JP2000138605A - Multi-user receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-user receiver with which a large interference elimination effect is obtained although the receiver is of a comparatively small scale. SOLUTION: Upon the receipt of a CDMA signal, antennas 1-1-1-N output a high-rate user signal to a 1st stage interference elimination processing section 2-1. Interference elimination processing sections 2-1-2-N of each stage that process the high-rate user signal apply antenna directivity control and a multi-user interference canceller for interference elimination of the high-rate user signal. Demodulation sections 4-1-4-KL that process the low-rate user signal receive an interference elimination residual signal for each antenna obtained through interference elimination processing of (M-1) stages for the high-rate user signal depending on an antenna directivity specific to each user signal, demodulates the signal and provides an output of each low-rate user signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-user receiving apparatus, and in particular, to code division multiple access (CDMA) for users having different signal powers.
The present invention relates to a multi-user receiving apparatus that receives a multiple access (UE) signal and demodulates each user signal and cancels mutual interference.

[0002]

2. Description of the Related Art Code division multiple access (CDMA) has the potential to increase subscriber capacity and is expected to be applied to mobile communication cellular systems. However, on the receiving side, there is a problem of interference of other user signals accessed simultaneously.

[0003] As a method of removing such interference, there are a method of removing interference by antenna directivity control using an adaptive antenna, and a method of removing interference by a multi-user interference canceller.

As a method using a multi-user interference canceller, for example, a multi-user receiver using interference weight control in a parallel multi-stage configuration has been proposed, and this multi-user receiver is simple and has excellent characteristics.

On the other hand, in the CDMA system, it is possible to multiplex signals of a plurality of media in the same frequency band. The signals of the plurality of media include, for example, audio, video, data, and other signals. Such signals have different information transmission rates and different required reception qualities. Assuming the same required reception quality for each user signal having a different transmission rate, a user signal having a high transmission rate requires a large transmission power. Even at the same transmission rate, a user signal with a high required reception quality requires higher transmission power.

As described above, a user signal having a high transmission rate or a required reception quality causes a large interference with a user signal having a low transmission rate or a required reception quality. In particular, when the transmission rates are different, the transmission power of each user signal increases in proportion to the transmission rate, which is an important problem.

When the interference of another user signal is removed only by antenna directivity control using an adaptive antenna, the number of user signals is large in a CDMA system with one transmission rate.
If they are uniformly distributed in the cell, almost the same reception quality can be obtained for each user signal regardless of its positional relationship.

However, in a CDMA system in which user signals of a plurality of transmission rates are multiplexed, when user signals having different transmission rates are located in the same direction from the base station, the transmission rate is determined by the antenna directivity toward the user signal having a lower transmission rate. , A high-rate user signal causes great interference with a low-rate user signal. That is, the reception quality of each user signal varies greatly depending on the positional relationship, and the overall system characteristics deteriorate.

[0009] A multi-user spatio-temporal interference canceller has been proposed in which an adaptive antenna and a multi-user interference canceller are organically coupled. This technology is described in "CDMA
Multi-user Spatio-Temporal Interference Cancellation Method "(Ishii, Yoshida and Gogawa, 1998 IEICE General Conference, B-5-1
26 pp. 489).

In this apparatus, the interference estimation value of each user signal is converted into an interference estimation value for each antenna element by using the reception antenna weight, and interference is removed at each antenna element input before directivity control. This coupling device has excellent interference removal characteristics, and the size of the device is relatively small.

When a multi-user spatio-temporal interference canceller is used, CDMA for multiplexing user signals of a plurality of transmission rates is used.
Even in a system, interference of a high-rate user signal in the same direction, which cannot be removed by antenna directivity control, can be removed by a multi-user interference canceller. Interference can be suppressed.

FIG. 5 shows a configuration for receiving user signals at a plurality of transmission rates using a multi-user spatiotemporal interference canceller. In this configuration, there is no distinction in interference cancellation processing for user signals of different transmission rates, and mutual space-time interference cancellation is performed. For simplicity, the user signals at a plurality of transmission rates are assumed to be a high-rate user signal and a low-rate user signal, and the numbers of the user signals are K _H and K _L , respectively.

Assuming that the number of antennas is N (N is an integer equal to or greater than 1), the antennas 101-1 to 101-N receive the CDMA signal, and the first-stage interference cancellation processing section 102- of the high-rate and low-rate user signals. 1 interference estimator (IEU:
InterferenceEstimation Un
it) 103-1-1 to 103-1-K _H , 104-1
And outputs it to the -1~104-1-K _L.

When M (M is an integer of 2 or more) stages of interference cancellation processing units 102-1 to 102-M are formed, interference estimation units 103 of interference cancellation processing units 102-1 to 102-M of each stage are formed.
-1-1 to 103-1-K _H , ..., 103-M-1
103-M-K _H, 104-1-1~104-1-
_{K L, ......, 104-M} -1~104-M-K L input and a symbol replica corresponding to the interference removal residual signal and the front of the same user signal obtained for each antenna in the preceding stage interference removing process Then, each stage receives and demodulates with the antenna directivity unique to each user signal, generates a symbol replica of the current stage, and transmits it to the next stage.

