JP3408155B2 - Diversity communication device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity communication device in which a plurality of wireless systems share a plurality of antennas to perform diversity transmission / reception.

[0002]

2. Description of the Related Art In recent years, various PHS (Personal Handyphone Syste) compatible with high traffic areas such as urban areas and metropolitan areas
m) Base station equipment is provided. A conventional base station that supports high traffic will be described below. The base station includes two wireless systems 1 and 2 (hereinafter, system 1 and system 2), and each system has a TDMA / TDD (Time
Division Multiple access / Time Division Duplex) method enables simultaneous transmission / reception with multiple mobile stations.

FIG. 11 is a diagram showing a frame structure of transmission and reception in the TDMA / TDD system of the base station. In the figure, the upper part shows the frame structure of system 1 and the lower part shows the frame structure of system 2, and a 5 ms frame is further divided into 8 slots. , Are line 1 and line 2, respectively
Ri (i = 1, 2, 3, 4) is a receiving slot, Ti (i = 1, 2, 3, 4) is a transmitting slot, and R is
i and Ti (i = 1, 2, 3, 4) are corresponding transmission / reception slots.

In this frame structure, when all slots are used for communication channels, a maximum of eight mobile stations can be communicated by assigning different transmission / reception slots to a plurality of mobile stations. FIG. 12 is an example of a frame configuration when each transmission / reception slot of the frame configuration of FIG. 11 is assigned to different mobile stations.

In the figure, PS1 to PS8 are eight mobile stations, and as can be seen, the base station performs transmission / reception with two mobile stations in each slot. In such a frame structure, the base station shares four antennas between the system 1 and the system 2, and performs diversity transmission / reception for each slot shown in FIG. In other words, in the system 1, in each reception slot, the reception wave of the antenna with the best reception state among the four antennas is selected as the reception antenna and demodulated, and in each transmission slot, as the reception antenna in the corresponding reception slot. The selected antenna is selected as a transmission antenna and a transmission wave is output. Similarly system 2
Also, in each reception slot, the reception wave of the antenna with the best reception condition among the four antennas is selected as the reception antenna and demodulated, and in each transmission slot, the antenna selected as the reception antenna in the corresponding reception slot. The transmission wave is output by using as a transmission antenna.

However, in a certain receiving slot, when the same antenna is selected as the receiving antenna for both system 1 and system 2, both systems demodulate the received wave of the receiving antenna, but in the corresponding transmitting slot. One system uses the reception antenna as a transmission antenna, and the other system uses an antenna other than the reception antenna as a transmission antenna to output a transmission wave from each transmission antenna.

Because, in order for both systems to output their respective transmission waves from the same antenna in the same slot,
This is because a circuit such as a synthesizing circuit is required, and the power loss increases accordingly. Therefore, by using different antennas in each transmission slot, the combining circuit is omitted and the power loss is reduced.

[0008]

However, the method of using different transmission antennas in each transmission slot in the above-mentioned conventional base station has a problem that the effect of the transmission diversity cannot be obtained when the reception signal level is low. is there. For example, in a certain reception slot, the received signal level for each antenna of system 1 and system 2 is shown in FIG.
In the case as shown in 3, the antenna 102 is selected as the transmission antenna of the system 1 and the antenna 101 is selected as the transmission antenna of the system 2. As a result of selecting the antennas in this way, the reception signal level of the transmission antenna of the system 1 is 3, and this value is lower than the reception signal level 4 of the transmission antenna of the system 2.

In view of the above problems, it is an object of the present invention to provide a diversity communication device that improves the effect of diversity transmission.

[0010]

In order to solve the above problems, the diversity communication apparatus of the present invention is controlled so that a plurality of radio systems share a plurality of antennas and different antennas are selected in the same transmission slot. In the diversity communication device, the detection means for detecting the reception level in the reception slot for each radio system and each antenna, and the transmission level corresponding to the reception slot with reference to the detected reception level for each radio system and each antenna Allocating means for allocating an antenna to each wireless system, determining means for determining whether the receiving level of the receiving slot in each wireless system is higher than a predetermined threshold, and determining that the receiving level is low in the same receiving slot If there are two or more specified wireless systems, remove the remaining wireless system except the one wireless system. The determination means having slot changing means for changing to a vacant transmission / reception slot, the maximum reception signal level in each radio system among the reception signal levels for each antenna detected in the same reception slot of a plurality of transmission / reception systems is It may be configured to determine whether or not each is lower than the threshold value.

In the determining means, the received signal level of each antenna assigned to the assigning means is lower than the threshold value among the received signal levels of the respective antennas detected in the same receiving slot of a plurality of transmission / reception systems. It may be configured to determine whether or not.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) FIG. 1 is a circuit block diagram showing a configuration of a main part of a base station 100 according to an embodiment of the present invention. The base station 100 is roughly divided into a high-frequency output side and an antenna switching unit, and RF (high-frequency).
Unit, an IF (intermediate frequency) unit, and a baseband unit, and transmission / reception diversity using four antennas is performed using two systems of carrier waves by using the TDMA / TDD frame shown in FIG. Wireless communication between.

