JP2001358625A - Transmitter and transmission diversity method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the received power control error at a mobile station, when diversity reception is conducted with antennas at a base station. SOLUTION: Each divided data is spread using spread codes, which are orthogonal to each other in a diffusion part 104, 105 at a base station, and the diffused data are sent from an antenna 106, 107. The received signal is received inversely with the same inverse diffusion code, which was used at the base station, in an inverse diffusion part 202, 203 of a mobile station, the inversely diffused signal is demodulated in demodulating parts 204, 205, a received power is measured from the demodulated result in received power measuring parts 207, 208, and the received power measured is combined in a received power combining part 209, and the transmitting power is controlled in a transmitting power control unit 212 based on the received power combined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a CDMA / TDD.
TECHNICAL FIELD The present invention relates to a transmission apparatus and a transmission diversity method using the same method.

[0002]

2. Description of the Related Art CDMA (Code Division Multiple Acc)
The ess (code division multiple access) method is one of the multiple access methods in which a plurality of stations simultaneously communicate in the same frequency band in a wireless transmission system such as a mobile phone or a mobile phone. Since transmission is performed by spreading to a band that is sufficiently wider than the width, high frequency use efficiency can be achieved, and it is characterized by being able to accommodate many users.

In the CDMA system, when a desired transmitting station is located far away and an undesired transmitting station (interfering station) is nearby, the signal is transmitted from the interfering station based on the reception power of the signal transmitted from the desired transmitting station. There is a near-far problem that the received power of the signal becomes large, and the cross-correlation between spreading codes cannot be suppressed only by the processing gain and communication becomes impossible.

[0004] Therefore, in a cellular system using the CDMA system, transmission power control according to the state of each transmission path is required in an uplink from a communication terminal to a base station. Also, as a countermeasure for fading, which is a cause of line quality degradation in land mobile communication, transmission power control for compensating for instantaneous fluctuations in received power is required.

[0005] Here, TDD (Time Division Duple) is used as a duplex system in the multiple access communication system.
x) The method may be used. The TDD system is a system in which communication is performed by time-dividing the same radio frequency into transmission / reception, and since the transmission and reception are in the same band, the frequency correlation of fading fluctuation between the transmission wave and the reception wave is 1.

[0006] In the TDD system, if the switching time between the two is sufficiently short, the time correlation in the propagation path conditions such as mutual fading fluctuation is high, so that the open loop for controlling the transmission power based on the reception power in the communication terminal. Transmission power control can be performed.

[0007] When a base station has a plurality of antennas, transmission diversity for selecting an optimum transmission antenna from received power at each antenna may be applied. By applying transmission diversity, space diversity is not required in the communication terminal, and the size of the communication terminal can be reduced.

[0008] Hereinafter, CDMA / TD which performs conventional open loop transmission power control and applies transmission diversity.
A base station and a communication terminal of the D-type wireless transmission system will be described with reference to the drawings.

FIG. 3 is a block diagram showing a configuration of a base station in a conventional radio transmission system. The base station shown in FIG. 3 includes a modulating section 301 for modulating transmission data and a spreading section 302 for multiplying the modulated signal by a spreading code A to spread the signal.
An antenna control unit 303 for switching a transmission antenna;
Antenna 304 and antenna 305 for transmitting and receiving signals
, A despreading unit 306 that despreads the received signal by multiplying it by a spreading code B, and a demodulation unit 307 that demodulates the despread signal.
And an antenna selection unit 308 that measures a received signal level from a demodulation result and selects a transmission antenna.

[0010] Transmission data is modulated by modulation section 301 and spread by spreading code A in spreading section 302. Then, the spread signal is transmitted from either antenna 304 or antenna 305 controlled by transmission antenna control section 303.

The signals received by antennas 304 and 305 are despread by despreading section 306 using spreading code B. The despread signal is demodulated in demodulation section 307, the received data is extracted, and the demodulation result is input to transmission antenna selection section 308 as antenna selection information. Then, the transmission antenna selection unit 30
At 8, the received signal levels of the two antennas are compared based on the demodulation result, and the antenna received at the higher level is selected as the antenna to be transmitted in the next slot, and a signal indicating the selection result is transmitted. Output to antenna control section 303.

FIG. 4 is a block diagram showing a configuration of a communication terminal in a conventional wireless transmission system. 4 includes an antenna 401 for transmitting and receiving a signal, a despreading unit 402 for multiplying a received signal by a spreading code A and despreading,
A demodulation section 403 for demodulating the despread signal and a reception power measurement section 404 for measuring the reception signal level from the demodulation result
A modulator 405 for modulating transmission data, a spreading unit 406 for multiplying the modulated signal by a spreading code B and spreading the same,
And a transmission power control unit 407 that performs transmission power control based on the reception power.

