JPH07303092A - Receiver - Google Patents

Abstract

PURPOSE:To provide an accurate demodulated signal from a CDMA(code division multiple access) received signal. CONSTITUTION:When a base band signal (r) is received, at an interference removing part 4, first-stage estimate signals for M pieces of stations provided while removing an inter-station interference amount at an interference removing means 41-1. Next, the inter-station interference amount is removed from the first-stage estimate signals by an interference removing means 41-2 and estimate signals further for M pieces of stations are provided. Thus, final estimate signals (symbol estimated values) t-1 to t-M for M pieces of stations are outputted by an interference removing means 41-K on a K-th stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver, and can be applied to, for example, a base station reception system and a mobile station reception system by code division multiple access.

[0002]

2. Description of the Related Art In recent years, as one of techniques for improving frequency utilization efficiency in mobile communication, CDMA (Code Division Multiple Access: Code Division Multiple)
Research and development on the triple access method are actively conducted. In this CDMA, the interference signals from other transmitting stations other than the desired wave, which are multiplexed in the spreading / despreading process, are treated in the same manner as thermal noise, so that the number of transmitting stations proportional to the process gain is the same. It is possible to use frequency bands at the same time.

In this CDMA system, for example,
In direct sequence (DS), transmitting stations such as users who use the same frequency are separated by pseudo-orthogonal codes, but it is difficult to completely separate them, and it is desirable to select them according to the correlation between the codes. An interference wave from a transmission station other than the wave is superimposed on the desired wave. An important issue is how to remove this interference wave to obtain the desired wave.

For example, in the transmitting device of each transmitting station, a spread code is applied to the transmission data to spread the spectrum, convert it into a high frequency signal and transmit it from the antenna. On the other hand, in the receiving device of the receiving station, the high frequency signal captured by the receiving antenna is converted into a baseband signal, multiplied by a spreading code (or despreading code) synchronized with the desired transmitting station, and one symbol is added. A demodulated signal is obtained.

As described above, in addition to the desired wave signal from the target transmitting station, the interference signal of the interference wave from another transmitting station is superimposed on the demodulated signal. Furthermore, it is considered that this interference signal has a smaller level than the desired desired signal.

[0006]

However, in a communication network system based on an actual CDMA system, it is considered that a plurality of (at least several stations) transmitting stations may perform transmission at the same time. In such a communication environment, when each transmitting station asynchronously uses a non-orthogonal code such as a pseudo-random code as a spreading code, a transmission signal transmitted by a certain transmitting station is transmitted to other than the receiving station of the communication partner. On the other hand, it is received as an interference wave and added to the received data.

As a result, the greater the number of transmitting stations forming the CDMA communication network system, the greater the influence on the received data due to the above-mentioned interference wave, and the level of the interference wave is increased to some extent to the received data. In that case, the error rate of the received data is increased, and the deterioration of the data quality cannot be ignored.

[0008] Due to such a problem, it is not easy to increase the number of access stations of the transmitting stations which compose the communication network system in CDMA.

However, compared to TDMA and FDMA, CDMA has confidentiality, so privacy can be maintained in a telephone call. Furthermore, since it is less susceptible to the effects of multipath, it is possible to perform stable reception with less fading. Therefore, a mechanism for solving the above-mentioned problem while applying CDMA, that is, interference caused by intersymbol interference. There has been a demand for a receiver that improves the wave rejection performance and can accurately estimate and output signals from a plurality of stations. Further, it has been demanded to realize a base station system and a mobile station system with a receiving device that has achieved such a request, in order to improve the performance of a CDMA communication system.

[0010]

Therefore, the receiving apparatus of the present invention comprises receiving means for receiving signals for code division multiple access from a plurality of transmitting stations. Further, each despreading code corresponding to each spreading code assigned to each transmitting station is used to estimate a signal from each transmitting station from the received signal, and interference between the spreading codes is also provided. Alternatively, the inter-station interference amount caused by the interference between the despreading codes is estimated, and the signal from each transmitting station is estimated (for example, symbol estimation) while removing the inter-station interference amount from the received signal. The above problem is solved by providing station signal estimating means for outputting each estimated signal (for example, each symbol estimated value).

Further, the receiving apparatus having such a configuration is applied to, for example, a base station receiving system or a mobile station receiving system.

[0012]

In general, when a pseudo random code such as a PN code is used as a spreading code or a despreading code, there is inter-code interference, and when they are received, they interfere with each other and a received signal from each station by correlation processing or the like. , The error rate is large. Therefore, in the present invention, each time an estimated signal of a certain station is obtained, for example, the amount of inter-station interference given to the received signal of the other station by that station is estimated.

Further, by removing this inter-station interference amount from the received signal and estimating the signal from another station from the received signal after this removal by, for example, correlation processing, the effect of inter-station interference It is possible to obtain a probable signal (for example, a symbol signal) in the absence of the signal.

Further, by repeating the removal of the inter-station interference amount as described above, the influence of the inter-station interference is greatly reduced, and it becomes very erroneous to estimate the signal from each transmitting station in such a state. A demodulated signal with a low rate can be obtained.

By applying such a receiving apparatus to a base station receiving system or a mobile station receiving system, it is possible to improve the receiving performance of the system and contribute to increasing the number of base stations or mobile stations. Of.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described with reference to the drawings. Therefore, the outline of this embodiment will be first described. The transmission signal of the transmission station i in the baseband in the spread spectrum communication can be generally expressed by the following equation (1).

R _i (n) = d _i · PN _i (1) Here, r _i (n) is the transmission data actually transmitted by the i transmission station at time n, and d _i is the value of the symbol data to be transmitted. And this value is actually represented, for example, by +1 or -1. The time of the symbol length of the symbol data does not change. PN _i is a spreading code string used by the transmitting station i, and PN _i (n) is spreading data for spreading the transmission data at time n.

Also, the received signal r (n) in the baseband
Can be regarded as the sum of the transmission signals of all transmitting stations and M stations, and can be expressed by the following equation (2).

R (n) = Σr _i (n) i = 1 to M (2) When the signal of the transmitting station i is detected by correlation detection, the received signal r and the spreading code PN _i of the transmitting station i are detected. It is possible to demodulate by performing the correlation calculation in the interval of 1 symbol.
Correlation detection output (symbol correlation value) R _{i of} one symbol
Can be represented by the following equation (3).

R _i = 1 / G · Σ {PN _i (n) · Σr _j (n)} = d _i + 1 / G · Σ [PN _i (n) · Σ {d _j PN _j (n)}] n = 1 to G, j = 1 to M, and i ≠ j (3) In this equation (3), G is a spreading length (symbol section length).
I am trying. The first term on the right side of the equation (3) is the transmission data of the transmitting station i, and the second term on the right side is the interference signal for M-1 stations other than the transmitting station i.

When the spreading codes are orthogonal to each other, the correlation detection output becomes equal to the transmission data d _i , but when a non-orthogonal spreading code is used, there must be an interference signal corresponding to the correlation between the spreading codes. Therefore, the bit error rate of the demodulated data increases. Furthermore, when the transmitting stations are asynchronous, it is not easy to directly calculate the second term on the right side of the above equation (3).

Therefore, before the symbol estimation value of a certain transmitting station i is obtained, an interference wave signal given to another station by the transmitting station, that is, the signal d _j · PN of the second term on the right side of the equation (3).
_It estimates _j (n) and removes it from the received signal used by other stations for demodulation. In particular, the transmission signal from each transmitting station is estimated while repeating such an interference removing operation, and the interference amount of the second term on the right side of Expression (3) is reduced to obtain a demodulated signal with a low error rate.

Therefore, in this embodiment, each time the symbol delimiter is detected by the control means (before the input of one symbol is completed), the symbol estimation value calculation means of the station and the transmission station i sends the symbol delimiter. For each incoming symbol, its input signal (received signal) r (n) and spreading code PN
The correlation with _i (n) is calculated and the symbol estimate is estimated.

Further, in the interference amount calculating means, the product with the spreading code PN _i (n) is taken and re-spreading,
The interference amount estimated value of the symbol section is estimated. In the removing means, the interference amount estimation value of the transmitting station i is removed from the input signal. The input signal in that symbol section has interference removed according to the symbol estimation value of the previous station, and the removal by the authority further removes the interference amount estimation data of the authority from the signal.

This processing operation is repeated for all stations, and this is set as one step, and this one step is repeated for several steps.

After the interference removal in a certain symbol section is performed at the i-th station in the k-th stage, the interference is removed once in all stations other than the i-station until the interference removal is performed in the i-th station at the k + 1-th stage. ,
Using the result, the interference removing operation is performed in the i-th station at the (k + 1) th stage. Since such a relationship is the same for all stations, by constructing in multiple stages, interference based on the symbol estimation value of each station will be removed one after another from the baseband signal obtained by reception.

The interference elimination processing operation by such a series of means is independently performed for each station and stage where the data has reached the symbol delimiter by the control means. If there is an error in the symbol estimation, interference signals from other stations will remain, but by constructing in multiple stages, the effects of interference will be gradually removed, and based on the removed signals, Further, the symbol is estimated to estimate the latest amount of interference, and the interference is accurately removed every step.

Such accurate interference removal makes it possible to obtain a demodulated signal with a low error rate. According to the present invention, the above-described series of means performs interference removal processing of interference signals from a plurality of stations on a plurality of symbols, thereby performing demodulation with a small estimation error.

[First Embodiment]: (Structure of Receiving Device): FIG. 1 shows the CDMA of the first embodiment.
FIG. 3 is a functional configuration diagram of a reception device for a mobile phone. The receiving device mainly includes an antenna unit 1, a wireless device 2, a control unit 3, and an interference removing unit 4.
And a code determination unit 6.