The antenna switching unit includes four antennas 101 to 104 which are selectively used for transmission / reception diversity.
Band limiting filters 405 to 408 that pass only signals in the communication band from the received signals, antenna changeover switches 151 and 152 for connecting the transmission signals of each system to the antenna in the transmission slot, and the transmission slot and the reception slot. Transmit / receive switch 1 that is switched by
11 to 114 and C / N ratio (carrier to noise rati
o: ratio of received signal power to receiver noise temperature) is less deteriorated and band limiting filters 405 to 4 in the receiving slot
Low noise amplifiers 415 to 418 for amplifying the reception signal input via 08, isolators 419 and 420 for passing the transmission signal only in one direction, and a distributor for distributing the reception signal of each antenna after amplification into two systems. 421-424
And a low-pass filter 4 that suppresses high-frequency spurs that are unnecessary waves generated during processing other than the carrier wave used for communication.
25 and 426, and power amplifiers (also referred to as HPA) 427 and 428 for amplifying signals up to a power level for transmission.

In the antenna switching section, the antenna switching switch 151 transmits the transmission signal of one system to the antenna 1
It can be switched to any of 01 to 104. Further, the antenna changeover switch 152 can switch the transmission signal of the other system to any of the antennas 101 to 104. In this configuration, any of the four antennas can be used for each system, but the use of the same antenna at the same time is excluded.

The RF section is a PLL synthesizer section 435,
Using the local frequency signal from 436, the steps from RF signal to IF signal (from IF signal to RF signal) are processed for two systems for each of the two carriers. One system is mainly composed of the receiving unit 431 and the transmitting unit 433, and the other system is mainly composed of the receiving unit 432 and the transmitting unit 434. The local frequencies of the PLL synthesizer units 435 and 436 are set by the PLL control units 437 and 438.

In the RF section, the receiving section 431 receives the RF signals from all four antennas via the RF section during reception, measures the received signal level of each antenna, and converts the RF signal into an IF signal. The detected received signal level measurement value is sent to the first via the A / D processing unit 443.
It is output to the determination unit 445 and used for antenna selection by transmission / reception diversity. Further, the transmitting unit 433 converts the IF signal from the IF unit into an RF signal during transmission, and
A427, low-pass filter 425, isolator 41
It outputs to the antenna switching part via 9. Receiver 4
The same applies to 32 and the transmission unit 434.

The IF unit, from the IF signal to the baseband signal (baseband signal to IF
The steps up to the signal) are mainly processed by the modulation / demodulation units 451 and 452. In the IF unit, the first determination unit 445 and the control unit 44
6 controls the selection of the diversity antenna.

The first judging section 445 determines, for each reception slot,
Among the measured values of the reception signal level input from the reception unit 431 via the A / D processing unit 443, the maximum reception signal level and the second and third reception signal levels are obtained, and the maximum reception signal level is calculated. The first-ranked antenna, the second-ranked antenna which gives the second-order received signal level, and the third-ranked antenna.
It is determined that the antenna is the third-ranked antenna given the received signal level of the second rank. Further, the combination of the maximum received signal level and the first antenna and the determined second antenna are output to the control unit 446 as the determination result. Similarly, the first determination unit 4
The reference numeral 45 obtains the maximum received signal level and the second and third received signal levels among the measured values of the received signal level inputted from the receiving section 432 through the A / D processing section 444, and obtains the maximum received signal level. A first-ranked antenna that gives a level, a second-ranked antenna that gives the second-order received signal level, and a third-ranked antenna that gives the third-order received signal level are determined.

The second determination unit 134 monitors the maximum reception signal level of both systems for each reception slot, and when the maximum reception signal level of both systems is low in the same reception slot, the communication channel of either system is detected. Output to the control unit 446 to switch to another slot. Specifically, the second determination unit 134 determines whether the maximum reception signal level for each system and each reception slot obtained by the first determination unit 445 is higher (H) or lower (L) than a predetermined level, The determination result is recorded in the storage unit 133 in association with each system and each reception slot.

FIG. 2 shows an example of the maximum reception signal level for each system and each reception slot obtained by the first determination section 445. In the figure, each maximum received signal level is 10
It is displayed in stages, and "-" indicates that it is an empty slot. The second determination unit 134 determines whether or not each of the maximum received signal levels is higher than a predetermined level (for example, 5). If the maximum received signal level is higher, the determination value table of the storage unit 133 is set as H and the determination value table is set as L when it is lower. Remember. The second determination unit 134 updates the determination value table for each frame. Here, the predetermined level indicates the minimum value of the range acceptable as the received signal.

FIG. 3 shows the case where the predetermined level is 5.
It is a judgment value table corresponding to. . Second determination unit 134
Refers to the recorded judgment value table for each reception slot, detects a reception slot in which both system 1 and system 2 are L, and stores the reception slot number.

When a receiving slot which is L in both systems is detected, the second judging section 134 detects the receiving slot of the switching destination in order to switch the communication channel of one system in the slot to another slot. Then, the reception slot number is stored. Here, the receiving slot to be switched to is limited to an empty slot in both systems, or a slot in which one is empty and the other is H.