The signal received by antenna 401 is despread by spreading code A in despreading section 402, demodulated by demodulating section 403, the received data is extracted, and the demodulated result is received by receiving power measuring section 404. Is input to
Then, reception power measurement section 404 measures the reception power from the demodulation result, and the measurement result is input to transmission power control section 407. The transmission power control unit 407 determines a transmission power value from the transmission power value of the base station and the target reception power value at the base station.

The transmission data is modulated by modulation section 405, despread by spreading code B in spreading section 406, and is controlled by transmission power control section 4 based on the determined transmission power value.
At 07, the power is amplified and wirelessly transmitted from the antenna 401.

[0015] As described above, the conventional wireless transmission system includes:
A base station selects one antenna from a plurality of antennas to transmit a signal, and a communication terminal performs open-loop transmission power control based on the received power of a received signal.

[0016]

However, in the conventional radio transmission system, the communication terminal performs transmission power control targeting only the antenna transmitted by the base station. In this case, there is a problem that transmission power control is not performed for an antenna that is not transmitting, and a transmission power control error occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a transmission apparatus capable of suppressing a transmission power control error in base station reception when reception is performed by a plurality of antennas at the base station. Aim.

[0018]

In order to solve the above problems, the present invention provides a method for transmitting a plurality of transmission data distributed by the number of transmission antennas at a base station side using different spreading codes from each other. Transmit the radio data in parallel from the antenna, and on the communication terminal side, despread the received data using the same spreading code as the transmitting side, measure and combine the received power, and control the transmitted power based on the combined received power. I do.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A transmitting apparatus according to the present invention employs a configuration including a distributing means for distributing transmission data into a plurality of transmission data, and a transmitting means for transmitting the distributed transmission data from different antennas in parallel.

According to this configuration, on the receiving side, transmission power control can be performed with all the antennas that perform reception as targets, so that a transmission power control error can be suppressed small and the total transmission power value can be reduced.

[0021] The transmission apparatus of the present invention has the above configuration,
It is desirable that transmission data transmitted from different antennas be configured to be different spread data. Further, a base station apparatus according to the present invention includes the transmission device.

The transmission diversity method according to the present invention includes a distribution step of distributing transmission data to a plurality of transmission data, and a transmission step of transmitting the distributed transmission data from different antennas in parallel.

According to this method, on the receiving side, transmission power control can be performed with all the antennas that perform reception as targets, so that a transmission power control error can be reduced and the total transmission power value can be reduced.

In the transmission diversity method of the present invention, it is desirable that transmission data transmitted from different antennas is different spread data.

Hereinafter, an embodiment of a wireless transmission system including a transmission device according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a configuration of a base station of a wireless transmission system including a transmission device according to an embodiment of the present invention. In the base station of FIG. 1, data distribution section 101 distributes transmission data to the number of antennas. As a method of distributing data, there is a method of distributing data by serial / parallel conversion, or a method of simply distributing the same data so that the same data is transmitted from each antenna.

Modulating sections 102 and 103 modulate the distributed transmission data, spreading section 104 multiplies the modulated signal by spreading signal A1, and spreads the spread signal. Spreading section 105 spreads the modulated signal to the spreading signal. A2 is multiplied and spread. The antenna 106 and the antenna 107 wirelessly transmit the spread signal and receive the signal transmitted from the communication terminal. Despreading section 108 multiplies the received signal by spreading code B to despread,
Demodulation section 109 demodulates the despread signal to extract received data.

When the base station transmits only a common control channel such as a perch channel which is always transmitted in parallel, interference with other downlinks can be suppressed to a small level. In addition, since a channel whose transmission power is not controlled can be used for the uplink, the transmission power control of the uplink is not affected at all.

Next, the flow of signals transmitted and received in the base station of FIG. 1 will be described. Transmission data is distributed by the data distribution section 101 for the number of antennas,
And modulated by the modulator 103 and input to the spreading section 104 and the spreading section 105. Each of the distributed data is spread with a different spreading code sequence in spreading section 104 and spreading section 105. At this time, it is desirable that each spreading code sequence be a code sequence that is as orthogonal as possible. The spread signals are transmitted in parallel from antennas 106 and 107.

The signals received by antennas 106 and 107 are despread by despreading section 108 using spreading code B. The despread signal is demodulated by demodulation section 109, and received data is extracted.

