JP2000216756A - Spread spectrum communication system and transmitter and receiver configuring the system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To acquire a spread code phase of a receiver at a high speed with high accuracy with respect to a spread spectrum communications system and a transmitter and the receiver being components of the system. SOLUTION: In this spread spectrum communications system, the transmitter and the receiver which are components of the system use an increased transmission power level for a signal used for acquiring a spread code phase more than the transmission power level for a signal which is not used for acquiring the spread code phase and acquires the spread code phase, by using the signal whose transmission power is increased. Thus, phase information can be acquired at a high speed with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication system and a transmitter and a receiver constituting the spread spectrum communication system, and more particularly to a spread spectrum signal transmitted by the transmitter, the receiver being capable of acquiring a spread code phase. The present invention relates to a spread spectrum communication system in which the accuracy of a spread code phase acquired by a receiver is increased by increasing transmission power of a used signal portion, and a transmitter and a receiver constituting the system.

[0002]

2. Description of the Related Art A conventional spread spectrum communication system is designed to improve the error rate characteristics of a received wave while suppressing the transmission power of a communication partner. So-called RAKE reception is performed in which delayed waves that arrive with a delay are combined.

A conventional spread spectrum communication system will be described with reference to FIGS. Fig. 4-a, -b
Represents a conventional spread spectrum communication system. In the figure, 1 is a mobile station, 2 is an antenna, 3 is a high frequency amplifier, 4 is a frequency converter for performing frequency conversion from a radio frequency to an intermediate frequency, 5 is a demodulator, 6 is an A / D converter, and 7 is an input signal. A rake receiving unit that performs despreading at different timings to extract a direct wave and a delayed wave and aligns timings, a correlation unit 8 that correlates an input signal,
Reference numeral 9 denotes a spreading code generation unit for providing a spreading code to the correlation unit, and 1
0 is a phase control unit that controls the phase of the spread code generated by the spread code generation unit 9, 11 is a control unit that controls the phase control unit 10, creates a delay profile, and supplies phase information to the RAKE reception unit 7; 12 is a searcher, 13
Is a coder / decoder, 14 is an A / D converter, 15 is a microphone, 16 is a D / A converter, 17 is a speaker, 18 is a timing control unit that performs timing control, and 19 is framing of transmission data and the like. Unit, 20 is a spread unit that generates a spread spectrum signal, 21 is a D / A converter, 22 is a modulator that performs modulation, 23 is a frequency converter that converts the frequency from an intermediate frequency to a radio frequency, and 24 is control of the amplification factor. A transmission power control unit for controlling the gain of the variable gain amplifier; 26, a base station;
27 is the SIR (Signal to Interference Rat) of the received signal
io: signal-to-interference ratio), 28 is an SIR determination unit that instructs creation of a transmission power control signal, 29 is a framing unit that frames transmission data and the like, and 30 is an input signal. A combining unit that performs combining (maximum ratio combining) after performing weighting in proportion to the reliability is shown.

First, a spread spectrum signal transmitted from an antenna 2 of a mobile station 1 is received by an antenna 2 of a base station 26, and a high frequency component of the received signal is amplified by a high frequency amplifier 3, and a radio frequency is converted by a frequency converter 4. It is down-converted from the number to the intermediate frequency, demodulated by the demodulator 5, and then converted to a digital signal by the A / D converter. One of the digitally converted received signals is input to the searcher 12 and the other is input to the rake receiving unit 7.

The signal input to the searcher 12 is correlated with the spread code generated by the spread code generator 9 by the correlator 8. The spread code is controlled by the phase control unit 10 and is shifted in phase little by little (for example, shifted by about ８ of one chip of the spread code). The correlation value obtained as the output is the sum of the squares of the signal input to the searcher 12 and the spreading code. When the phase is correlated, a large value must be obtained, and conversely, the correlation must not be obtained. If it is small, it will be a small value. Thereby, the control unit 11 acquires data of the correlation value with respect to the phase change. FIG. 5 expresses a change in phase on the horizontal axis and a correlation value on the vertical axis, and is called a delay profile. In the figure, B, C, and the like having a large correlation value are considered to be delayed waves of A, and the others are considered to be thermal noise and interference due to spread spectrum signals emitted from other mobile stations. The control unit 11 controls, for example, the three highest correlation values (A,
The phase information of (B, C) is provided to the rake receiving unit 7. RA
Using the phase information (spread code phase) of the direct wave and the delayed wave, the KE receiver 7 performs despreading on the direct wave A and the delayed waves B and C, respectively. Then, adjust the delay according to each delay amount, adjust the timing,
The combining unit 30 performs weighting in proportion to the reliability, and then performs combining (maximum ratio combining).