The second determination unit 134 notifies the control unit 446 of the slot number so as to switch either one of the L reception slots of the communication channels to the reception slot of the switching destination, and instructs the slot switching. . Control unit 44
In each reception slot, 6 receives from the RF the IF received signal corresponding to the first antenna determined by the receiving units 431 and 432 according to the determination result of the first determining unit 445.
Instruct to convert to.

Further, the control unit 446, based on the determination result of the first determination unit 445, the antenna changeover switches 151, 1
By controlling the switch setting of 52, two systems (TDMA processing units 471 and 472) using different carrier waves are controlled.
(Based on the baseband signal of the above) is optimally distributed among the four antennas. Specifically, the first determination unit 445 first, in each transmission slot,
It is checked whether or not the two first-ranked antennas determined in the immediately preceding reception slot corresponding to the slot are the same antenna.

As a result of the investigation, if the antenna pairs are not the same and are different from each other (the pair of antennas 101 and 102 and the pair of 103 and 104), the first antenna which is different for each system is used for transmission. Then, the switch settings of the above combinations are controlled. As a result of the examination, if the antenna pair is the same or the same, the maximum received signal level of the modulated signal of system 1 and the maximum received signal level of the modulated signal of system 2 are compared, and the system having the larger maximum received signal level is compared. Select the 2nd or 3rd antenna for the modulated signal of No. 1 and the 1st antenna for the modulated signal of the other system, and set the switch settings of the above combinations so that transmission is performed using each antenna. Control.

The control unit 446 further includes a second determination unit 134.
When the slot numbers of the switching source and the switching destination are notified and the slot switching instruction is accepted, communication channel switching control is performed on the mobile station by referring to the mobile station allocation table for each system and each reception slot as shown in FIG. Send a signal. The baseband unit inputs / outputs a baseband signal to / from the IF unit for each slot so as to synchronize transmission / reception data for a plurality of slave units with a TDMA / TDD frame.
The A processing units 471 and 472 are provided.

The detailed processing procedure of slot switching of the second determination section will be described below with reference to FIG. Second determination unit 13
4 searches for a reception slot whose judgment value in the judgment value table of the storage unit 133 is L in both systems (step 601). As a result, if found, the slot number is set to the variable L.
Is stored in the memory inside the second determination unit 134 (step 603).

Next, the second judging section 134 searches for a receiving slot in which both systems are free, or one is free even if one is free (step 603). As a result, if found (step 604), the slot number is stored as a variable M (step 60).
5). The second determination unit 134 stores the L stored in this way.
And M as the slot switching source and slot switching destination, respectively, to the control unit 446 (step 609).

By such a processing procedure, since the communication channel of one system is switched to the other slot in the receiving slot in which both systems are L, reduction of the effect of transmission diversity is avoided. The above is the case where there is a switch-destination slot. However, in steps 603 and 604, if both slots are free, or if a slot in which one is free and one is H is not found, The 2 determination part 134 performs steps 606-608.

More specifically, the second judging section 134 has a slot in which one system is vacant and the other system is L, and both systems are H
(Step 606). If both slots exist (step 607), the slot number of one system is empty and the other system is L is stored as a variable L, and the slot numbers of both systems H are stored as variables. Store as M. Then, the second determination unit 134 notifies the control unit 446 of L and M,
It is instructed to switch the communication channel of slot number L to slot number M (step 609).

By doing so, a slot in which one system is H and one system is vacant is created, so that the second judging section 134 uses one communication channel of the L slot for both systems in that slot. Just move it. In step 606, one system is empty and the other system is L.
If the slot of No. and the slot of H in both systems are not found, the second determination unit 134 finishes the slot switching process, waits for the next empty slot, and when there is an empty slot, switches the slot again. Process.

By performing the processing as described above, the base station 100 of the present invention switches the communication channel of one system to another slot when both systems are L in the same transmission slot, so that the diversity effect is obtained. improves. (Second Embodiment) FIG. 6 is a circuit block diagram showing a main part of a base station 200 according to a second embodiment of the present invention.
In the figure, only the portion corresponding to the antenna switching unit in the base station 100 shown in FIG. 1 is shown. The other parts are the same as those in FIG. 1, and the description of the same configurations will be omitted and only the different points will be described below.

The different points are as follows. That is, in the above-described base station 100, as shown in FIG. 1, in the transmission system, two HPAs 427, 4 are arranged in the signal flow direction.
28, 2 antenna changeover switches 151, 152, 4
While the individual transmission / reception switches 111 to 114 are arranged in order, in the base station 200 of the present embodiment,
As shown in FIG. 6, two antenna changeover switches 151,
152, four HPAs 143-146, and four transmission / reception switches 111-114 are arranged in this order. Furthermore, two antenna changeover switches 151,
The difference is that system switching switches 153-156 are newly inserted between 152 and four HPAs 143-146. The system changeover switches 153 to 156 are provided to improve the isolation of the transmission system.

Antenna changeover switches 151, 152, system changeover switches 153-156, transmission / reception switch 111
The switching control of 114 to 114 is performed by the control unit 446.
Incidentally, the four middle switches 152-146 of HPAs 143-146.
It is desirable to control each transmission slot so that power is supplied only to the HPA connected to 156. In this case, the control unit 446 cooperates with the switches 153 to 156 to control the HP.
Power control of A may be performed. Thereby, the power consumption can be further reduced.