At the same time, interference estimators 103-1-1 to 103-1-1 to
3-1-K _H ,..., 103-M-1 to 103-M-K
_{H, 104-1-1~104-1-K L, ......} , 104
-M-1 to 104-M-K _L convert and output a spread signal relating to the difference between the current-stage symbol replica and the previous-stage symbol replica for each antenna.

The delay units 105-1-1 to 105-1-N,
..., 105- (M-1) -1 to 105- (M-1)-
N is the received signal or the interference cancellation residual signal for each antenna, and the interference estimating units 103-1-1 to 103-1-K _H ,.
..., 103-M-1~103- M-K H, 104-1-
_{1~104-1-K L, ......, 104} -M-1~104
-M-K _L as the result of delaying until the output.

Subtractors 106-1-1 to 106-1-N,
..., 106- (M-1) -1 to 106- (M-1)-
N is the interference estimator 103-1-1 to 103-1-1 of each stage of each user signal.
103-1-K _H ,..., 103-M-1 to 103-M
_{-K H, 104-1-1~104-1-K L,} ......, 1
04-M-1~104-M- K L the output of the subtracting for each antenna to obtain the interference removal residual signal for each of the current stage antenna. Final stage interference estimating units 103-M-1 to 103-M-K _H ,
104-M-1~104-M- K L outputs a demodulated signal of each user signal high-rate and low-rate.

The interference estimating units 103-1-1 to 103-103 of each stage
-1-K _H , ..., 103-M-1 to 103-M-
_{K H, 104-1-1~104-1-K L,} ......, 10
The structure of 4-M-1~104-M- K L shown in FIG.

A plurality of path unit processing units are provided corresponding to a multipath propagation path including a plurality of paths (# 1 to #L). The despreading means 11-1 to 11-N receive the interference removal residual signal for each preceding antenna and perform despreading for each antenna. The multipliers 12-1 to 12-N are provided with despreading means 11-1 to 11-N.
Antenna weighting is performed by multiplying the outputs of 11-N by weights w ₁ to w _N.

The adder 13 combines the outputs of the multipliers 12-1 to 12-N. The multiplier 14 weights the symbol replica corresponding to the same user signal at the previous stage. Adder 1
5 adds the output of the adder 13 and the output of the multiplier 14.

The detector 16 passes the output of the adder 15 (#
Demodulation is performed using the transmission path estimation value in units of 1 to #L). The detector 16 includes a transmission path estimating unit 17, a complex conjugate unit 18, and a multiplier 19, performs synchronous detection and demodulation, and performs weighting for realizing maximum ratio combining of a plurality of paths (# 1 to #L). Have a role to do.

The adder 20 synthesizes the output of the detector 16 for each path (# 1 to #L). The determiner 21 determines the output of the adder 20. The multiplier 22 generates a symbol replica of the current stage by multiplying the output of the decision unit 21 by the transmission path estimation value for each path (# 1 to #L), and outputs the symbol replica to the next stage.

The subtractor 23 subtracts the output of the multiplier 14 from the output of the multiplier 22. The multiplier 24 weights the output of the subtractor 23. Multipliers 25-1 to 25-N are multipliers 2
The output of No. 4 is multiplied by complex conjugate weights w ₁ ^* / _{N to} w _N ^* / N obtained by normalizing the weight used in the antenna weighting by the number of antennas.

The spreading means 26-1 to 26-N include a multiplier 25.
The outputs of -1 to 25-N are spread for each antenna. The adders 27-1 to 27-N add the outputs of the paths (# 1 to #L) of the spreading means 26-1 to 26-N for each antenna.

Here, the first-stage interference estimation section 103-1-1
~103-1-K _H, 104-1-1~104-1-K
_L receives an antenna reception signal as an interference removal residual signal for each antenna at the preceding stage, and uses 0 as a symbol replica corresponding to the same user signal at the preceding stage.

The final stage interference estimator 103-M-1 to 103
_{3-M-K H, 104} -M-1~104-M-K L outputs only is the output demodulated signal of the adder 20 does not perform interference estimation processing after. In the final stage, the process of updating the interference elimination residual signal is not performed.

As the weights w _{1 to} w _N to be multiplied to perform the antenna directivity control, steering antenna weights and adaptive control weights determined separately based on the estimation of the arrival direction of the user signal are used. The weighting coefficients to be multiplied by the multipliers 14 and 24 are, for example, 1- (1−α) ^m−1 (α is a real number equal to or less than 1, m is an integer of 2 or more and M or less) and α. . These coefficients have a function of alleviating the interference removal operation. Instead of removing all the interference components in the first stage, the interference components are gradually removed in a plurality of stages.

