JPH07221700A - Cdma/tdd mode radio communication system - Google Patents

Abstract

PURPOSE:To perform the transmission power control with high accuracy in a moving machine. CONSTITUTION:In addition to the constitution of a conventional CDMA/TDD mode radio communication system, a base station 100 is provided with a means 15 generating a pilot signal which is constant in a transmission power level and is known in each moving machine 200 to each moving machine 200 and a means 16 transmitting the pilot signal to the moving machine via a transmission line 5. Each moving machine 200 is provided with a means 19 measuring the reception power of the received pilot signal and a means 8 controlling the transmission power of the power amplifier circuit 10 based on the reception power of the measured pilot signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CDMA / TDD wireless communication system.

[0002]

2. Description of the Related Art In recent years, the demand for land communication such as automobiles and mobile phones has increased remarkably, and effective frequency utilization technology for securing more subscriber capacity on a limited frequency band has become important. Is coming. As one of multiple access methods for effective use of frequency, code division multiple access (C
The (DMA) method is drawing attention. In the CDMA system, when the signal level from a mobile device close to the base station is high on the uplink from the mobile device to the base station, a near-far problem occurs in which signals from other mobile devices cannot be received. From
It is necessary to control the transmission power of the mobile station so that the base station receives the same level from any mobile station.

On the other hand, in the time division two-way transmission (TDD) system in which transmission and reception are performed in the same frequency band, the propagation conditions of transmission and reception are the same, so if one of the propagation conditions can be known, it is already possible. One of the propagation conditions can be known. Thereby, it is possible to measure the received power in the mobile device and control the transmission power of the mobile device based on the measured value.

A transmission power control technique in a conventional CDMA / TDD wireless communication system will be described below with reference to FIG. In FIG. 3, 1 is a base station and 2 is a mobile device. Reference numeral 3 is a data channel spreading means for spreading the transmission data of the base station 1, and 4 is a despreading means for obtaining the received data. Reference numeral 5 is a transmission path, 6 is a data channel despreading means for obtaining received data in the mobile device 2, and 7
Is a data signal reception level measuring means for measuring the level of received data, and 8 is a transmission power control means for controlling the transmission power of the mobile device according to the reception level. Reference numeral 9 is a spreading means for spreading the transmission data of the mobile device 2, and 10 is a power amplifier circuit. 11 is the transmission data of the base station 1, 1
Reference numeral 2 is reception data of the base station 1, 13 is reception data of the mobile device 2, and 14 is transmission data of the mobile device 2.

Next, the operation of the above conventional example will be described. In the base station 1, the transmission data 11 is spread by the data channel spreading means 3. The spread signal is added to the spread signals of other channels and transmitted to the mobile device 2 through the transmission path 5. The signal received by the mobile device 2 is despread by the data channel despreading means 6 and the received data 13 is obtained. The data signal reception level measuring means 7 measures the reception level from the reception data 13. The transmission power control means 8 estimates the amount of attenuation of the transmission path 5 from the measured value of the reception level, and the mobile device 2 transmits the transmission data 14
Is determined by the spreading means 9 and amplified by the power amplification circuit 10 for transmission. The data transmitted from the mobile device 2 via the electric transmission path 5 is despread by the despreading means 4 in the base station 1 to obtain the reception data 12. When the power level of the transmission data 11 transmitted from the base station 1 is constant, the attenuation amount of the transmission line 5 can be accurately obtained, and the transmission power of the mobile device 2 can be accurately controlled. You can

[0006]

However, in the above-mentioned conventional transmission power control technique, when the transmission power level of the transmission data 11 changes, it is impossible to accurately obtain the attenuation amount of the transmission line 5. , Accurate transmission power control cannot be performed. Further, the contents of the transmission data transmitted from the base station 1 to each mobile device 2 are different,
Since the respective separate spread channels are used, the estimated attenuation amount of the transmission path 5 in each mobile device 2 is different, and the base station 1 uses the estimated attenuation amount of the transmission path 5 as a basis. Since the transmission power of each mobile device 2 is determined by the above, the power from each mobile device 2 arriving at the base station 1 becomes unequal.