The configuration of the base station 200 of the second embodiment has the following advantages over the first embodiment. That is, according to the base station 200, the power loss in the latter stage of the HPAs 143 to 146 is smaller than that in the first embodiment, and the HPA performance (performance for performing low distortion amplification) is low. As described above, since the HPA output may be low, it is possible to reduce the power consumption as compared with the first embodiment. That is, the antenna 1
The size of the radio wave output from 01 to 104 is fixed, and immediately before that, the transmission / reception changeover switches 111 to 1
Since there are only 14, only the power loss should be taken into consideration in HPAs 143-146. Therefore, HPA can use a low-performance amplifier. On the other hand, when a high-performance amplifier is used, amplification control can be performed in a place where efficiency is low, resulting in high efficiency.

When the HPA is at the frontmost stage as in the first embodiment, the magnitude of the power output from the antenna,
Considering the amount of attenuation in multiple circuits, HPA performance,
Since it is necessary to determine the utilization efficiency, it is necessary to have a better performance and high efficiency as the HPA. However, in the second embodiment, the HPA is present for each antenna, which is the case. Eliminates the need for performance and efficiency.

In addition, in the second embodiment, since the amplification by HPA is performed after selecting the antenna, the advantage that the isolation between the transmission systems can be easily achieved due to the presence of the system changeover switches 153 to 156. There is. (Third Embodiment) FIG. 7 is a circuit block diagram showing a configuration of a main part of a base station 300 according to a fourth embodiment of the present invention.

The base station 300 is the base station 10 shown in FIG.
0, the configuration of the antenna switching unit is different, and a cross switch 46 is provided between the baseband unit and the IF unit.
The difference is that 0 is newly provided. Hereinafter, the same points will not be described, and different points will be described. The antenna switching unit includes four antennas 101 to 104 that are selectively used for reception / transmission diversity, and band limiting filters 405 to 408 that pass only signals in the communication band from the received signals.
And antenna changeover switches 409 and 410 for connecting the transmission signal of each system to the antenna in the transmission slot.
And a reception signal input via the transmission / reception change-over switches 411 to 414 that are switched depending on the transmission slot and the reception slot and the band limiting filters 405 to 408 in the reception slot.
The low noise amplifiers 415 to 418 that amplify with little deterioration in the ratio of the received signal power to the receiver noise temperature), the isolators 419 and 420 that pass the transmission signal in only one direction, and the reception signals of the respective antennas after amplification are 2 Distributors 421 to 424 that distribute to the system, low-pass filters 425 and 426 that suppress high-frequency spurious waves that are unnecessary waves generated during processing other than the carrier waves used for communication, and power that amplifies signals to the power level for transmission. Amplifier (also called HPA) 42
7, 428.

In the antenna switching unit, the antenna switching switch 409 transmits the transmission signal of one system to the antenna 4
Only 01 and 402 can be switched. Further, the antenna changeover switch 410 can switch the transmission signal of the other system to only the two of the antennas 403 and 404. In this configuration, it seems that only two of the four antennas can be used in each system, but by combining with switching of the cross switch 460 described later, all of the four antennas can be used. However, using the same antenna at the same time, and simultaneously using the antennas 401 and 402 (antennas 403 and 404)
It is excluded to use.

In each transmission slot, the determination unit 445 first checks whether or not the two first-ranked antennas determined in the immediately preceding reception slot corresponding to the slot are the same antenna. As a result of the examination, the antenna pairs (antenna 40
1 and the pair of 403 and the pair of 403 and 404), the switch setting of the above combination is controlled so that the first antenna different for each system is used for transmission.

As a result of the examination, if the antenna pair is the same or the same, the maximum received signal level of the modulated signal of the system 1 and
The maximum received signal level of the modulated signal of the system 2 is compared, and the second-ranked antenna or the third-ranked antenna is used for the modulated signal of the system having the larger maximum received signal level, and the modulated signal of the other system is compared. The switch setting of the above combination is controlled so that the first antenna is selected and transmission is performed using each antenna.

The cross switch 460 located between the baseband section and the IF section switches between straight connection and cross connection under the control of the control section 446. In the cross connection, the TDMA processing units 471 and 4 are provided as compared with the straight connection.
The two baseband signals from 72 are exchanged for the modulation / demodulation units 451 and 452 of the IF unit. In the case of cross connection, in order to switch the carrier frequencies at the same time, the control unit 446 causes the PLL control unit 437 and the PLL
The setting of the local frequency for the control unit 438 can also be replaced. As a result, the routes from the baseband signal to the generation of the IF signal and the RF signal can be exchanged.

The operation of the base station according to the third embodiment configured as described above will be described with reference to an example of ranking according to the received signal level shown in FIG. As a first operation example, for example, it is assumed that the first slot of the first system and the first slot of the second system are used for communication. In the reception section, each of the reception units 431 and 432 receives a signal, measures the reception level, and outputs the RSSI signal.

