JPH05327569A - Diversity transmission/reception system - Google Patents

Abstract

PURPOSE:To simplify the constitution of a base station by controlling the antenna switching for diversity transmission/reception by a centralized base station. CONSTITUTION:In a centralized base station 1, the reception signal from a mobile machine which is received through a radio base station 2 has an unnecessary wave eliminated and is inputted to demodulators 10 and 11. A distributed carrier is inputted to a discriminator 15 to determine a reception line having a higher level. One of demodulators 10 and 11 is selected based on this result, and the output is outputted by a switch 14. The base band signal input is converted to frequencies corresponding to respective antennas in accordance with the comparison result of the discriminator by a variable carrier source, and they are taken out as outputs of modulating circuits 3a to 3n. Modulation outputs converted to desired frequencies have frequencies multiplexed by a multiplexer/demultiplexer 6 and are inputted to an electric/optical converter 8. The converted optical signal is sent to a base station 2 by an optical fiber 16 and is transmitted from the selected antenna.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a mobile communication system for performing mutual communication between a mobile terminal and a toll base station, and particularly to a transmission / reception diversity system configured to switch a plurality of antennas provided in a radio base station at the toll base station.

[0002]

2. Description of the Related Art Conventionally, radio signals received by a plurality of antennas in a radio base station are demodulated by different demodulators,
Control of diversity reception, which is configured to select the optimum demodulator output after comparing the levels or error rates of the received signals of the respective antennas, is all performed by the radio base station.

FIG. 5 is a block diagram showing an example of the conventional diversity reception system as described above, and shows the configuration of a radio base station. In the figure, when a voice baseband signal is input to the radio base station 61 from the exchange, the voice baseband signal is converted into a radio signal by the modulator 67, and then the transmission antenna selection switch 66 and the transmission / reception separator 64 or 65 are transmitted. Radio waves are radiated from the antenna 62 or 63 to the mobile device 76 via the. The received signal from the mobile device is input to the demodulators 72 and 71 through the receivers 69 and 70, and the quality of the signal from the receiver is given to the error rate detector 68 by the distributors 73 and 74. The determination is made according to 68, and the switch 75 selects and outputs a high-quality demodulator output.

[0004]

In a mobile communication system configured to form a service area by a set of a large number of small wireless zones, a large number of wireless zones must be provided, and a very large number of base stations must be provided. ..

Therefore, in order to make the system economical, it is necessary to manufacture individual base stations at low cost. Further, in this case, there is no choice but to place severe restrictions on the installation location of the wireless base station, and there is a strong demand for downsizing and simplification of the wireless base station.

However, in the conventional mobile communication system as described above, since the base station controls the antenna selection for performing diversity transmission / reception, the structure of the base station becomes complicated, and its size and economy are reduced. There was a problem that it was difficult to convert.

The present invention has been made in order to solve the above-mentioned conventional problems, and the structure of the base station is simplified, so that a mobile communication system having a large number of base stations can be economically constructed. Its purpose is to provide a means that can be built.

[0008]

The above-mentioned problems can be solved by the means described in the claims. That is, the present invention is a communication method in which a toll base station and a mobile device are connected to each other via a radio base station to perform mutual communication, and the toll base station and the radio base station are connected by a wide band transmission line, and the radio base station Is a control method in a diversity transmission / reception method using a plurality of antennas, wherein the invention of claim 1 receives a radio channel signal from a mobile terminal by a plurality of antennas of a radio base station, and each reception signal is different. The frequency-converted received signal is frequency-multiplexed, the frequency-multiplexed signal is transmitted to the toll base station through a wideband transmission line, and the tow base station multiplexes the received frequency-multiplexed signal.
The pair of received signals, which have been frequency-converted by the distributor, are filtered by their respective bandpass filters, demodulated into baseband signals by different demodulators, and the quality of each received signal is compared by the decision unit. , A high-quality demodulated baseband signal is selected and output, while the transmission from the centralized base station to the mobile station terminal determines the output antenna by changing the carrier frequency according to the result of the determiner. Different modulation signal, the frequency-converted modulation signal is frequency-multiplexed with another modulation signal by a multiplexing / distributing device, and the frequency-multiplexed signal is transmitted to a radio base station via a wideband transmission line. This is a diversity transmission / reception system configured to convert the received frequency-multiplexed signals into desired radio frequencies and transmit the converted signals.

