JPH07212816A - Diversity communication equipment - Google Patents

Abstract

PURPOSE:To improve the effect of diversity with a simple constitution and to prevent the degradation in line quality caused by zone switching with respect to mobile communication. CONSTITUTION:Base stations in remote places are defined as diversity branches, and a centralized base station 17 concentratedly provided with/modems connected to base stations is provided. The centralized base station 17 is provided with a reception radio signal switch 22 which outputs reception signals from plural base stations having high levels, means 12 and 12' which measure the signal qualities of respective outputs, demodulators 8 and 8' which demodulate respective outputs, and a reception switch 14 which selects one of demodulators 8 and 8' in accordance with measured signal qualities. A transmission signal is sent to the base station selected for reception. Though switching in the reception radio signal switch 22 corresponds to conventional zone switching and the frequency in switching is low, switching in the reception switch 14 corresponds to switching of diversity branches and the frequency in switching is high.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio access system for connecting mobile terminals in a radio zone to a public network by using a radio line having a space as a medium, and particularly to a radio zone in which modulators and demodulators are centrally arranged. In the centralized base station device that transmits the modulated output signal via the optical fiber transmission line to the wireless base station that is placed in, the wireless communication between the mobile terminal and multiple wireless base stations is simultaneously connected and switched to the public line. The present invention relates to a diversity communication device that improves call quality by connecting.

[0002]

2. Description of the Related Art FIG. 5 shows an example of the configuration of a conventional diversity communication device for a wireless base station. The wireless base station 1 performs diversity wireless communication by using a plurality of antennas 5 and 5 ′ which are connected to the exchange 2 by a wired communication line 3 and which are installed apart from the mobile terminal 4. It is considered that the channel quality of the propagation path between one antenna and the mobile terminal is easily deteriorated due to fading or obstacles, but the channel quality is unlikely to be simultaneously deteriorated between the plurality of antennas and the mobile terminal. Therefore, the line quality can be improved by installing a plurality of antennas at distant positions and switching or combining received signals. The radio base station includes an interface circuit 6 for terminating the public line 3, a modulator 7 and a plurality of demodulators 8 and 8 ', a transmission amplification circuit 9 and a plurality of reception amplification circuits 10 and 10', and a transmission amplification circuit output. A transmission switcher 11 for switching signals to output to one of a plurality of antennas, reception level detectors 12 and 12 'for detecting the level of a reception signal, and a line terminating device for switching reception signals received by a plurality of antennas. It is composed of a reception switcher 14, a transmission / reception separator 15, and a control circuit 16.

The transmission signal of the mobile terminal 4 is transmitted by a plurality of antennas 5.
And 5 ', received by the receiving amplifier circuits 10 and 10' and demodulated by the demodulators 8 and 8 ', respectively, and output as a baseband signal, and the receiving switcher 14 selects the receiving signal having the higher receiving level. The interface circuit 6 connects to the public line.

On the transmission side, the output of the interface circuit 6 is input to the modulator 7, the modulation output is input to the transmission amplification circuit 9, converted to a radio frequency, amplified to the required transmission power, and selected by the transmission switcher 11. Or it is transmitted from 5 '.

The control circuit 16 switches the reception signal received by each antenna by the reception switcher 14 based on the reception level detected by the reception level detector 12 and connects it to the interface circuit input. The control of the transmission switcher receives the transmission signal of the mobile terminal by each antenna and selects the antenna with the higher level to transmit.

[0006]

In the prior art, a plurality of antennas are installed in the vicinity of the radio base station and the distance between the antennas cannot be increased, so that the correlation of the received power is strong and the effect of improving the line quality by the diversity reception is obtained. It was small.

Further, when there is an obstacle between the radio base station and the mobile terminal, the sight lines of a plurality of antennas and the mobile terminal are often blocked at the same time, and there is a drawback that the compensation effect is small.

Further, in the conventional configuration, when the mobile terminal moves in the wireless zone and the reception level drops, the line quality is deteriorated at the time of switching in order to prevent line disconnection by switching to the destination wireless zone. There was a flaw.

It is an object of the present invention to improve the diversity effect with a simple structure and prevent the deterioration of the line quality due to zone switching in mobile communication.