However, the following problem cannot be solved only by performing RAKE reception at the receiver. In general, as the mobile station moves away from the base station, the reception electric field strength of a signal received at the base station tends to decrease. Therefore, in a spread spectrum communication system aiming at effective use of frequency by discriminating a signal from another mobile station based on a difference of a spreading code, a mobile station whose reception electric field strength has decreased is more base station side. Therefore, the degree of interference of the spread spectrum signal transmitted from the mobile station existing in (1) becomes strong (SIR is deteriorated), and the noise component cannot be sufficiently removed.

[0007] Such a problem is called a near-far problem. Therefore, transmission power control is being performed to solve this near-far problem. That is, regardless of the signal transmitted from any mobile station, the base station controls the transmission power of the mobile station so that the SIRs are all equal, and the mobile station located far from the base station and the mobile station located near it are controlled. S with the station
Control to eliminate extreme differences in IR is performed.

[0008] This control will be described. One of the signals obtained by the RAKE receiving unit 7 in the base station 26 performing the maximum ratio combining based on the phase information from the control unit 11 is transmitted to the base station control station, and the other is estimated by the SIR estimating unit 27 to estimate the SIR. Is performed. Then, the SIR determination unit 28 compares the estimated SIR value with a threshold value, and when the estimated value is less than the threshold value, causes the framing unit 29 to generate a control signal for increasing the transmission power of the mobile station. Instruct the transmission power control signal generation command signal to the framing unit 29 to instruct to generate a control signal for lowering the transmission power when it exceeds the threshold value.

Here, the configuration of the framing unit 29 will be described with reference to FIG. FIG. 6 shows the configuration of the framing unit 29. In the figure, reference numeral 901 denotes a buffer for buffering transmission data; 902, a pilot signal generation unit for generating a pilot signal; 903, a control signal generation unit for generating a control signal; and 904, transmission power control for generating a transmission power control signal. A signal creation unit 905 represents a selector for selectively sending an input signal to the spreading unit.

[0010] Encoded transmission data such as an audio signal is input to a buffer 901, and the data is temporarily stored. Then, at the timing given from the timing control unit 18, the read audio data and the like are sent to the diffusion unit 20 via the selector. Further, the pilot signal creation unit 902, the control signal creation unit 903, and the transmission power control signal creation unit 904 also transmit the pilot signal, the control signal, and the transmission power control signal (2 bits) via the selector 905 at the timing given from the timing control unit 18. Diffusion unit 2
Send to 0. The signal sent to the spreading section 20 is controlled by the timing control section 18 in the order of a pilot signal, a transmission power control signal, transmission data, and a control signal. Name).

However, the transmission power control signal creation unit 904
Upon receiving the transmission power control signal creation command signal from the SIR determination unit 28 and receiving a control signal creation command to increase the transmission power of the mobile station (for example, +1.0 dB),
It outputs "11" and outputs "00" when it receives a control signal creation command to lower (-1.0 dB). When the transmission power control signal creation command signal is not transmitted from the SIR determination unit 28, for example, "11", "0"
By transmitting the signal "0" alternately, the average transmission power is maintained.

Then, the signal subjected to the timing control is transmitted to the spreading section 20, subjected to code spreading processing, and subjected to D / A
The signal is converted by the converter 21 into an analog signal. The analog signal is modulated by the modulator 22, converted from the intermediate frequency to the radio frequency by the frequency converter 23, amplified by the variable gain amplifier 24, and transmitted from the antenna 2 to the mobile station 1. .

On the other hand, the mobile station 1 transmits a spread spectrum signal including a transmission power control signal from the base station 26 via the antenna 2, the high frequency amplifier 3, the frequency converter 4, the demodulator 5, and the A / D converter 6. The RAKE receiving unit 7 receives the RAKE of the received signal based on the phase information detected by the searcher 12 (configured by the correlation unit 8, the spreading code generating unit 9, the phase control unit 10, and the control unit 11). Perform reception. Then, the transmission power control signal included in the signal after RAKE reception is sent to transmission power control section 25.