According to the invention of claim 2, the radio channel signal from the mobile terminal is received by the two antennas of the radio base station, one of the received signals is converted to a different frequency, and the frequency-converted signal and the received signal are received. The signal is frequency-multiplexed, and the frequency-multiplexed signal is transmitted to the toll base station through a wide band transmission line. In the toll-base station, the received frequency-multiplexed signal is frequency-converted and then distributed by the multiplexer / distribution device to be frequency-converted. The pair of received signals are filtered by each band-pass filter, then demodulated by different demodulators, the quality of each received signal is compared by the determiner, and the demodulated signal with better quality is selected and output. On the other hand, in the transmission from the toll base station to the mobile terminal, modulation of different frequencies is performed by changing the carrier frequency according to the result of the judging device in order to determine the output antenna. Signal, the frequency-converted modulated signal is frequency-multiplexed with another modulation signal by a multiplexing / distributing device, the frequency-multiplexed signal is frequency-converted, and transmitted to a wireless base station via a wideband transmission line. Is a diversity transmission / reception system configured to transmit the frequency-multiplexed signal received in step 1 as a desired radio frequency.

Further, the invention of claim 3 receives a radio channel signal from a mobile terminal by a plurality of antennas of a base station,
Each received signal is converted to a different intermediate frequency, the intermediate frequency signals having different frequencies are frequency-multiplexed, and the frequency-multiplexed signal is transmitted to the toll base station through a wideband transmission path. After separating the signal with each bandpass filter to achieve the desired frequency,
The electric signals are demodulated into baseband signals by different demodulators, the quality of each received signal is compared by a determiner, and a demodulated baseband signal with good quality is selected and output. From the transmission to the mobile terminal, the modulated signal is input to the transmission switch that branches and selects based on the determination result of the determiner, and the output signal is frequency-multiplexed with a plurality of different modulated signals by the multiplex distribution device, and Converts the frequency multiplexed signal output from the multiplexer / distributor to different intermediate frequencies, combines the intermediate frequency signals, and transmits them to the base station via the wideband transmission line. It is a diversity transmission / reception system configured to distribute, convert to the same radio frequency, and transmit.

[0011]

According to the present invention, a plurality of diversity signals received by a base station are frequency-multiplexed by frequency conversion and then transmitted to a centralized base station through a wide band transmission line to perform diversity control within the centralized base station. Furthermore, a multiplex / distribution device is also used, which allocates a plurality of arbitrary modulated signals to a radio base station and distributes received signals of different frequencies from a plurality of terminals to respective demodulators.

According to the present invention, a plurality of uplink and downlink diversity signals are transmitted and received by the radio base station and the toll base station by frequency multiplexing, for example, by one optical fiber and a pair of electric / optical converters. be able to.
Further, since the centralized base station demodulates the radio signal and sets the frequency of the modulated signal for selecting the antenna, the demodulator and the error rate or signal level detector of the radio base station are not required, which simplifies and downsizes the radio base station. And economicization are possible.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a communication system according to a first embodiment of the present invention, in which signal transmission between a wireless base station 2 and a centralized base station 1 in a mobile communication system is transmitted by optical fibers 16 and 17. The structure when it does is shown.

As shown in the figure, the radio base station 2 receives antennas 37 and 38 that form a radio transmission path between the mobile station terminals in the radio zone, a transmission signal to the mobile station and a reception signal from the mobile station. Transmitter / receiver separators 39, 40 for separating, amplifiers 31, 33 for amplifying the respective received signals, mixers 26, 27 for converting the respective received signals to different frequencies, and bandpass filters 34, 35 for removing unnecessary waves, a plurality of A combiner 36 for frequency-multiplexing the received signal, an electric / optical converter 19 for transmitting the frequency of the received signal from the mobile station to the toll base station, and an optical signal transmitted from the toll base station 1 to the mobile station. Optical / electrical converter 18 for, band filters 20, 21 for separating the frequency-multiplexed signal from the centralized base station 1,
Mixers 22 and 23 for converting a diversity transmission signal frequency-converted by a centralized base station into a radio frequency for a mobile device,
And bandpass filters 28 and 29 for removing unnecessary waves and amplifiers 30 and 32.

