JPH10247898A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To resume communication only by one transmission disconnection, without disconnecting a communication network when an antenna system selected at the time of the transmission of a base station breaks down by permitting the base station to select an antenna, based on the presence or absence of a re-transmission request signal from a terminal station at transmission timing. SOLUTION: If the antenna breaks down, when the antenna is selected by information at the time of reception and a signal from a terminal station is transmitted in the base station, for example, the terminal station cannot receive signals from the base station. In the terminal station at that time, a timing holding/clock disconnection detection circuit 18 detects the clock disconnection, transmits it to a TMDA/TDD(time division multiplex access)/(time division duplex) control circuit 17 held when signal synchronism is normally established and transmits clock disconnection detection to a re-transmission request circuit 19. The base station receives a re-transmission request sent from the terminal station, and can continue communication, without disconnecting the communication network for selecting not the antenna having the fault but the other antenna, so as to transmit information in the reception state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a time division multiple access.
Using a frequency alternating communication system (TDMA / TDD system), a single frequency signal is alternately transmitted and received between a base station and a plurality of terminal stations at a predetermined cycle, and the base station performs reception diversity and transmission diversity. The present invention relates to a wireless communication system for improving communication quality.

[0002]

2. Description of the Related Art Conventionally, in radio communication, fading causes deterioration of channel quality such as a decrease in reception level and an increase in an error rate. The same applies to the above-described TDMA / TDD system, and various measures such as transmission space diversity and reception space diversity have conventionally been taken to improve this problem.

[0003] Among them, transmission or reception space diversity (hereinafter referred to as transmission SD or reception SD) uses a plurality of antennas for transmission or reception, receives radio waves whose fading fluctuations have little correlation with each other, and has a high reception level. It is widely known as a method for selecting a reception wave.

[0004] The transmission SD or the reception SD is referred to as TDMA.
/ TDD scheme, when applied to a single frequency uplink,
Since the downlink is transmitted and received alternately, it is difficult to select an antenna as compared with general communication. With respect to such selection means, for example, Japanese Patent Application Laid-Open No. 7-31590 and Japanese Patent Application Laid-Open No. 64-57835 are known.

Japanese Patent Application Laid-Open No. 7-31590 discloses a TDD.
The present invention relates to the provision of a diversity antenna selection method for performing transmission and reception in a system. In the TDMA / TDD system, the transmission timing is time-division-divided, and the selected antenna determined to be good during reception is not good during transmission. Therefore, a memory for storing data of the reception level of each antenna is provided. Predict the reception level at the next transmission slot time from the data stored in
It discloses a method of selecting the antenna having the highest predicted reception level at the next transmission slot time. Here, the prior art will be described with reference to the drawings.

FIG. 4 is a block diagram showing the configuration of a base station for explaining the antenna selection switching means in the above publication. The antenna 21 and the antenna 22 are selected by the antenna switch 24. The reception signals of the antennas 21 and 22 are transmitted to the transceiver 2 via the antenna switch 24, respectively.
The reception signal of the antenna 1 is input to the reception unit 263 in 6, and the reception signal of the antenna 2 is input to the reception unit 264, and the reception level is detected by the reception level detector 23 after high frequency amplification. The outputs of the receiving units 263 and 264 are demodulated by the demodulating units 266 and 267, respectively, and are input to the bit error occurrence rate detector 29, respectively.

The antenna selected at the time of the transmission slot is
The CPU 28 detects with the reception level detector 23 and
In step 5, antenna switching control is performed by predicting from data accumulated in time series.

The antenna to be selected at the time of the reception slot is
From the reception levels of the antennas 21 and 22 accumulated in the memory 25 in time series and the bit error occurrence rate of the reception signals of the antennas 21 and 22 which are the outputs of the bit error occurrence rate detector 29, the antenna having the best quality of the reception signal is determined. I predict.

The CPU 8 outputs a reception antenna selection signal at a reception slot switching timing based on the prediction result.
The signal is input to decoding section 269 via reception antenna selection section 265.

As a result, at the time of reception, a received signal from the antenna having the highest reception quality is demodulated and decoded, and further transmitted from the antenna 1 or 2 having the highest reception level.

As another technique, for example, Japanese Patent Application Laid-Open No. 64-57835 discloses a method for improving the economical efficiency and frequency utilization by using a time-division antenna having a route diversity configuration. .

[0012]

In the conventional TDMA / TDD transmission SD as described above, a signal transmitted from a terminal station is received at a base station by a plurality of antennas.
When performing transmission at the next transmission timing with an antenna with good reception status, if a failure occurs in the selected antenna system, the terminal station will not be able to receive the signal, the signal will be out of synchronization, and the next transmission will not be possible from the terminal station. Will be disconnected.