That is, in the first stage where the transmission path estimation error and the judgment symbol error are large, the interference cancellation operation is relaxed to suppress the interference cancellation error, and the interference cancellation ability is distributed to the subsequent stage where the transmission path estimation error and the judgment symbol error are improved. In addition, it is possible to optimize the interference removal characteristics in the final stage. In particular, this interference weight control is very effective in a parallel type multi-user receiving apparatus, and various methods can be considered for weighting the interference weight control.

[0029]

In the above-mentioned conventional multi-user receiving apparatus, spatio-temporal interference is removed without discrimination between user signals having different transmission rates, and uniform and excellent reception quality is realized for each user signal. However, the number of despreading units and spreading units that occupy most of the processing amount in the interference estimating unit increases in proportion to the number of antennas, so that the apparatus scale becomes enormous.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a multi-user receiving apparatus capable of obtaining a large interference removing effect with a relatively small apparatus scale.

[0031]

A first multi-user receiving apparatus according to the present invention includes a plurality of antennas for receiving a plurality of code division multiplex access signals, and the plurality of code division multiplexes received by the plurality of antennas. A multi-user receiving apparatus that demodulates an access signal and removes interference between the plurality of code division multiplex access signals, wherein the plurality of code division multiplex access signals satisfy a preset condition among the plurality of code division multiplex access signals. Antenna directivity control and interference cancellation by a multi-user interference canceller for one signal group, and antenna directivity control for a second signal group of the plurality of code division multiple access signals that does not satisfy the condition. The configuration is such that interference cancellation is performed only by using the interference.

A second multi-user receiving apparatus according to the present invention includes a plurality of antennas for receiving a plurality of code division multiple access signals, and demodulates the plurality of code division multiple access signals received by the plurality of antennas. A multi-user receiving apparatus for performing interference cancellation on the plurality of code division multiple access signals, wherein a first signal group satisfying a preset condition among the plurality of code division multiple access signals is Means for performing antenna directivity control and interference cancellation by a multi-user interference canceller, and interference cancellation using only antenna directivity control for a second signal group among the plurality of code division multiple access signals that does not satisfy the condition. Means for performing the following.

A third multi-user receiving apparatus according to the present invention includes a plurality of antennas for receiving a plurality of code division multiplex access signals, and demodulates the plurality of code division multiplex access signals received by the plurality of antennas. A multi-user receiving apparatus for performing interference cancellation processing of a plurality of stages on each of the plurality of code division multiplex access signals to perform interference cancellation, wherein a predetermined condition of the plurality of code division multiplex access signals is satisfied. An interference cancellation residual signal for each antenna obtained in the interference cancellation processing of the preceding stage and a symbol replica corresponding to the same user signal in the preceding stage are input to the satisfied first signal group, and each stage of the interference cancellation processing is input. In each user signal is received and demodulated with an antenna directivity unique to the user signal, and a symbol replica of the current stage is generated and transmitted to the next stage,
A spread signal relating to a difference between the current-stage symbol replica and the previous-stage symbol replica is converted and output for each antenna, and the output signal is subtracted from the interference-cancellation residual signal for each of the previous-stage antennas. The interference cancellation is performed by updating the interference cancellation residual signal for each signal, and a second one of the plurality of code division multiple access signals that does not satisfy the condition is used.
Inputting an interference cancellation residual signal for each antenna from which each signal of the first signal group has been removed at least once, and receiving and demodulating each user signal with an antenna directivity specific to each user signal. Is configured to remove interference.

A fourth multi-user receiving apparatus according to the present invention includes a plurality of antennas for receiving a plurality of code division multiple access signals, and demodulates the plurality of code division multiple access signals received by the plurality of antennas. A multi-user receiving apparatus for performing interference cancellation processing of a plurality of stages on each of the plurality of code division multiplex access signals to perform interference cancellation, wherein a predetermined condition of the plurality of code division multiplex access signals is satisfied. Inputting the interference cancellation residual signal for each antenna obtained by the interference cancellation processing at the preceding stage and the symbol replica corresponding to the same user signal at the preceding stage to the first signal group that satisfies each stage of the interference cancellation processing Means for receiving and demodulating each user signal with an antenna directivity unique to each user signal, means for generating a symbol replica of the current stage and transmitting it to the next stage, A spread signal related to a difference between a symbol replica and the preceding symbol replica is converted and output for each antenna, and the output signal is subtracted from the interference removal residual signal for each preceding antenna to remove interference for each current antenna. Means for performing the interference removal by updating a residual signal; and each signal of the first signal group with respect to a second signal group of the plurality of code division multiple access signals that does not satisfy the condition. Means for receiving the interference cancellation residual signal for each antenna that has been removed at least once, receiving the demodulated signal with an antenna directivity unique to each user signal, and demodulating the received signal.