In the toll base station 1, the received signal from the mobile station received via the radio base station 2 is converted back into an electric signal by the optical / electrical converter 9, and then the frequency-multiplexed signal is multiplexed by the multiplexing / distributing device 7. Are distributed, unnecessary waves are removed by bandpass filters 12 and 13, and the respective received signals are demodulated by the demodulator 1
It is input to 0 and 11. Ie antennas 37 and 3
The received signals from 8 are input to demodulators 10 and 11, respectively, and the transmitted signals from the mobile device are demodulated.

The distributed carriers are input to the determiner 15, and a high-level reception path (antenna) is determined.
(Or the baseband signals of the demodulators 10 and 11 are input and compared by the error rate.) Based on the result, the demodulators 10 and 11
Either one of 11 is selected and output by the switch 14. The respective outputs of the modulation circuits 3a to 3n are extracted by converting the baseband signal input into the frequency of the frequency band corresponding to each antenna by the variable carrier source in the modulation circuit according to the comparison result of the judging device. ..

The unnecessary wave is removed by the variable band filter. The modulated outputs converted to desired frequencies are frequency-multiplexed by the multiplexer / distributor 6 and then input to the electric / optical converter 8. The converted optical signal is the optical fiber 1
It is transmitted to the wireless base station 2 by 6 and transmitted from the antenna selected previously.

FIG. 2 is a diagram showing a configuration of a communication system according to a second embodiment of the present invention, in which signal transmission between the radio base station 2 and the toll base station 1 in the mobile communication system is carried out by the optical fiber 1.
6 and 17 show a configuration for transmission.

As shown in the figure, the radio base station 2 has amplifiers 48 and 49 for amplifying the reception signals of the transmission / reception separators for separating the reception signals from the mobile stations in the radio zone, and one of the reception signals having different frequencies. A mixer 50 for conversion, a band filter 51 for removing unnecessary waves, a combiner 36 for frequency-multiplexing a plurality of received signals, an electric / optical converter 19 for transmitting a received signal from a mobile station to a centralized base station, a centralized unit Bandpass filter 4 for separating the frequency-multiplexed signal from base station 1
1, 42, a mixer 4 for converting a diversity transmission signal frequency-converted by a centralized base station into a radio frequency for a mobile device
3 and a bandpass filter 45 for removing unnecessary waves, and amplifiers 46 and 49.

In the centralized base station 1, after the received signal from the mobile station via the radio base station 2 is returned to an electric signal by the optical / electrical converter, it is intermediated by the mixer 55, the oscillator 52, and the filter 56 for removing unnecessary waves. The frequency-converted signal into a frequency band, the frequency-multiplexed signal of the intermediate frequency is distributed by the multiplexer / distributor 7, unnecessary waves are removed by the band filters 12 and 13, and the respective received signals are input to the demodulators 10 and 11. It

That is, the received signals from the antennas 37 and 38 are input to the demodulators 10 and 11, respectively, and the transmitted signals from the mobile unit are demodulated. The distributed carriers are input to the determiner 15, and a high-level reception path (antenna) is determined. (Or, the baseband signals of the demodulators 10 and 11 are input and compared by the error rate.) Based on the result, one of the demodulators 10 and 11 is selected and the switch 14 is selected.
Outputs a baseband signal.

The baseband signal input is converted to a frequency in the frequency band of each antenna by the variable carrier source 44 whose frequency changes in accordance with the comparison result of the judging device and taken out. The unnecessary wave is removed by the variable band filter 43. The respective modulated outputs converted to desired frequencies are frequency-multiplexed by the multiplexer / distributor 6 and then input to the electric / optical converter 8. The converted optical signal is transmitted to the wireless base station 2 by the optical fiber 16 and transmitted from the selected antenna.

FIG. 3 shows the numerical symbols 3a to 3 in FIGS.
It is a figure which shows the example of a structure of the modulation circuit shown by n, and the spectrum of a modulation output, (a) shows the structure of a modulation circuit, (b) has shown the spectrum of a modulation output. In the figure, the baseband signal input is a modulator 58, a variable carrier source 60,
Also, it is taken out as a modulation output by the variable band filter 59 which removes unnecessary waves. The frequency of the modulated output is set by changing the frequency of the carrier wave of the variable carrier wave source to the frequency band of each antenna based on the result of the decision unit 15. Therefore, the spectrum of the modulation output appears in two frequency bands as shown in the figure when there are two antennas.