The high frequency signal captured by the antenna section 1 is frequency-converted by the receiving circuit of the radio device 2, converted into a baseband signal r, output, and given to the interference removing section 4. In the receiving device, the characteristic configuration is mainly that of the interference removing unit 4,
The control unit 3 controls this. Further, the interference removing unit 4
Is composed of k interference cancellation stages 41-1 to 41-k, and is a signal after interference cancellation from an interference reception signal from each station,
That is, the symbol estimation values t-1 to t-M for M stations are output.

Symbol estimation values t-1 to t-M for M stations
Are then given to the code determination unit 6, respectively. The code determination unit 6 performs, for example, a Viterbi decoding process on the output signals t-1 to t-M of the interference removal unit 4 to perform code determination, and then performs a code (for example, logical 1 or 0). ) Is identified and the reproduction output W1-
To get the WM.

The specific structure of the above-mentioned radio 2 will be described later with reference to FIG. The specific configuration of the interference removing unit 4 will be described later with reference to FIGS. Further, a specific configuration of the code determination unit 6 will be described later with reference to FIGS. 8 and 9.

In the following description, X- (i, j)
The description format of (1) represents the X part of the i station at the jth stage.

(Specific Structure of Interference Removal Unit 4): FIG.
(No. 1) and FIG. 3 (No. 2) are specific functional configuration diagrams of the interference removing unit 4. The interference removing unit 4 is specifically composed of interference removing stages 41-1 to 41-K. Each of the interference canceling stages 41-1 to 41-K includes a station interference canceling unit 31-
(1, 1) to 31- (M, 1) to 31- (1, K) to
31- (M, K).

(Specific configuration of station interference canceller 31):
FIG. 4 is a specific functional configuration diagram of the station interference removing unit 31.
Specifically, the station interference canceller 31 mainly includes a channel signal estimator 21 and an interference canceller 22. In addition, the channel signal estimation unit 21 includes a symbol estimation unit 11
And an interference amount calculation unit 12. Furthermore, the symbol estimator 11 is, more specifically, the correlation calculator 10
And a spread code generator 111 and an adder 13. The interference amount calculation unit 12 is, specifically, the multiplier 12
It is composed of two. Further, the interference removing circuit 22 is specifically configured by an adder 221.

(Specific Configuration of Correlation Calculation Unit 10): FIG. 5 is a specific functional configuration diagram of the correlation calculation unit 10. The correlation calculation unit 10 is specifically composed of a multiplier 112, a cumulative adder (ACC) 113, and a normalization circuit 114.

(Operation of the interference removing unit 4): ((Operation of the first station of the first interference removing stage 41-1)):
Next, a specific operation of the interference removing unit 4 will be described. Therefore, first, d, which is the baseband signal r from the wireless device 2,
I- (1, 1) is a channel signal estimating unit 21- (1, 1) of the first station interference canceling unit 31- (1, 1) of the first stage 41-1 of the interference removing stage, and a symbol estimating unit of (1, 1). 11- (1,1). Then, when the input data reaches the symbol delimiter, that is, when the input of one symbol is completed, the symbol estimation unit 11- (1,1) outputs the input data dI- (1,1) as The symbol is estimated by calculating the correlation with the spread code of the first station. Specifically, this correlation is performed by sum of products and normalization.

Each chip of the symbols spread to the G chips is generated by the spread code generating unit 111- (1,1) and is multiplied by the spread code by the multiplier 112- (1,1). That is, the a-th chip of the input symbol is multiplied by the a-th spreading code of the spreading code corresponding to the symbol. This multiplication result is added to the accumulator (ACC) 113-
Give to (1, 1). ACC113- (1,1) is 1
The sum of G products of symbols is calculated. This ACC11
3- (1, 1) is cleared for each symbol. This total sum is calculated in the normalization circuit 114- (1, 1) by the diffusion number G.
Is normalized to obtain a symbol estimation value.

The symbol estimation value C- (1,1) is input to the interference amount calculation unit 12- (1,1), and at the same time, as the value of the first stage of this station, the symbol estimation of the authority of the next stage is performed. Part 11
-Given to (1, 2). The symbol estimated value is an estimated value of the symbol data for the first station and represents an estimated value of the interference amount for the other stations.

In the interference amount calculator 12, the spread code generator 1
11- (1,1), and the symbol estimate C- (1,1) is re-multiplied with the same spreading code that was previously used for correlation in the channel signal estimator 21. And diffuse. Due to this re-spreading, the interference amount estimation value S- (1,1) becomes the interference canceling circuit 22- (1,
Given in 1). In the interference cancellation circuit 22- (1,1), the interference amount estimated value S- (1,1) is calculated from the signal dI- (1,1) input to the channel signal estimation unit 21- (1,1).
Is calculated by the adder circuit 221- (1, 1). this is,
The difference between the data obtained by re-spreading by the previous a-th spreading code and the a-th chip of the previous input symbol is calculated. This difference result is the station interference canceller 31-
It is the output signal dO- (1,1) of (1,1).

This output signal dO- (1,1) is an input signal dI- to the station interference canceller 31- (2,1) of the next station.
It becomes (2, 1). This input signal is a signal having a value after the interference amount estimated in the first stage / first station is removed.

((Operation of the second station of the interference canceling stage 41-1 of the first stage)): Even in the symbol estimating section 11- (2,1) of the next first stage and the second station, Similarly, when the input data reaches the symbol delimiter, that is, when the input of one symbol is completed, the input data dI- (2,1)
And the correlation with the spread code of the second station is calculated to estimate the symbol. After that, re-spreading and interference removal processing is performed as in the first station. The output signal dO- (2,1) of the station interference canceller 31- (2,1) is used as the next station interference canceller 31 for the third station.
-(3, 1).

The above operation is repeated for M stations. That is, the station interference canceling unit 31- (1,
By performing station interference cancellation from 1) to 31- (M, 1), interference for all stations is removed. That is, the symbol estimation values for all stations are removed from the baseband signal r.

The output signal dO- (M, of the Mth station interference canceling section 31- (M, 1) of the first interference canceling stage 41-1.
1) is the output signal e-1 of this interference cancellation stage 41-1 as shown in FIG. 2, and this output signal is the interference cancellation error signal. This interference cancellation error signal e-1 can also be said to be a symbol estimation error in the first interference cancellation stage 41-1.

In the above, the symbol estimation value C of the first station
-(1, 1) and the interference amount estimated value S- (1, 1) can be expressed by the following equations (4) and (5), and the sum range is one symbol.

C _1,1 = 1 / G · Σr · PN _i (4) S _1,1 = PN _i · C _1,1 (5) The i-th station after the first station in the first stage Symbol estimate C-
(I, 1) and the interference amount estimated value S- (i, 1) can be expressed by the following equations (6) and (7).

C _{i, 1} = 1 / G · Σ {(r−ΣS _{j, 1} ) · PN _i } j = 1 to i−1 (6) S _{i, 1} = PN _i · C _{i, 1} ... (7).

This C _{i, 1} is the symbol estimation value C-
(I, 1), where S _{i, 1} is the estimated interference amount S−.
(I, 1), and PN _i represents the spread code sequence of station i. Here, Σ (X · PN) represents that the correlation is obtained by taking the product sum of a and PN in the section of the diffusion length G, and the discrete time is omitted. Interference removal error e-1 after the end of the first stage
Is given by the following expression (8) and becomes an input signal to the next second interference cancellation stage 41-2.

E ₁ = r−ΣS _{i, 1} i = _{1 to} M (8).

(Second interference removal stage 41-2):
Then, the interference removal error signal e-1, which is input to the second interference removal stage 41-2, that is, dI- (1, 2) is sent to the symbol estimation section 11- (1, 2), and the first stage Similar to the eye, when the input data reaches the symbol break, that is, 1
Input data dI-
The correlation between (1, 2) and this first spread code is calculated. The correlation value obtained at this time is the symbol estimation value C in the previous stage of the same symbol section as the correlation value is obtained here.
-It is a corrected value of (1, 1).

This symbol estimated value C- (1, 1) is sent from the previous stage. In this embodiment, a simple addition is performed to correct the symbol estimated value C- (1,1). In the second and subsequent stages, the correlation value is C ^* -(i
j) and the sum of the symbol estimation value of the preceding stage is the symbol estimation value C- (i, j) of that stage.

The correlation value C ^* -(1, 2) is subjected to processing such as re-spreading and interference removal as in the first stage, and the station interference removal unit 31
-(1,2) output signal dO- (1,2), that is, the output signal of the station interference canceling unit 31- (1,2) is the second station of the next second interference canceling stage 41-2. Eye station interference removing unit 31-
It is input to (2, 2).

Thereafter, similarly to the first-stage interference canceling stage 41-1, the interference is sequentially eliminated for each station, and at the same time, the symbol estimation value sent from the first-stage interference eliminating stage is obtained at this stage. It is corrected by the correlation value obtained.

C of the first station of the second interference elimination stage 41-2
^* -(1,2), C- (1,2), S- (1,2)
And can be respectively expressed by the following equations (9), (10) and (11).

C ^* _1,2 = 1 / G · Σ {e ₁ · PN ₁ } (9) C _1,2 = C ^* _1,2 + C _1,1 (10) S _1,2 = PN ₁ C ^* _1,2 (11) C ^* -(i, 2) and C- (i, 2) of the i-th station after the first station of the second interference cancellation stage 41-2, S- (i,
2) is represented by the following equations (12), (13) and (14).