A fifth multi-user receiving apparatus according to the present invention includes a plurality of antennas for receiving a plurality of code division multiple access signals, and demodulates the plurality of code division multiple access signals received by the plurality of antennas. What is claimed is: 1. A multi-user receiving apparatus for performing interference cancellation on a plurality of code division multiple access signals in a plurality of stages, wherein an interference cancellation residual signal for each antenna obtained in a previous stage interference cancellation process and a same user signal on a previous stage And a symbol replica corresponding to the above, received and demodulated at each stage of the interference elimination process with an antenna directivity unique to each user signal and generated a current stage symbol replica and transmitted to the next stage, An interference estimator for converting a spread signal relating to a difference between a current-stage symbol replica and the preceding-stage symbol replica for each antenna and outputting the spread signal; From said signal delayed by a predetermined value the interference removal residual signals for each antenna by a delay device of the first
A first subtractor for reducing the output of each stage of the interference estimating unit of each signal of the signal group for each antenna and updating the interference cancellation residual signal for each antenna of the current stage, and the plurality of code division multiple access signals. Of the first signal group that satisfies a predetermined condition among the first signal group, and the interference cancellation residual for each antenna from which each signal of the first signal group is removed at least once. A demodulation unit that receives the difference signal, receives and demodulates the signal with an antenna directivity unique to each user signal, and outputs the received signal is provided for each signal of the second signal group that does not satisfy the above condition.

That is, in a CDMA system in which user signals having different signal powers are multiplexed, a user signal having a large signal power is subjected to antenna directivity control and interference cancellation by a multi-user interference canceller, and a user signal having a small signal power is subjected to a interference. By performing interference removal only by antenna directivity control, it is possible to obtain a large interference removal effect with a relatively small device scale.

In particular, in a CDMA system in which user signals of a plurality of transmission rates are multiplexed, interference of high-rate user signals in the same direction that cannot be removed by antenna directivity control is removed by a multi-user interference canceller, thereby reducing the low-rate user signal. By giving priority to the interference of the high-rate user signal with respect to the user signal, excellent interference removal performance can be easily realized.

[0038]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a multi-user receiving apparatus according to one embodiment of the present invention.
In the figure, a multi-user receiving apparatus according to an embodiment of the present invention performs conventional multi-user spatio-temporal interference cancellation on a high-rate user signal, and performs the final stage Only the antenna directivity control is performed using the interference removal residual signal to the input, that is, the signal from which the high-rate user signal is removed from the received signal.

In a CDMA system that multiplexes user signals of a plurality of transmission rates, the number of high-rate user signals is small, but the influence of the interference is great. Conversely, the influence of the interference of each low-rate user signal is small, but the number is large.
Therefore, in the multi-user receiving apparatus according to one embodiment of the present invention, since the operation of the multi-user interference canceller for each low-rate user signal can be omitted, a decrease in interference removal performance can be suppressed, and the processing amount can be greatly increased. Can be reduced.

In the multi-user receiving apparatus according to one embodiment of the present invention, when the number of antennas is N (N is an integer of 1 or more), the antennas 1-1 to 1-N receive CDMA signals and receive high-rate user signals. The signal is processed in the first stage interference removal processing unit 2
-1 interference estimation unit (IEU: Interference)
Estimation Unit) 3-1-1-3-
And outputs it to the 1-K _H.

In the case where M (M is an integer of 2 or more) stages of interference cancellation processing units 2-1 to 2-M are formed, interference estimation units 3-1-1 to 3- at each stage of a high-rate user signal. 1-K _H , ...
, 3-M-1 to 3-M-K _H receive the interference cancellation residual signal for each antenna obtained in the interference cancellation processing in the preceding stage and the symbol replica corresponding to the same user signal in the preceding stage, and perform interference cancellation. At each stage of processing, the signal is received and demodulated with the antenna directivity unique to each user signal, and a symbol replica of the current stage is generated and transmitted to the next stage.

At the same time, interference estimating units 3-1-1 to 3-1-1
K _H ,..., 3-M-1 to 3-M-K _H convert a spread signal relating to the difference between the current-stage symbol replica and the previous-stage symbol replica for each antenna and output the converted signal.

Delay units 5-1-1 to 5--1-N,..., 5
-(M-1) -1 to 5- (M-1) -N represent the received signal or the interference cancellation residual signal for each antenna,
1-1-3-1-K _H ,..., 3-M-1 to 3-MK
Delay until the processing result of _H is output. Subtractor 6
1-1 to 6-1-N, ..., 6- (M-1) -1 to 6-
(M-1) -N is an interference estimating unit 3 for each signal of each user signal.
-1-1-1-K _H ,..., 3-M-1 to 3-M-
The output of K _H is reduced for each antenna to obtain an interference cancellation residual signal for each antenna at the current stage. Last stage interference estimation section 3-M-1
~3-M-K _H outputs a demodulated signal of each user signal of the high-speed rate.

