JPH10242935A - Processing gain variable cdma communication system and transceiver-receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and power consumption of the processing gain variable code division multiple access(CDMA) communication system for spread spectrum by reducing the number of diffusion code generators in a diffusion circuit on the transmitter side of the system and reducing the number of correlation detecting matched filters on the receiver side. SOLUTION: The transmitter side diffusion circuit 11 is constituted so as to include only one diffusion code generator 14 having the shortest period to execute multiplication n times at the symbol speed of n times and a receiving side reverse diffusion circuit 23 is constituted so as to include only one matched filter allowed to be correlated with a diffusion code of the shortest period to switchably output the output of the filter and a correlational added output obtained by adding the output of the filter to an output delayed from the output at the symbol speed of n times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a CDMA (Code D)
ivision Multiple Access: Code division multiple access) Digital radio communication system and its transceiver, in particular, variable processing gain type C for adaptively changing the processing gain of a spread spectrum code used for each burst according to the state of a propagation path
The present invention relates to a DMA communication system and a transceiver.

[0002]

2. Description of the Related Art For example, a processing gain variable type CD of a direct spread spectrum communication system using pseudo random noise (PN).
As an example of an adaptive modulation scheme for MA, "variable processing gain / coding rate using soft power control DS / CDM"
Characteristics of the A method ”Abeda et al., [IEICE Technical Report SST95-11]
(1995-05)], there is a CDMA system with a variable processing gain. FIG. 7 is an explanatory diagram of the method. The lower part of FIG. 7 shows a time transition of the reception power of the channel, and the upper part shows an example of a burst transmission signal in which the processing gain is changed according to the reception power at each time. The hatched portion is a portion used for transmission during one berth.

[0003] As shown in FIG.
The MA method considers that the strength of the received power corresponds to the degree of deterioration of the reception propagation path, and performs CDM according to the strength of the received power.
This is a method of switching and modulating the spreading code period (symbol speed) of A. That is, when the received power level is high, the deterioration in the propagation path can be regarded as small, so that a spreading code cycle (for example, 32 chips / symbol) with a small processing gain is used, and when the received power level is low, the deterioration in the propagation path is used. Is assumed to be large, and a spreading code cycle having a high processing gain (eg, 128
By using (chip / symbol), the deterioration of the error rate can be reduced.

[0004] Table 1 is a table showing an example of the relationship between the processing code and the spreading code period of the above-mentioned variable processing gain system.

[0005]

[Table 1]

In FIG. 7, when the received power level is higher than the set value A, 32 [chip / symbol] is used as the spread code cycle, and when the received power level is lower than the set value B, 128 [chip / symbol] is used as the spread code cycle. In the example shown above, 64 [chip / symbol] is selected as the spreading code period when A is equal to or less than B and is equal to or greater than B.

Here, if the chip rate and the amount of information to be transmitted in one burst are constant, the spreading bandwidth is constant, while the portion used for transmission during one burst according to the spreading code period (FIG. 7). The length (time) of the shaded area changes. That is, when the spreading code period is 128, all of one burst length is used for transmission, whereas when the spreading code period is 32, 1 is used.
Transmission is completed in 1/4 of the burst time, and nothing is transmitted after the transmission is completed, thereby generating an empty slot portion. Therefore, this method has an advantage that, on average, it is possible to increase the channel capacity that can be used in the cell where the communication terminal exists (an area having an interference relationship with each other).

FIG. 8 is a block diagram of a conventional transceiver with a variable processing gain CDMA communication system. The variable processing gain CDMA communication system of the above-mentioned reference is described as an MS (mobile station) BS.
(Base station) This is a configuration example applied to an uplink for transmitting data from MS 30 to BS 40 in bidirectional communication. In the figure, frequency f ₁ is used for the uplink (from MS to BS),
Shows the case of performing mutual communication using the frequency f ₂ in downlink (MS from BS).

The BS 40 receives the signal transmitted by the MS 30 at the frequency f ₁ by the antenna 21 after being deteriorated by the propagation path, and down-converts the signal by the RF unit 22 to obtain a reception spread signal. This received spread signal is input to the despreading circuit 41 and also to the channel quality estimating circuit 28. The channel quality estimating circuit 28 detects the amount of deterioration in the propagation path of the signal received from the MS 30. As a measure of the deterioration amount, there is C / I (desired signal-to-interference power ratio) in addition to the reception power.