FIG. 4 is a diagram showing the configuration of the communication system of the third embodiment of the present invention, in which the signal transmission between the radio base station 2 and the toll base station 1 in the formula is carried out by the optical fibers 16 and 17. The structure when transmitting is shown.

The radio base station 2 has antennas 37 and 38 that form a radio transmission path with a mobile station terminal in a radio zone, and a transmission / reception separator 39 that separates a transmission signal to the mobile station and a reception signal from the mobile station. , 40, an amplifier 31 for amplifying the received signal,
33, oscillators 24 and 25 for converting respective received signals into different frequencies, phase comparator 57 for stabilizing the oscillators, mixers 26 and 27, bandpass filters 34 and 35 for removing unnecessary waves, and a plurality of received signals A frequency multiplexer 36, an electric / optical converter 19 for transmitting a received signal from a mobile station to the toll base station, and an optical / electrical device for sending an optical signal transmitted from the toll base station to the mobile station. Converter 18, bandpass filters 20 and 21 for separating frequency-multiplexed signals from the centralized base station, oscillators 24 and 25 for converting the diversity transmission signal frequency-converted by the centralized base station into a radio frequency to the mobile station, and a mixer 22. , 23 and bandpass filters 28 and 29 for removing unnecessary waves and an amplifier 30,
And 32.

In the centralized base station 1, after the received signal from the mobile station received via the base station is returned to an electric signal by the optical / electrical converter 9, the frequency-multiplexed signals are distributed by the bandpass filters 58 and 59. One of the received signals that has been frequency-converted by the radio base station is converted to a desired frequency by the mixer 55 and the oscillator 52, and an unnecessary wave is removed by the band filter 56.
It is input to desired demodulators 10 and 11 by 7b. That is, the reception signals from the antennas 37 and 38 are input to the demodulators 10 and 11, respectively, and the transmission signals from the mobile device are demodulated. The distributed carriers are input to the determiner 15, and a high-level reception path (antenna) is determined.
(Or the baseband signals of the demodulators 10 and 11 are input and compared by the error rate.) Based on the result, the demodulators 10 and 11
Either one of 11 is selected and output by the switch 14. The transmission signals from the modulators 4a and 4b are switched to the switches 5a and 5b according to the determination result of the determination unit 15 described above.
And are frequency-multiplexed by the multiplexers / distributors 6a and 6b. The mixer 10 converts the frequency to a desired frequency by the mixer 53 and the oscillator 52, and the frequency-multiplexed signal from which the unnecessary wave is removed by the filter 54 and the other frequency-multiplexed signal are input and combined, and then the electric / optical converter. The optical signal input to 11 and converted is transmitted to the wireless base station 2 by the optical fiber 16 and transmitted from the previously selected antenna.

In the above embodiments, the centralized base stations are connected to each other by optical fibers, but the present invention is not limited to optical fibers. It goes without saying that any transmission line may be used.

[0028]

As described above, according to the present invention,
Since the centralized base station controls the antenna switching for performing diversity transmission / reception, the configuration of the base station can be simplified. Further, the present invention is capable of transmitting the uplink and downlink diversity signals in each of the base station and the toll base station by using one optical fiber, and can transmit a plurality of modulated signals to one zone (radio base station). Since they can be assigned, there is an advantage that the device can be downsized, simplified, and economical.

[Brief description of drawings]

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

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

FIG. 3 is a diagram showing an example of a configuration of a modulation circuit.

FIG. 4 is a diagram showing a third embodiment of the present invention.

FIG. 5 is a diagram for explaining conventional diversity reception.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Centralized base station 2 Radio | wireless base station 3a-3n, 57 Modulation circuit 4a, 4b Modulator 5a, 5b Switch 6,6a, 6b, 7,7a, 7b Multiplexing / distribution apparatus 22,23,26,27,43,50 , 53, 55
Mixer 12, 13, 28, 29, 34, 35, 41, 42, 4
5,51,54,56,58,59 Bandpass filter 57 Phase comparator 36,73,74 Combiner 24,25,44,52 Oscillator 8,19 Electric / optical converter 16,17 Optical fiber 9,18 Optical / Electric converter 30, 31, 32, 33, 46, 47, 48, 49
Amplifier 41,40 Transmission / reception separator 37,38 Transmission / reception antenna 10,11 Demodulator 15 Determinator 14 Receiving changeover switch 58 Modulator 59 Variable band filter 60 Variable carrier source