C ^* _{i, 2} = 1 / G · Σ {(e ₁ −ΣS _{j, 2} ) · PN _i } j = 1 to i−1 (12) C _{i, 2} = C ^* _{i, 2} + C _{i, 1} (13) S _{i, 2} = PN _i ^* C ^* _{i, 2} (14) The interference cancellation error signal e-2, which is the output of the second interference cancellation stage 41-2, is expressed by the following equation. It can be represented by (15). This signal is given to the next interference cancellation stage 41-3 at the third stage.

E ₂ = e ₁ −ΣS _{j, 2} j = _{1 to} M (15) The interference cancellation error signal e-2 output from the second interference cancellation stage 41-2, that is, the station interference cancellation unit 31. The output signal dO− (M, 2) of − (M, 2) becomes an interference removal error signal after the interference of all stations is removed twice from the baseband signal r. This signal becomes an input signal to the third interference canceling stage 41-3. Similar to the second stage, the third and subsequent interference removal stages 41-3 and later similarly remove interference for each station, and at the same time correct the symbol estimation value sent from the previous stage with the correlation value obtained by the authority. To do. This is repeated over K steps.

This K stage, i-th station C ^* -(i, K), C
-(I, K), S- (i, K) and e-K can be represented by the following equations (16), (17), (18) and (19), respectively.

C ^* _{i, k} = 1 / G · Σ {(e _k−1 −ΣS _{j, k} ) · PN _i } j = 1 to i−1 (16) C _{i, k} = C ^* _{i, k} + C _{i, k−1} (17) S _{i, k} = PN _i · C ^* _{i, k} (18) e _k = e _k−1 −ΣS _{j, k} j = _{1 to} M (19).

As described above, the elimination is repeated over K stages, and the symbol estimation values Ci, k of the respective stations obtained as a result are output ti (t-1 to t-M) of the interference elimination unit 4.
Becomes The symbol estimated value Ci, k is given to the code determination unit 6 as a demodulated signal.

Furthermore, the symbol sections of each station are scattered (various), and regardless of the positions of the symbols in the other stations, the interference cancellation is performed in parallel independently for each station in time correspondence. Considering a certain symbol section of a certain station,
Each time the data in the symbol section passes through the station interference canceling section of another station, the interference given by the other station is removed, and when passing through the station interference canceling section of the own station, the symbol of that symbol section of the own station Will be estimated and this will be repeated.

As a result, the received data that has been input is subjected to M.K times of repeated interference removal and correction operations until reaching the final stage, and the interference amount and transmission symbol of each station are estimated.
By a series of these processes, the symbol estimation values (t-1 to t-M) after interference removal are output as demodulation data, so that demodulation with a low bit error rate can be enabled.

(Demodulation Characteristics): FIG. 6 is a demodulation characteristic diagram of the receiving apparatus of the first embodiment. In the characteristic of FIG. 6, an evaluation of an error due to interference between transmitting stations when a pseudo random code (PN code) is used as a spreading code is shown. The horizontal axis represents the number of transmitting stations: M, the vertical axis represents the bit error rate after demodulation, the ◯ mark represents the error rate according to the first embodiment, and the X mark represents the error rate according to the conventional technique. . The error rate of this prior art is the error rate in demodulation by only one correlation with the spreading code,
Specifically, it is obtained by R _i according to the above formula (3).

Further, since the spreading code (spreading code) is a 42nd-order PN code, the cycle is 2 ⁴² -1, the spreading number N is 64, and the transmission data is the 9th-order PN code (the cycle is 511). ), And the number of stages K is 10. As can be seen from FIG. 6, the error rate can be made lower than in the conventional case even if the number of transmitting stations is much larger than in the conventional case.

(Specific Configuration of Radio Device 2): FIG. 7 is a specific functional configuration diagram of the radio device 2 of the first embodiment. The configuration of the wireless device 2 is mainly composed of a demodulation circuit for synchronously detecting a BPSK modulated signal, and mainly comprises an amplifier circuit 2a.
, Mixer 2g, oscillator 2f, bandpass filter (BPF) 2b, mixer 2e, and carrier recovery circuit (C
R) 2c and a low pass filter (LPF) 2d.

The high frequency signal Rf from the antenna unit 1 is A
After being amplified by MP2a, the mixer 2g mixes it with the local signal from the oscillator 2f in order to convert it into the intermediate frequency signal IF, converts it into IF and gives it to the BPF 2b. Here, unnecessary signals are removed and given to the CR 2c and the mixer 2e. The CR 2c reproduces the reference carrier frequency fc and supplies it to the mixer 2e. Here, the LPF is mixed (phase comparison).
Give to 2d. The waveform is shaped here and the baseband signal r
Is output as.

(Specific Structure of Code Judgment Unit 6): FIG.
FIG. 3 is a specific functional configuration diagram of the code determination unit 6 of the first embodiment. In FIG. 8, the code determination unit 6 includes code determination processing units 101 to 10M, and the code determination processing unit 101 is included.
-10M has the same structure. Further, the code determination processing unit 101 determines a code (for example, 1 or 0) from the output t-1 from the interference removal unit 4 and outputs a reproduction output W1. Similarly, the remaining code determination processing units 102-1
Similarly, 0M is to output the reproduction outputs W2 to WM by determining the signs of the outputs t-2 to t-M from the interference removing unit 4.

(Specific Configuration of Code Determination Processing Unit 101):
FIG. 9 is a specific functional configuration diagram of the code determination processing unit 101 of the first embodiment. The code determination processing unit 101 includes a Viterbi decoding circuit 101a and a code identification circuit 101b. The Viterbi decoding circuit 101a outputs the interference elimination output t
-1 is Viterbi decoded. That is, the maximum likelihood estimation is performed to estimate a probable code, and the estimation result is given to the code identification circuit 101b as a decoding result. Here, whether the code is 1 or 0 is identified from the decoding result and is output as the reproduction output W1.

(Specific Configuration of Control Unit 3): FIG. 10 is a specific functional configuration diagram of the control unit 3 of the first embodiment. The control unit 3 is for performing necessary control for each unit of the receiving device. Therefore, the control unit 3 includes a microprocessor (MP) 12a, a ROM 12b, and a RAM 12c.
And an interface unit 12d.

Further, these components are connected by the internal bus 12e. The ROM 12b stores a program for controlling each unit of the receiving device and for knowing the state of each unit.

The microprocessor (MP) 12a is R
Using the program stored in the OM12b, take in the status signals from each part and generate the necessary control signals.
It is given to each unit through the interface unit 12d. Also,
The RAM 12c temporarily stores data processed by the microprocessor (MP) 12a. In addition, a signal from the outside is temporarily stored at the request of the MP 12a.

For example, the supply control of the information of the number of transmission stations (M) to the interference removing unit 4, the supply control of the information of the interference elimination stage number (K), the control of the spread code generation (for example, the stage number), the code, etc. The code determination control for the determination unit 6 is performed.

(Effects of the First Embodiment): According to the CDMA receiver of the first embodiment described above, by including the interference canceller 4 as described above, it is included in the received signal given to the receiver. Estimate the amount of inter-station interference caused by spread (or de-spread) inter-code interference, and remove the interference from the received signal while separating and outputting the signals from each transmitting station. In this state, optimum symbol estimation can be performed, and the symbol estimation error rate can be reduced. Therefore, even if the number of transmitting stations is increased as compared with the conventional case, the influence of interference can be eliminated, and a highly reliable reproduction output can be obtained.

Furthermore, by constructing the interference elimination stage with two or more K stages and performing symbol estimation while eliminating inter-station interference,
It is possible to obtain a reproduction output signal from each station M having a very low error rate and high reliability. Further, by providing the code determination unit 6, it is possible to separate and output the likely reproduced data W1 to WM from each station.

Therefore, the number of multiple connections in CDMA can be increased. This can increase the transmission capacity and subscriber capacity of the communication network.

[Second Embodiment]: (Structure of Receiving Device): FIG. 11 is a CDM of the second embodiment.
It is a functional block diagram of the receiver for A. The receiving device includes an antenna unit 1, a wireless device 2, a control unit 3, and an interference removing unit 5.
And a correlation processing unit 7 and a code determination unit 6. Particularly, the parts different from the first embodiment are the interference removing unit 5 and the correlation processing unit 7. A specific configuration of the interference removing unit 5 will be described later with reference to FIGS. 12 to 15 and the like. (A) Spreading the symbol estimated value again with a spreading code and performing interference removal; b) It aims to realize further improvement of interference removal by adding corrections or restrictions to the symbol estimation value.

That is, by correcting and limiting the symbol estimation value obtained at each stage at each station, the convergence of symbol estimation is accelerated and a lower error rate is realized, so that more subscribers can communicate. It is configured to obtain.

In the second embodiment, the following expression (20) can be obtained from the expression (18) shown in the first embodiment. t ^* i = e _k + ΣS _{i, k} = r−ΣΣS _{j, k} + ΣS _{i, k} = r−ΣΣS _{j, k} k = 1 to K, j = 1 to M, and i ≠ j (20).

The right side of the equation (20) means that interference amount estimation values of all stations other than the own station are removed from the baseband received signal r over all stages, and only the signal of the own station is left. . That is, t ^* _i is the interference-removed data and the spread data sequence used for demodulation after interference removal, and can be obtained as being closer to the transmission signal of each i-station. Also,
The value obtained by correlating this with the spread code of each station is
It can be represented by 1).

[0080] _{1 / G · Σ {e k} · PN i} + ΣC i, k k = 1~K ... (21) the first term on the right side of the equation (21), that is, seen as sufficiently small to _{e k} In other words (if K is large because it is an estimation error after K steps have been canceled), the outputs t-1 to t-M of the interference canceller 4 of the above-described first embodiment are given by the following equation ( The signal represented by 22) is obtained.

T _i = ΣC _{i, l} l = 1 to K (22) The value obtained by correlating one symbol of t ^* i in the above equation (20) is the first when K is sufficiently large. Output ti of the embodiment
It is possible to obtain a value with a lower error rate than that.