[0010] The channel quality estimating circuit 28 determines the spreading code period of the next burst from the detected deterioration amount, and outputs it to the MS modulation information setting unit 29 and the despreading circuit 41 as spreading code period information. The despreading circuit 41 selects a despreading code to be used for a received spread signal received in the next burst using the given spreading code period information, and outputs a despread received correlation signal to the demodulator 24, The demodulator 24 demodulates the data,
Data communication is realized by outputting S demodulated data.

On the other hand, the MS modulation information setting device 29
0 is converted to binary data as spreading code cycle information, using a spreading code cycle used when transmitting in the next burst;
Output to the modulator 25 as a modulation parameter. Modulator 2
Reference numeral 5 incorporates this modulation parameter and BS transmission data in one burst, performs primary modulation, and outputs the result to the multiplier 26 as a transmission baseband signal. The modulator 26 performs secondary modulation by multiplying the transmission baseband signal by a fixed period spreading code output from the spreading code generator 27 to generate a transmission spread signal. The RF unit 22 up-converts the transmission spread signal and transmits the signal from the antenna 21.

The MS 30 receives the downlink signal of the frequency f ₂ from the antenna 16 and down-converts the RF signal by the RF unit 15 to obtain a received spread signal. This received spread signal is transmitted to BS4
0 is input to a despreading circuit 17 for despreading with a code having the same pattern as the spreading code generated by the spreading code generator 27,
The received correlation signal after despreading is used as a modulation parameter detection circuit 18
And output to the demodulator 19. The demodulator 19 demodulates data from the received correlation signal and outputs MS demodulated data to realize data communication.

On the other hand, the modulation parameter detection circuit 18 detects a modulation parameter incorporated in a part of the BS transmission burst from the received correlation signal for each burst, and extracts a spreading code period to be selected for spreading the next burst. Then, the signal is output to the spreading code generator 34 and the adaptive modulator 32 of the processing gain variable spreading circuit 31. The adaptive modulation unit 32 determines a corresponding one symbol width from the spreading code period input from the modulation parameter detection circuit 18, performs primary modulation for one burst according to the MS transmission data, and multiplies the transmission baseband signal by the multiplier 33. Output to The multiplier 33 generates a spread signal by multiplying (secondarily modulating) the output of the spread code generator 34 that outputs a spread code having a cycle designated by the modulation parameter detection circuit 18 and the transmission baseband signal. I do.
RF section 15 up-converts the spread signal and outputs the result from antenna 16.

FIG. 9 is a block diagram showing the details of a part of the transmission / reception circuit of FIG. 8. FIG. 9A shows an example of the configuration of the processing gain variable spreading circuit 31 on the transmission side of the MS 30, and FIG.
5 shows a configuration example of a despreading circuit 41 on the receiving side of 0.

In FIG. 9A, reference numeral 35 in the adaptive modulation section 32 denotes a modulator, and 36 denotes a symbol rate switch. Reference numerals 37, 38, and 39 in the spread code generator 34 denote spread code generators that generate spread codes having periods 32, 64, and 128. Reference numeral 47 denotes a spread code switch for switching the cycle of the spread code. The spread code cycle switching signal output from the modulation parameter detection circuit 18 is input to the symbol rate switch 36 and the spread code switch 47, and three types of symbol rates (32 chips / symbol, (64 chips / symbol, 128 chips / symbol), and one of three spreading code generators 37, 38 and 39 for generating spreading codes at three periods. Modulator 35
Performs primary modulation according to the selected symbol rate and outputs a transmission baseband signal. Multiplier 33 multiplies the spreading code from the spreading code generator of the selected period by the transmission baseband signal (secondarily modulates) and outputs the multiplied code, thereby changing the transmission spread signal with the processing gain changed. RF unit 1
5 is output.