Next, the configuration of the communication terminal of the wireless transmission system in the above embodiment will be described with reference to the block diagram shown in FIG. In the communication terminal of FIG. 2, antenna 201 wirelessly transmits a signal and receives a signal transmitted from the communication terminal. Despreading unit 202 and despreading unit 203
Performs despreading by multiplying the received signal by the same code as the spreading code A1 and the spreading code A2 used on the transmission side. The demodulation unit 204 demodulates the signal despread with the spreading code A1, the demodulation unit 205 demodulates the signal despread with the spreading code A2, and the data synthesis unit 206 distributes the demodulated data before distribution. Return to the shape.

Received power measuring section 207 measures received power from the demodulated result of demodulating section 204, and received power measuring section 208 measures received power from the demodulated result of demodulating section 205. Received power combining section 209 combines the received powers of the signals transmitted in parallel. As a method of synthesizing the received power, there is a method of simply adding, or a method of adding after weighting each received power.

Modulating section 210 modulates the transmission data, and spreading section 211 spreads the modulated signal by multiplying by a spreading code B. The transmission power control unit 212 determines a transmission power value from the combined reception power, and amplifies the transmission signal power to the determined transmission power value.

Next, the flow of signals transmitted and received by the communication terminal of FIG. 2 will be described. The signal received by antenna 201 is despread by despreading section 202 using spreading code A1, and despreading is performed by despreading section 203 using spreading code A2. The signal despread by the spreading code A1 is demodulated by the demodulation unit 204, and the demodulation result is input to the reception power measuring unit 207. The signal despread by the spreading code A2 is demodulated by the demodulation unit 205, and the demodulation result is obtained. Is input to the received power measuring section 208. The demodulated signals are combined by the data combining unit 206 to become received data.

The received power measuring section 207 measures the received power from the demodulation result of the demodulation section 204, and the received power measuring section 208 measures the received power from the demodulated result of the demodulation section 205. Is the received power combining unit 2
09 is input.

Then, the received power values are combined by the received power combining unit 209, and the combined received power value is input to the transmission power control unit 212. In the transmission power control unit 212,
The transmission power value is determined from the transmission power value of the base station and the target reception power value at the base station.

The transmission data is modulated by the modulation section 210, despread by the spreading code B by the spreading section 211, and based on the determined transmission power value.
At 12, the power is amplified and wirelessly transmitted from the antenna 201.

As described above, the base station transmits signals spread using orthogonal spreading codes from each antenna, and the communication terminal synthesizes the received power of the signals despread by each spreading code. By determining the transmission power, open-loop transmission power control can be performed for all antennas.

[0039]

As described above, according to the transmitting apparatus of the present invention, the communication terminal can perform open-loop transmission power control for all antennas of the base station. Can be suppressed small, and the total transmission power value of the communication terminal can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a base station of a wireless transmission system including a transmission device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a communication terminal of the wireless transmission system according to the embodiment.

FIG. 3 is a block diagram showing a configuration of a base station in a conventional wireless transmission system.

FIG. 4 is a block diagram showing a configuration of a communication terminal in a conventional wireless transmission system.

[Explanation of symbols]

 101 Data distribution unit 102, 103, 210 Modulation unit 104, 105, 211 Spreading unit 106, 107, 201 Antenna 108, 202, 203 Despreading unit 109, 204, 205 Demodulation unit 206 Data combining unit 207, 208 Received power measurement unit 209 Receive power combiner 212 Transmit power controller

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhiko Hiramatsu 4-3-1 Tsunashima Higashi, Kohoku-ku, Yokohama-shi, Kanagawa F-term (reference) in Matsushita Communication Industrial Co., Ltd. 5K022 EE02 EE11 EE21 5K028 AA01 BB04 CC05 DD01 DD02 HH02 SS02 5K059 CC02 5K067 AA43 BB03 BB04 CC04 CC10 CC24 EE02 EE10 GG01 GG08 GG09 GG11 KK03

Claims (5)

[Claims] 1. A transmitting apparatus comprising: a distribution unit that distributes transmission data to a plurality of transmission data; and a transmission unit that transmits the distributed transmission data from different antennas in parallel. 2. The transmitting apparatus according to claim 1, wherein the transmission data transmitted from different antennas are spread different data. 3. A base station apparatus comprising the transmitting apparatus according to claim 1 or 2. 4. A transmission diversity method comprising: a distribution step of distributing transmission data into a plurality of pieces; and a transmission step of transmitting the distributed transmission data from different antennas in parallel. 5. The transmission diversity method according to claim 4, wherein the transmission data transmitted from different antennas is spread different data.