JP2010161782A - Wireless base station - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless base station of adaptive array system which prevents generation of noise (jarring and grating sounds) from the signal even when a wireless mobile station receives a signal transmitted to another path-multiplexed mobile station. <P>SOLUTION: When two mobile stations, PS-A and PS-B, are path-multiplexed, a clock generating part 52 generates a clock by shifting a transmission time of a symbol to the mobile station PS-B by a 0.5 symbol period from a transmission time of a symbol to the mobile station PS-A. By such adjustment of transmission timing as this, even if a mobile station receives a symbol transmitted to another path-multiplexed mobile station, reception time of the symbol is shifted from reception time of a symbol to own station and is not synchronizing to each other, and the received symbol to another mobile station is not demodulated as before; therefore, meaningless noise (jarring and grating sounds) are not generated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an adaptive array radio base station that spatially multiplexes and transmits a transmission signal to a mobile station with different directivity patterns.

In recent years, in digital communication devices, information is transmitted by modulating a carrier wave with a digital information signal (baseband signal) for efficient transmission.
In digital communication, effective use of frequency resources is achieved by increasing the transmission speed and increasing the number of channels accommodating multiple users at the same frequency by time division multiplexing. Furthermore, a spatial multiplexing system that accommodates a plurality of channels at the same time at the same frequency by using an adaptive array system has attracted attention.

  The adaptive array method is a method in which a directivity pattern (also called an array antenna pattern) is adaptively formed by a plurality of antennas so that radio waves reach only users in a specific direction. For example, in the case of an adaptive array apparatus having four sets of radio units including a transmission circuit, a reception circuit, and an antenna, the amplitude and phase of the transmission signal for each transmission circuit at the time of transmission, and the amplitude and phase for each reception circuit at the time of reception. By adjusting each, directivity patterns at the time of transmission and at the time of reception can be formed. The details of the adaptive array method are described in “Special Issue on Adaptive Signal Processing in Spatial Domains and its Applied Technology” (Volume of the Institute of Electronics and Communication Engineers VOL.J75-B-II NO.11 NOVEMBER). Description is omitted.

  In an adaptive array radio base station, by forming different directivity patterns for a plurality of mobile stations, it is possible to multiplex a plurality of mobile stations at the same time and communicate at the same time. This communication is called path division multiple access (PDMA, Path Division Multiple Access, hereinafter referred to as path multiplexing) communication. Since this PDMA is described in “Path Division Multiple Access (PDMA) Mobile Communication System” (The IEICE Tech. RCS93-84 (1994-01), pp37-44), its details are omitted.

  As described above, a radio base station using the adaptive array scheme can effectively use one wave (one frequency) by forming different directivity patterns.

JP-A-9-260939

  However, in a radio base station using an adaptive array system, when a mobile station assigned the same frequency and multiplexed by path approaches as the mobile station moves, the mobile station picks up a signal sent to the other mobile station. It will end up. FIG. 9 is an explanatory diagram illustrating an example in which a mobile station receives a signal transmitted toward another mobile station. In the figure, PS-A to PS-D indicate mobile stations, and these are assigned the same frequency. 31, 32, 33, and 34 indicated by solid lines represent directivity patterns of communication channels directed to the mobile stations PS-A, PS-B, PS-C, and PS-D, respectively. Assuming that PS-B has moved as indicated by an arrow a in the figure, a situation occurs in which PS-B after movement receives a signal transmitted from the base station to PS-A. Then, PS-B demodulates the message sequence from the received signal to PS-A, and generates meaningless noise (beeger sound).

  This is because the base station sends a signal to be transmitted to the mobile station after performing a secret scramble process so that it can be descrambled only by the private key code unique to the mobile station held by the mobile station. Therefore, the mobile station can correctly descramble only the signal sent to its own station, and even if signals to other mobile stations are received, the secret key code does not match, so descrambling, This is because it is converted into a meaningless message string, which is output as noise (beeger sound). Such veger sounds are unsuitable because they cause discomfort to the user.

  In order to prevent the generation of a beaker sound, before outputting a signal to the speaker on the mobile station side, it is determined whether the signal is a beager sound or a sound by using a frequency analysis technique or the like, If it is determined that the signal is not output to the speaker. However, it is difficult for the determination means to be perfect, and it is necessary to mount the determination means on all the mobile stations, which impairs the simplicity of the mobile stations.