FIG. 9B is a diagram showing a configuration example of a variable processing gain type despreading circuit 41 of the BS 40. In the figure, 42,
43 and 44 are matched filters, and 45 and 46 are switching devices. Since the received signal from the transmitting side mobile station (MS) uses any one of a plurality of types of spreading code periods, the number of matched despreading filters (hereinafter, referred to as the number of types) corresponding to the type of spreading code to be demodulated. MF).
In the example of the figure, for each of the three types of spreading codes, the MF 42 for the spreading code cycle 32 (32 chips / symbol), the MF 43 for the spreading code cycle 64 (64 chips / symbol), and the spreading code cycle 128 (128 chips / symbol) MF 44 is provided, and switches 45 and 46 are simultaneously switched by a spreading code cycle switching signal provided from the channel quality estimating circuit 28. The received spread signal input from the RF unit 22 is despread by the spreading code of the corresponding MF to obtain a reception correlation output.
Output to

FIG. 10 shows a correlation output waveform from the MF corresponding to three types of spreading codes. The horizontal axis indicates time. Upper row is 32
The correlation output of chip / symbol is shown, and the middle and lower rows show the correlation output of 64 chips / symbol and 128 chips / symbol, respectively. Since the correlation output signal of the MF has a sharp correlation peak when the spreading code used on the transmission side and the spreading code set in the MF coincide with each other, a sharp peak appears at a symbol switching portion. . The other signal components are uncorrelated and become white noise. If there is a delayed wave, the peak can be detected with a delay corresponding to the delay time. Therefore, if the delay amount is within one symbol section, the leading wave and the delayed wave can be separated, and the phases of the two waves are adjusted. In-phase synthesis with phase correction (RAKE technology)
As a result, a path diversity effect can be obtained, which can contribute to an improvement in the error rate. As the spreading code period becomes longer, the symbol length becomes longer, and as a result, the correlation peak becomes higher, so that the error rate is improved.

The conventional circuit configuration example shown in FIG. 8 uses the variable processing gain type CDMA system of the above-mentioned reference for MS transmission and BS transmission.
Although this example is applied to the reception uplink only, in the case of an actual device, it can also be applied to the BS transmission and MS reception downlink.

[0019]

However, in the conventional CDMA system with variable processing gain, the spreading circuit 31 on the transmitting side is used.
In addition to the drawback that a plurality of spread code generators are required, the demodulation circuit on the receiving side has a drawback that the number of MFs corresponding to the type of the spread code cycle is required. The MF is one of the basic components for realizing a CDMA communication device, and at the same time, one of the circuits having the largest circuit scale and the largest power consumption. For this reason, an increase in MF is disadvantageous for downsizing and reducing power consumption of a mobile phone.

The present invention relates to the above-mentioned conventional processing variable gain type CD.
It is an object of the present invention to provide a variable gain CDMA communication system and a transceiver which solve the problems of the type and number of spreading code generators corresponding to the period of the spreading code generated in the MA communication system and the above-mentioned problems due to the type and number of MF. Aim.

[0021]

According to a first aspect of the present invention, there is provided a CDMA communication system having a variable processing gain according to the present invention, wherein a processing gain of a spread spectrum code used by a transmitting side for each burst is obtained by obtaining a processing gain of a receiving side from a receiving side. In a variable-gain CDMA communication system that adaptively changes according to the following equation, a predetermined symbol rate is used as a basic symbol rate, and m is composed of the basic symbol rate and a symbol rate having a symbol length n times (n is an integer). (M is an integer) symbol rate groups are set, and the transmitting side is provided with means for generating a shortest period code having a spreading code length equal to the symbol length of the basic symbol rate, and a spreading code obtained from the receiving side is provided. A transmission baseband signal obtained by primary-modulating transmission data at a specified symbol rate n times of the symbol rate group switched by the cycle switching signal. And a transmission spread signal is created and transmitted by repeatedly multiplying the shortest-period spreading code n times so as to have a period corresponding to the designated symbol rate, and the receiving side corresponds to the shortest-period spreading code. A matched filter for correlating with the shortest-period spreading code pattern, a delay element for taking an n-times correlation thereof stepwise, an adder circuit, and a switch for selecting a correlation output thereof, A demodulated data is obtained by demodulating the received correlation output obtained by inputting the received spread signal from the side to the despreading means, and estimating and detecting the channel quality of the propagation path from the received spread signal and according to the situation. A spreading code cycle is transmitted to the transmitting side together with transmission data as the spreading code cycle switching signal.