To solve this problem, if the cause of the failure of the selected antenna system is deterioration of the spatial propagation state,
According to the technique disclosed in Japanese Patent Application Laid-Open No. 7-31590, it is possible to select the antenna system by storing the reception state and predicting the reception state of each antenna system at the transmission timing based on the data accumulated in time series. It is possible.
However, there is a problem that it cannot be avoided because the technology described in Japanese Patent Application Laid-Open No. Hei 7-31590 is difficult to predict when the cause is device failure or dew condensation of the antenna body.

Further, when the above-mentioned problem occurs, not only reception of the terminal station becomes impossible, but also the base station,
Since a signal from the terminal station cannot be received, SD control cannot be performed, the failed antenna system cannot be selected and recovered, the communication network is cut off, and the communication network must be re-established.

As described above, the object of the present invention is to provide a TDM
A configuration of a wireless communication system capable of performing stable control without avoiding communication network disconnection not only in a wireless section but also in a failure of an antenna itself due to a failure of an antenna system when performing transmission SD in the A / TDD method. It is to propose.

[0016]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention uses a TDMA / TDD system between a base station having a plurality of antennas and performing reception diversity and transmission diversity and a plurality of terminal stations. In a wireless communication system that transmits and receives signals, the base station receives signals from the terminal stations at the plurality of antennas at a reception timing, and signals from the antennas at which the quality of the received signals is optimal. At the transmission timing, when not receiving the retransmission request signal from the terminal station, selecting and transmitting the antenna obtained at the reception timing, and when receiving the retransmission request signal, at the reception timing An antenna different from the obtained antenna is selected.

At the reception timing, the terminal station outputs data transmitted from the base station, extracts a clock signal, and, if signal synchronization is established by the clock signal, The present invention is characterized in that the timing is held, the retransmission request signal is generated when the clock signal is interrupted, and the transmission data or the retransmission request signal is transmitted to the base station at the transmission timing.

Further, the transmission of the retransmission request signal is performed at a timing holding the synchronization timing.

The quality of the reception signal is characterized in that an error rate or a reception level of the reception signal is detected for each output of the plurality of antennas, and each of the outputs is compared to detect an optimum antenna output.

The terminal station includes a TDD switch for transmitting a transmission / reception signal using a single antenna at the transmission timing and the reception timing.

When signal synchronization is established at the terminal station and communication is performed normally, the synchronization timing established by the clock extracted from the received signal is retained, so that it is retained when the extracted clock is cut off. The retransmission request signal can be transmitted to the base station at the synchronization timing.

By this means, the base station can receive the retransmission request signal, and in the reception state, it is possible to recognize the failed antenna system, so that a normal antenna system is selected and transmitted to the terminal station. can do. As a result, communication can be restarted without interrupting the communication network by only once interrupting transmission.

[0023]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 1 shows the configuration of a radio communication system including a base station and a terminal station. The base station 1 has antennas A3 and B4, and has a TDMA /
Transmission and reception are performed alternately in time series in order to perform communication by the TDD method. That is, the base station 1 receives the signal transmitted from the terminal station 2 at the reception timing by both the antennas A3 and B4. Both reception states are monitored, and an antenna to be transmitted at the next base station transmission timing is selected and transmitted to the terminal station 2. FIG. 2 is a block diagram illustrating a configuration of the base station 1.

Reference numeral 101 denotes a diversity antenna A3.
And an antenna switch that switches between the antenna B4 and the antenna B4 under the control of the control circuit 106.

The received signals received by the two antennas A3 and B4 are demodulated by the demodulators 103 and 104, respectively, and thereafter, the system having the best reception quality obtained by the reception monitoring circuit 105 is judged and controlled. According to the output of the circuit 106, the demodulated signal is selected by the selecting means 107 and output as received data.

On the other hand, the output of the demodulators 103 and 104 is monitored for the quality of the received signal by the reception monitoring circuit 105, and the result is input to the control circuit 106. Then, the antenna having the optimum reception quality is selected by the control signal of the control circuit 106 at the next transmission timing.

Further, the reception monitoring circuit 105 receives a retransmission request signal sent from the terminal station 2 and inputs a retransmission request signal to the control circuit 106, which is different from the currently selected antenna. A selection switching signal is output so as to select another antenna.

As a result, the control circuit 106 can switch from the faulty antenna to the normal antenna and transmit.

Here, the content of monitoring the reception state of the reception monitoring circuit 105 includes a method of detecting and comparing the bit error rate of the received signal in the base station 1 and a method of detecting and comparing the reception level. May be used together.