Also, a demodulation unit (DEM: Demodulation Unit) 4-1 for a low-rate user signal.
To 4-K _L inputs the interference removal residual signals for each antenna obtained by the interference removal processing M-1 stage of user signals of high-rate, received and demodulated by each user signal inherent antenna directivity And outputs a demodulated signal of each user signal at a low rate.

FIG. 2 shows the interference estimators 3-1-1 to 3-1-1-K _H ,.
It is a block diagram showing the structure of _{M-1~3-M-K H} .
In the figure, interference estimating units 3-1-1 to 3-1-1-K _H ,..., 3-M-1 to 3- at each stage of a high-rate user signal.
M-K _H is an interference estimating section 103-for high-rate and low-rate user signals in a conventional multi-user receiver.
1-1 to 103-1-K _H , ..., 103-M-1 to 1
_{03-M-K H, 104-1-1~104-1} -K L,
......, 104-M-1~104- M-K have the same configuration as _L, a plurality of paths (# 1~ # L) corresponding to the multipath propagation formed of a plurality of path unit processing unit It has.

The despreading means 11-1 to 11-N receive the interference cancellation residual signal for each antenna at the preceding stage and despread for each antenna. Multipliers 12-1 to 12-N are despreading means 1
Antenna weighting is performed by multiplying the outputs of 1-1 to 11-N by weights w ₁ to w _N.

The adder 13 combines the outputs of the multipliers 12-1 to 12-N. The multiplier 14 weights the symbol replica corresponding to the same user signal at the previous stage. Adder 1
5 adds the output of the adder 13 and the output of the multiplier 14.

The detector 16 passes the output of the adder 15 (#
Demodulation is performed using the transmission path estimation value in units of 1 to #L). The detector 16 includes a transmission path estimating unit 17, a complex conjugate unit 18, and a multiplier 19, performs synchronous detection and demodulation, and performs weighting for realizing maximum ratio combining of a plurality of paths (# 1 to #L). Have a role to do.

The adder 20 combines the outputs of the detector 16 for each path (# 1 to #L). The determiner 21 determines the output of the adder 20. The multiplier 22 generates a symbol replica of the current stage by multiplying the output of the decision unit 21 by the transmission path estimation value for each path (# 1 to #L), and outputs the symbol replica to the next stage.

The subtractor 23 subtracts the output of the multiplier 14 from the output of the multiplier 22. The multiplier 24 weights the output of the subtractor 23. Multipliers 25-1 to 25-N are multipliers 2
The output of No. 4 is multiplied by complex conjugate weights w ₁ ^* / _{N to} w _N ^* / N obtained by normalizing the weight used in the antenna weighting by the number of antennas.

The spreading means 26-1 to 26-N are connected to the multiplier 25.
The outputs of -1 to 25-N are spread for each antenna. The adders 27-1 to 27-N add the outputs of the paths (# 1 to #L) of the spreading means 26-1 to 26-N for each antenna.

Here, the first-stage interference estimating units 3-1-1-3
For −1−K _H , an antenna reception signal is input as an interference cancellation residual signal for each antenna in the preceding stage, and 0 is used as a symbol replica corresponding to the same user signal in the preceding stage. The interference estimating units 3-M-1 to 3-M-K _{H at the} final stage output only the demodulated signal output from the adder 20, and do not perform the subsequent interference estimating process. In the final stage, the process of updating the interference elimination residual signal is not performed.

As the weights w _{1 to} w _N to be multiplied for performing the antenna directivity control, steering antenna weights and adaptive control weights determined separately based on the estimation of the arrival direction of the user signal are used. The weighting coefficients to be multiplied by the multipliers 14 and 24 are, for example, 1- (1−α) ^m−1 (α is a real number equal to or less than 1, m is an integer of 2 or more and M or less) and α. .

[0054] FIG. 3 is a block diagram showing the configuration of a demodulation unit 4-1 to 4-K _L user signal of low-rate in Fig.
In the figure, a plurality of path unit processing units are provided corresponding to a multipath propagation path including a plurality of paths (# 1 to #L).

The despreading means 51-1 to 51-N receive the interference cancellation residual signal for each antenna obtained by the M-1 stage interference cancellation processing of the high-rate user signal, and despread for each antenna. Do. The multipliers 52-1 to 52-N are provided with despreading means 5.
Antenna weighting is performed on the outputs of 1-1 to 51-N.

The adder 53 combines the outputs of the multipliers 52-1 to 52-N. The detector 54 demodulates the output of the adder 53 using the transmission path estimation value for each path. The adder 58 combines the output of the detector 54 for each path and outputs a demodulated signal.

As the weights w _{1 to} w _N to be multiplied for performing the antenna directivity control, steering antenna weights and adaptive control weights determined separately based on the estimation of the arrival direction of the user signal are used.