(Structure of Interference Canceller 5): FIG. 12 (No. 1) and FIG. 13 (No. 2) are concrete functional block diagrams of the interference canceller 5. In FIG. 12, the interference removal stage 51
, 51-2, ... Are shown. Furthermore, FIG.
Includes an interference removal stage 51-k of the interference removal unit 5, multipliers 91 to 9M for respreading, and adders 81 to 8M for correction. Each of the interference canceling stages 51-1 to 51-k has a station interference canceling unit 61- (1,1) to 61- (M,
1) to 61- (1, k) to (M, k).

(Structure of Station Interference Canceller 61): FIG.
FIG. 4 is a specific functional configuration diagram of the station interference canceller 61. 14 is different from the station interference canceller 31 of the first embodiment in that the correction calculator 14 is newly provided and the interference amount calculator 15 is improved. Then, the interference amount calculation unit 15 includes the adder 123 and the multiplier 12
2 and. Furthermore, the symbol estimation unit 11A
The improvement of the configuration of is also a part different from the first embodiment.

Therefore, the station interference canceller 31 of the first embodiment.
The explanation will focus on the parts that are different from the above. That is, the adder 13 obtains the sum of the output signal of the correlation calculation unit 10 of the symbol estimation unit 11A and the symbol estimation value of the previous stage. The addition result is given to the correction calculation unit 14. This correction calculator 14
Then, the symbol estimated value is corrected and the corrected value is given to the interference amount calculation unit 15 as the symbol estimated value C. Further, the corrected symbol estimated value is given to the station interference canceller 61 in the next stage. Station interference removing units 61 (1, K) to 6 at the final stage K
1 (M, K) gives the corrected symbol estimation value C to the corresponding re-spreading multipliers 91 to 9M.

Further, the interference amount calculation unit 15 also has a different configuration from the interference amount calculation unit 12 of the first embodiment, and the corrected symbol estimated value from the correction calculation unit 14 is given to the adder 123. The adder 123 obtains a difference value between the corrected symbol estimated value and the symbol estimated value from the previous stage, and gives this difference value to the multiplier 122. The multiplier 122 multiplies this difference value by the spreading code from the spreading code generation unit 111 and performs re-spreading. Similar to the interference canceling circuit 22 of the first embodiment described above, the result of this multiplication is obtained by the adder 221 taking the difference from the input signal dI and giving it as the output signal dO to the next station interference canceling section 61.

(Structure of Correction Calculation Unit): FIG. 15 is a specific functional block diagram of the correction calculation unit 14. The correction calculation unit 14 includes a gain adjustment unit 130 and a symbol correction unit 13.
1 and a symbol limiting unit 132.

The gain adjusting section 130 is the symbol estimating section 1
The power of the addition output signal from the 1 A adder 13 is normalized. Therefore, for example, the average value of a few symbols of the input symbol estimation value is normalized to be 1, for example. This normalized signal is
It is given to the next symbol correction unit 131.

The symbol correction unit 131 of FIG. 15 corrects the estimated symbol value. Then, the corrected signal is given to the next symbol limiting unit 132,
Here, the symbol estimation value is limited and output, and the corrected symbol estimation value C is output to the next-stage station interference removing unit 61, and the interference amount calculating unit 15 is also given to obtain the interference amount.

The symbol correction unit 131 performs correction using a linear function, for example, as a correction function.
Further, the symbol limiting unit 132 limits the symbol estimated value so as not to exceed a certain value. Therefore, the above correction and limitation are realized by using the following equations (23) to (28).

C ^* _{i, k} = 1 / G · Σ {(e _k−1 −ΣS _{j, k} ) · PN _i } j = 1 to i−1 (23) C _{i, k} = limit [proj { _{^{gainC (C * i, k +}} C i, k-1)}] ... (24) S i, k = PN i · (C i, k -C i, k-1) ... (25) gainC (x) = x / x ^* (26) proj (x) = AX (27) limit (x) = max (x ≧ xmax), x (−xmax <x <xmax), −max (x ≦ −xmax) … (28).

Note that the gainC () in the above equation (26) is the adjustment in the gain adjusting section, and x ^* represents the average value of the symbol estimated values for several symbols. Furthermore, equation (2
7) proj () represents the process performed by the symbol correction unit 131, and A represents the correction parameter. Furthermore,
Max in Expression (28) represents a limiting parameter, and represents a maximum value that limits the symbol estimation value.

With the above configuration, the symbol sections of each station are scattered (various), and each station is independent in time correspondence regardless of the positions of symbols in other stations.
Interference cancellation is performed in parallel. Focusing on a certain symbol section of a station, each time the data in that symbol section passes through the station interference canceling section of another station, the interference given by the other station is canceled and the station interference canceling section of the own station is removed. When passing through, the symbol of the symbol section of the own station is estimated and this is repeated.

As a result of the above, the received data that has been input is subjected to M.K times of repeated interference removal and correction operations until the final stage, and the interference amount and transmission symbol of each station are estimated. By a series of these processes, the spread signals (t ^* -1 to t ^* -M) after interference removal are output as demodulation data, which enables demodulation with a low bit error rate.

(Demodulation Characteristic): FIG. 17 is a demodulation characteristic diagram by the receiver of the second embodiment. FIG. 17 shows a case where a pseudo random code (PN code) is used as the spreading code,
It shows an evaluation of errors due to interference between transmitting stations. The horizontal axis represents the number of transmitting stations: M, the vertical axis represents the bit error rate after demodulation, the square mark represents the error rate according to the second embodiment, and the cross mark represents the error rate according to the conventional technique. . still,
The error rate of this prior art is the error rate in demodulation by only one correlation with the spreading code, and is specifically obtained by R _i in the above equation (3).

Further, since the spreading code (spreading code) is a 42nd-order PN code, the cycle is 2 ⁴² -1, the spreading number N is 64, and the transmission data is the 9th-order PN code (the cycle is 511). ), And the number of stages K is 10. As can be seen from FIG. 6, the error rate can be made lower than in the conventional case even if the number of transmitting stations is much larger than in the conventional case.

(Specific Structure of Correlation Processing Unit 7): FIG.
6 is a functional configuration diagram of the correlation processing unit 7 of the second embodiment. The correlation processing unit 7 includes a multiplier 71a and a PN code generator 71s.
And an integrator 71d. With such a configuration, for example, the output t ^* -1 of the interference removing unit 5 is the multiplier 7
1a, the PN from the PN code generator 71s
The sign and the multiplication are performed, and the multiplication result is given to the integrator 71d. The integrator 71d integrates the multiplication result and outputs the integration result as V ^* 1. This integration result is the sign determination unit 6
Given to.

Other outputs of the interference canceller 5 t ^* -2 to t
^* -M is processed in the same manner as described above, and integration results V ^* 2 to V are obtained.
^* M is obtained and given to the code determination unit 6. Code determination unit 6
Then, the code is determined in the same configuration as in the first embodiment described above, and the reproduction outputs W1 to WM are obtained.

(Effects of the Second Embodiment): According to the CDMA receiver of the second embodiment described above, by providing the interference canceller 5 as described above, the received signal given to this receiver can be improved. Estimate the amount of inter-station interference caused by the included spreading (or despreading) inter-code interference, and remove the inter-station interference amount from the received signal while separating and outputting the signals from each transmitting station. Optimal symbol estimation can be performed in the removed state, and the error rate of symbol estimation can be reduced. Therefore, even if the number of transmitting stations is increased as compared with the conventional case, the influence of interference can be eliminated, and a highly reliable reproduction output can be obtained.

Further, the interference canceling stage is composed of two or more K stages, and symbol estimation is performed while canceling inter-station interference.
It is possible to obtain a reproduction output signal from each station M having a very low error rate and high reliability.

Further, the symbol estimation value is re-spread, an interference removal error is added to the re-spreading value, and the correction calculation section 14 is provided in each station interference removal section 61 to speed up the convergence of the symbol estimation. It is possible to obtain symbols with a low error rate.

Further, by providing the correlation processing section 7 and the code judging section 6, it is possible to separate and output the reproduced data that is likely to be transmitted from each station.

Therefore, the number of multiple connections in CDMA can be increased. This can increase the transmission capacity and subscriber capacity of the communication network. Moreover,
By providing the gain adjustment unit 130 of the correction calculation unit 14,
Even if there is a change in the power of the input signal, the effect of removing interference is constantly obtained.

Further, by correcting the symbol estimation value, demodulation can be performed with a lower error rate.
The number of subscribers (the number of simultaneous connections) in the communication network can be increased.

[Third Embodiment]: In the third embodiment, as the symbol data to be transmitted, a transmitting station in the base band in the case of spreading with two kinds of spreading codes of I phase (in-phase) and Q phase (quadrature phase) The transmission signal of i can also be generally represented by the above-mentioned formula (1).

In addition, r _i (n) and PN _i (n) both represent complex signals, and include both I-phase and Q-phase signals. That is, r _i = r _i I + j · r _i Q, PN _i = PN
_i I + j · PN _i Q. In the third embodiment, the symbol data d _{i to} be transmitted is differentially encoded (Different).
ial coding).

Furthermore, the received signal r (n) in the baseband
Can be regarded as the sum of the transmission signals of all transmitting stations and M stations, and can be represented by the above equation (2).

When the signal of the transmitting station i is detected by the correlation detection, it is possible to demodulate by performing the correlation calculation between the received signal r and the spread code PN _i of the transmitting station i in the interval of 1 symbol. Further, the correlation detection output (symbol correlation value) R _i of one symbol can be expressed by the following equation (29).