[0010]

The features of the present invention for achieving the above-mentioned object are a centralized control station in which a plurality of modulators and demodulators are centrally arranged, and a transmission / reception amplifier and an antenna in a plurality of radio zones. In a centralized control wireless base station device that transmits a modulated output signal to a wireless base station via a transmission path and connects the wireless base station and a mobile terminal by a wireless line, the transmission signal is one of a plurality of wireless base stations. And a reception radio that outputs the reception signals from a plurality of different radio base stations of different levels by switching the reception switch from the radio base station transmitted through the uplink transmission path A signal switch, means for constantly monitoring the signal quality of each received signal of the switch, a demodulator connected to each output of the switch, and one of the outputs of each demodulator are selected and output. Signal switching device and a control circuit that compares the signal quality for each received signal and controls switching of the reception switching device and the transmission switching device according to the result, and transmits the signal transmitted by the mobile terminal to a plurality of wireless devices separated from each other. To receive by the antenna of the base station, transmit the received signal to the centralized control station, compare the signal quality of each received signal, and select the radio base station to select and transmit the received signal according to the result of the comparison. Thus, the diversity communication device switches the transmission / reception branch.

[0011]

When the line of sight is obstructed due to an obstacle between the mobile terminal and one radio base station, another radio base station can be used to receive the transmission wave of the mobile terminal. Further, when the mobile terminal moves, the reception level at the moving away radio base station decreases, but the reception level at the moving and approaching radio base station has a high probability of increasing. By comparing the reception level or error rate of the mobile terminal's transmission signal received at the radio base station, it is possible to determine the radio zone in which the mobile terminal has moved and implement wireless zone switching during a call. Also increases. Also, by using the demodulated signal to identify the mobile terminal that transmitted the signal, it is possible to reduce branch selection errors even when receiving signals from a plurality of mobile terminals.

[0012]

FIG. 1 shows a first embodiment of the present invention. The centralized base station 17 is connected to the exchange 2 by the communication line 3,
An interface circuit 6 that terminates a communication line, a modulator 7, a transmission switcher 11 that switches the modulator output signal to a plurality of wireless base stations 1 and outputs the received signal, and a received signal of the wireless base station transmitted by an optical fiber. A reception radio signal switch 22 for connecting the demodulator to the demodulator, and reception level detectors 12 and 12 'for measuring the reception level of the signal input to the demodulator and outputting the measurement result to the control circuit 16. The demodulators 8 and 8 ', the reception switcher 14 for switching and connecting the demodulation output signals of the reception signals at the plurality of wireless base stations to the interface circuit, and the control circuit 16 for controlling the switching connection between the plurality of wireless base stations. Composed. The wireless base station 1 includes a transmission amplification circuit 9, a reception amplification circuit 10, a transmission / reception separator 15, and an antenna 5. Signal transmission between the toll base station and the radio base station is performed by the downstream optical fiber transmission line 19 and the upstream optical fiber transmission line 20.

The downlink signal transmitted from the exchange 2 to the interface circuit 6 via the communication line 3 is input to the modulator 7, and the modulation output signal is input to the transmission switcher 11 and output to the output terminal selected by the control circuit 16. To be done. The output signal of the transmission switcher 11 is transmitted to the radio base station 1 through the downlink optical fiber transmission line 19, power-amplified by the transmission amplification circuit 9, and transmitted from the antenna 5 through the transmission / reception separator 15.

The transmission signal of the mobile terminal 4 received by the antenna 5 of the radio base station 1 is input to the reception amplifier 10 through the transmission / reception separator 15 and is transmitted to the centralized base station 17 through the upstream optical fiber transmission line 20. Multiple wireless base stations 1,
The reception signals 1 ′ and 1 ″ are selected by the reception signal switcher 22 from a plurality of different radio base stations having high reception levels, input to demodulators 8 and 8 ′, and demodulated. The signal switch 22 selects a distributor 25 and n inputs and switches to one output to output n inputs 1
Composed of output switches.

The control circuit 16 includes a reception switch and a modulator 7 for switching connection between the demodulator 8 and the interface circuit 6.
It controls a transmission switcher for switching connection between the optical fiber transmission line 19 and the downstream optical fiber transmission line 19. The transmission wave of the mobile terminal is received by the antennas 5, 5'and 5 "of the plurality of radio base stations 1, 1'and 1", transmitted to the centralized base station by the optical fiber transmission lines 20, 20 'and 20 ", and received at the reception level. From the highest received level detected by the detector, only the number of demodulators is selected and connected to the demodulators to be demodulated The mobile terminal that transmitted the signals is identified from the demodulated signals to prevent selection errors. The demodulated signals of the plurality of demodulators have a high reception level by the reception switcher 14, and the same signal before and after the mobile terminal that transmitted the signal is selected at high speed and input to the interface circuit. Bowl 22
The switching by means corresponds to the conventional zone selection and the switching frequency is low, whereas the frequency by the diversity switching unit 14 is high. The diversity communication device of this configuration allows diversity reception by the antennas of a plurality of wireless base stations installed at distant locations, so that when one mobile antenna loses visibility of one antenna, the other antenna's perspective is lost. Can improve the diversity effect because it does not deteriorate. Further, there is a feature that the wireless base station of the switching destination due to the movement of the mobile terminal 17 can be optimized by detecting the reception level of the mobile terminal 4 by the plurality of demodulators at the time of switching. In addition, when the mobile terminal moves in the wireless zone and the reception level drops, the reception level at the base station in another wireless zone is detected and switching to the destination wireless zone is performed at high speed before the reception error rate deteriorates. By doing so, it is possible to prevent the deterioration of the line quality. The reception level detector 12 detects the reception levels of a plurality of radio base stations in the preceding stage of the reception wireless signal switch 22 to control the switching of the reception wireless signal switch 22 as in the present configuration example. It is obvious that the effect of is obtained.