  Therefore, even when the mobile station receives a signal sent to another mobile station that has been path-multiplexed, the mobile station does not add the function of the mobile station. It is an object of the present invention to provide a radio base station that prevents generation of a beager sound.

  In order to solve the above problems, the radio base station of the present invention is an adaptive array radio base station that spatially multiplexes and transmits a transmission signal to a mobile station with different directivity patterns, and the plurality of mobile stations Multiplexing means for spatially multiplexing the clock phase of the transmission symbol in the transmission signal to the station by shifting each other regardless of the direction of the mobile station.

The radio base station of the present invention is an adaptive array radio base station that spatially multiplexes and transmits a transmission signal to a mobile station with different directivity patterns, and is a transmission symbol in transmission signals to the plurality of mobile stations There are provided multiplexing means for spatially multiplexing the clock phases of the clock phases with respect to each other regardless of the direction of the mobile station.
According to this configuration, in the mobile station, even when a signal sent to another mobile station is received, the synchronization clock for acquiring the symbol is different from the synchronization clock for acquiring the symbol for the local station. The symbol cannot be demodulated correctly. As a result, it is possible to prevent the generation of meaningless noise (beeger sound) in the mobile station.

It is a block diagram which shows the structure of the principal part of the wireless base station in embodiment of this invention. An example of an allocation management table is shown. It is explanatory drawing of the TDMA / TDD frame for performing time division multiplexing. 3 is a diagram illustrating a configuration of a signal adjustment unit 51. FIG. It is a figure which shows the structure of the user process part 51a. It is explanatory drawing which shows the example transmitted by shifting the symbol data of one user. It is a block diagram which shows the structure of the principal part of the radio | wireless mobile station in embodiment of this invention. The I component obtained by synchronous detection is shown. It is explanatory drawing which shows the example in which a mobile station receives the signal sent toward other mobile stations.

<Schematic configuration of radio base station>
FIG. 1 is a block diagram showing a configuration of a main part of a radio base station in the embodiment of the present invention.
The radio base station includes radio units 11, 21, 31, 41, antennas 10, 20, 30, 40, a modem unit 60, a control unit 80, a baseband unit 70, and a signal processing unit 50. .
<Wireless unit 11>
The radio unit 11 includes a transmission unit 12 and a reception unit 13. The transmission unit 12 modulates the baseband signal (symbol data) input from the signal processing unit 50 to an intermediate frequency signal (hereinafter abbreviated as IF signal), and the IF signal is a high frequency signal (hereinafter abbreviated as RF signal). And is amplified to a transmission output level and output to the antenna 10. The receiving unit 13 converts the received signal from the antenna 10 into an IF signal and demodulates it into a baseband signal (symbol data).

Since the radio units 21, 31, and 41 have the same configuration as the radio unit 11, the description thereof is omitted.
<Modem unit 60>
The modem unit 60 converts and demodulates the baseband signal by a π / 4 shift QPSK (Quadrature Phase Shift Keying) method.
<Control unit 80>
Specifically, the control unit 80 is composed of a CPU and a memory, and controls the entire radio base station. In particular, when receiving a call from a mobile station via a control channel, a control unit 80 receives a call from the network. At the time, a communication channel is allocated to the mobile station. FIG. 2 shows an example of the allocation management table. In the assignment management table of FIG. 6, the horizontal direction indicates time division communication channels, and the vertical direction indicates path division multiplexing. PS-A to PS-D in the column indicate assigned mobile stations. In the figure, PS-A, PS-C, and PS-D are time-division multiplexed, and PS-A and PS-B are path-multiplexed.
<Baseband part 70>
The baseband unit 70 is connected to a network (public network or private network) not shown in the figure, and performs baseband signal connection with the telephone network 90.

  The baseband unit 70 performs time division multiplexing processing. FIG. 3 is an explanatory diagram of a TDMA / TDD frame for performing time division multiplexing. Here, a TDMA / TDD frame of a so-called PHS telephone system is shown. In the figure, T0 to T3 are transmission time slots, and R0 to R3 are reception time slots. The control channel (CCH in the figure) is composed of a pair of transmission time slots and reception time slots (T0, R0). Further, the communication channels TCH1, TCH2, and TCH3 are respectively configured by pairs of (T1, R1), (T2, R2), and (T3, R3). The communication channels TCH1, TCH2, and TCH3 are distinguished by time division, but each communication channel further includes a plurality of communication channels by path multiplexing.

