KR19990088362A - Cdma receiving apparatus and cdma communicating method - Google Patents

Abstract

The analog signal received by the first antenna 101 is converted into a digital signal by the first AD converter 103 and stored in the first memory 105. The first phase rotating unit 109 controls the amount of phase rotation of the received signal, and the first amplifier 111 amplifies the amplitude of the received signal. The same processing is also performed on the analog signal received by the second antenna 102. After each signal is added by the adder 113, the correlation detector 114 performs correlation detection and outputs a despread signal. As a result, the number of correlators is reduced, and the size and weight of the apparatus are reduced.

Description

CD receiver and CD communication method {CDMA RECEIVING APPARATUS AND CDMA COMMUNICATING METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CDMA receiving apparatus and a CDMA communication method for performing wireless communication using a CDMA system, RAKE synthesis of received signals, and detecting correlation.

In recent years, in cellular systems such as automobiles and mobile phones, a frequency effective use technology for securing more subscriber capacity on a limited frequency band has been important.

As one of the multiple access schemes that effectively use frequency, a code division multiple access (CDMA) scheme has attracted attention. The CDMA system can achieve excellent communication quality due to wide bandwidth, sharp correlation characteristics due to spreading codes, and the like.

One CDMA scheme is a direct spread scheme that multiplies a spread code by a transmission signal. In the case of using the direct spreading scheme, the diversity effect can be increased by RAKE receiving and multiplying multipath components.

Hereinafter, the reception processing of the conventional CDMA receiving apparatus will be described using the block diagram of FIG. In addition, FIG. 1 shows the case of QPSK modulation with 2 antenna branches and 1 finger per branch of RAKE synthesis.

The in-phase component and orthogonal component of the analog signal received by the first antenna 11 are respectively stored in the first storage unit 15 after being converted into digital signals by the first AD converter 13. .

The digital signal output from the first storage unit 15 is estimated by the first line state estimating unit 21 based on the multiplexed pilot signal and the phase rotation amount and the reception level.

The in-phase component of the digital signal output from the first storage unit 15 is despread by the first correlation detector 17, and the correlation value of the bit rate is output to the phase rotation unit 23. Similarly, the orthogonal component of the digital signal output from the first storage unit 15 is despread by the second correlation detector 18, and the correlation value of the bit rate is output to the first phase rotation unit 23.

The correlation value between the orthogonal component and the in-phase component is equal in magnitude to the amount of phase rotation of the received signal and based on the amount of phase rotation output from the first line state estimation unit 21 in the first phase rotation unit 23 and in the rotation direction. The bit is controlled so as to be reversed. The amplitude is amplified based on the amplification amount output from the first line state estimating section 21 in the first amplifying section, and then output to the adding section 27.

The analog signal received by the second antenna 12 is processed similarly to the analog signal received by the first antenna 11 and output to the adder 27. By adding each signal input to the adder 27, it is possible to synthesize a maximum ratio of the received signals.

By phase-compensating the signals received by the different antennas from the respective transmission paths and synthesizing them at the maximum ratio, the amount of variation in fading can be significantly reduced compared to the signal before synthesis, and the communication quality can be improved.

However, the conventional CDMA receiving apparatus must have a large number of correlators in a multipath environment or for diversity reception by a plurality of antennas, and the circuit size becomes large, and thus the device cannot be miniaturized and reduced in weight. Has

An object of the present invention is to provide a CDMA receiving apparatus and a CDMA communication method capable of reducing the number of correlators and miniaturizing and reducing the weight of the apparatus.

The present invention controls the amount of phase rotation of a signal received at each antenna to amplify the amplitude of the received signal. The above object is achieved by detecting correlation after outputting each signal and outputting a despread signal.

The above and other objects, features, aspects, advantages, and the like of the present invention will become more apparent from the following detailed embodiments described with reference to the accompanying drawings.

1 is a block diagram showing the configuration of a conventional CDMA receiving apparatus;

2 is a block diagram showing the configuration of a CDMA receiving apparatus according to the first embodiment;

3 is a block diagram showing the configuration of a CDMA receiving apparatus according to a second embodiment;

Fig. 4 is a block diagram showing the configuration during two code multiplexing of the CDMA receiving apparatus according to the second embodiment;

Fig. 5 is a block diagram showing the structure of a CDMA receiving apparatus combining the first embodiment and the second embodiment.

Explanation of symbols for the main parts of the drawings

103: first AD conversion unit 105: first storage unit

107: first line state estimation unit 109: first phase rotation unit

111: first amplifier 113: adder

114: correlation detector

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Example 1)

In the first embodiment, a case of correlation detection of signals received by different antennas simultaneously through respective paths will be described.