A second embodiment of the present invention is shown in FIG. The toll base station 17 is line-connected to the exchange 2 by the communication line 3, and an interface circuit 6 for terminating the communication line,
Modulator 7, transmission switcher 11 that switches and outputs modulator output signals to a plurality of wireless base stations, and received wireless signal switch that switches received signals of wireless base stations transmitted by an optical fiber to connect to a demodulator A plurality of demodulators, error rate detectors 13 and 13 'for detecting an error in the demodulated output signal of the received signal, calculating an error rate of the demodulated output signal of the received signal, and outputting the calculation result to the control circuit 16. 8 and 8 ', a reception switcher 14 for switching and connecting demodulation output signals of received signals at a plurality of wireless base stations to an interface circuit, and a control circuit 16 for controlling switching connection between a plurality of wireless base stations. It

A transmission wave of a mobile terminal is transmitted by a plurality of radio base stations 1,
The error rate of the demodulated signal received by the 1'and 1 "antennas 5, 5'and 5", transmitted to the centralized base station by the optical fiber transmission lines 20, 20 'and 20 ", demodulated by the demodulator and the error rate detector The mobile terminal that has transmitted the signal is identified from the demodulated signal to prevent selection errors.

The demodulated signals of the plurality of demodulators have a low error rate due to the reception switch, and the same signals before and after the switching of the mobile terminals that transmitted the signals are selected at high speed and input to the interface circuit for branch selection of diversity. What is done is different from the first embodiment.

A third embodiment of the present invention is shown in FIG. The centralized base station 17 is connected to the exchange 2 by a plurality of communication lines 3 and has a plurality of interface circuits 6 for terminating the communication line 3 and a transmission switcher 11 for switching the interface circuit output to a plurality of modulators for output. ', A plurality of modulators 7, 7', 7 "and the reception levels of the signals transmitted from the radio base stations 1, 1'1" through the optical fiber and input to the demodulators 8, 8 ', 8 ". An error in the demodulation output signal of the reception signal detected by each of the radio base stations by detecting the error of the reception level detector 12, 12 ', 12 "that is measured and output to the control circuit 16 or the radio base station. An error rate detector 13, which calculates the rate and outputs the calculation result to the control circuit 16,
13 ′, 13 ″, a plurality of demodulators 8, 8 ′, 8 ″, a reception switcher 14 for switching and connecting demodulation output signals of reception signals of a plurality of radio base stations to an interface circuit, and a plurality of radio base stations. It is composed of a control circuit 16 for controlling the switching connection with the station. The wireless base station 1 includes a transmission amplification circuit 9, a reception amplification circuit 10, a transmission / reception separator 15, and an antenna 5.

The downlink signal transmitted from the exchange 2 to the interface circuit 6 through the communication line 3 is transmitted by the transmission switcher 1.
1'switches the control circuit 16 to the input terminal of the modulator 7 connected to the selected radio base station. Also,
The demodulated output signal is switched by the reception switcher 14 from among the plurality of demodulated outputs in terms of both the reception level and the error rate, and the input signal is switched to an arbitrary interface circuit 7 and input to the exchange station through the communication line 3. The second embodiment is different from the first embodiment in that it can be connected to a plurality of lines because it is transmitted to two. The modulator 7 and the demodulator 8 can switch a radio signal by the transmission switch 11 ′ and the reception switch 14 to connect to an arbitrary radio base station, so that the radio line switching control is flexible for the movement of the mobile terminal. This is different from the configuration of FIG.