R _i = 1 / 2G · Σ {PN ^# _i (n) · Σr _j (n)} = d _i + 1 / 2G · Σ {PN ^# _i · Σ (d _j · PN _j (n))} n = 1~G, j = 1~M, and the i ≠ j ... (29) equation (29), G is the diffusion length (symbol section length), ^PN _{# i} complex conjugate signal of PN _i (PN _i I-j
-PN _i Q). Furthermore, this equation (29)
The first term on the right side of is the transmission data of the transmitting station i, and the second term on the right side is the interference signal for M-1 stations other than the transmitting station i.

Further, in this embodiment, every time a symbol delimiter is detected by the control means (before the input of one symbol is completed), it is sent by the symbol estimated value calculation means of that station and the transmitting station i. For each symbol, its input signal (received signal) r (n) and spreading code PN _i (n)
And the symbol estimate is estimated. At this time, in fact for use in the calculation of the correlation, the complex conjugate of the PN _i as indicated above signal _{^PN #} i ^(PN i I
-J · PN _i Q).

(Structure of Receiver of Third Embodiment): The basic structure of the receiver of the third embodiment is almost the same as that of the first embodiment shown in FIG. The difference is that the interference canceller 4 outputs the symbol estimation values t-1 to t-M for M stations, but "Because these signals include I signals and Q signals and are complex signals, Hereafter, what indicates a complex signal is assumed to include the I signal and the Q signal even though it is shown by one line in the figure. Furthermore, the calculations related to this signal are also performed on signals of complex numbers. "

In the first embodiment described above, the QPSK (DQPS
When the asynchronous detection circuit for K) is applied to the wireless device 2, the output I signal and the output Q signal are obtained as shown in FIG. Then, the above-described interference canceller 4a is provided for these output I and Q signals. The same effect as that of the first embodiment can be obtained by performing weighting processing on the output signal of the interference removing unit 4a and giving it to the code determining unit 6a.

That is, in FIG. 18, the receiving device comprises an antenna unit 1, a radio unit 2a, a control unit 3, and an interference removing unit 4.
a and a code determination unit 6a. Further, the interference removing unit 4a is composed of interference removing stages 41a-1 to 41a-K.

(Structure of Interference Removal Unit 4a): FIG.
FIG. 20 is a functional configuration diagram of the interference removing unit 4a. The interference removing unit 4a includes interference removing stages 41a-1 to 41a-K. Further, the interference elimination stages 41a-1 to 41a-
K is the station interference cancellers 31a- (1,1) to 31a-.
From (M, 1) to 31a- (1, K) to 31a- (M,
K).

(Specific configuration of station interference canceller 31a):
FIG. 21 is a specific functional configuration diagram of the station interference removing unit 31a. The configuration of FIG. 21 is different from that of FIG. 4 of the above-described first embodiment in that the configuration is such that the station interference can be removed for the I signal and the Q signal. Specifically, the station interference canceller 31a mainly includes the channel signal estimator 21a.
And an interference removing circuit 22a. Furthermore,
The channel signal estimation unit 21a includes a symbol estimation unit 11a.
And an interference amount calculation unit 12a.

Furthermore, the symbol estimating section 11a is specifically, the correlation calculating section 10 and the I-phase spreading code generating section 111.
a1, a Q-phase spreading code generator 111a2, and an adder 1
3a1 and 13a2. The interference amount calculation unit 12a is specifically composed of multipliers 121a1 to 121a4. The interference removal circuit 22a is specifically configured by adders 221a1 and 221a2.

(Specific Structure of Correlation Calculation Unit 10a):
FIG. 22 is a specific functional configuration diagram of the correlation calculation unit 10a. 22, the correlation calculation unit 10a specifically includes the multipliers 112a1 to 112a4 and the adder 113.
a1, 113a2 and accumulator (ACC) 114a
1, 114a2 and normalization circuits 115a1 to 115a2
It consists of and.

(Operation of the interference removing unit 4a): ((Operation of the first station of the first interference removing stage 41a-1)): Next, a specific operation of the interference removing unit 4a will be described. Therefore, first, din- (1,1), which is the baseband signal r from the wireless device 2a (since this is a complex signal, the I-phase signal din-I and the Q-phase signal din-Q are used.
Represents the channel signal estimation unit 21a- (1,1) symbol estimation unit 11a- (of the station interference elimination unit 31a- (1,1) of the first station of the first stage 41a-1 of the interference elimination stage. 1,
Give to 1). When the input data reaches the delimiter of symbols, that is, when the input of one symbol is completed, the symbol estimation unit 11a- (1,1) inputs the input data d
The symbol for which the correlation between in- (1,1) and the spread code of the first station is calculated is estimated. Specifically, this correlation is performed by sum of products and normalization.

Spreading code generator 111a1- (1,1),
111a2- (1,1) generates spreading codes of I phase and Q phase, respectively, and each chip of the symbols spread to the input G chip has G symbols for one symbol used for this spreading. 21 and multipliers 112a1- (1,1) to 112a4- (1,
The multiplication is performed in 1).

That is, the a-th chip of the input symbol is
The product of the spreading code corresponding to the symbol and the a-th spreading code is calculated. Furthermore, the multiplier 112a1 and the multiplier 112a3
The result of multiplication with is added to the adder 113a1 and the multiplier 112a2
And the multiplication result of the multiplier 112a4 to the adder 113a2. The results are respectively added to the accumulator (ACC) 1
14a1 to (1,1) 114a2- (1,1).

Each ACC 114a finds the sum of G products for one symbol. Each ACC 114a is cleared for each symbol. This summation is used for each normalization circuit 114a1.
-(1,1), 114a2- (1,1) is normalized by the spreading number G to obtain the symbol estimation value of each phase.

Symbol estimation value C-I- (1,1) of each phase
(I-phase) and C-Q- (1,1) (Q-phase) are input to the interference amount calculation unit 12a- (1,1), and at the same time, as the value of the first stage of this station, Symbol estimation unit 21a of the authorities of
Given to (1,2). The symbol estimated value is an estimated value of the symbol data for the first station and represents an estimated value of the interference amount for the other stations.

In the interference amount calculation unit 12a, the same spreading / spreading code as that generated by each spreading code generation unit 111a- (1,1) and used previously for correlation in the channel signal estimation unit 21a, Each symbol estimated value C- (1,1) is multiplied again to perform spreading. By this re-spreading, the interference amount estimated value S-I- (1,1) of each phase,
S-Q- (1,1) is an interference canceling circuit 22a- (1,1).
Given to.

In the interference removing circuit 22a- (1,1), the signal din- (1,1) input to the channel signal estimating unit 21a- (1,1) is used to calculate the difference for each phase. This is the difference from the previous a-th chip. These difference results indicate that the station interference canceller 31a- (1,
1) output signals dout-I- (1,1), dout-
Q- (1,1).

These output signals dout- (1,1)
Becomes an input signal din- (2,1) to the station interference canceller 31a- (2,1) of the next station. This input signal is 1 stage / 1
This is a signal having a value after the interference amount estimated at the station is removed.

((Operation of the second station of the interference elimination stage 41a-1 of the first stage)): The symbol estimation unit 11a- (2,1) of the next first stage and the second station is also the first station. Similarly, when the input data reaches the symbol break, that is, when the input of one symbol is completed, each input data din-I-
The symbols are estimated by calculating the correlation between (2,1), din-Q- (2,1) and each spreading code of the second station. After that, re-spreading and interference removal processing is performed as in the first station. Output signal dou of station interference canceller 31a- (2,1)
t-I- (2,1) and dout-Q- (2,1) are given to the next station interference canceller 31a- (3,1).

The above operation is repeated for M stations. That is, the station interference canceling unit 31a- of the interference canceling stage 41a-1.
By performing station interference cancellation from (1,1) to 31a- (M, 1), interference for all stations is removed. That is, the symbol estimation values for all stations are removed from the baseband signal r of each phase.

Further, M of the first interference elimination stage 41a-1
The output signals dout- (M, 1) of both phases of the station interference canceling section 31a- (M, 1) are the output signals e-1 of the interference canceling stage 41a-1 as shown in FIG. , This output signal is the interference cancellation error signal. This interference removal error signal e-1 can be said to be a symbol estimation error in the first interference removal stage 41a-1. e-1 is also a complex signal having I-phase and Q-phase signals. In the above, the symbol estimation value C- (1,1) of the first station and the interference amount estimation value S- (1,1)
Can be expressed by the following equation (30) and the above equation (5), and C _1,1 = 1 / 2G · Σ (r · PN _i ^# ) (30) The range of the sum is 1 symbol. And C, S, and
r, e and PN are complex signals including I and Q phase signals,
The formula is also calculated in complex.

Further, the symbol estimation value C- (i, 1) at the i-th station and the interference amount estimation value S- after the first station in the first stage.
(I, 1) can be expressed by the following equation (31) and the above equation (7).

C _{i, 1} = ½G · Σ {(r−ΣS _{i, 1} ) · PN ^# _i } j = 1 to i−1 (31) This C _{i, 1} is the symbol estimation value C- ( i, 1).
The interference cancellation error e-1 after the completion of the first stage is represented by the above equation (8) and becomes an input signal to the next interference cancellation stage 41a-2.

(Second interference elimination stage 41a-2):
The interference cancellation error signals e-1, din- (1, 2) input to the second interference cancellation stage 41a-2 are the symbol estimation unit 1
1a- (1,2), input data dI- (1,2) when the input data reaches the symbol delimiter as in the first stage, that is, when the input of one symbol is completed.
And the correlation with the spread code of the first station is calculated. The correlation value obtained at this time is the symbol estimation value C- (1,
It is the corrected value of 1).