The other signals after the RAKE reception are:
The data is decoded by the decoder 13 and the D / A converter 16
Is output as a voice from the speaker 17 via the. The sound input from the microphone 15 is transmitted to the A / D converter 1.
4. Encoded by the coder / decoder 13 and input to the framing unit 19 as transmission data. The configuration of the framing unit 19 will be described with reference to FIG. FIG.
Shows an example of the configuration of the framing unit 19.

In the drawing, components denoted by the same reference numerals as those in FIG. 6 represent the same members. Transmission data such as audio data is input to the buffer 901 and the data is temporarily stored. The audio data and the like read at the timing given from the timing control unit 18 are sent out to the spreading unit 20 via the selector. Further, pilot signal creation section 902, control signal creation section 903, and transmission power control signal creation section 904 also transmit pilot signal, control signal, and transmission power control signal at timing given from timing control section 18 via selector 905 to spreading section 20. Send to Then, by this timing control unit 18,
Signals sent to spreading section 20 generate pilot signals, transmission power control signals (signals such as “11” and “00”, but base station 26 normally ignores these signals),
The transmission data and the control signal are controlled in this order.

The signal subjected to the timing control is code-spread by the spreading unit 20, modulated by the modulator 22, subjected to frequency conversion by the frequency conversion unit 23, and then input to the variable gain amplifier 24. Here, the transmission power control unit 25 that has received the transmission power control signal controls the gain of the variable gain amplifying unit 24 at the start timing of one slot acquired from the timing control unit 18. That is, if the transmission power control signal is “11”, the amplification factor is increased, and the transmission power is maintained until the next signal of “00” is received,
If it is "00", the amplification factor is reduced, and its transmission power is maintained until the next signal "11" is received.

Therefore, the signal transmitted from the antenna 2 of the mobile station 1 is subjected to transmission power control for SIR equalization. When the base station 26 receives the signal, the SIR after the RAKE reception becomes The values are kept within the threshold value, and the SIR with other mobile stations under similar control is made uniform. The above is the transmission power control (SIR equalization control) for solving the near-far problem performed in the conventional spread spectrum communication system.

[0018]

As described above, in the conventional spread spectrum communication system, the correlation value is measured by the correlation unit 8 in the searcher 12, and the RAKE reception is performed based on the phase information obtained from the result. It is carried out. However,
In order to perform RAKE reception effectively, it is necessary to detect this phase information by integrating correlation values detected at different timings a plurality of times. Because the difference between the interference wave and the delayed wave usually does not appear as a significant difference in the correlation value by only one correlation value measurement, accurate phase information of the delayed wave cannot be detected, and an error due to the synthesis of the delayed wave cannot be obtained. This is because the rate characteristics cannot be improved.

However, even though RAKE reception is performed effectively, the number of times of integration of correlation values cannot be increased without limit. This is because an increase in the number of times of integration processing causes an adverse effect that the followability of the phase information to the phase change of the delay wave accompanying the movement of the mobile station is reduced. Meanwhile, to avoid this,
If a method of increasing the phase information detection speed by limiting the measurement target of the correlation value to one mobile station and continuously measuring the correlation value performed at different timings is adopted, the spread code 1 The process of calculating the correlation value while shifting the chip by of a chip is performed continuously, so that the process of the searcher 12 cannot catch up, and one mobile station continuously monopolizes the searcher. This causes another problem that the delay profile creation of other mobile stations is prevented.

Therefore, in practice, the number of integration processes is limited to a range that is not sufficient to obtain highly accurate phase information.
Since the synthesis of the delayed waves is performed based on the phase information with reduced accuracy, the deterioration of the error rate characteristics after the RAKE reception is allowed. Also, the transmission power control of the mobile station for SIR equalization, which is performed as a solution to the near-far problem, is based on the SIR estimation result of the signal after the RAKE reception performed based on the phase information with reduced accuracy as described above. , The transmission power is sufficient, but RAKE
Since the accuracy of the phase information used for reception is low, apparently S
The IR is considered to be degraded, and by performing transmission power control that is not originally required, interference with other mobile stations is strengthened.

It is an object of the present invention to suppress the number of integration processes in a searcher and to obtain a high-speed and accurate spread code phase. It is another object of the present invention to solve the true near-far problem by using the spread spectrum communication system.

