JP3512779B2 - Communication terminal device and wireless communication method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication terminal device and a wireless communication method for controlling open loop transmission power.

[0002]

2. Description of the Related Art CDMA (Code Division Multiple Acc
ess: code division multiple access) is one of multiple access methods in which multiple stations simultaneously communicate in the same frequency band in wireless transmission systems such as car phones and mobile phones. It uses the spectrum of information signals as the original information band. Since the data is spread and transmitted in a band sufficiently wider than the width, high frequency utilization efficiency can be achieved and many users can be accommodated.

In the CDMA system, when the desired transmitting station is distant and the undesired transmitting station (interfering station) is near, the interference signal is transmitted from the interfering station due to the received 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 the spread codes cannot be suppressed only by the processing gain, and communication becomes impossible.

Therefore, in the cellular system using the CDMA system, it is necessary to control the transmission power according to the state of each transmission line in the uplink from the communication terminal to the base station. In land mobile communications, transmission power control is necessary to compensate for instantaneous fluctuations in received power as a measure for fading, which is the cause of line quality degradation.

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

In the TDD system, when the switching time between the two is sufficiently short, there is a high time correlation in the propagation path conditions such as fading fluctuations, so that the communication terminal controls the open power based on the received power. It is possible to control the transmission power of

Further, when the base station has a plurality of antennas, there is a case in which transmission diversity is applied to select an optimum transmission antenna from the received power at each antenna. By applying the transmission diversity, the communication terminal does not need the space diversity, and the communication terminal can be downsized.

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

FIG. 3 is a block diagram showing the configuration of a base station in a conventional wireless transmission system. The base station shown in FIG. 3 has a modulation unit 301 that modulates transmission data and a spreading unit 302 that multiplies the modulated signal by a spreading code A to spread the signal.
And an antenna control unit 303 that switches the transmission antenna,
Antenna 304 and antenna 305 for transmitting and receiving signals
A despreading unit 306 that despreads the received signal by multiplying the spreading code B, and a demodulation unit 307 that demodulates the despread signal.
And an antenna selection unit 308 that selects a transmission antenna by measuring the received signal level from the demodulation result.

The transmission data is modulated by the modulation unit 301 and spread by the spreading code A by the spreading unit 302. Then, the spread signal is transmitted from either the antenna 304 or the antenna 305 controlled by the antenna control unit 303.

The signals received by the antenna 304 and the antenna 305 are despread by the despreading unit 306 by the spreading code B. The despread signal is demodulated by demodulation section 307 to extract received data, and the demodulation result is used as antenna selection information by antenna selection section 30.
8 is input. Then, in the antenna selection unit 308,
Based on the demodulation result, the magnitudes of the received signal levels at the two antennas are compared, the antenna received at the large level is selected as the antenna to be transmitted in the next slot, and the signal indicating the selection result is sent to the antenna control unit 303. Is output.

FIG. 4 is a block diagram showing a configuration of a communication terminal in a conventional wireless transmission system. The communication terminal shown in FIG. 4 includes an antenna 401 for transmitting and receiving a signal, a despreading section 402 for multiplying a received signal by a spreading code A and despreading the signal.
A demodulation unit 403 that demodulates the despread signal and a reception power measurement unit 404 that measures the reception signal level from the demodulation result.
A modulation unit 405 that modulates transmission data, a spreading unit 406 that multiplies the modulated signal by a spreading code B and spreads the signal.
The transmission power control unit 407 controls the transmission power based on the reception power.

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

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

As described above, the conventional wireless transmission system is
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 reception power of a received signal.

[0016]

However, in the conventional wireless transmission system, in the communication terminal, since the transmission power control is performed by targeting only the antenna transmitted by the base station, the reception is performed by the plurality of antennas in the base station. When doing so, there is a problem that transmission power control is not performed based on an antenna that is not transmitting, and a transmission power control error occurs.