First of all, the judging section 445 is constituted by the receiving sections 431 and 43.
The RSSI signal from 2 determines which antenna has the highest reception level. Therefore, the reception level is shown in FIG.
In the first system, the antenna 401, the second
The determination unit 44 where the antenna 404 is high in the system
5 determines and outputs a determination signal to the control unit 446. Upon receiving the signal, the control unit 446 receives the determination signal, and the cross switch 460 determines that the first system is the antenna 40 in the transmission section.
The first and second sides are controlled so that the second system selects the antennas 403 and 404 side.
Controls the antenna 401 and the antenna changeover switch 410 selects the antenna 404.

Therefore, the transmission signal of the first system passes through the cross switch 460 without crossing and is transmitted from the antenna 401 selected by the antenna changeover switch 409.
Further, the transmission signal of the second system also passes through the cross switch 460 without crossing and is transmitted from the antenna 404 selected by the antenna changeover switch 410. Next, as a second operation example, the second slot of the first system and the second slot of the second system
It is assumed that the slots are simultaneously used for communication. This is indicated by RX2 and RX6 in FIG. As described above, the reception units 431 and 432 perform reception in the reception section,
The reception level is measured and an RSSI signal is output.

First, the determination unit 445 is configured to include the reception units 431 and 43.
The RSSI signal from 2 determines which antenna has the highest reception level. Therefore, the reception level is shown in FIG.
According to the example shown in FIG. 3, if the antenna 401 is higher in the first system and the antenna 401 is higher in the second system, the determination unit 44
5 determines and outputs a determination signal to the control unit 446. However, with this configuration, it is not possible to output a transmission signal using the same antenna.

Therefore, in order to select a different antenna, the following processing is continuously performed. First, of the reception levels received by the first system and the second system, the highest reception level of both is compared, and the system having the lower received signal level is determined. In the case of FIG. 8, in the antenna 401 having the highest reception level, the first system is the second system.
Since the reception level is lower than that of the system, the lower first system is preferentially selected. That is, the antenna selected in the first system is the antenna 401. However, since the transmission antenna to be selected for the second system has not been decided, the determination is made as follows.

Next, the determination unit 445 tries to determine the antenna to be transmitted by the undetermined second system. At that time, the reference level is the reception level shown in FIG. In the second system, the reception level from the antenna 402 is the next highest (third) after the antenna 401, so the antenna 402 is selected. However, the first line is HPA42
7, the low pass filter 425, the isolator 419, and the antenna changeover switch 409 are used, so that system cannot be used.

Therefore, it becomes necessary to perform control so that the remaining HPA 428, the low-pass filter 426, the isolator 420, the antenna changeover switch 410, and the like are used. Therefore, the determination unit 445 determines to transmit by the antenna 3 (7th) having the next highest reception level and outputs a determination signal. Based on this determination signal, the control unit 446 controls the cross switch 460 to select the antenna 401 for the first system and the antenna 403 for the second system in the transmission section.

As a result, the antenna changeover switch 409
Selects the antenna 401, and the antenna changeover switch 41
0 selects the antenna 403. Also, the third
As an example of operation, it is assumed that the third slot of the first system and the third slot of the second system are used for communication. In the reception section, each of the reception units 431 and 432 receives the transmitted signal, measures the reception level, and outputs the RSSI signal. The determining unit 445 first receives the RSSI from the receiving units 431 and 432.
The signal determines which antenna has the highest reception level.

Next, as a fourth operation example, it is assumed that the third slot of the first system and the third slot of the second system are simultaneously used for communication. This is indicated by RX3 and RX7 in FIG. As described above, the reception units 431 and 432 perform reception in the reception section, measure the reception level, and
Output SSI signal. First, the determination unit 445 is the reception unit 4
The RSSI signals from 31, 432 determine which antenna has the highest reception level. Therefore, the determination unit 445 determines that the reception level is higher in the antenna 401 in the first system and the antenna 401 in the second system than the example shown in FIG. 8, and outputs a determination signal to the control unit 446.

However, as described above, according to this configuration, the same antenna cannot be used to output a transmission signal. Therefore, as in the second example, the following processing is continuously performed in order to select a different antenna. First,
Of the reception levels received in the first system and the second system, the highest reception level of both is compared,
The system with the lower received signal level is determined.

In the case of RX3 and RX7 of FIG. 8, in the antenna 401 having the highest reception level, the second system has a lower reception level than the first system. Therefore, the lower second system is preferentially given. Select. That is, the antenna selected in the second system is the antenna 401. However, since the transmission antenna of the first system to be selected has not been determined, the determination is performed as follows.

Next, the determination unit 445 tries to determine the antenna to be transmitted by the undetermined first system. At that time, the reference level is the reception level shown in FIG. In the first system, the reception level from the antenna 403 after the antenna 401 is high (third), so the antenna 403 is selected. Unlike the second example, the antenna 403 does not use the same transmission system, so the first system uses the antenna 403 and the second system uses the antenna 401 to perform transmission.