This symbol estimated value C- (1,1) is sent from the previous stage, and the correlation value is added to it by the adders 13a1 (1,2), 13a2 (1,2) for each phase. Addition is performed to correct this symbol estimated value C- (1, 1). In the second and subsequent stages, the correlation value is C ^* -(i, j), and the sum of the symbol estimation value of the previous stage is the symbol estimation value C of that stage.
-(I, j).

The correlation value C ^* -(1, 2) is subjected to processing such as re-spreading and interference removal as in the first station, and the station interference removal unit 31
The output signal dout- (1,2) of a- (1,2), that is, the output signal of the station interference canceling unit 31a- (1,2) is 2 of the next interference canceling stage 41a-2. It is input to the station interference canceller 31a- (2, 2) of the station.

Thereafter, similarly to the first-stage interference canceling stage 41a-1, the interference is sequentially removed for each station, and at the same time, the symbol estimation value sent from the first-stage interference canceling stage is obtained at this stage. It is corrected by the correlation value obtained.

C ^* -(1,2), C- (1,2), S- (1 ,,) at the first station of the second interference cancellation stage 41a-2.
2) means the following equation (32) and the above equation (1)
0) and the above equation (11).

[0135] _{^{C * 1,2 = 1 / 2G ·}} Σ of ^{_{{e 1 · PN 1 #}}} ... (32) 2 -stage interference cancellation stages 41a-2 1 station subsequent to, the i station th ^{C *} - (I, 2), C- (i, 2), S- (i,
2) is represented by the following equation (33), the above equation (13), and the above equation (34).

C ^* _{i, 2} = 1 / 2G · Σ {(e ₁ −ΣS _{j, 2} ) · PN _i ^# } j = 1 to i−1 (33) S _{i, 2} = PN _i · C ^* _{i, 2} ... (34) The interference cancellation error signal e-2, which is the output of the second interference cancellation stage 41a-2, can be expressed by the above-mentioned equation (15). This signal is given to the next third interference cancellation stage 41a-3.

The interference removal error signal e-2 output from the second interference removal stage 41a-2, that is, the station interference removal unit 31a-
The output signal dout- (M, 2) of (M, 2) becomes an interference removal error signal after the interference of all stations is removed twice from the baseband signal r. This signal becomes an input signal to the next interference canceling stage 41a-3. Similar to the second stage, the third and subsequent interference removing stages 41a-3 and later also remove interference one by one for each station, and at the same time correct the symbol estimation value sent from the previous stage with the correlation value obtained by the authority. To do. This is repeated over K steps.

Further, C ^* -(i,
K), C- (i, K), S- (i, K) and e-K are respectively the following formula (35), the above formula (17), the above formula (18) and the above formula (19). ) Can be represented.

C ^* _{i, k} = 1 / 2G · Σ {(e _k−1 −ΣS _{j, k} ) · PN _i ^# } j = 1 to i−1 (35) As described above, K stages And the resultant symbol estimation value C _{i, k of} each station becomes the output ti (t-1 to t-M) of the interference canceling unit 4a.
This symbol estimation value C _{i, k} is a demodulated signal,
It is given to the code determination unit 6a.

(Demodulation Characteristics): With regard to the demodulation characteristics of the third embodiment, the characteristics similar to those of the above-described first embodiment can be obtained with the above-mentioned configuration.

(Structure of Radio 2a): FIG.
It is a concrete functional block diagram of the radio | wireless machine 2a of an Example. The configuration of this wireless device 2a is QPSK (DQPSK: Diff).
It is mainly composed of a demodulation circuit for asynchronously detecting the modulated signal.
a, a mixer 2g, an oscillator 2f, a bandpass filter (BPF) 2b, mixers 2e and 2j, a carrier recovery circuit (CR) 2c, and a lowpass filter (LPF) 2
d, 2k.

The high frequency signal Rf from the antenna section 1 is A
After being amplified by MP2a, the mixer 2g mixes it with the local signal from the oscillator 2f in order to convert it into the intermediate frequency signal IF, converts it into IF and gives it to the BPF 2b. Here, unnecessary signals are removed.

Thereafter, in the demodulation process for the QPSK (DQPSK) modulated signal, two two-phase phase demodulations are independently performed. That is, two reference carrier waves f1 having different π / 2 phases,
f2 and the received signal IF1 are phase-compared (mixed) by mixers 2e and 2j, and given to LPFs 2d and 2k.
Here, the waveform is shaped, and two series of baseband signals I and Q are obtained as demodulation outputs.

(Specific Configuration of Code Determination Unit 6a): FIG. 24 is a specific functional configuration diagram of the code determination unit 6 of the third embodiment. The code determination unit 6a includes a code determination processing unit 101.
The code determination processing unit 101A to
The 10MAs have the same configuration. Interference removal unit 4a
The code determination processing unit 101A determines the code (for example, 1 or 0) from the output t-1 and outputs the reproduction output W1. Similarly, the remaining code determination processing units 102A to 102A-10
Similarly, the MA outputs t-2 to t-M from the interference removing unit 4a.
Is determined and the reproduction outputs W2 to WM are output.

(Specific Structure of Code Judgment Processing Unit 101A): FIG. 25 shows the code judgment processing unit 101 of the third embodiment.
It is a concrete functional block diagram of A. This code determination processing unit 1
01A is a weighting processing unit 101a and an adder 101m.
, Viterbi decoding circuit 101p, and code identification circuit 101q
It consists of and.

The processing for the estimation error after interference removal for one station will be specifically described. That is, from the interference removing unit 4a, I
A symbol estimation value, which is a complex signal including a phase signal and a Q-phase signal, is output, and as shown in FIG.
Given to. Here, the differentially encoded signal is demodulated to original data. The input estimation signal (two phases of I phase and Q phase) is given to the delay device D101b and the multiplier 101c.

The delay device D101b delays by one symbol, converts it into a complex conjugate signal, and supplies it to the multiplier 101c. The multiplier 101c performs multiplication, and the multiplication result is the adder 1
Give to 01m. The operations up to this point deal with complex signals. The adder 101m adds the given I-phase and Q-phase signals to strengthen the signal power and reduce the error rate.

Next, the Viterbi decoding circuit 101p performs Viterbi decoding on the demodulated data. That is, the maximum likelihood estimation is performed to estimate a probable code, and the estimation result is given to the code identification circuit 101q as a decoding result. Here, the code is 1 from the decoding result.
It is identified as either 0 or 0 and is output as the reproduction output W1.

(Effect of Third Embodiment): According to the CDMA receiver of the third embodiment, the CDMA is QPSK (DQPSK) modulated by quadrature modulation from the transmission side.
Even when a signal is received, it is separated into an I phase and a Q phase, and the same station interference cancellation as in the above-described first embodiment is performed on each of them, so that the same as in the above-described first embodiment. It is possible to obtain various effects.

"Fourth Embodiment": This fourth embodiment is "how to carry out the above second embodiment when a QPSK (DQPSK) modulated CDMA signal by quadrature modulation is received from the transmitting side. It shows if you can make the same effect by changing it. '

That is, in the configuration of the second embodiment described above, the QPS
Asynchronous detection circuit for K (DQPSK) is installed in the wireless device 2a.
When applied to, the output I signal and the output Q signal are obtained as shown in FIG. The interference removing unit 5a described above is provided for these output I and Q signals. The same effect as that of the second embodiment can be obtained by performing the weighting process after performing the correlation process on the output signal of the interference removing unit 5a and applying the weighting process to the code determining unit 6a.

FIG. 26 is a functional block diagram of the CDMA receiver of the fourth embodiment. In FIG. 26,
The receiving device includes an antenna unit 1, a wireless device 2a, and a control unit 3.
And an interference removal unit 5a, a correlation processing unit 7a, and a code determination unit 6a. The difference from the above-described second embodiment is that the value obtained by correlating the spread code of each station is expressed by the following equation (36).

1 / 2G · Σ {e _k · PN _i ^# } + ΣC _{i, k} k = _{1 to} K (36) The first term on the right side of the equation (36), that is, e _k is assumed to be sufficiently small. If it is considered (if K is large because it is an estimation error after K stages have been canceled), the outputs t-1 to t-M of the interference canceller 4 of the first embodiment described above are expressed by the above equation. The signal represented by (22) is obtained.

The value obtained by correlating one symbol of t ^* i in the above equation (20) gives a value with a lower error rate than the output ti of the first embodiment when K is sufficiently large. It is a thing.

(Structure of Interference Removal Unit 5a): FIGS. 27 and 28 are functional block diagrams of the interference removal unit 5a. The interference removing unit 5a includes interference removing stages 51a-1 to 51a-K, re-spreading multipliers 91 to 9M, and correction adders 81 to 8.
It is composed of M and. The interference removal stage 51a-1 is composed of station interference removal units 61a- (1,1) to 61a- (M, 1).

(Structure of Station Interference Canceller 61a): FIG.
9 is a functional block diagram of the station interference removing unit 61a. The station interference canceller 61a includes a channel signal estimator 21a and an interference canceller 22a. Channel signal estimation unit 2
1a is a symbol estimation unit 11A and a correction calculation unit 14a.
1, 14a2, and an interference amount calculator 15a. The symbol estimation unit 11A includes a spread code generation unit 111-
1, 111-2, the correlation calculator 10, and the adder 13a
1 and 13a2.

The interference amount calculation unit 15a includes an adder 123a.
1, 123a2, 122a1, 122a2 and multiplier 1
21a1-121a4.

The adders 13a1 and 13a2 obtain the sum of the output signal of the correlation calculation section 10 of the symbol estimation section 11A and the symbol estimation value of the preceding stage for each phase. The addition result is given to the correction calculators 14a1 and 14a2. The correction calculators 14a1 and 14a2 correct the symbol estimation value for each phase, and the corrected value is used as the symbol estimation value C (CI,
It is given to the interference amount calculation unit 15a as CQ). Further, the corrected symbol estimated value is used as the next station interference canceller 61a.
Give to.