According to a second aspect of the present invention, the variable gain CDMA transceiver according to the present invention allows the transmitting side to adaptively adjust the processing gain of the spread spectrum code used for each burst in accordance with the condition of the propagation path obtained from the receiving side. The receiving side estimates the state of the propagation path from the received spreading signal, specifies the spreading period to the transmitting side, and correlates with the spreading code pattern of the received spreading signal to input the inverse to the demodulator. In a variable processing gain type CDMA transceiver having a spreading circuit, a predetermined symbol rate is used as a basic symbol rate, and m (m) symbols each including the basic symbol rate and a symbol rate having a symbol length of n times (n is an integer). ) Is set, and the spreading circuit on the transmission side has a shortest cycle code having a spreading code length equal to the symbol length of the basic symbol rate. A generated spread code generator, a symbol rate switch that switches and outputs a specified n times the symbol rate of the symbol rate group by a spread code cycle switch signal obtained from the receiving side, and a symbol rate switch. A modulator for linearly modulating transmission data at an output to output a transmission baseband signal, and a shortest period code output from the spreading code generator so as to have a period corresponding to the transmission baseband signal and a designated symbol rate. And a multiplier for repeatedly multiplying by n times and outputting a transmission spread signal, wherein the despreading circuit on the receiving side is a matched filter that correlates with a shortest cycle spreading code pattern corresponding to the shortest cycle code, A delay element for providing a delay corresponding to the symbol length of each of the m symbol rate groups for stepwise correlating an n-times correlation thereof; And an adder circuit for adding the output of the pseudo filter and the output of the delay element to obtain a correlation addition output, and a number of correlation addition outputs corresponding to the m symbol rate groups corresponding to the state of the propagation path obtained from the received spread signal. And a switching unit for selecting the spread code cycle switching signal.

[0023]

FIG. 1 is a block diagram showing a first embodiment of the present invention. In the figure, different points from the conventional one are a spreading circuit 11 and a despreading circuit 23, each having one generator and one MF. FIG. 2 is a partial block diagram showing the details, FIG. 2A is a configuration example of the spreading code cycle switching type spreading circuit 11, and FIG. 2B is a configuration example of the despreading circuit 23. .

In FIG. 2A, the adaptive modulation section 12 which inputs a spread code cycle switching signal to a symbol rate switch 36 and selects three types of symbol rates in accordance with the selected spread code cycle is a conventional technique. The configuration is the same as that of the adaptive modulation unit 32. The difference from the prior art is that in the prior art, the spreading code generators are provided by the number of the spreading code periods, whereas in the present invention, the spreading code having the shortest period (32 chips / symbol, the shortest period code). Is that only one generator 14 is used. When the period is long (64 and 128 chips / symbol), the shortest period code output from the generator 14 is repeated a plurality of times (two and four times) and used for spreading. In the transmission section of one burst (when the number of transmission symbols is fixed), an empty slot section is generated according to the transmission symbol rate and the advantage that the channel capacity can be increased remains the same as described in the conventional method. .

In the spreading code cycle switching type despreading circuit 23 shown in FIG. 2B, all the received spread signals from the RF unit 22 are input to the MF42 of 32 chips / symbol which uses the shortest cycle code for despreading. . Spreading code period 32 (32
(chip / symbol),
The correlation output (32 chips) of the MF 42 is output to the switch 46 and becomes the reception correlation output.

Spreading code period 64 (32 chips × 2 = 64 ch)
When a signal spread by (ip / symbol) is received, the output obtained by delaying the output of the MF 42 by 32 chips by the delay element 51 and the output of the MF 42 are input to the addition circuit 52 and added, so that the shortest period code is obtained. Are accumulated for two cycles to obtain a correlation output of (64 chips).

Spreading code period 128 (32 chips × 4 = 12
When a signal spread by 8 chips / symbol is received, the output of the adder circuit 52 and the output of the adder circuit 52 delayed by 64 chips by the delay element 53 are added to the adder circuit 5.
By inputting to 4 and adding, a correlation peak of (128 chips) in which the shortest cycle codes are accumulated for 4 cycles is obtained.

These three types of correlation outputs [32 chips, 64 chi
p, 128 chips] to the switch 46 and, based on the spread code cycle switching signal from the channel quality estimating circuit 28, selectively outputs the correlation output having the same spread code cycle as the cycle used for spreading on the transmission side. This output is provided to a demodulator 24 to demodulate.