At this time, the control unit 446 controls the cross switch 460 to transmit the signal to the antenna 4 when the signal is transmitted.
03, the second system is controlled so as to be able to transmit via the antenna 401. In this way, the systems are interchanged (the first system is the antennas 403 and 404, and the second system is the antenna 40).
1, 402 is used for transmission), the transmission unit 433,
The control unit 446 controls the PLL control units 437 and 438 so that the transmission frequencies of the signal 434 are also adjusted to the respective frequencies. Thereby, the frequency suitable for the channel can be transmitted.

That is, when the transmission signal from the first system is transmitted by the antennas 401 and 402, the PLL synthesizer section 435 outputs the local frequency so that the frequency corresponds to each slot in the first system. However, when the transmission signal from the second system is transmitted by the antennas 401 and 402, the PLL synthesizer unit 435 outputs the local frequency so that the frequency corresponds to each slot in the second system. is doing.

Further, as a fifth operation example, it is assumed that the fourth slot of the first system and the fourth slot of the second system are simultaneously used for communication. This is RX4, RX8 in FIG.
It shows with. As described above, each reception unit 4 in the reception section
31 and 432 perform reception, measure the reception level, and then RS
Output SI signal. First, the determination unit 445 uses the reception unit 43.
Which antenna has the highest reception level is determined from the RSSI signals from 1, 432. Therefore, according to the example shown in FIG.
02, in the second system, the determination unit 445 determines that the antenna 401 is high, and outputs a determination signal to the control unit 446.

However, as described above, according to this configuration, the same antenna cannot be used to output a transmission signal. Therefore, the following processing is continuously performed in order to select a different route. First, of the reception levels received by the first system and the second system, the highest reception level of both is compared, and the system having the lower received signal level is determined.

In the case of FIG. 8, in the antenna 402 having the highest reception level, the highest reception level of the first system is lower than that of the second system. Therefore, the lower first system is preferentially selected. That is, the antenna selected in the first system is the antenna 402. However, since the transmission antenna to be selected for the second system has not been decided, the determination is made as follows.

Next, the determination unit 445 tries to determine the antenna to be transmitted by the undetermined second system. At that time, the reference level is the reception level shown in FIG. In the second system, the highest level received on a route other than the used route is the highest received level from the antenna 404 (fourth), so the antenna 404 is selected. Therefore, the determination unit 445 determines that the antenna 404 having a high reception level
(4th) is determined to be transmitted, and a determination signal is output. Based on this determination signal, the control unit 446 causes the cross switch 460 in the transmission section, the first system to be the antenna 401,
The second system controls to select the antenna 403.

As a result, the antenna changeover switch 409
Selects the antenna 402, and the antenna changeover switch 41
0 will select the antenna 404. (Fourth Embodiment) FIG. 9 is a circuit block diagram showing a configuration of a main part of a base station 400 in a fourth embodiment of the present invention.

The base station 400 is roughly divided into an antenna switching section, an RF (high frequency) section, and an IF section from the high frequency output side.
The reception / transmission diversity, which is composed of the (intermediate frequency) part and the baseband part, and which uses four antennas, is wirelessly communicated with a plurality of slave units by the TDMA / TDD frame using the carrier waves of two systems. . The configuration of the base station 400 of FIG. 9 is almost the same as that of the base station of FIG. 7 in the RF unit, the IF unit, and the baseband unit, and the same points will be omitted and different points will be mainly described below.

The main difference lies in the control contents of the antenna switching unit, the judging unit 445 and the control unit 446. The antenna switching unit includes four antennas 101 to 104 that are selectively used for reception / transmission diversity.
, Band limiting filters 405 to 408 that pass only signals in the communication band from the received signal, transmission / termination resistance changeover switches 481, 482, 487, 488, and transmission / reception changeover switches 483, 484, 485, 486.
And circulators 491 to 494, which are multi-port passive non-reciprocal elements having a function of outputting a port input to an adjacent port in a specific direction, and an antenna changeover switch 495 for connecting a transmission signal of each system to an arbitrary antenna in a transmission slot. 496 and C / N ratio (carrier to noise r
ratio: the ratio of the received signal power to the receiver noise temperature) is small and the band limiting filter 405 to 405 in the receiving slot.
Low noise amplifiers 415 to 418 for amplifying a reception signal input via 408, isolators 419 and 420 for passing a transmission signal only in one direction, and a distributor for distributing the reception signal of each antenna after amplification into two systems. 421-424
And a low-pass filter 4 that suppresses high-frequency spurs that are unnecessary waves generated during processing other than the carrier wave used for communication.
25 and 426, and power amplifiers (also referred to as HPA) 427 and 428 for amplifying signals up to a power level for transmission.

In the antenna switching section, the circulators 491 to 494 function as transmission / reception switching switches. Of these, circulators 492, 493
Has a function of selecting transmission signals of two systems. Therefore, the circulators 492 and 493 are circuits to which diodes as shown in FIG. 10 are added. Circulator 492 (or 49
3) transmission / termination resistance changeover switch 482 (or 4
A diode which is turned on / off by a control signal from the control unit 446 is connected to the port on the side 87). When this diode is on, the diode-connected port internally totally reflects the signal that is originally output to the outside.
The totally reflected signal is output from the port next to it. By turning on the diode, the transmission signal from the transmission / reception changeover switch 485 can be totally reflected inside the diode-connected port and output to the port to which the antenna 102 is connected.