FIG. 3 shows a block diagram of the terminal station 2. The terminal station 2 switches the TDD switch 11 by controlling the transmission and the reception alternately in a time series according to a control signal from the TDMA / TDD control circuit 17. The signal transmitted from the base station 1 at the reception timing of the terminal station 2 is received by the receiver 14, and the demodulator 15 generates a received data signal.
At this time, the clock extraction circuit 16 determines the transmission / reception switching timing and extracts a clock for establishing signal synchronization.
The extracted clock is supplied to the TDMA / TDD control circuit 17.
The signal is transmitted to the TDD switch 11 while synchronizing the signal and establishing the transmission / reception switching timing. Further, the extracted clock is sent to the timing holding and clock loss detecting circuit 18 to hold the synchronization timing at the time of establishing the synchronization.

The modulator 13 converts the transmission data signal into a TDMA signal.
The signal is modulated at the timing established by the / TDD control circuit 17 and transmitted to the transmitter 12, and transmitted through the TDD switch 11 at the transmission timing of the terminal station.

During communication according to the above-described procedure, for example, when the base station 1 selects the antenna A3 based on information at the time of receiving a signal from the terminal station 2 and performs transmission, if a failure occurs in the antenna A3, the terminal station 2 The signal from the base station 1 cannot be received. At this time, in the terminal station 2, the timing holding and clock loss detecting circuit 18 detects the clock loss and the synchronization timing held when the signal synchronization is normally established by the TDMA.
At the same time as sending the signal to the / TDD control circuit 17, a clock loss detection is sent to the retransmission request circuit 19.

The modulator 13 modulates the retransmission request signal from the retransmission request circuit 19 and transmits the modulated signal from the transmitter 12 to the base station.

The base station 1 receives the retransmission request sent from the terminal station 2, and in the reception state, the antenna A3 which has failed.
, The antenna B4 can be selected and transmitted, so that communication can be continued without breaking the communication network.

In the configuration described above, the base station has been described with two antennas A3 and B4 for simplicity, but the present invention is not limited to this, and the present invention is applicable to two or more antennas. Is possible.

[0037]

The effect of the present invention is that when the antenna system selected at the time of transmission at the base station breaks down, communication can be restarted without disconnecting the communication network by only once disconnection.

The reason is that, when signal synchronization is established in the terminal station and communication is normally performed, the synchronization timing established by the clock extracted from the received signal is retained, so that when the extracted clock is cut off, The retransmission request signal can be transmitted to the base station at the held synchronization timing.

As a result, the base station can receive the retransmission request signal, and in the reception state, can recognize the failed antenna system. Therefore, a normal antenna system is selected and transmitted to the terminal station. This is because you can do it.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of a wireless communication system according to an embodiment of the present invention.

FIG. 2 is a block diagram of a base station 1 of FIG.

FIG. 3 is a block diagram of a terminal station 2 of FIG.

FIG. 4 is a block diagram of a conventional base station.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base station 2 Terminal station 3 Antenna A (base station) 4 Antenna B (base station) 5 Antenna C (terminal station) 11 TDD switch 12 Transmitter 13 Modulator 14 Receiver 15 Demodulator 16 Clock extraction circuit 17 TDMA / TDD Control circuit 18 Timing hold and clock loss detection circuit 19 Retransmission request circuit 101 Antenna switch 102 Modulator 103, 104 Demodulator 105 Reception monitoring circuit 106 Control circuit 107 Selection means

Claims (5)

[Claims] 1. A wireless communication system having a plurality of antennas and transmitting and receiving signals between a base station performing reception diversity and transmission diversity and a plurality of terminal stations using a TDMA / TDD method, The station receives a signal from the terminal station at the plurality of antennas at a reception timing, receives a signal from an antenna that optimizes the quality of the received signal, and transmits a retransmission request from the terminal station at a transmission timing. When a signal is not received, an antenna obtained at the reception timing is selected and transmitted.When the retransmission request signal is received, an antenna different from the antenna obtained at the reception timing is selected. Wireless communication system. 2. The terminal station outputs data transmitted from the base station and extracts a clock signal at a reception timing. When signal synchronization is established by the clock signal, the terminal station performs synchronization. Holding the timing, and when the clock signal is cut off, generating the retransmission request signal; and transmitting the transmission data or the retransmission request signal to the base station at the transmission timing. 2. The wireless communication system according to 1. 3. The wireless communication system according to claim 2, wherein the transmission of the retransmission request signal is performed at a timing holding the synchronization timing. 4. The quality of the received signal is characterized by detecting an error rate or a received level of a received signal for each output of the plurality of antennas, and comparing each of them to detect an optimum antenna output. The wireless communication system according to claim 1. 5. The wireless communication system according to claim 2, wherein the terminal station includes a TDD switch that transmits a transmission / reception signal using a single antenna at the transmission timing and the reception timing.