[0022]

According to the present invention, in a spread spectrum communication system including a transmitter and a receiver for performing communication by transmitting and receiving a spread spectrum signal, the receiver includes a spread spectrum signal from the transmitter. Acquiring means for acquiring a spread code phase of a signal, wherein the transmitter determines a level of a signal used by the acquirer of the receiver to acquire a spread code phase among spread spectrum signals transmitted to the receiver. A spread-spectrum communication system having transmission power control means for performing transmission power control for increasing the transmission power to be higher than the level of a signal not used for obtaining a spread code phase is used.

According to the present invention, there is provided a spread spectrum communication system including a transmitter and a receiver for performing communication by transmitting and receiving a spread spectrum signal.
The receiver, the acquisition means for acquiring the spread code phase of the spread spectrum signal from the transmitter, for the transmitter,
Requesting means for requesting start of transmission power control, wherein the transmitter, upon receiving the request, obtains the receiver of the spread-spectrum signal transmitting to the receiver for a predetermined period of time. For use in a spread spectrum communication system having transmission power control means for performing transmission power control for increasing the level of a signal used for obtaining a spreading code phase as compared with the level of a signal not used for obtaining a spreading code phase. Was.

In the present invention, spread spectrum signals from a plurality of transmitters are received, a spread code phase of the spread spectrum signal is obtained, and the spread code phase is despread using the spread code phase. Do
Transmission for performing transmission power control on the transmitter that transmitted the spread spectrum signal so that the signal quality of the despread signal is equal to the signal quality of the despread signal from another transmitter after despreading. A receiver that transmits a power control signal, and a transmitter that transmits a spread spectrum signal to the receiver and, when receiving the transmission power control signal, controls transmission power according to the transmission power control signal. In the spread spectrum communication system, when the transmitter receives the transmission power control signal, the transmitter spreads the level of a signal used by the receiver to acquire a spreading code phase for a fixed time when increasing the transmission power by the signal. Spectra characterized by further comprising transmission power control means for further performing transmission power control for increasing the transmission power to be higher than the level of a signal not used for obtaining a code phase. Using spread communication system.

According to the present invention, in a receiver for receiving a spread spectrum signal, a spread code phase information of the received spread spectrum signal is obtained by using a signal of a portion of the received spread spectrum signal whose transmission power is increased. A receiver characterized by having an acquiring means for acquiring the. Further, in the present invention, in a transmitter for transmitting a spread spectrum signal, when transmitting a predetermined signal, transmission power control for performing transmission power control for increasing the transmission power above the level of a signal outside the predetermined signal and transmitting the signal. A transmitter characterized by having means was used.

In the present invention, the receiver receives the spread spectrum signal transmitted from the transmitter, and obtains the code spread phase of the received spread spectrum signal by the obtaining means. On the other hand, the transmitter, by the transmission power control means,
Among the spread spectrum signals transmitted to the receiver, the transmission power control is performed so that the level of the signal used by the receiver to obtain the spread code phase is higher than the level of the signal not used to obtain the spread code phase. Then, the spread spectrum signal subjected to the transmission power control is transmitted.

Further, in the present invention, the receiver receives the spread spectrum signal transmitted from the transmitter, and obtains the spread code phase of the received spread spectrum signal by the obtaining means. The notification unit requests the transmitter to start transmission power control. On the other hand, when the transmitter receives a request to start transmission power control from the receiver, the transmission power control means causes the receiver to transmit a spread code phase out of the spread spectrum signals transmitted to the receiver for a fixed time. , The transmission power control is started such that the level of the signal used for the acquisition of the signal is higher than the level of the signal not used for the acquisition of the spread code phase, and the spread spectrum signal subjected to the transmission power control is transmitted.

In the present invention, the receiver obtains the spread code phase of the received spread spectrum signal, despreads the spread spectrum signal using the spread code phase, and transmits the spread spectrum signal. Transmitting a transmission power control signal for performing transmission power control to the transmitter so that the quality of the despread signal is equal to the despread signal quality of the spread spectrum signal from another transmitter; Thereby, the signal quality of spread spectrum signals transmitted from a plurality of transmitters is made uniform. On the other hand, the transmitter
When the transmission power is controlled by the transmission power control signal from the receiver and the transmission power is increased by the transmission power control, the spread spectrum signal is transmitted to the receiver for a certain period of time. Of which
It also performs transmission power control so that the level of the signal used by the receiver to obtain the spread code phase is higher than the level of the signal not used to obtain the spread code phase. Send a signal.