The station interference canceller 61 (1, K) at the final stage K
.About.61 (M, K) give the corrected symbol estimated values C to the corresponding respreading multipliers 91 to 9M, respectively. However, the multipliers 91 to 9M are for calculating a complex signal, and the configuration thereof is the same as that of the interference amount calculator 15a.

Further, also in the interference amount calculator 15a, the corrected symbol estimated values from the correction calculators 14a1 and 14a2 are given to the adders 123a1 and 123a2, respectively. This adder 123 obtains a difference value between the corrected symbol estimated value and the symbol estimated value from the previous stage for each phase,
This difference value is given to each of the multipliers 121a1 to 121a4.

From this point onward, the spread code generators 111a1 and 111a are the same as the interference amount calculator 12a of the third embodiment.
The input signal din is re-spread with the spreading code generated in 2
Is added to the adders 221a1 and 221a2 and is given to the next station interference canceller 61a as output signals dout-I and dout-Q.

(Structure of Correction Calculation Unit): Correction Calculation Unit 1
The specific configuration of 4a1 and 14a2 is similar to the configuration of FIG. 15 described above. That is, the symbol correction unit 131 specifically corrects using a linear function as a function for correction. Further, the symbol limiting unit 132 limits the symbol estimated value so as not to exceed a certain value. Therefore, the following equation (37) and the above equations (24) to (2)
8) etc. are used to realize the above correction and limitation.

C ^* _{i, k} = 1 / 2G · Σ {(e _k−1 −ΣS _{j, k} ) · PN ^# _i } j = 1 to i−1 (37) The above result is input. The received data is subjected to M.K times of repeated interference removal and correction operations until reaching the final stage, and the interference amount and transmission symbol of each station are estimated. By a series of these processes, the spread signals (t ^* -1 to t ^* -M) after interference removal are output as demodulation data, which enables demodulation with a low bit error rate.

(Demodulation Characteristics): FIG. 31 is a demodulation characteristic diagram of the receiving apparatus of the fourth embodiment. This FIG. 31 shows a case where a pseudo random code (PN code) is used as the spreading code,
It shows an evaluation of errors due to interference between transmitting stations. The horizontal axis represents the number of transmitting stations: M, the vertical axis represents the bit error rate after demodulation, the squares represent the error rate according to the fourth embodiment, and the crosses represent the error rate according to the conventional technique. The error rate of this prior art is the error rate in demodulation based on only one correlation with the spreading code, and is specifically obtained by R _i in the above equation (29).

Since the spreading code (spreading code) is a 42nd-order PN code, the period is 2 ⁴² −1 and the spreading number N is 6
4 and the transmission data is 9th-order PN code (cycle is 51
1) and the number of stages K is 10. This FIG. 31
As can be seen from the above, the error rate can be made lower than in the conventional case even if the number of transmitting stations is much larger than in the conventional case.

(Specific Configuration of Correlation Processing Unit 7a): FIG. 30 is a functional configuration diagram of the correlation processing unit 7a. This Figure 30
In, the spread code generator 1 for the symbol estimator 11A
11-1 and 111-2 and the correlation calculation part 10a. With such a configuration, when the output t ^* -1 of each phase of the interference removing unit 5a is given to the correlation calculating unit 10a, the correlation with the spreading code from the spreading code generating units 111-1 and -2 is calculated, and the correlation is calculated. The result is a complex signal V ^* 1 including I and Q phase signals.
Output as. This correlation result is given to the code determination unit 6a.

Output of other interference removing unit 5a t ^* -2
t ^* -M is processed in the same manner as described above, and the integration result V ^*
2 to V ^* M are obtained and given to the code determination unit 6a. The code determination unit 6a makes a determination with the same configuration as that of the third embodiment, and obtains the reproduction outputs W1 to WM.

(Effect of Fourth Embodiment): According to the CDMA receiver of the fourth embodiment, the CDMA is QPSK (DQPSK) modulated by quadrature modulation from the transmitting side.
Even when a signal is received, it is separated into an I-phase and a Q-phase, and the same station interference cancellation as in the above-described second embodiment is performed on each of them, so that the same or more than the above-mentioned second embodiment is obtained. The effect of can be obtained.

(Other Embodiments) (1) In the interference cancellers 4 and 4a of the above-described first and third embodiments, the interference cancellers 41 and 41a are not K stages but one stage. Even if there is, there is an effect of improving compared to the conventional. Further, even if the re-diffusion as shown in the second and fourth embodiments and the interference removal error eK are added to the one interference removal stage, the effect of improvement can be obtained. In addition, one interference removal stage 41, 4
1a, each station interference canceller 31, 31a has a second embodiment, a fourth embodiment.
The improvement effect can also be obtained by providing the correction calculators 14 and 14a as shown in the embodiment.

(2) Also, the station interference canceller 3 of the first embodiment.
The improvement effect can also be obtained by providing the correction calculation unit 14 in 1. Further, the station interference canceller 61 of the second embodiment is provided with the correction calculator 14, but in addition to the normalization with the mean value x * as shown in the second embodiment, the mean value x * is symbolized. The same effect can be obtained by using the limiting parameter max of the limiting unit.

Further, although the correction calculating section 14 is provided with the gain adjusting section 130, if there is no change in the power of the input signal, the limiting parameter max of the equation (28) may be given appropriately. Furthermore, the gain adjusting unit 140 or the AGC
(Automatic Gain Control) It is also preferable to dispose an amplifier or the like in front of the interference removing unit 4 or 5 and adjust it at the stage of the baseband signal r. Also, the limiting parameter ma of the equation (28)
A configuration in which x is appropriately controlled according to the input power is also preferable.

Further, the limiting parameter max of the equation (28)
May be controlled to the average value x * of the symbol estimated values for several symbols in equation (26). (3) Further, in the above embodiment, the CDM by wireless communication is used.
Although the explanation was made with A in mind, it may be applied to wired communication. Further, by providing an optical / electrical conversion circuit, it can be applied to optical communication in which the transmission path is an optical transmission path. Further, by providing the acoustic / electric conversion circuit, the transmission line can be applied to acoustic communication in an acoustic space. Also, CDMA
It is also conceivable to transmit the signal through the electric power transmission line, and in this case, the receiving device can be configured by providing a conversion circuit between the electric power transmission line and the wireless device instead of the antenna unit.

(4) Furthermore, BPSK (DBPS
In addition to K) and QPSK (DQPSK), various demodulation circuits such as a demodulation circuit (signal conversion circuit) for a QAM modulation signal and a demodulation circuit for a GMSK modulation signal can be applied.

(5) It is also preferable that the receivers of the above-mentioned first to fourth embodiments include path diversity processing for compensating for multipath and the like. For example, when performing path diversity for two paths, in the case of the above-described first embodiment or second embodiment, one interference cancellation stage 41 or 51 has M stations × L paths (L = L). 2) It is necessary to include the station interference canceling unit 31 or 61. In such a case, the interference canceller 4 or 5 outputs the estimated signals t-1 to t after interference cancellation.
-(Mx2) or t ^* -1 to t ^* -(Mx2) is obtained.

That is, two estimated signals corresponding to the signals of each station are obtained corresponding to the number of paths. RAKE processing is performed on the two path signals of each station. That is,
This can be realized by performing weighting processing on two path signals for each station and combining the two weighted signals to obtain a signal after path diversity for each station.

(5a) For example, BPSK (DBPSK)
When an asynchronous detection circuit for QPSK or QPSK (DQPSK) is applied to the wireless device 2, for example, when performing 3-path diversity for each station, the interference canceller 4 removes three interferences for three paths for each station. An estimated signal (complex signal of I phase and Q phase) is obtained.

Next, in order to perform RAKE processing, path diversity is performed with the configuration shown in FIG. 32 instead of the code determination processing section shown in FIG. 27 for each station signal.

More specifically, for example, the process for the estimated signal after the interference removal for one station will be specifically described.
The first to third path signals are output for each phase from and are given to the weighting processing unit 101d as shown in FIG. For example, the first path signal (for two phases of I phase and Q phase)
Is given to the delay device (D) 101e and the multiplier 101f. Then, the delay device 101e delays by one symbol, converts it into a complex conjugate signal, and supplies it to the multiplier 101f. Multiplier 101f performs multiplication and the multiplication result is added by adder 1
01n.

Furthermore, another second path signal (I phase, Q phase 2
The same weighting processing as that of the above-described first path signal is performed on the third path signal and the third path signal (two phases of the I phase and the Q phase), and the result is given to the adder 101n. The adder 101m adds (combines) the signals after the weighting processing for the first path signal to the third path signal to obtain the signal V after compensation for one station.
1 can be obtained. It is preferable that this signal is then given to the Viterbi decoder 101p for code determination processing.
It is possible to realize a highly reliable receiving apparatus by performing the same processing as described above on the signals of other stations.

(6) Further, by applying the receiving devices of the above-mentioned first to fourth embodiments to a CDMA base station receiving system, the receiving performance of the base station is improved and the subscriber capacity is increased. You can Furthermore, the receiving characteristics can be improved by applying the receiving devices of the above-described first to fourth embodiments to a CDMA mobile station receiving system. Incidentally, in the case of a mobile station system, it is possible to apply even a configuration of a receiving device having a required number of stations without performing estimation for M stations unlike the case of a base station.

(7) Furthermore, in the spreading code generators of the first and second embodiments, the PN code is the M series, the Gold code, the GMW series, the Bent series, the No series, and the W series.
It is possible to apply any of the Alsh series, the majority logic synthesis series, the Geffe series, and the like.