The configuration of the CDMA receiving apparatus according to the first embodiment will be described with reference to the block diagram of FIG. 2 shows the case of QPSK modulation with 2 antenna branches and 1 finger per branch of RAKE synthesis.

In the CDMA receiving apparatus shown in FIG. 2, the first antenna 101 and the second antenna 102 are transmitted from a communication counterpart and receive signals transmitted through respective transmission paths at the same timing. The first AD converter 103 and the second AD converter 104 convert analog signals received by the first antenna 101 and the second antenna 102 into digital signals, respectively. The first storage unit 105 and the second storage unit 106 temporarily store the digital signals converted by the first AD conversion unit 103 and the second AD conversion unit 104, respectively.

The first line state estimating unit 107 and the first line state estimating unit 108 estimate the line states of the signals output from the first storage unit 105 and the second storage unit 106. The first phase rotation unit 109 and the second phase rotation unit 110 control the phases of the signals output from the first storage unit 105 and the second storage unit 106 on a chip-by-chip basis according to the line state. The first amplifying unit 111 and the second amplifying unit 112 amplify the amplitudes of the signals output from the first phase rotating unit 109 and the second phase rotating unit 110 in accordance with the line state.

The adder 113 adds signals output from the first amplifier 111 and the second amplifier 112. The correlation detector 114 detects the correlation by the despreading process of multiplying the spread code by the signal output from the adder 113, and outputs the despread signal.

Next, the reception processing of the CDMA receiving apparatus according to the first embodiment will be described.

First, the in-phase component and orthogonal component of the analog signal received by the 1st antenna 101 are respectively converted into the digital signal by the 1st AD conversion part 103, and are memorize | stored in the 1st memory | storage part 105. FIG.

The digital signal output from the first storage unit 105 is estimated by the first line state estimating unit 107 based on the pilot signal multiplexed and the phase rotation amount and the reception level.

Further, the digital signal output from the first storage unit 105 is controlled for each chip such that the first phase rotation unit 109 has the same magnitude as the phase rotation amount of the received signal and the rotation direction is reversed, and the first amplifier unit ( The amplitude is amplified by 111 and output to the adder 113.

The analog signal received by the second antenna 102 is processed similarly to the analog signal received by the first antenna 101 and output to the adder 113.

Each signal input to the adder 113 is added and then despreaded by the correlation detector 114 to output a despread signal.

Next, the output signal of the CDMA receiving apparatus according to the first embodiment will be described in comparison with the conventional CDMA receiving apparatus.

For example, consider a code in which one symbol is four chips. A vector of the in-phase component and the quadrature component of the AD-converted signal received from the first antenna is a, b, c, and d in order from the first chip. Similarly, the vector of the in-phase component and the quadrature component of the signal received from the second antenna and AD converted is e, f, g, h in order from the first chip. Incidentally, the coefficients of the correlator are α, β, γ, δ in order from the first chip. In addition, the phase rotation amount and amplitude of the received signal of the first antenna are -p and m, respectively, and the phase rotation amount and amplitude of the received signal of the second antenna are -q and n, respectively.

In the conventional CDMA receiving apparatus, the correlation value s1 of the first antenna and the correlation value s2 of the second antenna are expressed by the following equation (1).

s1 = aα + bβ + cγ + dδ

s2 = hα + iβ + jγ + kδ

At this time, since it is necessary to obtain a correlation value for each of the orthogonal component and the in-phase component of the first antenna, and the orthogonal component and the in-phase component of the second antenna, a total of four correlation detectors are required. And if the rotation amount of angle (theta) is set to R ((theta)), RAKE synthesis value T becomes as following Formula (2).

T = (aα + bβ + cγ + dδ) mR (p)

+ (hα + iβ + jγ + kδ) nR (q)

Here, the CDMA receiving apparatus executes transmission power control based on the power value of the despread signal. The value required for this control is only the in-phase component of the RAKE synthesis value T.

Next, in the CDMA receiving apparatus according to the first embodiment, the received signals of the first antennas are sequentially amR (p), bmR (p), cmR (p), and dmR (p) from the first chip. The received signal of the second antenna is hnR (q), inR (q), jnR (q), and knR (q) in order from the first chip. Therefore, the addition values are sequentially in order from the first chip, amR (p) + hnR (q), bmR (p) + inR (q), cmR (p) + jnR (q), dmR (p) + knR ( q). Therefore, the correlation value s becomes as shown in Equation 3 shown below.

s = (amR (p) + hnR (q)) α + (bmR (p) + inR (q)) β

+ (cmR (p) + jnR (q)) γ + (dmR (p) + knR (q)) δ

s = (aα + bβ + cγ + dδ) mR (p)

+ (hα + iβ + jγ + kδ) nR (q)

As is apparent from the above equations (2) and (3), the correlation value s of the CDMA receiver in Embodiment 1 coincides with the RAKE synthesis value T.