Further, in the present invention, the receiver for receiving the spread spectrum signal may include, by the acquisition means, a signal of a portion of the received spread spectrum signal whose transmission power is increased in the received spread spectrum signal. Obtain using Further, in the present invention, the transceiver for transmitting the spread spectrum signal, by the transmission power control means, when transmitting a predetermined signal, performs control to increase the transmission power above the level of the signal which is not the predetermined signal,
The spread spectrum signal subjected to such transmission power control is transmitted.

[0030]

Embodiments of the present invention will be described below. In the present invention, the base station controls the transmission power of the mobile station so that the signal level for which the correlation value is measured is higher than the level of the non-measurement signal, so that the correlation value in the searcher in the base station is increased. , While improving the error rate characteristics after RAKE reception.

The operation of the spread spectrum communication system according to the present invention will be described with reference to FIGS. Figure 1
a and -b show an example of the configuration of the spread spectrum communication system according to the present invention. In the drawing, components denoted by the same reference numerals as those in FIGS. 4A and 4B indicate the same members.

The base station 26 was used as a receiver, the mobile station 1 was used as a transmitter, the searcher 12 was used as acquisition means, and the timing control unit 18 and the transmission power control unit 25 were used as transmission power control means. Further, the framing unit 19, the spreading unit 20, the D / A converter, the modulator 22, the frequency converter 23, the variable gain amplifier 24, and the antenna 2 including the transmission power control signal creating unit 904 were used as requesting units.

The spread spectrum signal transmitted from the antenna 2 of the mobile station 1 is received by the antenna 2 of the base station 26, the high-frequency component is amplified by the high-frequency amplifier 3, and the frequency converter 4 down-converts the radio frequency to the intermediate frequency. After the conversion, the signal is demodulated by the demodulator 5. The demodulated signal is converted into a digital signal by the A / D converter 6 and input to the searcher 12. The searcher 12 detects the phase information and sends the phase information to the rake receiving unit 7 by the same processing as the above-described conventional technique.

The RAKE receiving section 7 performs despreading on each of the direct wave and the delayed wave based on the phase information. Then, after performing the delay adjustment according to the respective delay amounts and adjusting the timings, the combining unit 30 performs the combining (maximum ratio combining) after performing the weighting in proportion to the reliability. One of the signals obtained by the RAKE receiving unit 7 in the base station 26 performing the maximum ratio combining based on the phase information from the control unit 11 is as follows:
The SIR is transmitted to the base station control station, and the other is estimated by the SIR estimator 27.

Then, the SIR determination unit 28 determines the estimated S
Compare the IR value to a threshold and if the estimate is below the threshold,
A control signal (hereinafter, referred to as a U signal) that causes the framing unit 29 to increase the transmission power of the mobile station 1 and a control signal (hereinafter, referred to as D) that decreases the transmission power when the transmission signal exceeds a threshold value.
A U and D signal generation command signal is sent to the framing unit 29 so as to generate a signal. When the U signal creation command signal is sent to the framing unit 29, the correlation value of a predetermined portion of the signal (for example, the PILOT signal) previously determined with the mobile station in the received signal must be measured. To the control unit 11 (hereinafter, this signal is referred to as a special measurement signal).

Here, the configuration of the framing unit 29 will be described with reference to FIG. FIG. 2 shows an example of the configuration of the framing unit 29. In the figure, the same reference numerals as in FIG. 6 denote the same members. Transmission data such as voice data, a pilot signal created by the pilot signal creation unit 902, a control signal created by the control signal creation unit 903, and a transmission power control signal created by the transmission power control signal creation unit 904 are: The signal is sent to the spreading unit 20 via the selector 905 at the timing given from the timing control unit 18. However, the transmission power control signal creation unit 904 receives the U and D signal creation command signal from the SIR determination unit 28, and receives this command to generate a U signal (for example, “11”) and a D signal.
A signal (for example, “00”) is output.