(8) Furthermore, in the case where the transmission data is interleaved (scrambled to avoid a block error) on the transmission data on the transmission side, the code judging section of the first and second embodiments described above. 6, it is preferable to include a circuit (deinterleaver) for performing deinterleaving (descramble) at the input of the Viterbi decoding circuit 101a in FIG. It is preferable to apply interleaving and deinterleaving similarly to the third and fourth embodiments.

[0183]

As described above, according to the present invention, by using each despreading code corresponding to each spreading code assigned to each transmitting station, the signal from each transmitting station is converted from the above received signal. Estimate the amount of inter-station interference caused by the interference between the spreading code or the interference between the despreading code, from each transmitting station while removing this inter-station interference amount from the received signal The signal of each station can be accurately obtained while eliminating the inter-station interference amount included in the received signal by providing the station signal estimating means for estimating the signal of 1 and outputting each estimated signal.

Therefore, by applying such a receiving apparatus to, for example, a base station receiving system or a mobile station receiving system, the receiving performance of the system is improved, the subscriber capacity in CDMA is increased, and the communication reliability is improved. can do.

[Brief description of drawings]

FIG. 1 is a functional configuration diagram of a CDMA receiver according to a first embodiment of the present invention.

FIG. 2 is a functional configuration diagram (1) of an interference removing unit according to the first embodiment.

FIG. 3 is a functional configuration diagram (No. 2) of the interference removing unit according to the first embodiment.

FIG. 4 is a functional configuration diagram of a station interference canceller of the first embodiment.

FIG. 5 is a functional configuration diagram of a correlation calculation unit according to the first embodiment.

FIG. 6 is a demodulation characteristic diagram of the first embodiment.

FIG. 7 is a functional configuration diagram of the wireless device of the first embodiment.

FIG. 8 is a functional configuration diagram of a code determination unit according to the first embodiment.

FIG. 9 is a functional configuration diagram of a code determination processing unit according to the first embodiment.

FIG. 10 is a functional configuration diagram of a control unit according to the first embodiment.

FIG. 11 is a functional configuration diagram of a CDMA receiver according to a second embodiment.

FIG. 12 is a functional configuration diagram (1) of an interference removal unit of the second embodiment.

FIG. 13 is a functional configuration diagram (No. 2) of the interference removing unit according to the second embodiment.

FIG. 14 is a configuration diagram of a station interference canceller of the second embodiment.

FIG. 15 is a functional configuration diagram of a correction calculation unit according to the second embodiment.

FIG. 16 is a configuration diagram of a correlation processing unit according to the second embodiment.

FIG. 17 is a demodulation characteristic diagram of the second embodiment.

FIG. 18 is a configuration diagram of a receiving device according to a third embodiment.

FIG. 19 is a functional configuration diagram (1) of an interference removing unit of the receiving device according to the third embodiment.

FIG. 20 is a functional configuration diagram (2) of an interference canceling unit of the receiving device according to the third embodiment.

FIG. 21 is a functional configuration diagram of a station interference canceling unit of the interference canceling unit of the receiving device of the third embodiment.

FIG. 22 is a functional configuration diagram of a correlation calculation unit of a station interference cancellation unit of an interference cancellation unit of the receiving device of the third embodiment.

FIG. 23 is a functional configuration diagram of a wireless device of a receiving device according to a third embodiment.

FIG. 24 is a functional configuration diagram of a code determination unit of the receiving device according to the third embodiment.

FIG. 25 is a functional configuration diagram of a code determination processing unit of the code determination unit of the receiving device of the third embodiment.

FIG. 26 is a functional configuration diagram of a receiving device according to a fourth embodiment.

FIG. 27 is a functional configuration diagram (1) of an interference canceling unit of the receiving device of the fourth embodiment.

FIG. 28 is a functional configuration diagram (No. 2) of the interference removing unit of the receiving device according to the fourth embodiment.

FIG. 29 is a functional configuration diagram of a station interference canceller of the interference canceller of the receiving device of the fourth embodiment.

FIG. 30 is a functional configuration diagram of a correlation calculation unit of a station interference cancellation unit in the interference cancellation unit of the receiving device of the fourth embodiment.

FIG. 31 is a demodulation characteristic diagram of the fourth embodiment.

FIG. 32 is a partial configuration diagram of another embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Antenna part, 2 ... Radio | wireless machine, 3 ... Control part, 4, 5 ... Interference removal part, 41-1 to 41-k, 51-1 to 51-K ...
Interference elimination stage, 6 ... code determination unit, 7 ... correlation processing unit, 31,
61 ... Station interference canceller, C ... Symbol estimation value, e-1 to e
-K ... Interference removal error signal, t-1 to t-M, t ^* -1 to
t ^* -M ... Signal after interference removal (symbol estimation value).

Claims (11)

[Claims] 1. Each transmission using receiving means for receiving signals for code division multiple access from a plurality of transmitting stations and each despreading code corresponding to each spreading code assigned to each transmitting station. A signal from a station is estimated from the received signal, and the amount of inter-station interference caused by the interference between the spreading codes or the interference between the de-spreading codes is estimated, and the amount of inter-station interference is received by the receiving unit. A receiving device comprising: a station signal estimating means for estimating a signal from each transmitting station while removing the signal from the signal and outputting each obtained estimated signal. 2. The receiving device according to claim 1, wherein the station signal estimating means estimates M signals (2 or more) from M (2 or more) transmitting stations, respectively. Station interference removal means ~
M-th (second or more) station interference removing means is provided, wherein the first station interference removing means captures the received signal,
The first estimated signal obtained by estimating the signal from the other transmitting station is output, and the amount of inter-station interference given to the signals from other transmitting stations is estimated by using the first estimated signal. Is removed from the received signal to output a first cancellation error signal, and the Mth station interference canceling means fetches the (M-1) th cancellation error signal from the (M-1) th station interference canceling means, While outputting the Mth estimated signal obtained by estimating the signal from the transmitting station,
Using this M-th estimated signal, the inter-station interference amount given to the signal from another transmitting station is estimated, and this inter-station interference amount is referred to as the M-th
A receiving device having a configuration for outputting an M-th removal error signal removed from the first removal error signal. 3. The receiving apparatus according to claim 2, wherein the station signal estimating means connects M × L (L = 2 or more) station interference canceling means in series by a number required for path diversity. A receiver characterized by being present. 4. The receiving apparatus according to claim 2 or 3, wherein the station signal estimating means includes M or (M × L) first station interference canceling means to Mth or serially connected units. The (M × L) th station interference canceling means is configured as one interference canceling stage, and this interference canceling stage is provided at least K or more (2 or more), and the first estimated signal of the first interference canceling stage to the M or the (M ×
L) estimated signal and Mth or (M × L) th cancellation error signal are given to the second interference cancellation stage, and first station interference cancellation means of the Kth (second or more) interference cancellation stage Is the M-th or (M × L) th K-th interference cancellation stage
Inter-station interference amount is also re-estimated while re-estimating using the cancellation error signal of No. 1, and the first estimated signal to the M-th or (M × L) -th estimated signal from the K−1 th interference cancellation stage is obtained. The corrected and output M-th or (M × L) -th station interference canceling means of the K-th interference canceling stage removes the inter-station interference amount.
XL) removal error signal is output. 5. The receiving device according to claim 2, wherein the station signal estimating means performs re-spreading on the first estimated signal to the M-th or (M × L) -th estimated signal, and further. The Mth or (M × L) th removal error signal is added to each of these respread signals to correct and output the first estimated signal to the Mth or (M × L) th estimated signal. A receiver characterized by: 6. The receiving apparatus according to claim 4, wherein the station signal estimating means converts the first estimated signal to the Mth or (M × L) th estimated signal corrected in the Kth interference cancellation stage. Respreading is performed on the signal, and the Mth or (M × L) th cancellation error signal of the Kth interference cancellation stage is added to the respective respread signals to add the first estimation signal to the Mth estimation signal. Alternatively, the receiving device is characterized in that the (M × L) th estimated signal is re-corrected and output. 7. The receiving device according to claim 2, wherein the first station interference removing means to the Mth or (M × L) th station of each interference removing stage of the station signal estimating means. The interference removing means is provided with a correcting means for performing level adjustment on the first estimated signal to the M-th or (M × L) th estimated signals for further correction, and for limiting the correction result to a predetermined value or less. The limitation result for the first estimated signal to the M-th or (M × L) estimated signal is output, and the limited first estimated signal to the M-th or (M × L) estimated signal are output. A receiver provided for estimating the amount of interference between stations. 8. The receiving apparatus according to claim 1, wherein the receiving means includes level adjusting means for adjusting the level of a received signal. 9. The receiving apparatus according to claim 1, wherein the output signal of the station signal estimating means is subjected to weighting processing to output a signal, or the station signal estimating means. Second processing means for performing correlation processing and weighting processing on the output signal of the means to output the signal,
A receiver provided with any one of the above. 10. The receiving device according to claim 1, wherein the output signal of the station signal estimating means, the output signal of the first processing means, or the output signal of the second processing means. A receiving device comprising a code determining means for performing code determination from the output signal and outputting each code for the signal from each transmitting station. 11. The receiving device according to claim 1, wherein a radio wave capturing unit that captures a radio signal and receives and outputs an electric signal, a transmission line signal capturing unit that captures the electric signal from a wired transmission line of the electric signal. Or an optical / electrical conversion means for converting an optical signal into an electric signal, or an acoustic / electrical conversion means for converting an acoustic signal into an electric signal, and a signal for a signal from any of these means is provided. A receiving device comprising a signal converting means for performing conversion and supplying a signal converted output signal to the receiving means.