 11]

It is a signal format and timing detection explanatory diagram.

[Fig. 12]

It is operation explanatory figure of each part of the transmission / reception device in the synchronous control of 1st Example.

[Fig. 13]

It is a block diagram of the attenuator control signal generation part.

[Fig. 14]

It is a chart explaining the relationship between a mode and various signals.

[Fig. 15]

It is a block diagram of the base station transmitter / receiver of the 2nd Example.

[Fig. 16]

It is operation explanatory figure of each part of the transmission / reception device in the synchronous control of 2nd Example.

[Fig. 17]

It is explanatory chart of a switch output terminal and a switch control signal in each mode.

[Fig. 18]

Signals in each mode TRS, V_CONTIt is a diagram explaining the relationship between the switch control signal and the switch control signal.

[Fig. 19]

This is a synchronous control processing flow.

[Fig. 20]

It is a block diagram of the base station transmitter / receiver of the 3rd Example.

[Fig. 21]

It is a block diagram of the synchronous control circuit in 3rd Example.

[Fig. 22]

It is an operation time chart of a synchronous control circuit.

[Fig. 23]

It is explanatory drawing of the transmission / reception timing of a 4-channel multiplex TDMA-TDD system.

[Explanation of symbols]

TPA ... Transmission power amplifier FE ... front end DM ... Demodulation section ANT ... antenna ANT-SW Antenna switch AT ... Attenuation means TRMG ... Signal generator SYCC ... Synchronous control unit