The signal including the transmission power control signal code-spread by the spreading section 20 is converted into an analog signal by a D / A converter 21 and modulated by a modulator 22. The modulated signal is converted into a radio frequency by the frequency converter 23, amplified by the variable gain amplifier 24, and transmitted from the antenna 2. The mobile station 1 similarly receives the signal transmitted from the base station 26 via the antenna 2, the high-frequency amplifier 3, the frequency converter 4, the demodulator 5, and the A / D converter 6, and receives the received signal by RAKE reception. Part 7 and Searcher 12
(Composed of a correlator 8, a spreading code generator 9, a phase controller 10, and a controller 11).

As described above, the searcher 12 has direct waves,
The phase information of the delayed wave is obtained, and the phase information is provided to the rake receiving unit 7. The rake receiving unit 7 performs despreading on each of the direct wave and the delayed wave based on the phase information. Then, the delay is adjusted in accordance with the respective delay amounts, the timing is adjusted, and weighting in proportion to the reliability is performed, followed by synthesis (maximum ratio synthesis).

The U and D signals, which are transmission power control signals, of the combined signal are transmitted to the transmission power control unit 25. Of the other signals, the audio signal is
The data is decoded by the decoder 13 and the D / A converter 16
Is converted into an analog signal, and then output as a sound from the speaker 17. The audio input from the microphone 15 is converted into a digital signal by the A / D changer 14, input to the coder / decoder 13, and the coder / decoder 13 encodes the audio signal and supplies it to the framing unit 19.

Here, the configuration of the framing unit 19 will be described with reference to FIG. FIG. 3 shows an example of the configuration of the framing unit 19. In the figure, the components denoted by the same reference numerals as those in FIG. 2 represent the same members. Transmission data such as audio data is input to the buffer 901 and the data is temporarily stored. And the timing control unit 1
At the timing given from 8, the divided audio data and the like are sent out to the spreading section 20 via the selector. Also, a pilot signal creation unit 902 and a control signal creation unit 90
3. The transmission power control signal creation unit 904 (“11”, “0”
0, etc., but in any case, the base station 26
This signal is usually ignored).
8, a pilot signal, a control signal, and a transmission power control signal are sent to the spreading section 20 via the selector 905. The signal sent to the spreading section 20 is controlled by the timing control section 18 in the order of a pilot signal, a transmission power control signal, transmission data, and a control signal.

The signal subjected to the timing control is code-spread by the spreading unit 20, converted into an analog signal by the D / A converter 21, modulated by the modulator 22, and then by the frequency conversion unit 23. Converted to radio frequency. The signal converted to the radio frequency is input to the variable gain amplifier 24 and amplified. However, the amplification factor is determined by the transmission power control unit 2
5. That is, the transmission power control signals (U and D signals) of the spread spectrum signals transmitted from the base station 26 are input to the transmission power control unit 25, and the transmission power control signals are D signals (“00”). In
The gain of the variable gain amplifying unit 24 is reduced by a predetermined value at the beginning timing of one slot acquired from the timing control unit 18 (for example, -0.1 dB), and then the gain until the U and D signals are received. And keep it down. But U
When the signal (“11”) is received, the timing control unit 18
The gain of the variable gain amplifier 24 is increased (+0.1 dB) at the timing of the beginning of one slot obtained from the base station, but a predetermined signal (for example, PILOT) predetermined between the base station and the base station.
Signal) only when transmitting the signal (e.g., +5.0 dB).

The control of the amplification factor in the mobile station 1 can be always performed without requesting from the base station. However, as in this embodiment, the base station instructs to increase the transmission power. Sometimes, only during a certain period of time, the degree of interference with other mobile stations can be minimized. Therefore, the signal transmitted from the antenna 2 of the mobile station 1 is not only subjected to transmission power control for SIR equalization, but also a signal portion used for measurement of a correlation value by the correlation unit 8 of the base station 26 is: As a result, the transmission power can be temporarily increased as compared with a signal not to be measured.

The signal transmitted from the antenna 2 of the mobile station 1 is received by the base station 26, and the received signal is input to the rake receiving unit 7 and the searcher 12. Then, the control unit 11, which has received the special measurement signal from the SIR determination unit 28, measures the correlation value of the signal (for example, the PILOT signal) of the predetermined portion in the received signal for a certain period of time (e.g., the PILOT signal). For example, at the timing of receiving the PILOT signal), the spread code generation unit 9 outputs the spread code, and the correlation unit 8 measures the correlation value. However, since this measurement is performed on a signal whose transmission power has been increased, the difference between noise and interference of another mobile station and a delayed wave appears more conspicuously as a difference in correlation value than before. For this reason, it is possible to detect phase information with high accuracy even when the number of integration processes is almost the same as that of the related art, or if necessary, even more suppressed.