The present invention has been made in view of the above points, and when a base station performs reception with a plurality of antennas, it is possible to suppress a transmission power control error in the reception of the base station to be small and a radio communication method. The purpose is to provide.

[0018]

In order to solve the above-mentioned problems, according to the present invention, the base station side spreads transmission data distributed by the number of transmission antennas by using different spreading codes, and then performs a plurality of transmissions. Wireless transmission is performed in parallel from the antennas, the reception data is despread on the communication terminal side using the same spreading code as the transmission side, the reception power is measured and combined, and the transmission power is controlled based on the combined reception power. To do.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION A communication terminal apparatus according to a first aspect of the present invention is a communication terminal apparatus that receives spread signals spread by a plurality of different spreading code sequences and transmitted in parallel from different antennas. A plurality of receiving means for despreading the transmission signals with the different spreading code sequences to obtain reception signals, and combining the reception signals obtained by the plurality of reception means to generate combined reception data. Data combining means for obtaining, measuring means for measuring the received power of the transmission signal for each of the different antennas, combining means for combining a plurality of measured received powers to obtain combined received power, and the combined received power And a transmission power control means for performing open loop transmission power control.

The CDMA / TDD communication terminal apparatus of the second aspect of the present invention spreads with a plurality of different spreading code sequences,
In a CDMA / TDD communication terminal apparatus that receives transmission signals transmitted in parallel from different antennas, a plurality of receptions each having a despreading unit and despreading the transmission signals with the different spreading code sequences to obtain a reception signal Means, data synthesizing means for synthesizing received signals obtained by the plurality of receiving means to obtain combined received data, and measuring means for respectively measuring received powers of the plurality of received signals received by the receiving means. A combining unit that combines a plurality of measured reception powers to obtain a combined reception power; a transmission power control unit that performs open loop transmission power control using the combined reception powers;
The configuration including is adopted.

The CDMA / TDD communication terminal apparatus according to the third aspect of the present invention is a plurality of signals obtained by spreading data distributed for a plurality of antennas by different spreading code sequences, and different antennas. CDs that receive the plurality of signals transmitted in parallel from each of them and perform despreading processing on each of them
In the MA / TDD communication terminal device, a measuring unit that measures the received power of each of the received signals, a combining unit that combines the measured received powers to obtain combined received power, and the combined received power. And a transmission power control means for performing open loop transmission power control by using.

According to these configurations, CDMA / TDD
When performing diversity reception with multiple antennas in the wireless communication method, the communication terminal side can control the transmission power by targeting all the antennas that receive the base station. Can be suppressed to a small value and the total transmission power value can be reduced.

A radio communication method according to a fourth aspect of the present invention is a radio communication method in a communication terminal apparatus for receiving transmission signals spread by a plurality of different spreading code sequences and transmitted in parallel from different antennas of a base station apparatus. Therefore, the despreading process of the transmission signal is performed with the different spreading code sequence to obtain a reception signal, the reception signals are combined to obtain combined reception data, and the reception signal of each different antenna is received. A method is adopted in which power is measured, a plurality of measured reception powers are combined, and open loop transmission power control is performed using the combined reception powers.

The CDMA / TDD radio communication method according to the fifth aspect of the present invention is spread by a plurality of different spreading code sequences,
A CDMA / TDD wireless communication method in a communication terminal apparatus for receiving transmission signals transmitted in parallel from different antennas of a base station apparatus, wherein a plurality of receptions are performed by performing despreading processing of the transmission signals with the different spreading code sequences. Acquiring a signal, acquiring combined reception data by combining the acquired reception signals, respectively measuring the reception power of the plurality of reception signals,
A method of combining a plurality of measured reception powers and performing open loop transmission power control using the combined reception powers is adopted.

A CDMA / TDD wireless communication method according to a sixth aspect of the present invention is a plurality of signals obtained by spreading data distributed according to the number of antennas of a base station device with mutually different spreading code sequences. A CDMA / TDD wireless communication method in a communication terminal device that receives a plurality of signals transmitted in parallel from different antennas of the base station device and performs despreading processing, the received power of the plurality of received signals. Is measured, a plurality of measured reception powers are combined, and open loop transmission power control is performed using the combined reception powers.