Claims (3)

[Claims] 1. A communication system in which a toll base station and a mobile device are connected to each other via a radio base station to perform mutual communication, wherein the toll base station and the radio base station are connected by a wide band transmission line, and the radio base station In a diversity transmission / reception method using multiple antennas, a wireless channel signal from a mobile terminal is received by multiple antennas of a wireless base station, each received signal is converted to a different frequency, and the frequency-converted received signal is converted to Frequency-multiplexed, the frequency-multiplexed signal is transmitted to the toll base station through a wide band transmission line, and in the toll-base station, the received frequency-multiplexed signal is distributed by the multiplexer / distribution device, and the pair of frequency-converted received signals are respectively After filtering with the band-pass filter of, the demodulator demodulates to the baseband signal, and the quality of each received signal is compared with the judging device. A demodulated baseband signal with good output is selected and output.On the other hand, for transmission from the toll base station to the mobile terminal, the carrier frequency is changed by changing the carrier frequency according to the result of the determiner to determine the output antenna. Converting to a different modulation signal, frequency-modulating the frequency-modulated modulation signal with another modulation signal by a multiplexing / distributing device, and transmitting the frequency-multiplexed signal to a radio base station via a wideband transmission line. A diversity transmission / reception system characterized by converting the received frequency-multiplexed signals into desired radio frequencies and transmitting them. 2. A communication system in which a centralized base station and a mobile device are connected to each other via a wireless base station to perform mutual communication, wherein the centralized base station and the wireless base station are connected by a broadband transmission line, In a diversity transmission / reception method using multiple antennas, a radio channel signal from a mobile terminal is received by two antennas of a radio base station, one received signal is converted to a different frequency, and the frequency-converted signal and the received signal are received. The signal is frequency-multiplexed, and the frequency-multiplexed signal is transmitted to the toll base station through a wide band transmission line. In the toll-base station, the received frequency-multiplexed signal is frequency-converted and then distributed by a multiplexer / distributor to perform frequency conversion. The pair of received signals thus obtained are filtered by respective bandpass filters, then demodulated by different demodulators, and the quality of each received signal is compared by a decision device. The demodulated signal of higher quality is selected and output.On the other hand, the transmission from the toll base station to the mobile terminal is performed by changing the carrier frequency according to the result of the judging device to determine the output antenna. , The frequency-converted modulation signal is frequency-multiplexed with another modulation signal by a multiplexing / distributing device, the frequency-multiplexed signal is frequency-converted and transmitted to a radio base station via a wideband transmission line, A diversity transmission / reception system characterized in that frequency-multiplexed signals received by a radio base station are transmitted as desired radio frequencies. 3. A communication system in which a centralized base station and a mobile device are connected to each other through the base station to perform mutual communication, wherein the centralized base station and the base station are connected by a wide band transmission line, and a plurality of antennas are provided in the base station. In the diversity transmission / reception method using the, the wireless channel signal from the mobile terminal is received by the plurality of antennas of the base station, each received signal is converted into a different intermediate frequency, and the intermediate frequency signals with different frequencies are frequency-multiplexed. , The frequency multiplexed signal is transmitted to the toll base station through a wide band transmission line, and the toll base station separates the received frequency multiplexed signal by each band filter to obtain a desired frequency, and then the electrical signal Each demodulator demodulates to a baseband signal, and the quality of each received signal is compared by a judgment device, and a demodulated baseband signal with good quality is selected and output. On the other hand, for transmission from the toll base station to the mobile terminal, the modulated signal is input to a transmission switch that branches and selects based on the judgment result of the judgment device, and the output signal is output by a plurality of modulation signals and frequencies which are different depending on the multiplex distribution device. After multiplexing, the frequency-multiplexed signals output from each multiplexing / distributing device are converted into different intermediate frequencies, each intermediate-frequency signal is combined, transmitted to the base station via the broadband transmission path, and received at the base station. Diversity transmission / reception method characterized by distributing multiple signals with different frequency bands, converting to the same radio frequency and transmitting.