The present invention solves the above-mentioned conventional problems and is a CDMA / TD capable of highly accurate transmission power control.
An object is to provide a D-system wireless communication system.

[0008]

In order to achieve the above object, the present invention provides a means for a base station to transmit a pilot signal having a constant power level to each mobile station and known to each mobile station. In each mobile unit, highly accurate transmission power control is performed based on this pilot signal.

[0009]

According to the present invention, with the above configuration, it is possible to accurately control the transmission power and solve the problem that communication becomes impossible due to the near-far problem.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 100 is a base station, 200 is a mobile device, and those indicated by reference numerals 3 to 14 are those shown in the above-mentioned conventional example of FIG. 3 except for the control by the transmission power control means 8. It is the same. Reference numeral 15 denotes a pilot signal generating means for generating a known pilot signal in each mobile device 200, which has a constant transmission power, and 1
Reference numeral 6 is a pilot channel spreading means for spreading the pilot signal. Reference numeral 17 denotes pilot signal transmission level setting means for setting the transmission level of the pilot signal,
Reference numeral 18 is a pilot channel spreading means for obtaining a pilot signal in the mobile device 200. Reference numeral 19 is a pilot signal reception level measuring means for measuring the reception level of the pilot signal, and 20 is data quality measuring means for measuring quality such as bit error rate (BER) and frame error rate (FER) of the received data. is there. Reference numeral 21 is a synchronization acquisition means for acquiring the synchronization of the spreading code by the pilot signal, 22 is a synchronization holding means for holding the synchronization of the spreading code by the pilot signal, and 23 is a phase detection for obtaining the phase of the carrier wave by the pilot signal. Means, 24 is a frequency offset detecting means for obtaining an offset of a carrier frequency in a local oscillator of the mobile equipment 200, and 25 is an output using the frequency offset detecting means 24.
Is a local oscillator frequency adjusting means for adjusting the frequency of the local oscillator.

CDMA / TDD configured as described above
The operation of the wireless communication system will be described with reference to FIGS. 1 and 2. In FIG. 2, 26 is a pilot signal transmitted from the base station 100, and 27 is a transmission / reception timing of the mobile device 200. In FIG. 1, pilot signal generating means 15 generates a pilot signal whose transmission power is constant and which is known in each mobile station 200. The pilot signal is spread by the pilot channel spreading means 16 and then, together with the transmission data 11 spread by the data channel spreading means 3, is directed to each mobile device 200 on the transmission path 5 in a burst on at least one spreading channel. Sent. The pilot signal transmitted from the base station 100 via the transmission line 5 is as shown in FIG.
As shown in FIG. 5, each mobile unit 200 transmits the received data by despreading the data signal by the data channel despreading means 6 from the signal received in this time slot, which is transmitted in the time slot in which the mobile unit 200 receives. Got 13,
The pilot signal is despread by the pilot channel despreading means 18 to be obtained. The reception power of the obtained pilot signal is measured by the pilot signal reception level measuring means 19, the reception power of the reception data 13 is measured by the data signal reception level measuring means 7, and the data quality of the reception data 13 is measured by the data quality measuring means. It is measured by 20.
Then, the transmission power in the power amplifier circuit 10 when the transmission data 14 is spread by the spreading means 9 and transmitted to the base station 100 takes into consideration not only the reception level of the pilot signal and the reception data 13 but also the quality of the data channel. And control. Alternatively, the control is performed only based on the reception level of the pilot signal and the data quality. Mobile station 200 to transmission path 5
The data transmitted to the base station 100 via the despreading unit 4 is despread by the despreading means 4 to obtain the received data 12.