According to these methods, CDMA / TDD
When performing diversity reception with multiple antennas in the wireless communication method, the communication terminal side can control the transmission power by targeting all the antennas that receive the base station. Can be suppressed to a small value and the total transmission power value can be reduced.

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a base station according to an embodiment of the present invention. In the base station of FIG.
The data distribution unit 101 distributes the transmission data to the number of antennas. The data distribution method includes 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.

The modulators 102 and 103 modulate the distributed transmission data, the spreader 104 multiplies the modulated signal by the spread signal A1 and spreads it, and the spreader 105 spreads the modulated signal on the spread 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 and despreads it,
The demodulation unit 109 demodulates the despread signal and extracts received data.

If the base station transmits in parallel only common control channels such as perch channels that are always transmitted, interference with other downlinks can be suppressed. Moreover, since a channel for which transmission power control is not performed can be used for the uplink, it does not affect the transmission power control of the uplink at all.

Next, the flow of signals transmitted and received by the base station shown in FIG. 1 will be described. The transmission data is distributed by the data distribution unit 101 to a plurality of antennas, and the modulation unit 102
And is modulated by the modulator 103 and input to the spreading unit 104 and the spreading unit 105. Then, the distributed data are spread by spreading units 104 and 105 with different spreading code sequences. At this time, it is desirable that the spreading code sequences are code sequences that are as orthogonal as possible. This spread signal is transmitted to the antenna 106 and the antenna 10.
7 is transmitted in parallel.

The signals received by the antenna 106 and the antenna 107 are despread by the despreading unit 108 with the 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 above embodiment will be described using the block diagram shown in FIG. Figure 2
In the communication terminal, the antenna 201 wirelessly transmits a signal and receives the signal transmitted from the communication terminal. The despreading unit 202 and the despreading unit 203 despread the received signal by multiplying it by the same code as the spreading code A1 and the spreading code A2 used on the transmitting side. The demodulation unit 204 demodulates the signal despread with the spread code A1, and the demodulation unit 205 receives the spread code A.
The demodulated signal is demodulated in 2, and the data synthesizing unit 206 restores the demodulated data to the form of the data before being distributed.

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 demodulation result of the demodulation section 205. The reception power combiner 209 combines the reception powers of the signals transmitted in parallel. As a method of combining received power, there is a method of simply adding, a method of weighting each received power, and then adding.

Modulation section 210 modulates transmission data, and spreading section 211 multiplies the modulated signal by spreading code B and spreads it. The transmission power control unit 212 determines a transmission power value from the combined reception power and amplifies the power of the transmission signal 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 the antenna 201 is despread by the despreading unit 202 with the spreading code A1 and is despread with the spreading code A2 by the despreading unit 203. The signal despread by the spreading code A1 is demodulated by the demodulation unit 204, the demodulation result is input to the reception power measuring unit 207, and 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 unit 208. The demodulated signals are combined by the data combining unit 206 to form the received data.

Further, the reception power measuring section 207 measures the reception power from the demodulation result of the demodulation section 204, and the reception power measuring section 208 measures the reception power from the demodulation result of the demodulation section 205 to obtain each reception power. The measurement result of the received power combining unit 2
09 is input.

Then, the received power combiner 209 combines the received power values, and the combined received power value is input to the transmission power controller 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 unit 210, despreading is performed by the spreading unit 211 with the spreading code B, and the transmission power control unit 2 is based on the determined transmission power value.
The power is amplified at 12 and wirelessly transmitted from the antenna 201.