The antenna changeover switch 495 can switch the transmission signal of one system to the two of the antennas 101 and 102 and the antenna 103 via the circulator 493. Also, the antenna changeover switch 496 is
The transmission signal of the other system is sent to the antenna 102 and the antenna 103 via the circulator 492.
Can be switched to. With this configuration, it seems that only three of the four antennas can be used in each system, but by combining with the switching of the cross switch 460, which will be described later, all of the four antennas can be used. However, the use of the same antenna at the same time is excluded.

The antenna changeover switch 495,
496 may have three outputs instead of four outputs, and the transmission path toward the transmission / reception changeover switch 483 and the transmission / reception changeover switch 486 is not used. In addition, the cross switch 460
And the positional relationship between the modulation / demodulation units 451 and 452 may be exchanged. That is, either the baseband signal or the IF signal may be exchanged between the two systems.

According to this embodiment, the cross switch 46
0 and the circulators 492, 493 share part of the antenna switching at the level of the baseband signal or IF signal, so that the circuit configuration required for switching at RF is simpler. Designing and manufacturing the RF part is easy. In each of the above-described embodiments, the base station has four antennas, but the number of antennas provided in the base station is not limited to four.
Any number is acceptable. However, at least three or more are preferable. Also in that case, each antenna is provided with a receiving unit and a transmission / reception changeover switch.

In each of the above embodiments, the base station is assumed to perform communication with the mobile station by simultaneously using two TDD frames including the first TDD frame and the second TDD frame. The number of frames is not limited to two and may be any number. When the base station uses three or more TDD frames at the same time as described above, it is only necessary to allocate one of the channels as a control channel, so that the base station can further increase the number of mobile stations. Communication can be relayed. However, if the base station is
When using the DD frame, the base station is provided with the same number of HPAs, antenna changeover switches, reception selection switches and demodulation circuits as the TDD frames used. Further, each receiving unit is provided with the same number of tuning circuits and RSSI circuits as the TDD frames used. Further, the determination unit determines, for each TDD frame used, a combination of a reception signal level in descending order and an antenna that gives the reception signal level up to a rank corresponding to the number, and selects the determination result (or control unit). Output).

When the same antenna is determined as the first antenna for the modulation signals of different systems corresponding to each TDD frame used as the transmission diversity, the selection unit (or the control unit) determines that the same antenna is the first antenna. Of the modulated signals having that antenna as the first antenna, the modulated signal having the smallest maximum received signal level is assigned to the first antenna. Further, the modulated signal having the second lowest maximum received signal level is assigned to the second antenna of the modulated signal. If the second antenna is the same as the first antenna determined for the modulated signals of other systems,
The modulated signal with the smaller received signal level provided by this antenna is assigned to this antenna. In this way, when the same antenna is determined for the modulation signals of different systems, the selection unit (or control unit) gives priority to the modulation signal with the smaller received signal level given by the antenna. The modulated signal with the higher received signal level is assigned to the lower antenna.

In the present embodiment, the reception diversity has been described using the antenna selection diversity, but the reception diversity system is not limited to the antenna selection diversity and may be, for example, combined diversity. It is desirable to further include a phase control circuit when performing composite diversity. This is because the reception signals received by the respective antennas have a phase difference, and the phase control circuit combines the phases of the reception signals of the respective antennas and then combines them. However, even with synthetic diversity, it is not always necessary to provide a transfer control circuit.

In the above embodiment, the received signal levels of the two wireless systems are both (Low,
Low), one channel (transmit, receive slot)
However, it may be configured as follows. That is, the second determination unit may compare the reception level of the antenna actually selected from the plurality of antennas for both two wireless systems with a predetermined level. In this case, when the antenna with the highest reception level competes in two wireless systems (the same antenna), the judgment result may be different from pattern 1, but the judgment is made for the actually selected antenna. Therefore, when both of the two wireless systems are at the low level, it is considered that the wireless system determined to be low will move to another communication channel more reliably.

Further, the determination as to whether it is high or low is made by the second determination unit 134, for the maximum reception level or the selected reception level in each radio system, a plurality of past frames (for example, 10 frames: influence of movement of a person). It is also possible to obtain an average of (time that is considered to appear) and determine whether the average value is high or low. Furthermore, in the above embodiment, regardless of whether or not the maximum level antennas of the two radio systems compete (are the same) (Low,
Although one channel of (Low) is moved, the following may be adopted. That is, if the maximum level antennas of the two wireless systems do not compete, (Low, Low)
In this case, since both radio systems exert the transmission diversity effect to the maximum extent, they may not be moved, but may be moved only when they compete. In this case, the number of competitions in a plurality of past frames (time at which the influence of movement is considered to appear) may be further obtained, and movement may be performed when the number of times exceeds a predetermined value (for example, 5 times).

Further, in the above-mentioned embodiment, when the empty channel does not exist, it is not moved, but two speech channels may be switched at the same time. For example, the two call channels to be exchanged may be temporarily stopped (a voice announcement to the effect that the call will be temporarily stopped is sent from the master unit), and the call channels to the two slave units may be allocated again. .