FIG. 4 is a block diagram showing a configuration of a multi-user receiving apparatus according to another embodiment of the present invention. In the figure, a multi-user receiving apparatus according to another embodiment of the present invention includes a low-rate user signal demodulation unit (DEM: Demod).
ulation Unit) 4-1~4-K _L enters the interference removal residual signals for each antenna obtained in the first stage of the interference removing process of the user signals of high-rate, received by the user signal-specific antenna directivity The configuration is the same as that of the multi-user receiving apparatus according to one embodiment of the present invention except that the demodulated signal is demodulated and a demodulated signal of each user signal at a low rate is output. I have.
The operation of the same component is the same as that of the embodiment of the present invention.

In the multi-user receiving apparatus according to one embodiment of the present invention, demodulation of a low-rate user signal is performed by using an interference cancellation residual signal for each antenna obtained by M-1 stage interference cancellation processing of a high-rate user signal. Because of the input, a delay occurs by the time required for the M-1 stage interference removal processing of the high-rate user signal. The amount of delay depends on the detection method, device mounting method, and the like, and is generally not negligible. C
In the DMA system, high-speed closed-loop transmission power control is used. Therefore, if there is a demodulation delay, its characteristics are greatly deteriorated.

Therefore, it is necessary to keep this delay as small as possible. In another embodiment of the present invention, similarly to the embodiment of the present invention, multi-user spatio-temporal interference cancellation is performed on a high-rate user signal, and only antenna directivity control is performed on a low-rate user signal. However, the input uses the interference cancellation residual signal for each antenna obtained in the first stage interference cancellation processing of the high-rate user signal.

In this configuration, since the low-rate user signal is demodulated from the interference cancellation residual signal from which the high-rate user signal is not sufficiently removed, the reception quality of the low-rate user signal is slightly deteriorated. Can be minimized. In a system that also uses transmission power control, the overall characteristics may be improved.

It should be noted that, in addition to the above-described embodiments of the present invention and the other embodiments, as an input for demodulating a low-rate user signal, interference removal at an arbitrary stage of a high-rate user signal may be performed. A configuration using the interference removal residual signal for each antenna obtained by the processing is considered, and these are also included in the present invention. The multi-user receiving apparatus of the present invention is also effective when the required signal quality of each user signal is different or the signal power of each user signal is different for other reasons.

As described above, in a CDMA system in which user signals having different signal powers are multiplexed, interference elimination is performed on a user signal having a high signal power by antenna directivity control and a multi-user interference canceller, and a user signal having a low signal power is obtained. By performing interference removal only by controlling the antenna directivity, a large interference removal effect can be obtained with a relatively small device scale.

In particular, in a CDMA system in which user signals of a plurality of transmission rates are multiplexed, interference of high-rate user signals in the same direction, which cannot be eliminated by antenna directivity control, is eliminated by a multi-user interference canceller. Interference of a high-rate user signal with respect to a user signal can be preferentially suppressed, and excellent interference removal performance can be easily realized.

Further, the interference cancellation residual signal obtained in the first stage interference cancellation processing of the high-rate user signal is input to
By demodulating a low-rate user signal, the demodulation delay can be reduced.

[0066]

As described above, according to the present invention, a plurality of antennas for receiving a plurality of code division multiple access signals are provided, and a plurality of code division multiple access signals received by the plurality of antennas are demodulated and a plurality of antennas are received. A multi-user receiving apparatus that performs interference cancellation for a plurality of code division multiplex access signals in a plurality of stages, wherein an antenna for a first signal group satisfying a preset condition among a plurality of code division multiplex access signals is provided. By performing interference cancellation using directivity control and a multi-user interference canceller, and performing interference cancellation using only antenna directivity control on a second signal group that does not satisfy the conditions of a plurality of code division multiple access signals, a comparison is made. There is an effect that a large interference removal effect can be obtained with a relatively small device scale.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a multi-user receiving device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of an interference estimating unit at each stage of a high-rate user signal in FIG. 1;

FIG. 3 is a block diagram showing a configuration of a demodulation unit for a low-rate user signal in FIG. 1;

FIG. 4 is a block diagram illustrating a configuration of a multi-user receiving device according to another embodiment of the present invention.

FIG. 5 is a block diagram illustrating a configuration example of a conventional multi-user receiving apparatus.