Further, since the pilot signal is known in the mobile station 200, the synchronization acquisition means 21 and the synchronization holding means 22 use the received pilot signal to acquire the synchronization and the synchronization holding of the spread signal, and the phase detection means. 23 to detect the phase of the carrier wave, the frequency offset detecting means 24 to detect the frequency offset in the local oscillator, and the local oscillator frequency adjusting means 25 to compensate for the detected frequency offset or the carrier frequency shift due to the Doppler effect. Can be done.

Further, in the base station 100, the pilot signal transmission level setting means 17 makes the transmission power level of the pilot signal higher than the signal level of the other spreading channel so that the pilot signal received from the other spreading channel is received. It is possible to lower the relative level of interference. As a result, the accuracy of the transmission power control, synchronization acquisition / holding, phase detection, frequency offset detection, and local oscillator frequency adjustment described above can be improved.

Further, the pilot signal generated by the pilot signal generating means 15 of the base station 100 is assumed to be an arbitrary code sequence, but the code sequence is all the same data sequence of "1" or "0". You may comprise. In this case, the circuit configuration of the pilot signal generation means 15, the pilot signal reception level measurement means 19, the synchronization acquisition means 21, the synchronization holding means 22, the phase detection means 23, the frequency offset detection means 24, and the local oscillator frequency adjustment means 25 is used. It becomes simple and the circuit scale can be reduced.

As described above, according to the above embodiment, since the transmission power of the pilot signal transmitted from the base station 100 to each mobile unit 200 is constant and is known to the mobile unit 200, the transmission path is known. 5 can be accurately estimated, and even when Rayleigh fading occurs due to the movement of the mobile device 200 and the attenuation of the transmission line 5 changes rapidly, it can be followed by the pilot signal.

[0016]

According to the present invention, as is apparent from the above-described embodiment, the base station transmits the pilot signal having a constant power level to each mobile unit and known to each mobile unit to at least one spreading channel. By providing means for transmitting in bursts, each mobile device can perform highly accurate transmission power control based on this pilot signal,
An excellent CDMA / TDD wireless communication system can be realized without making communication impossible due to the near-far problem. .

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a CDMA / TDD wireless communication system according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a transmission / reception timing of a pilot signal in the present embodiment.

FIG. 3 is a schematic block diagram of a conventional CDMA / TDD wireless communication system.

[Explanation of symbols]

 1, 100 base station 2, 200 mobile device 3 data channel spreading means 4 despreading means 5 transmission line 6 data channel despreading means 7 data signal reception level measuring means 8 transmission power control means 9 spreading means 10 power amplification circuit 11 base station Transmission data 12 reception data of base station 13 reception data of mobile device 14 transmission data of mobile device 15 pilot signal generation means 16 pilot channel spreading means 17 pilot signal transmission level setting means 18 pilot channel despreading means 19 pilot signal reception level measurement Means 20 Data quality measuring means 21 Synchronization acquisition means 22 Synchronization holding means 23 Phase detection means 24 Frequency offset detection means 25 Local oscillator frequency adjustment means 26 Pilot signal 27 Transmission / reception timing of mobile unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masatoshi Watanabe 4-3-1, Tsunashima-higashi, Kohoku-ku, Yokohama-shi, Kanagawa Matsushita Communication Industrial Co., Ltd.

Claims (12)