The RAKE receiving section 7 can effectively perform RAKE reception using this highly accurate phase information, and naturally the error rate characteristics of the signal after the RAKE reception are improved.
In addition, the SIR estimating unit 27 can perform SIR estimation using the signal obtained by effectively synthesizing the delayed waves, and can perform accurate transmission power control of the mobile station 1 for equalizing the SIR. In addition, it is possible to suppress the influence on other mobile stations due to unnecessary increase in transmission power, and to contribute to the solution of a true distance problem.

In this embodiment, since the PILOT signal provided at a position near the beginning of one slot in the communication channel is used so that the transmission power control timing can be easily obtained, the mobile station 1 is temporarily stopped. The transmission power is controlled at the time of transmitting the PILOT signal, but may be controlled at the time of transmitting another signal. However, in that case, the transmission power control timing given to the transmission output control unit 25 in the mobile station 1 may be the timing of the other signal.

In this embodiment, the signal for increasing the transmission power and the signal for measuring the correlation value are predetermined.
It is also possible to make these information coincide by exchanging these information as control signals. However, it is generally not preferable to increase the control signal, so that it is preferable to determine the control signal in advance. When the base station 26 performs AGC (Auto Gain Control) in order to suppress the effect of fading, the base station 2
In 6, the timing information at which the transmission power of the mobile station 1 temporarily increases may be given to the control means for controlling the automatic gain control.

In this embodiment, a signal (signal represented by "11") used for performing normal transmission power control for SIR equalization is changed only to a signal portion whose correlation value is to be measured. Although the signal is also used as a signal for performing control for further increasing the transmission power of the mobile station, it can be realized by separately creating a signal for starting such a partial transmission power increase control. .

Further, in the present embodiment, the SIR estimation value is used especially for the determination of the signal quality. However, the quality determination based on the signal after despreading using the acquired spread code phase may be performed. For example, another value can be used as a reference.

[0049]

According to the present invention, a transmitter transmits a spread spectrum signal by increasing the signal level of a signal used by a receiver to obtain a spread code phase with respect to a signal not used to obtain a spread code phase. Therefore, the difference between the direct wave, the delayed wave, and the like and the interference wave becomes remarkable, and it becomes easy for the receiver to acquire the spread code phase. Therefore, the spread code phase can be obtained at high speed and with high accuracy without taking any special measures such as increasing the number of integration processes, and the followability to the change of the spread code phase due to the movement of the transmitter is enhanced. In particular, when RAKE reception is performed, RAKE reception can be effectively performed by synthesizing a direct wave and a delayed wave using the high-speed and accurate spreading code phase, and an error after RAKE reception can be achieved. The rate characteristics can also be improved. It should be noted that the control for increasing the transmission power in the present invention is performed (with preferential treatment) on the signal portion used for obtaining the spreading code phase in the receiver, and the control for increasing the transmission power is performed to other transmitters more uniformly than the control for increasing the transmission power. Interference can be kept low.

According to the present invention, the transmitter can control the start timing of the control for increasing the signal level of the predetermined portion and transmitting the signal by the receiver. Since the control is stopped, not only the above effect can be obtained, but also the interference with other transmitters can be further reduced. Also, the load associated with the increase in the transmission power of the transmitter can be minimized.

Further, according to the present invention, the receiver performs despreading of the received spread spectrum signal using the obtained spread code phase, and compares the despread signal quality with the spread spectrum signal from another transmitter. The transmission power control is instructed to the transmitter that has transmitted the spread spectrum signal so that the signal quality after despreading becomes the same. On the other hand, the transmitter performs the transmission power control for equalizing the instructed signal quality and sets the level of the signal used by the receiver to obtain the spread code phase to the signal level not used to obtain the spread code phase. The transmission power is also increased.

As a result, the receiver can acquire the spreading code phase at high speed and with high accuracy, and can also efficiently perform despreading using the spreading code phase. Therefore, the transmission power control based on the signal quality of the despread signal becomes appropriate, and the phenomenon of performing unnecessary transmission power control is reduced, and interference with other transmitters can be reduced. Therefore, a true perspective problem can be solved.