[Explanation of symbols]

1-1 to 1-N antenna 2-1 to 2-M interference removal processing unit 3-1-1 to 3-1-1-K _H , ..., 3-M-1 to 3-M
-K _H interference estimation unit 4-1 to 4-K _L demodulator 5-1-1~5-1-N, 5-2-1~5-2-N delayer 6-1-1～6-1 -N, 6-2-1 to 6-2-N, 2
3 Subtractors 11-1 to 11-N Despreading means 12-1 to 12-N, 14, 19, 22, 24, 25-
1 to 25-N, 52-1 to 52-N Multiplier 13, 15, 20, 27-1 to 27-N, 53 Adder 16 Detector 17 Transmission path estimating means 18 Complex conjugate means 21 Judgment device 26-1 -26-N Diffusing means 51-1 to 51-N Despreading means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihisa Gogawa 5-7-1 Shiba, Minato-ku, Tokyo F-term within NEC Corporation (reference) 5J021 AA05 AA06 DB01 EA02 FA00 FA09 FA14 FA15 FA16 FA25 FA32 HA05 HA10 JA07 5K022 EE02 EE32 EE35 5K052 AA02 BB02 CC06 DD03 EE17 FF31 GG19 GG31 GG42

Claims (13)

[Claims] A plurality of antennas for receiving a plurality of code division multiplex access signals; a plurality of antennas for receiving the plurality of code division multiplex access signals; demodulation of the plurality of code division multiplex access signals received by the plurality of antennas; A multi-user receiving apparatus that performs interference cancellation on a first signal group that satisfies a preset condition among the plurality of code division multiple access signals, the antenna directivity control and the multi-user interference canceller And a second signal group that does not satisfy the condition among the plurality of code division multiple access signals is subjected to interference cancellation only by antenna directivity control. User receiving device. 2. The first signal group is a signal group in which at least one of signal power, transmission rate, and required reception quality is high, and the second signal group is the signal power and the transmission rate. 2. The multi-user receiving apparatus according to claim 1, wherein at least one of the request reception quality and the required reception quality is a low signal group. 3. A plurality of antennas for receiving a plurality of code division multiple access signals, wherein the plurality of code division multiple access signals received by the plurality of antennas are demodulated and the plurality of code division multiple access signals are mutually transmitted. A multi-user receiving apparatus that performs interference cancellation on a first signal group that satisfies a preset condition among the plurality of code division multiple access signals, the antenna directivity control and the multi-user interference canceller And a means for performing interference removal only by antenna directivity control for a second signal group of the plurality of code division multiple access signals that does not satisfy the condition. Multi-user receiving device. 4. The first signal group is a signal group in which at least one of signal power, transmission rate, and required reception quality is high, and the second signal group is the signal power and the transmission rate. 4. The multi-user receiving apparatus according to claim 3, wherein at least one of the request reception quality and the required reception quality is a low signal group. 5. A plurality of antennas for receiving a plurality of code division multiple access signals, the plurality of code division multiple access signals received by the plurality of antennas being demodulated, and the plurality of code division multiple access signals being mutually demodulated. A multi-user receiving apparatus that performs interference cancellation processing in a plurality of stages to perform interference cancellation on the first signal group that satisfies a preset condition among the plurality of code division multiple access signals. Inputting the interference cancellation residual signal for each antenna obtained in the interference cancellation processing in the previous stage and the symbol replica corresponding to the same user signal in the previous stage, and the antenna directivity unique to each user signal in each stage of the interference cancellation processing At the same time, demodulates, generates a current-stage symbol replica and transmits it to the next stage, and compares the current-stage symbol replica with the previous-stage symbol replica. The spread signal related to the difference is converted and output for each antenna, and the output signal is subtracted from the interference removal residual signal for each previous antenna to update the interference removal residual signal for each antenna at the current stage to remove interference. And the interference cancellation residual for each antenna in which each signal of the first signal group is removed at least once for a second signal group that does not satisfy the condition of the plurality of code division multiple access signals A multi-user receiving apparatus configured to receive a signal, receive the signal with an antenna directivity unique to each user signal, and demodulate the signal to thereby remove interference. 6. The first signal group is a signal group in which at least one of signal power, transmission rate, and required reception quality is high, and the second signal group is the signal power and the transmission rate. 6. The multi-user receiving apparatus according to claim 5, wherein at least one of the request reception quality and the required reception quality is a low signal group. 7. A plurality of antennas for receiving a plurality of code division multiplex access signals, the plurality of code division multiplex access signals received by the plurality of antennas are demodulated and the plurality of code division multiplex access signals are mutually transmitted. A multi-user receiving apparatus that performs interference cancellation processing in a plurality of stages to perform interference cancellation on the first signal group that satisfies a preset condition among the plurality of code division multiple access signals. Inputting the interference cancellation residual signal for each antenna obtained in the interference cancellation processing at the preceding stage and the symbol replica corresponding to the same user signal at the preceding stage, and inputting the antenna directivity unique to each user signal at each stage of the interference cancellation processing Means for receiving and demodulating at the same time, means for generating a symbol replica of the current stage and transmitting the symbol replica to the next stage, and a symbol replica of the current stage and the symbol replica of the preceding stage. Converting a spread signal relating to the difference from Rica for each antenna, outputting the converted signal, and subtracting the output signal from the interference cancellation residual signal for each preceding antenna to update the interference cancellation residual signal for each current antenna. Means for performing the interference elimination in the above, and an antenna in which each signal of the first signal group is eliminated at least once with respect to a second signal group of the plurality of code division multiple access signals that does not satisfy the condition. Means for receiving the interference cancellation residual signal for each user signal, receiving the demodulated signal with an antenna directivity unique to each user signal, and demodulating the received signal, thereby removing the interference. 