FIG. 3A, FIG. 3B and FIG.
These three types of correlation signals [32 chip, 64 chip, 128 chi
[p] shows a correlation detection circuit and an example of its output waveform. Figures 3 and 4
The circuit example of FIG. 2 shows a portion related to the circuit configuration of FIG. Hereinafter, FIGS. 3A and 3B and FIG. 4C will be described.

FIG. 3 (A) In the case of 32 chips, the transmission output (M
F [32 chip] output) is a signal having a sharp correlation peak every 32 chips, irrespective of the selected spreading code period. Here, when a spread code cycle of 32 (32 chips / symbol) is selected and a spread signal is received, one symbol 32 ch
MS transmission data can be demodulated by demodulating data for each ip.

In the case of 64 chips shown in FIG. 3B, when a signal spread at a spreading code cycle of 64 (32 chips × 2 = 64 chips / symbol) is received, the output of the adder circuit 52 outputs two cycles of the shortest cycle code. Accumulated (64 chips) correlation peaks can be obtained. Here, since the spread code cycle uses the cycle of the shortest cycle code, a correlation peak appears every 32 chips, but a correlation value (inter-symbol interference in the figure) appearing at a position shifted by 1/2 symbol is an interference between preceding and succeeding symbols. And does not contribute to demodulation. The first half 32 chip portion (hatched portion) is used for demodulation.
By performing AKE combining, a processing gain for 64 chips is obtained, and demodulation can be performed with the same error rate characteristics as in the related art.

In the case of 128 chips in FIG. 4C, the same processing can be performed when a signal spread at a spreading code period of 128 (32 chips × 4 = 128 chips / symbol) is received. The output of the adder circuit 54 can obtain a correlation peak of (128 chips) in which four cycles of the shortest cycle code are accumulated. Again, the spread code cycle uses the cycle of the shortest cycle code, so there is inter-symbol interference as in the example of 64 chips, and a correlation peak appears every 32 chips. (Shaded area) only, and RAKE synthesis of that
A processing gain for 28 chips can be obtained.

As described above, if the despreading circuit 23 of the present invention is used, the correlation output is selectively switched and output in accordance with the spreading code period set on the transmitting side, and is demodulated. Regardless of the type, a CDMA receiver with a variable processing gain can be realized using only a single MF with a shortest cycle and a small circuit scale. Also, in the processing gain variable spreading circuit 11 on the transmission side, the spreading code generator may be one of the shortest cycle code generators, so that there is an effect of reducing the circuit scale.

Further, although the present invention has been described with respect to the case where the present invention is applied to data communication from the MS to the BS (downlink), it is apparent that the present invention can also be applied to data communication from the BS to the MS (uplink). FIGS. 5 and 6 are block diagrams showing a second embodiment of the present invention applied to both uplink and downlink lines. In the second embodiment, the transmitting side spreading circuit 61 and the receiving side despreading circuit 62 of both the MS 60 and the BS 70 have the same configuration, and the modulation information setting units 63 and 64 mutually transmit the modulation information of the communication partner. It is configured to send by setting.

FIG. 11 is a time chart showing the relationship between the spreading code and the symbol rate, wherein (A) is a conventional time chart and (B) is a time chart of the present invention. A,
B and C indicate three types of spreading codes, 32, 64, and 128, respectively.
chip / symbol. Conventionally, spreading code lengths A, B, C
Also changes the symbol length. In the present invention, the same spreading code A is used regardless of the symbol length. Accordingly, there is an effect that the same operation as that of the related art can be performed with only one type (one) of the generator and the MF.

[0036]

As described above in detail, the effects of reducing the circuit scale and reducing the power consumption by implementing the present invention are great.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a main part of the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of the reception correlation output of FIG. 2 (B) of the present invention.

FIG. 4 is an explanatory diagram of the reception correlation output of FIG. 2 (B) of the present invention.

FIG. 5 is a block diagram on the MS side according to a second embodiment of the present invention.

FIG. 6 is a block diagram on the BS side according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of a variable processing gain CDMA communication system.

FIG. 8 is a diagram illustrating a configuration example of a conventional CDMA transceiver with variable processing gain.

FIG. 9 is a partial configuration example of a conventional variable processing gain type CDMA transceiver.

FIG. 10 is an explanatory diagram of a reception correlation output example of a conventional variable processing gain CDMA system.

FIG. 11 is a time chart showing a relationship between a spreading code and a symbol rate.