Further, since a signal for transmission power control for quality uniformity is used, it is not necessary to increase the amount of control signals, so that it is possible to prevent an increase in interference with other transmitters due to an increase in control signals. it can.

[Brief description of the drawings]

FIG. 1-a shows a spread spectrum communication system according to the invention.

FIG. 1-b shows a spread spectrum communication system according to the invention.

FIG. 2 shows a configuration of a framing unit 29 according to the present invention.

FIG. 3 shows a configuration of a framing unit 19 according to the present invention.

FIG. 4-a shows a conventional spread spectrum communication system item.

FIG. 4B shows a conventional spread spectrum communication system.

FIG. 5 shows a delay profile.

FIG. 6 shows a configuration of a framing unit 29.

FIG. 7 shows a configuration of a framing unit 19;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mobile station 2 Antenna 3 High frequency amplifier 4 Frequency converter 5 Demodulator 6 A / D converter 7 RAKE receiving part 8 Correlation part 9 Spread code generation part 10 Phase control part 11 Control part 12 Searcher 13 Coder / decoder 14 A / D Converter 15 Microphone 16 D / A converter 17 Speaker 18 Timing controller 19 Framer 20 Spreader 21 D / A converter 22 Modulator 23 Frequency converter 24 Variable gain amplifier 25 Transmission power controller 26 Base station 27 SIR Estimation unit 28 SIR determination unit 29 Frame conversion unit 30 Synthesis unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K022 EE02 EE21 EE31 5K060 BB07 CC04 DD04 FF06 HH06 LL01 5K067 AA23 BB02 CC10 DD27 DD42 EE02 EE10 GG08

Claims (5)

[Claims] 1. A spread spectrum communication system including a transmitter and a receiver for performing communication by transmitting and receiving a spread spectrum signal, wherein the receiver obtains a spread code phase of the spread spectrum signal from the transmitter. Means for obtaining the spread code phase of the portion of the spread spectrum signal to be used by the obtaining means of the receiver for obtaining the spread code phase among the spread spectrum signals transmitted to the receiver. A transmission power control means for performing transmission power control to increase the level of the spread spectrum signal in a portion not used for transmission. 2. A spread spectrum communication system including a transmitter and a receiver for communicating by transmitting and receiving a spread spectrum signal, wherein the receiver obtains a spread code phase of the spread spectrum signal from the transmitter. Means, and for the transmitter:
Requesting means for requesting start of transmission power control, wherein the transmitter, when receiving the request, obtains the receiver of the spread spectrum signal to be transmitted to the receiver for a certain period of time. Having transmission power control means for performing transmission power control to increase the level of the spread spectrum signal of the portion used for obtaining the spread code phase as compared with the level of the spread spectrum signal of the portion not used for obtaining the spread code phase, Characteristic spread spectrum communication system. 3. Receiving a spread spectrum signal from a plurality of transmitters, acquiring a spread code phase of the spread spectrum signal, despreading the spread spectrum signal using the spread code phase, Transmission power control for a transmitter that has transmitted a spread signal so as to perform transmission power control such that the signal quality of the signal after despreading matches the signal quality after despreading of the spread spectrum signal from another transmitter. A spread spectrum transmitter comprising: a receiver for transmitting a signal; and a transmitter for transmitting a spread spectrum signal to the receiver and, when receiving the transmission power control signal, controlling transmission power according to the transmission power control signal. In the communication system, the transmitter, when receiving the transmission power control signal, when increasing the transmission power by the signal, for a certain period of time, Transmission power control means for further performing transmission power control for increasing the level of the spread spectrum signal in the portion used by the receiver to obtain the spread code phase as compared to the level of the spread spectrum communication signal in the portion not used to obtain the spread code phase A spread spectrum communication system, comprising: 4. An acquiring means for acquiring, in a receiver for receiving a spread spectrum signal, spread code phase information of the received spread spectrum signal using a signal of a portion of the received spread spectrum signal whose transmission power has been increased. A receiver comprising: 5. A transmitter for transmitting a spread spectrum signal, comprising: transmission power control means for performing transmission power control for transmitting a predetermined signal at a transmission power higher than a level outside the predetermined signal when transmitting the predetermined signal. Features transmitter.