8. The first signal group is a signal group in which at least one of signal power, transmission rate, and required reception quality is high, and the second signal group is the signal power and the transmission rate. 9. The multi-user receiving apparatus according to claim 8, wherein at least one of the request reception quality and the required reception quality is a low signal group. 9. A plurality of antennas for receiving a plurality of code division multiplex access signals, the plurality of code division multiplex access signals received by the plurality of antennas being demodulated, and the plurality of code division multiplex access signals are mutually transmitted. A multi-user receiving apparatus that performs interference cancellation in a plurality of stages, and receives an interference cancellation residual signal for each antenna obtained in the interference cancellation process in the previous stage and a symbol replica corresponding to the same user signal in the previous stage, At each stage of the interference removal processing, each user signal is received and demodulated with an antenna directivity unique to each user signal, a current-stage symbol replica is generated and transmitted to the next stage, and the current-stage symbol replica and the previous-stage symbol are reproduced. An interference estimating unit that converts a spread signal related to a difference from a replica for each antenna and outputs the converted signal; Therefore, the first unit updates the interference removal residual signal for each antenna at the current stage by subtracting the output of the interference estimating unit of each stage of each signal of the first signal group from the signal delayed by a predetermined value for each antenna. A subtractor corresponding to each stage of each signal of a first signal group that satisfies a preset condition of the plurality of code division multiple access signals, and each signal of the first signal group. A demodulation unit that receives the interference cancellation residual signal for each antenna that has been removed at least once and receives and demodulates and outputs the user signal with an antenna directivity unique to each user signal for each of the second signal groups that do not satisfy the above condition. A multi-user receiving apparatus having a function corresponding to a signal. 10. The first signal group is a signal group in which at least one of a signal power, a transmission rate, and a required reception quality is high, and the second signal group is a signal group including the signal power and the transmission rate. 10. The multi-user receiving apparatus according to claim 9, wherein at least one of the request reception quality and the required reception quality is a low signal group. 11. The interference estimating unit includes a plurality of path unit processing units corresponding to a multipath propagation path including a plurality of paths, and inputs the interference removal residual signal for each of the preceding antennas, and First despreading means for performing despreading on the first
A first multiplier for weighting the output of the despreading means for the antenna, a first adder for synthesizing the output of the first multiplier, and weighting the symbol replica corresponding to the same user signal at the preceding stage. A second multiplier for performing the operation, a second adder for adding the output of the first adder and the output of the second multiplier, and a transmission path for each path, the output of the second adder. A first detector that demodulates using the estimated value is disposed in each of the plurality of path unit processing units, and a third adder that combines outputs of the first detector for each path; And a decision unit for judging the output of the adder of No. 3 is shared by the plurality of path unit processing units, and multiplies the output of the decision unit by the transmission path estimation value for each path to generate a current-stage symbol replica. Output to the next stage
A second subtractor for subtracting the output of the second multiplier from the output of the third multiplier, a fourth multiplier for weighting the output of the second subtractor, A fifth multiplier for multiplying an output of the fourth multiplier by a normalized complex conjugate of a weight used in the antenna weighting, a spreading unit for spreading an output of the fifth multiplier for each antenna, 11. The multi-user receiving apparatus according to claim 9, wherein a fourth adder for adding an output of each path of the means for each antenna is provided in each of the plurality of path unit processing units. 12. An interference estimating unit corresponding to a first stage of each signal of the first signal group inputs an antenna reception signal as an interference cancellation residual signal for each antenna of the preceding stage, and outputs the same received signal to the same user signal of the preceding stage. Using 0 as a corresponding symbol replica, an interference estimator corresponding to the last stage of each signal of the first signal group outputs only a demodulated signal which is an output of the third adder, and performs subsequent interference estimation. The multi-user receiving apparatus according to claim 11, wherein the processing is not performed. 13. A demodulation unit corresponding to each signal of the second signal group includes a plurality of path unit processing units corresponding to a multipath propagation path including a plurality of paths, A second despreading unit for inputting an interference cancellation residual signal for each antenna from which each signal has been removed at least once and performing despreading for each antenna, and performing an antenna weighting on an output of the second despreading unit A sixth multiplier, a fifth adder that combines the outputs of the sixth multiplier, and a second detector that demodulates the output of the fifth adder using a transmission path estimation value for each path. And a sixth adder that combines the outputs of the second detector for each path is provided in common with the plurality of path unit processing units. 13. The multi-user receiving device according to claim 9, wherein the receiving device is a multi-user receiving device.