In addition, the baseband unit 70 performs a secret scramble process on a baseband signal to be transmitted to a mobile station (user) with a pattern unique to the mobile station. The secret-scrambled signal is descrambled by the mobile station with a secret key code unique to the mobile station and can be returned to the original signal. However, if the secret key code does not match, the signal is not restored correctly, and noise (beeger) Sound).
<Signal processing unit 50>
The signal processing unit 50 is configured around a programmable digital signal processor, and includes a signal adjustment unit 51, a clock generation unit 52, and a response vector calculation unit 53.

  The clock generation unit 52 generates a unique clock for each mobile station (user) to be path-multiplexed and sends each to the signal adjustment unit 51. In the present embodiment, since the number of users to be path-multiplexed is two for simplification of description, the clock generation unit 52 uses the clock TA for user A (shown in FIG. 6B) and the user B. A clock TB (shown in FIG. 6C) is generated. The clock generation unit 52 normally generates the clock TA and the clock TB at the same time, but receives an instruction from the response vector calculation unit 52 to shift the symbol transmission time because the user's direction is close. In this case, the clock TB is generated by shifting the clock TB for the user B by 0.5 symbol period from the clock TA for the user A.

The signal adjustment unit 51 generates symbol data for each user from the symbol data input from the radio units 11 to 41 and outputs the symbol data to the modem unit 60. The signal adjustment unit 51 also generates radio data from the symbol data for each user sent from the modem unit 60. Symbol data for each of the units 11 to 41 is generated and output to the radio units 11 to 41.
FIG. 4 is a diagram illustrating a configuration of the signal adjustment unit 51. As shown in the figure, the signal adjustment unit 51 includes user processing units 51a and 51b for each user to be path multiplexed. In the figure, X1 to X4 and S1 to S4 indicate signal lines and terminals, but for convenience of explanation, symbol data names to be input / output by the signal lines and terminals are also indicated. X1 to X4 indicate symbol data transmitted from the radio units 11 to 41 to the signal adjustment unit 51, and S1 to S4 indicate symbol data transmitted from the signal adjustment unit 51 to the radio units 11 to 41.

The user processing unit 51a receives input of the symbol data X1 to X4 from the wireless units 11 to 41. The user processing unit 51 a generates user A symbol data Ua from these symbol data, and outputs the symbol data Ua to the modem unit 60.
Further, the user processing unit 51 a accepts input of the symbol data Ua of the user A from the modem unit 60. The user processing unit 51a generates symbol data Sa1 to Sa4 from the symbol data to the radio units 11 to 41, and outputs the respective symbol data to each radio unit. Similarly, the other user processing unit 51b outputs the symbol data Sb1 to Sb4 to each radio unit. As a result, the symbol data S1 (= Sa1 + Sb1) obtained by adding the symbol data Sa1 and Sb1 from each user processing unit is sent to the wireless unit 11.

Next, details of processing by the user processing unit will be described. FIG. 5 is a diagram illustrating a configuration of the user processing unit 51a.
The weight calculation unit 55 calculates the weight using the first several symbol data for each reception time slot. That is, the weight calculation unit 55 uses the symbol data X1 to X4 sent from the radio units 11 to 41 and the fixed symbol data D sent from the reference signal generation unit 506 according to the clock TA, and E = D− (Wa1). Weights Wa1 to Wa4 are calculated so as to minimize (X1 + Wa2 × X2 + Wa3 × X3 + Wa4 × X4). The weights Wa1 to Wa4 calculated in this way are used as initial values in the reception of the remaining symbol data of the reception time slot and in the transmission time slot which is a pair of the reception time slot.

  When receiving the symbol, the weight calculating unit 55 outputs the weights Wa1 to Wa4 calculated as described above according to the clock TA. The multipliers 521 to 524 and the adder 504 generate symbol data Ua (= Wa1 × X1 + Wa2 × X2 + Wa3 × X3 + Wa4 × X4) for the user A. The generated symbol data Ua for user A is sent to the modem unit 60.

  Further, when transmitting a symbol, the symbol data Ua sent from the modem unit 60 to the user A is temporarily stored in the buffer 507. The buffer 507 outputs the symbol data Ua according to the clock TA generated by the clock generation unit 52. The weight calculation unit 53 outputs the weights Wa1 to Wa4 calculated as described above according to the clock TA. Each of the multipliers 581 to 584 multiplies the symbol data Ua and the weights Wa1 to Wa4, and the symbol data Sa1 (= Wa1 × Ua), Sa2 (= Wa2 × Ua), and Sa3 (= Wa3 ×) as multiplication results. Ua) and Sa4 (= Wa4 × Ua) are output to the radio units 11 to 41.