[Claims] 1. A CDMA / TDD wireless communication system comprising a base station and one or more mobile stations, wherein the base station has a constant transmission power level for each mobile station and is known to each mobile station. A means for generating a pilot signal, and means for transmitting the pilot signal in a burst manner on at least one spreading channel, each mobile station measuring the received power of the pilot signal,
A CDMA / TDD system wireless communication system comprising: means for controlling transmission power based on the measured reception power of the pilot signal. 2. The CDMA / TDD system wireless communication system according to claim 1, wherein each mobile unit comprises a synchronization acquisition means for acquiring synchronization of a spread signal by a pilot signal transmitted from a base station. 3. The CDMA / TDD system wireless communication system according to claim 1, wherein each mobile device comprises a synchronization acquisition means for maintaining synchronization of a spread code by a pilot signal transmitted from a base station. 4. Each mobile device comprises phase detecting means for obtaining a phase of a carrier wave based on a pilot signal transmitted from a base station, and despreading means for demodulating data using an output of the phase detecting means. CDMA / according to claim 1.
TDD wireless communication system. 5. Each mobile unit uses a frequency offset detection unit for obtaining an offset of a carrier frequency in a local oscillator of the mobile unit based on a pilot signal transmitted from a base station, and the mobile unit using the output of the frequency offset detection unit. 2. The CDMA / TDD system wireless communication system according to claim 1, further comprising frequency adjusting means for adjusting the frequency of a local oscillator of the machine. 6. Each mobile station comprises a synchronization acquisition means for acquiring synchronization of a spread signal by a pilot signal transmitted from a base station, and a synchronization holding means for maintaining synchronization of a spreading code.
Phase detecting means for obtaining a phase of a carrier wave, despreading means for demodulating data by using an output of the phase detecting means, frequency offset detecting means for obtaining an offset of a carrier frequency in a local oscillator of the mobile device, The CDMA / TDD wireless communication system according to claim 1, further comprising frequency adjusting means for adjusting the frequency of the local oscillator of the mobile device using the output of the frequency offset detecting means. 7. The base station comprises pilot signal transmission level setting means for setting the transmission power of a pilot signal to be transmitted higher than the transmission power of a signal of another spreading channel. CDMA / T
DD wireless communication system. 8. A CDMA / TDD wireless communication system comprising a base station and one or more mobile units, wherein the base station has a constant transmission power level for each mobile unit and is known to each mobile unit. And means for transmitting the pilot signal in a burst manner on at least one spreading channel, each mobile station measuring the received power of the pilot signal. Data signal level measuring means for measuring received power of a data signal transmitted to the mobile device, and control means for controlling transmission power based on outputs of the pilot signal level measuring means and the data signal level measuring means. A CDMA / TDD wireless communication system. 9. A CDMA / TDD wireless communication system comprising a base station and one or more mobile stations, wherein the base station has a constant transmission power level for each mobile station and is known to each mobile station. And means for transmitting the pilot signal in a burst manner on at least one spreading channel, each mobile station measuring the received power of the pilot signal. , CDMA / TDD including data quality measuring means for measuring the quality of received data, and control means for controlling transmission power based on the outputs of the pilot signal level measuring means and the data quality measuring means.
Wireless communication system. 10. A CDMA / TDD wireless communication system comprising a base station and one or more mobile stations, wherein the base station has a constant transmission power level for each mobile station and is known to each mobile station. And means for transmitting the pilot signal in a burst manner on at least one spreading channel, each mobile station measuring the received power of the pilot signal. , Data signal level measuring means for measuring received power of a data signal transmitted to the mobile device, data quality measuring means for measuring quality of received data, the pilot signal level measuring means and the data signal level measuring means And a control means for controlling the transmission power based on the output of the data quality measuring means Wireless communication system. 11. A mobile station, each mobile station acquiring synchronization of a spread signal with a pilot signal transmitted from a base station, synchronization retaining means for retaining synchronization of a spreading code, and phase detection for determining a phase of a carrier wave. Means, a despreading means for demodulating data using the output of the phase detecting means, a frequency offset detecting means for obtaining an offset of a carrier frequency in a local oscillator of the mobile unit, and an output of the frequency offset detecting means. 11. The CDMA / according to any one of claims 8 to 10, further comprising frequency adjusting means for adjusting the frequency of the local oscillator of the mobile device.
TDD wireless communication system. 12. A data sequence in which all pilot signal generation means outputs "1" or all "0" in the base station.
12. The CDMA / TDD system wireless communication system according to claim 1, which is a data sequence of