In this way, by rotating the phases of signals received from different antennas, amplifying and adding amplitudes, and detecting the correlation, a correlation detection unit which is required for the RAKE synthesis in the past can be made as one, so that good communication can be achieved. The size and weight of the device can be reduced while maintaining the quality.

(Example 2)

In the second embodiment, a case of correlation detection of a signal received by the same antenna at different timings through respective paths will be described.

The configuration of the CDMA receiving apparatus according to the second embodiment will be described with reference to the block diagram of FIG. 3 shows a case where the number of antenna branches is 1, the number of fingers of RAKE synthesis is 2 per branch, and QPSK modulation.

In the CDMA receiving apparatus shown in FIG. 3, the antenna 201 is transmitted from a communication partner and receives signals transmitted through respective transmission paths at different timings. The AD converter 202 converts the analog signal received by the antenna 201 into a digital signal. The storage unit 203 temporarily stores the digital signal converted by the AD converter 202.

The line state estimating unit 204 estimates the line state of the signal output from the storage unit 203. The first delay unit 205 and the second delay unit 206 correct the delay amount of the signal output from the storage unit 203 according to the line state. The first phase rotation unit 207 and the second phase rotation unit 208 control the phases of the signals output from the first delay unit 205 and the second delay unit 206 on a chip-by-chip basis according to the line state. The first amplifying unit 209 and the second amplifying unit 210 amplify the amplitudes of the signals output from the first phase rotating unit 207 and the second phase rotating unit 208 according to the line state.

The adder 211 adds signals output from the first amplifier 209 and the second amplifier 210. The correlation detector 212 detects a correlation by a despreading process of multiplying a spread code by the signal output from the adder 211, and outputs a despread signal.

Next, the reception processing of the CDMA receiving apparatus according to the second embodiment will be described.

First, the in-phase component and orthogonal component of the analog signal received by the antenna 201 are converted into the digital signal by the AD converter 202 and then stored in the storage unit 203.

The digital signal output from the storage unit 203 estimates the phase rotation amount and the reception level based on the pilot signal multiplexed by the line state estimation unit 204.

In addition, the digital signal outputted from the storage unit 203 has a delay amount corrected in the first delay unit 205, and the first phase rotation unit 207 has the same magnitude as the phase rotation amount of the received signal and has a reverse rotation direction. The chip is controlled for each chip so that the amplitude is amplified by the first amplifier 209 and then output to the adder 211. Similarly, in the digital signal output from the storage unit 203, the delay amount is corrected in the second delay unit 206, and in the second phase rotation unit 208, the amount of phase rotation of the received signal is equal in magnitude and the rotation direction is reversed. The control unit is controlled so that the amplitude is amplified by the second amplifier 210 and then output to the adder 211.

Each signal input to the adder 211 is added and then despread by the correlation detector 212 to output the despread signal.

Next, the output signal of the CDMA receiving apparatus in Embodiment 2 will be described in comparison with the conventional CDMA receiving apparatus.

For example, consider a code in which one symbol is four chips. The time series of the vector which consists of an in-phase component and an orthogonal component of the signal received from the antenna and AD converted are a, b, c, d, e, and f in order. The first finger makes a the first chip of the symbol and the second finger makes c the first chip of the symbol. Incidentally, the coefficients of the correlator are α, β, γ, δ in order from the first chip. Further, the phase rotation amount and amplitude of the first finger are -p and m, respectively, and the phase rotation amount and amplitude of the second finger are -q and n, respectively.

In the conventional CDMA receiving apparatus, the correlation value s1 of the first finger and the correlation value s2 of the second finger are expressed by the following equation (4).

s1 = aα + bβ + cγ + dδ

s2 = cα + dβ + eγ + fδ

At this time, since it is necessary to obtain a correlation value for each of the orthogonal component and the in-phase component of the first finger and the orthogonal component and the in-phase component of the second finger, a total of four correlation detectors are required. And if the rotation amount of angle (theta) is set to R ((theta)), RAKE synthesis value T is represented by following formula (5).

T = (aα + bβ + cγ + dδ) mR (p)

+ (cα + dβ + eγ + fδ) nR (q)

Here, the CDMA receiving apparatus executes transmission power control based on the power value of the despread signal. The value required for this control is only the in-phase component of the RAKE synthesis value T.