  The weight calculation unit of the user processing unit 51b calculates the weight according to the clock TB and outputs the weight when transmitting / receiving the symbol, and the buffer of the user processing unit 51b receives the symbol data Ub to the user B according to the clock TB. Output. Here, since the directions of the user A and the user B are close to each other, when the clock generation unit 52 generates the clock TB with a delay of 0.5 symbol period with respect to the clock TA, it is output from the user processing unit 51b. The symbol data Sb1 to Sb4 are delayed by 0.5 symbol period with respect to Sa1 to Sa4 output from the user processing unit 51a.

FIG. 6 is an explanatory diagram illustrating an example in which the symbol data of one user is transmitted with a shift.
As shown in the figure, two mobile stations PS-A (user A) and PS-B (user B) are assigned to the same time division slot T1 by path multiplexing, and their directions are close to each other. It shall be. The clock generation unit 52 sends a clock TA to the user processing unit 51a, and sends a clock TB delayed by 0.5 symbol period with respect to the clock TA to the user processing unit 51b. As a result, the symbol data sent to each user is shifted. A0, A1, A2, and A3 in the figure indicate symbol data sent toward PS-A, and B0, B1, B2, and B3 in the figure indicate symbol data sent toward PS-B.

By adjusting the symbol transmission timing in this way, as described below, even if the mobile station receives symbol data sent to the other path-multiplexed mobile station, the transmission time of the symbol data is received. (Accordingly, the reception time) is not synchronized with the transmission time of the symbol data to the own station (accordingly, the reception time). Does not demodulate. If there is such a demodulation error, descrambling of the demodulated symbol (voice signal) is stopped, so that it is possible to prevent generation of meaningless noise (beeger sound). In other words, the radio base station changes the transmission time of the symbol for each mobile station so that it cannot be correctly demodulated even if the mobile station receives a signal from another mobile station. It is a big feature.
<Response vector calculation unit 52>
The response vector calculation unit 50 calculates a response vector indicating the direction from the base station to the mobile station from the symbol data input from the radio unit 11. A method for calculating the response vector will be described below. The response vector to the user A is Ra = (h _1A , h _2A , h _3A , h _4A ) ′, the response vector to the user B is Rb = (h _1B , h _2B , h _3B , h _4B ) ′, Let R = (Ra, Rb). Using symbol data X1 to X4 from the radio units 11 to 41, X = (X1, X2, X3, X4) ′. Further, using Ua and Ub calculated by the signal adjustment unit 51, U = (Ua, Ub) ′. Then, since the relational expression of X = RU is established, the response vector calculation unit 53 uses X and U to calculate response vectors Ra and Rb for each user. The response vector includes information indicating the direction of the user (mobile station) from the base station. When the direction is approximate, the mobile station can easily receive a signal transmitted to another mobile station, and the response vector calculation unit 53 determines that the difference between the direction of the user A and the direction of the user B is When the value is equal to or less than the predetermined value, the clock generation unit 52 is instructed to delay the generation time of the user B clock TB with respect to the generation time of the user A clock TA.

Next, processing of the radio mobile station on the side receiving the signal transmitted from the radio base station will be described.
<Configuration of wireless mobile station>
FIG. 7 is a block diagram showing a configuration of a main part of the radio mobile station in the embodiment of the present invention.

The radio mobile station includes a radio unit 200, an antenna 250, a signal processing unit 220, and an audio output unit 240.
<Radio unit 200>
The radio unit 200 includes a modulator 202, a transmission circuit 201, a switch 205, a reception circuit 203, and a demodulator 204.
<Timing unit 210>
The timing unit 210 includes a synchronization adjustment unit 211 and a clock generation unit 212. <Synchronization adjustment unit 211>
The synchronization adjustment unit 211 adjusts the clock generation time by the clock generation unit 212 so that the received and demodulated message sequence matches the synchronization word.

In addition, the synchronization adjustment unit 211 always checks for a match between the synchronization word and the message string even after the synchronization adjustment is completed, and performs synchronization readjustment and synchronization with the control unit 222 if they do not match. Notify the disconnect.
<Clock Generator 212>
The clock generation unit 212 generates a clock based on an instruction from the synchronization adjustment unit 211. The demodulator 204 demodulates the message sequence in accordance with this clock.