[Explanation of symbols]

 10, 30 Mobile station (MS) 11, 31 Variable processing gain type spreading circuit 12, 32 Adaptive modulation section 13, 33, 26 Multiplier 14, 37, 38, 39 Spreading code generator 15, 22 RF section 16, 21 Antenna 17 Despreading circuit (fixed processing gain) 18 Modulation parameter detection circuit 19, 24 Demodulator 20, 40 Base station (BS) 23, 41 Despreading circuit (variable processing gain) 25, 35 Modulator 27 Spreading code generator (Processing) Gain fixed) 28 line quality estimation circuit 29 MS modulation information setting circuit 34 spreading code generator 36 symbol rate switch 42, 43, 44 MF 45, 46 MF switch 47 spreading code switch 51 delay element (32 chip) 52, 54 Addition circuit 53 Delay element (64 chip) 60 Mobile station 61 Spreading circuit 62 Despreading circuit 63 BS modulation information setting unit 64 MS modulation information Setter 70 base station

Claims (2)

[Claims] 1. A variable processing gain type CD for adaptively changing a processing gain of a spread spectrum code used by a transmitting side for each burst in accordance with a condition of a propagation path obtained from a receiving side.
In the MA communication system, a predetermined symbol rate is set as a basic symbol rate, and m (m is an integer) symbol rate groups are set which include the basic symbol rate and a symbol rate having a symbol length of n times (n is an integer). Wherein the transmitting side is provided with means for generating a shortest cycle code having a spreading code length equal to the symbol length of the basic symbol rate, and among the symbol rate groups switched by a spreading code cycle switching signal obtained from the receiving side, The transmission spreading is performed by repeatedly multiplying the transmission baseband signal obtained by primary-modulating the transmission data at a specified symbol rate n times with the shortest-period spreading code n times so as to have a period corresponding to the specified symbol rate. A signal is generated and transmitted, and the receiving side correlates with a shortest cycle spreading code pattern corresponding to the shortest cycle spreading code. A de-spreading means comprising a matched filter, a delay element for taking an n-fold correlation thereof in a stepwise manner, an adder circuit and a switch for selecting a correlation output thereof, wherein the de-spreading means receives a spread signal received from the transmitting side; The demodulated data is obtained by demodulating the received correlation output obtained by inputting the received spread signal, and the spread code cycle according to the situation is estimated and detected by estimating the channel quality of the propagation path from the received spread signal as the spread code cycle switching signal. A variable processing gain type CDMA communication system, wherein the CDMA communication system is transmitted together with transmission data to the transmission side. 2. The transmitting side includes a spreading circuit that adaptively changes a processing gain of a spread spectrum code used for each burst in accordance with a state of a propagation path obtained from the receiving side. A variable processing gain type CDMA transceiver equipped with a despreading circuit for estimating the state of a channel and designating a spreading period to a transmitting side and correlating with a spreading code pattern of a received spread signal and inputting it to a demodulator. And a symbol rate group having a symbol length having a symbol length n times (n is an integer) the basic symbol rate and a symbol length having a symbol length of n times (n is an integer) is set as the basic symbol rate. A spreading code generator for generating a shortest period code having a spreading code length equal to the symbol length of the basic symbol rate, and a spreading code period obtained from a receiving side; And a symbol rate switch for switching and outputting a specified n-times symbol rate of the symbol rate group by a switching signal, and a modulation for primary-modulating transmission data with an output of the symbol rate switch and outputting a transmission baseband signal. And a multiplier for repeatedly multiplying the shortest period code output from the spreading code generator n times by n times so as to have a period corresponding to the transmission baseband signal and a designated symbol rate to output a transmission spreading signal. The despreading circuit on the receiving side is a matched filter that correlates with a shortest-period spreading code pattern corresponding to the shortest-period code, and the m filters for stepwise obtaining an n-times correlation thereof. And a delay element for providing a delay corresponding to each symbol length of each symbol rate group of the symbol rate group, an output of the matched filter and an output of the delay element, and a correlation addition output is performed. And a switch for selecting a correlation addition output of a number corresponding to the m symbol rate groups by a spreading code cycle switching signal corresponding to a state of a propagation path obtained from a received spread signal. Variable processing gain type CDMA characterized by the following:
Transceiver.