A fourth embodiment of the present invention is shown in FIG. The toll base station 17 is line-connected to the exchange 2 by the communication line 3, and an interface circuit 6 for terminating the communication line,
Modulator 7, transmission switcher 11 that switches and outputs modulator output signals to a plurality of wireless base stations, and received wireless signal switch that switches received signals of wireless base stations transmitted by an optical fiber to connect to a demodulator And the reception level detectors 12 and 12 'for measuring the reception level of the signal input to the demodulator and outputting the measurement result to the control circuit 16, or demodulating the reception signal by detecting an error in the demodulation output signal of the reception signal. Error rate detectors 13 and 13 'for calculating the error rate of the output signal and outputting the calculation result to the control circuit 16, a plurality of demodulators 8 and 8', and a demodulated output signal of a received signal at a plurality of radio base stations. Reception switcher 14 for switching and connecting to the interface circuit, control circuit 16 for controlling switching connection with a plurality of radio base stations, detection result of jitter of input signals of a plurality of demodulators and output signal A transmission timing adjuster 26 that measures the difference in the amount of propagation delay by comparing the detection results of signals used for synchronization correction of unique words or stop bits, and adjusts the transmission timing of the transmission signal output by the modulator. Composed. The wireless base station 1 includes a transmission amplification circuit 9, a reception amplification circuit 10, a transmission / reception separator 15, and an antenna 5.

The transmission timing adjuster 26 transmits from the radio base station 1 when the line control circuit 16 switches from the branch constituted by the antenna 1 of the radio base station 1 to the branch constituted by the antenna 5'of the radio base station 1 '. The difference in the amount of propagation delay including the delay in the optical fiber between the generated signal and the signal transmitted from the wireless base station 2, and the transmission switching device sets the signal transmission path of the modulator 7 from the wireless base station 1 to the wireless base station. It differs from the first embodiment in that the transmission timing of the modulator / demodulator 7 is delayed by the measured delay amount when switching to the station 1 '. By adjusting the transmission timing of the modulator 7 before and after branch switching so that the mobile terminal can receive at the same timing before and after branch switching, synchronization at the time of branch switching due to the spread of antenna sense The difference from the configuration of FIG. 1 is that the disconnection can be improved.

[0023]

As described above, in the diversity communication apparatus of the present invention, the site diversity is realized by receiving the transmission signal of the mobile terminal by the antennas of a plurality of distant radio base stations and switching it. A good line can be provided. Further, in the diversity communication device of the present invention, since the wireless modulation signal is switched in order to change the connection between the modulator / demodulator and the wireless zone of the moving destination as the mobile terminal moves, the switching from the mobile terminal to the wireless zone is performed. It is possible to switch without interruption without being aware of.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram showing a conventional configuration.

[Description of Codes] 1 radio base station 2 public network 3 communication line 4 mobile terminal 5 antenna 6 interface circuit 7, 7 ', 7 "modulator 8, 8', 8" demodulator 9 transmission amplification circuit 10 reception amplification circuit 11 , 11 'Transmission switching device 12, 12', 12 "Reception level detector 13, 13 ', 13" Error rate detector 14 Reception switching device 15 Transmission / reception separator 16 Control circuit 17 Centralized base station 19 Downstream optical fiber transmission line 20 Upstream optical fiber transmission line 22 Received radio signal switch 23 1 Input n output switch 25 Branch circuit 26 Transmission timing adjuster

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location 7605-5K H04B 7/26 108 B

Claims (4)

[Claims] 1. A centralized control station in which a plurality of modulators and demodulators are centrally arranged, and a radio base station in which transmission / reception amplifiers and a single antenna are arranged in a plurality of radio zones In a centralized control wireless base station device that performs transmission and connects the wireless base station and the mobile terminal by a wireless line, a transmission switch that switches and outputs the transmission signal to one of a plurality of wireless base stations, and an uplink transmission And a signal of each received signal of the switch, which switches the received signal from the wireless base station transmitted by the route and outputs the received signal from a plurality of wireless base stations having different high levels. A means for constantly monitoring the quality, a demodulator connected to each output of the switching device, a reception switching device that selects and outputs one of the outputs of each demodulator, and the signal quality for each reception signal. Compare It is equipped with a control circuit that controls the switching of the reception switching unit and the transmission switching unit according to the result of 1. and receives the signal transmitted by the mobile terminal by the antennas of a plurality of distant radio base stations and transmits the reception signal to the central control station. Then, the diversity communication device is characterized in that the transmission / reception branches are switched by comparing the signal qualities of the respective reception signals and selecting the radio base station that performs the reception signal selection and transmission according to the result of the comparison. 2. The diversity communication device according to claim 1, wherein the signal quality is a reception level or an error rate after demodulation of the reception signal, and the transmission signal is switched at the output side of the modulator. 3. The diversity communication device according to claim 1, wherein the signal quality includes both the reception level and the error rate after demodulation of the reception signal, and the transmission signal is switched at the input side of the modulator. 4. The diversity communication according to claim 1, further comprising: a transmission timing adjuster that measures a propagation delay amount of a reception signal of each branch and adjusts a transmission timing of the modulator according to the propagation delay amount when the branch is switched. apparatus.