Now, taking a demodulation by the mobile station PS-A as an example, a process of demodulating the signal with an error when receiving a signal sent to the other mobile station PS-B that has been path-multiplexed will be described. To do.
The demodulator 204 acquires an I component and a Q component by synchronously detecting the received signal. FIG. 8 shows the I component subjected to synchronous detection. The Q component can also be represented by a similar diagram although not shown.

The mobile station PS-A generates a synchronous clock every symbol period and acquires I _k .
T ₁ to t _{4 in} the figure are PS-A synchronous clock generation times. The demodulator 204 obtains I _{1 to} I ₄ = {0.5, −0.25, −0.75, 0.75} by using these synchronous clocks.
Thereafter, it is assumed that at time t _M , the mobile station PS-A moves to a point where the intensity of the transmission signal directed to PS-B is strong, for example, by approaching PS-B. As a result, the mobile station PS-A may receive a signal destined for another path-multiplexed mobile station PS-B without receiving a signal destined for the PS-A from the base station.

PS-A demodulates the signal with the same synchronous clock as before even after movement. T ₅ ~t ₉ in the figure, a synchronous clock generation time of PS-A. The demodulator 204 acquires I ₅ (F) to I ₉ (F) = {− 0.75, 0, 0.75, −0.25, 0.5} by using these synchronous clocks. However, as described in the signal processing unit 50 of the radio base station, the transmission time of symbol data sent from the base station to PS-B is 0.5 symbols relative to the transmission time of symbol data sent to PS-A. Since they are shifted by the period, the original signals to PS-B are signals I ₅ (T) to I ₉ (T) = {0.5, −0.25, 0 at t ₅ ′ to t ₉ ′. .5, -0.5, 0.75}.

As described above, the mobile station acquires an incorrect I _k (F) without acquiring the original I _k (T) sent to another mobile station. The mobile station will acquire an incorrect Q _k (F) for the same reason.
By the way, there is the following relationship between I _k and Q _k and the message string.
Message sequence _{{a 1, a 2, ...} , a n, a n + 1, ...} (a n, a n + 1) in the binary data string (X _k, Y _k) corresponding to. The following relational expression is established between the binary data string (X _k , Y _k ) and I _k , Q _k .

I _k = I _K−1 cos [θ (X _k , Y _k )] − Q _k−1 sin [θ (X _k , Y _k )]
_{Q k = I K-1 sin} [θ (X k, Y k)] + Q k-1 cos [θ (X k, Y k)]
When θ = −3π / 4, X _k = 1, Y _k = 1
When θ = 3π / 4, X _k = 0, Y _k = 1
When θ = π / 4, X _k = 0, Y _k = 0
When θ = −π / 4, X _k = 1, Y _k = 0
Based on the above _{equation, I k, I k-1} , Q k, from Q _k-1, 2 binary data string (X _k, Y _k) is obtained which from the message sequence a _n is obtained.

Therefore, I _k as described above, due to an error of the Q _k, message sequence a _n is also converted into naturally to the wrong message string. As a result, there may be a case where synchronization is lost due to the demodulated message sequence being different from the synchronization word, or a CRC error may occur even if the synchronization words match.
<Signal processing unit 220>
The signal processing unit 220 includes an error determination unit 221, a control unit 222, and a descrambling processing unit 223.
<Error determination unit 221>
The error determination unit 221 performs a CRC check on the message string sent from the wireless unit 200 and notifies the control unit 222 of the presence or absence of an error.
<Control unit 222>
When receiving a notification of out of synchronization from the synchronization adjustment unit 211 or when receiving an error notification from the error determination unit 221, the control unit 222 descrambles the message string to the descrambling processing unit 223. Stop it.
<Descramble processing unit 223>
The descrambling processing unit 223 descrambles the message string sent from the wireless unit 200. Since the message sequence sent to another mobile station is out of synchronization or an error has occurred, there is an instruction to stop descrambling by the control unit 222, and the descrambling processing unit 223 does not descramble the message sequence. . Therefore, the descrambling processing unit 223 does not descramble a message string to another mobile station whose secret key does not match.
<Audio output unit 240>
The audio output unit 240 includes a speaker, and outputs a message string (audio signal) descrambled by the descrambling processing unit 223. The descrambling processing unit 223 descrambles only a message string whose secret key keys match, so that no meaningless noise (beeger sound) descrambled by the wrong secret key key is generated. .