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

[0041]

As described above, according to the present invention,
Since the communication terminal can perform open-loop transmission power control for all antennas of the base station, the transmission power control error at the base station reception can be suppressed to a small value, and the total transmission power value of the communication terminal can be reduced. Can be made smaller.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a configuration of a communication terminal according to the above 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 Modulator 104, 105 diffusion unit 106 and 107 antennas 108 despreading unit 109 Demodulator 201 antenna 202, 203 despreader 204, 205 demodulator 206 Data synthesizer 207, 208 Received power measurement unit 209 Received power combiner 210 Modulator 211 Diffuser 212 transmission power control unit

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-10-98431 (JP, A) JP-A-9-238098 (JP, A) JP-A-9-102768 (JP, A) JP-A-7- 74694 (JP, A) JP 10-102768 (JP, A) JP 9-181662 (JP, A) JP 8-195703 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04B ⁷ /00-7/12 H04B 7/24-7/26 H04J 13/00 H04Q 7/00-7/38

Claims (6)

(57) [Claims] 1. Spreading with a plurality of different spreading code sequences,
In a communication terminal device for receiving transmission signals transmitted in parallel from different antennas, each having a despreading unit, a plurality of receiving means for despreading the transmission signals with the different spreading code sequences respectively to obtain a reception signal, Data combining means for combining the reception signals obtained by the plurality of receiving means to obtain combined reception data, measuring means for respectively measuring the reception power of the transmission signals of the different antennas, and a plurality of measured reception signals A communication terminal apparatus, comprising: combining means for combining powers to obtain combined reception power; and transmission power control means for performing open-loop transmission power control using the combined reception powers. 2. Spreading with a plurality of different spreading code sequences,
In a CDMA / TDD communication terminal apparatus for receiving transmission signals transmitted in parallel from different antennas, a plurality of receptions each having a despreading unit and despreading the transmission signals with the different spreading code sequences to obtain reception signals Means, data synthesizing means for synthesizing received signals obtained by the plurality of receiving means to obtain combined received data, and measuring means for respectively measuring received powers of the plurality of received signals received by the receiving means. CDMA comprising: a combining unit that combines a plurality of measured reception powers to obtain a combined reception power; and a transmission power control unit that performs open loop transmission power control using the combined reception powers. / T
DD communication terminal device. 3. A plurality of signals obtained by spreading data distributed to a plurality of antennas with different spreading code sequences, the plurality of signals being transmitted in parallel from different antennas, and receiving the plurality of signals, respectively. CD for despreading
In the MA / TDD communication terminal device, a measuring unit that measures the received power of each of the received signals, a combining unit that combines the measured received powers to obtain combined received power, and the combined received power. And a transmission power control means for performing open loop transmission power control by using the CDMA / TDD communication terminal apparatus. 4. Spreading with a plurality of different spreading code sequences,
A wireless communication method in a communication terminal device that receives a transmission signal transmitted in parallel from different antennas of a base station device, and obtains a reception signal by performing despreading processing of the transmission signal with the different spreading code sequence, Synthesize received reception signals to obtain combined reception data, measure the reception power of the transmission signals of each of the different antennas, combine the measured reception powers, and open using the combined reception powers. A wireless communication method characterized by performing loop transmission power control. 5. Spreading with a plurality of different spreading code sequences,
A CDMA / TDD wireless communication method in a communication terminal apparatus for receiving transmission signals parallel-transmitted from different antennas of a base station apparatus, wherein a plurality of receptions are performed by performing despreading processing of the transmission signals with the different spreading code sequences. Acquire signals, obtain combined reception data by combining the acquired reception signals, measure the reception power of each of the plurality of reception signals, combine the plurality of measured reception powers, and combine the received powers CDMA / TD characterized by performing open loop transmission power control using
D wireless communication method. 6. A plurality of signals obtained by spreading data distributed to the number of antennas of the base station device by different spreading code sequences, the signals being transmitted in parallel from different antennas of the base station device. A CDMA / TDD wireless communication method in a communication terminal device that receives a plurality of signals and performs despreading processing, comprising measuring the received power of each of the received signals and combining the measured received powers. Then, the CDMA / TDD wireless communication method is characterized by performing open loop transmission power control using the combined reception power.