Next, in the CDMA receiving apparatus according to the second embodiment, the received signal of the first finger is sequentially amR (p), bmR (p), cmR (p), and dmR (p) from the first chip. The received signal of the second finger is cnR (q), dnR (q), enR (q), fnR (q) in order from the first chip. Therefore, the addition values are sequentially amR (p) + cnR (q), bmR (p) + dnR (q), cmR (p) + enR (q), dmR (p) + fnR ( q). Therefore, the correlation value s is represented by the following formula (6).

s = (amR (p) + cnR (q)) α + (bmR (p) + dnR (q)) β

+ (cmR (p) + enR (q)) γ + (dmR (p) + fnR (q)) δ

s = (aα + bβ + cγ + dδ) mR (p)

+ (cα + dβ + eγ + fδ) nR (q)

Therefore, as apparent from the equations (5) and (6), the correlation value s of the CDMA receiving apparatus in Embodiment 2 coincides with the RAKE synthesis value T.

As described above, by detecting a correlation after correcting a delay amount of a signal received from an antenna at different timings, rotating a phase, amplifying an amplitude, and adding the amplitude, a correlation detection unit, which is conventionally required for a plurality of RAKE synthesis, is detected. Since it can be set to 1, the device can be miniaturized and reduced in weight while maintaining good communication quality.

In the case of multiplexing a plurality of signals, it is possible to cope by providing a correlation detector as many as the number of signals. Fig. 4 is a block diagram showing the configuration of two code multiplexing of the CDMA receiving apparatus according to the second embodiment.

In the CDMA receiver shown in Fig. 4, the first correlation detector 301 and the second correlation detector 302 correlate different signals by multiplying spread codes having orthogonality to each other. In addition, since the other structure in FIG. 4 is the same as that of FIG. 3, it attaches | subjects the same code | symbol as FIG. 3, and abbreviate | omits description.

Note that the present invention is not limited to the above-described embodiment, but the CDMA receiver may be configured by combining the first and second embodiments.

Fig. 5 shows a case where the number of antenna branches is 2 and the number of fingers of RAKE synthesis is 2 per branch, which is QPSK modulation, and is a configuration of a CDMA receiving apparatus combining the first and second embodiments.

As described above, according to the present invention, the distributed and received signals are subjected to delay control, phase rotation control, and amplitude control to be synthesized, and then subjected to correlation detection. A CDMA receiver and a CDMA communication method can be provided that realize weight reduction.

As mentioned above, although the invention made by this inventor was demonstrated concretely according to the said Example, this invention is not limited to the said Example and can be variously changed in the range which does not deviate from the summary.

The present invention is based on Japanese Patent Application No. 1998-139989, filed May 21, 1998, the entire contents of which are incorporated herein by reference.

Claims (9)

A plurality of phase rotation means for respectively controlling phase rotation of spread signals received from different antennas, Adding means for adding the spread signal whose phase is controlled; And a correlation detecting means for multiplying the added spread signal by a spread code to perform correlation detection. A plurality of delay means for respectively correcting delays of spread signals received at a plurality of different timings from the antenna; A plurality of phase rotation means for respectively controlling phase rotation of the spread signal output from these delay means; Adding means for adding the spread signal whose phase is controlled; And a correlation detecting means for multiplying the added spread signal by a spread code to perform correlation detection. The method of claim 2, And a plurality of antennas, each antenna receiving spread signals at a plurality of different timings. The method of claim 1, And the phase rotation means controls the phase rotation of the spread signal for each chip. A communication terminal apparatus comprising a CDMA receiving apparatus, The CDMA receiving apparatus, A plurality of phase rotation means for respectively controlling phase rotation of spread signals received from different antennas, Adding means for adding the spread signal whose phase is controlled; And correlation detecting means for multiplying the added spread signal by a spread code to perform correlation detection. A base station apparatus comprising a CDMA receiving apparatus, The CDMA receiving apparatus, A plurality of phase rotation means for respectively controlling phase rotation of spread signals received from different antennas, Adding means for adding the spread signal whose phase is controlled; And a correlation detecting means for multiplying the added spread signal by a spread code to perform correlation detection. And controlling the phase rotation of spread signals received from different antennas, and then adding these spread signals and multiplying spread codes to perform correlation detection. And correcting the delay of spread signals received at a plurality of different timings from an antenna, controlling phase rotation, and then adding these spread signals and multiplying spread codes to perform correlation detection. The method of claim 8, A CDMA communication method comprising a plurality of antennas, and receiving spread signals from a plurality of different timings from each antenna.