  As described above, the radio base station in the present embodiment performs a process of shifting the transmission time of symbols to be transmitted to path-multiplexed mobile stations by an appropriate time within one symbol period. By adjusting the transmission timing in this way, the mobile station cannot correctly demodulate the original symbol from the received signal even if it receives the symbol sent to the other mobile station that has been path-multiplexed. Demodulate the wrong symbol. As a result, it is possible to prevent the generation of meaningless noise (beeger sound) in the mobile station.

In addition, this invention is not limited to the said embodiment, Of course, the following modifications are also contained in this invention.
(Modification 1)
In the present embodiment, transmission timing adjustment when two mobile stations are path-multiplexed has been described, but the present invention is not limited to this. For example, when three mobile stations (PS-1, PS-2, PS-3) are path-multiplexed in the same time division slot, the PS for the transmission time of symbol data to PS-1 -2 by shifting the transmission time of symbol data to -2 by 0.33 symbol periods, and further shifting the transmission time of symbol data to PS-3 by 0.33 symbol periods. Symbol data sent to the mobile station can be easily demodulated erroneously.

Similarly, in general, when N paths are multiplexed, the transmission time of each symbol is K / N (K = 0, 1, 2,..., N−1) × T (symbol period). be able to.
Further, transmission timing adjustment is possible without being limited within one symbol period, such as shifting by one symbol period, 1.5 symbol period, or two symbol periods beyond one symbol period. For example, if the period is shifted by one symbol period, the value of the original symbol data is correctly demodulated, but the demodulated symbol sequence can be shifted. That is, since the original symbol sequence {a ₀ , a ₁ , a ₂ ,...} Is transmitted with a shift of one symbol period, the mobile station erroneously demodulates as {a ₁ , a ₂ , a ₃ ,. As a result, the symbol a ₀ is lost, and a synchronization word mismatch or a CRC error can be generated.
(Modification 2)
In this embodiment, the transmission timing of symbols is adjusted when the directions of two mobile stations that are path-multiplexed are approximate. However, the transmission timing is always adjusted regardless of the direction of the mobile stations. It is good to do.

  In addition, when multiple antennas are provided and the number of multiplexed paths that can be multiplexed is increased, the transmission times of symbols to each mobile station will be close to each other, and the mobile station erroneously assigns symbols to other mobile stations. It becomes difficult to demodulate. Therefore, when the number of multiplexed paths is small, the transmission timing is always adjusted, and when the number of multiplexed paths is large, transmission is focused on a set of mobile stations whose directions are approximate. The timing may be adjusted.

10 to 40 Antenna 11 to 41 Radio unit 12 Transmitter 13 Receiver 50 Signal processor 51 Signal adjuster 51a, 51b User processor 52 Clock generator 53 Response vector calculator 60 Modem unit 70 Baseband unit 80 Control unit 90 Telephone Network 200 Radio unit 201 Transmission circuit 202 Modulator 203 Reception circuit 204 Demodulator 205 Switch 210 Timing unit 211 Synchronization adjustment unit 212 Clock generation unit 220 Signal processing unit 221 Error determination unit 222 Control unit 223 Descramble processing unit 240 Audio output unit 250 Antenna 504 Adder 505 Weight calculation unit 506 Reference signal generation unit 507 Buffer 521 to 524 Multiplier

Claims (4)

An adaptive array radio base station that spatially multiplexes and transmits transmission signals to a plurality of mobile stations with different directivity patterns,
A multiplexing unit that spatially multiplexes the clock phases of transmission symbols in a transmission signal by shifting each other for a set of mobile stations whose response vectors are approximated among the plurality of mobile stations is provided. A wireless base station.   The multiplexing means is an arbitrary symbol including K / N (K = 0, 1, 2,..., N−1) × T (symbol period) and 0 for each of transmission symbols to N mobile stations. 2. The radio base station according to claim 1, wherein spatial multiplexing is performed by shifting by a number of times. The multiplexing means includes
Means for calculating a response vector for the base station of the mobile station based on signals received from the plurality of mobile stations;
The radio base station according to claim 1, wherein a mobile station that approximates the target response vector is selected based on the response vector. A wireless communication method in a wireless base station of an adaptive array system that spatially multiplexes and transmits transmission signals to a plurality of mobile stations with different directivity patterns,
A step of spatially multiplexing a set of mobile stations having approximate response vectors among the plurality of mobile stations by shifting clock phases of transmission symbols in a transmission signal from each other; Wireless communication method.

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