[0074]

The diversity communication device of the present invention is a diversity communication device in which a plurality of radio systems share a plurality of antennas and are controlled so that different antennas are selected in the same transmission slot. With reference to the detection means for detecting the reception level in each slot for each wireless system and each antenna, and the detected reception level for each wireless system and each antenna, an antenna is assigned to each wireless system in the transmission slot corresponding to the reception slot. When there are two or more assigning means, a determining means for determining whether the reception level of the receiving slot in each wireless system is higher than a threshold value, and a wireless system for which the receiving level is determined to be low in the same receiving slot. Slots for changing the remaining wireless systems to other vacant transmit / receive slots except for the one wireless system Further comprising a means.

With such a configuration, the diversity communication apparatus of the present invention, when it is determined that the reception level of each system is low in the same reception slot, the radio system other than the one radio system has another transmission / reception slot. Since it is changed to, it is not necessary to perform diversity by using low reception levels for each system, and the diversity effect is improved.

Among the received signal levels for each antenna detected in the same reception slot of a plurality of transmission / reception systems, the determination means determines whether the maximum received signal level in each radio system is lower than the threshold value. Is configured to determine. With such a configuration, the diversity communication device of the present invention, in the same reception slot, when the maximum received signal level of each wireless system is all lower than the threshold value, except for one wireless system, the remaining wireless systems. Is changed to another vacant transmission / reception slot, the effect of diversity transmission is improved.

Further, in the judging means, the received signal level of each antenna assigned to the assigning means is lower than the threshold value among the received signal levels of the respective antennas detected in the same receiving slot of a plurality of transmission / reception systems. It may be configured to determine whether or not. With this configuration, the diversity communication device of the present invention excludes one wireless system and leaves the remaining wireless systems open when other received signal levels of the antennas assigned to the respective wireless systems are all lower than the threshold value. Since the transmission / reception slot is changed to a different transmission / reception slot, the effect of diversity transmission is improved.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing a configuration of a main part of a base station 100 according to an embodiment of the present invention.

[Fig. 2] For each system obtained by a first determination unit 445,
It is an example of the maximum reception signal level for each reception slot.

FIG. 3 is a determination value table corresponding to FIG. 2 when the threshold value is 5.

FIG. 4 is a diagram showing a mobile station allocation table for each system and each reception slot.

FIG. 5 is a flowchart showing a more detailed processing procedure of a second determination unit.

FIG. 6 is a base station 200 according to the second embodiment of the present invention.
3 is a circuit block diagram showing a main part of FIG.

FIG. 7 is a base station 300 according to the fourth embodiment of the present invention.
3 is a circuit block diagram showing a configuration of a main part of FIG.

FIG. 8 is a diagram showing an example of ranking according to a received signal level.

FIG. 9 is a base station 400 according to the fourth embodiment of the present invention.
3 is a circuit block diagram showing a configuration of a main part of FIG.

FIG. 10 is a circuit diagram showing circulators 492 and 493 and diodes added thereto.

FIG. 11 is a diagram showing a frame configuration of transmission / reception according to the TDMA / TDD system of the base station.

FIG. 12 is an example of a frame configuration when each transmission / reception slot of the frame configuration of FIG. 11 is assigned to different mobile stations.

FIG. 13 is a diagram showing an example of a received signal level for each antenna.

[Explanation of symbols]

101-104 antenna 151, 152 Antenna changeover switch 111-114 transmission / reception changeover switch 405-408 Band limiting filter 415-418 low noise amplifier 419, 420 Isolator 421-424 distributor 425, 426 Low pass filter 427, 428 Power Amplifier (HPA)

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-183475 (JP, A) JP-A-6-338835 (JP, A) JP-A-7-131442 (JP, A) JP-A-9- 215051 (JP, A) JP 10-51365 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04B ⁷ /02-7/12 H04L 1/02-1/06

Claims (3)

(57) [Claims] 1. In a diversity communication device in which a plurality of radio systems share a plurality of antennas and are controlled to select different antennas in the same transmission slot, the reception level in the reception slot is set for each radio system and the antenna. Detection means for each of the radio systems, allocating means for allocating the antenna to each radio system in the transmission slot corresponding to the reception slot by referring to the detected reception level of each radio system and each antenna, and the reception slot in each radio system Determination means for determining whether or not the reception level is higher than a predetermined threshold value, and if there are two or more radio systems for which the reception level is determined to be low in the same reception slot, except for the one radio system, A slot changing means for changing the remaining wireless system to another vacant transmission / reception slot. Diversity communication apparatus according to symptoms. 2. The determination means, among the received signal levels for each antenna detected in the same reception slot of a plurality of transmission / reception systems, whether the maximum received signal level in each radio system is lower than the threshold value. The diversity communication device according to claim 1, wherein it is determined whether or not it is. 3. The determination means is characterized in that among the reception signal levels of the respective antennas detected in the same reception slot of a plurality of transmission / reception systems, the reception signal level of each antenna assigned to the assignment means is less than the threshold value. The diversity communication device according to claim 1, wherein it is determined whether or not it is low.