WO2000027062A1

WO2000027062A1 - Multi-user receiver

Info

Publication number: WO2000027062A1
Application number: PCT/JP1999/006079
Authority: WO
Inventors: Shousei Yoshida; Naoto Ishii; Akihisa Ushirokawa
Original assignee: Nec Corporation
Priority date: 1998-10-30
Filing date: 1999-11-01
Publication date: 2000-05-11
Also published as: JP2000138605A

Abstract

A multi-user receiver which receives CDMA user signals of mutually different transmission powers, modulates the user signals, and eliminates interference of the user signals. Antenna directivity control and interference elimination by a multi-user interference canceller are carried out for user signals having high transmission rates, out of the CDMA user signals having mutually different transmission rates and received by antennas (1-1 to 1-N) by interference eliminating sections (2-1 to 2-M) for the user signals having high transmission rates. An interference elimination residual signal for each antenna generated by (M-1)-stages interference elimination from the user signals having high transmission rates is inputted into demodulating sections (4-1 to 4-KL) for user signal having low transmission rates. The user signals having low transmission rates are received with the antenna directivities proper to the user signal having low transmission rates and demodulated. The demodulated signals of the user signals having low transmission rates are outputted from the demodulating sections.

Description

Description Multi-user receiver

Technical field:

The present invention relates to a multi-user receiving apparatus, and in particular, receives a plurality of code division multiple access (CDMA) user signals having different transmission powers from each other and receives each user signal. The present invention relates to a multi-user receiving apparatus capable of performing interference cancellation as well as signal demodulation.

Background technology:

The Code Division Multiple Access (CDMA) system has the potential to increase subscriber capacity and is expected to be applied to mobile communication cellular systems. However, on the receiving side, interference of other user signals that are accessed simultaneously is a problem.

There are two methods of removing such interference: 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 receiving apparatus f using interference weight control in a parallel multi-stage configuration has been proposed. This multi-user receiving apparatus 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, and data signals. Such signals have different information transmission rates and different required reception qualities. Assuming the same required reception quality for each user signal with a different transmission rate, a user signal with 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 great 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 using an adaptive antenna to remove the interference of other user signals only by antenna directivity control, if the number of user signals is large in a single transmission rate CDMA system and they are evenly distributed in the cell, However, almost the same reception quality can be obtained for each user signal regardless of the positional relationship.

However, in a CDMA system that multiplexes user signals of multiple transmission rates, if user signals with different transmission rates are located in the same direction from the beginning, the transmission rate is determined by the antenna directivity toward the user signal with a lower transmission rate. High-rate user signals are also received, and high-rate user signals cause great interference with low-rate user signals. That is, the reception quality of each user signal fluctuates greatly depending on its positional relationship, and the overall system characteristics deteriorate.

A multi-user spatio-temporal interference canceller that organically combines an adaptive antenna and a multi-user interference canceller has been proposed. This technology is described in "CD MA Multi-Choose Spatio-Temporal Interference Cancellation Method" (Ishii, Yoshida, and Gogawa, 1989, IEICE General Conference, B-5-126, pp. 489) ).

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

When a multi-user spatio-temporal interference canceller is used, even in a CDMA system in which user signals of multiple transmission rates are multiplexed, interference of user signals in the same direction and at a high rate that cannot be eliminated by antenna directivity control is a multi-user interference canceller. Therefore, interference of a high-rate user signal with a low-rate user signal caused by the positional relationship of each user signal can be suppressed.

Figure 1 shows the configuration for receiving user signals at multiple transmission rates using a multi-user spatiotemporal interference canceller. In this configuration, interference of user signals at different transmission rates is eliminated. There is no distinction in the destruction processing, and mutual space-time interference cancellation is performed. For simplicity, the user signals at multiple transmission rates are assumed to be high-rate user signals and low-rate user signals, and the numbers of user signals are denoted by KH and KL, respectively.

Assuming that the number of antennas is N (N is an integer of 1 or more), antennas 101—1 to 101—N receive the CDMA signal, and the interference of the first-stage interference cancellation processing section 102-1 of the high-rate and low-rate user signals. Estimation unit (IEU: Interference Estimation Unit)〗 03-1-1 to 103-1-KH, 104-1-1 to 104-1-Output to KL.

M (M is an integer equal to or greater than 2) When the interference cancellation processing units 102—1 to 102—M of the stage are formed, the interference cancellation processing units 102—1 to of each stage: The interference estimation unit 103 of I 02—M 1 1 1 to 103— 1— KH,…, 103-M- 1-103-M-KH, 104-1 1 1 to 104— 1—KL,…, 104-M- 1 to 104— M— KL is Input 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 receive and demodulate each stage with the antenna directivity unique to each user signal. At the same time, a symbol replica of the current stage is generated and transmitted to the next stage.

At the same time, the interference estimator 103-1—! 103- 1— KH, ···, 103— M— 1 to 103-M— KH, 104_ 1-] to 104— 1—KL,…, 104-M- 1 to 104— M— KL is the current stage A spread signal related to the difference between the symbol replica of the previous stage and the symbol replica of the preceding stage is converted and output for each antenna.

Delay device 105—1—1 to 105—1—N, ···, 105- (M-1) — 1 to: L 0 5— (M-1) —N is the interference cancellation residue for each received signal or antenna The difference signal is calculated by the interference estimator 103—1-1—1 to 103—1—KH,…, 103—M—1 to 103—M—KH, 104—1-1—104—1—KL,…, 104—M — 1 to: L 04-M — Delay until the KL processing result is output.

Subtractor 106— 1—1 to 106— 1—N,..., 106- (M−1) 1 1 to: I 06— (M−1) —N is the value of each stage of each user signal. Interference estimator 103—1—1 to 103 -1 -KH, ···, 103— M— 1 to: 103— M— KH, 104— 1— 1 to 104 1—KL,…, 104-M-1 to 104— M— KL It is subtracted for each antenna to obtain an interference cancellation residual signal for each antenna at the current stage. The final stage interference estimator 103-M-1 to 103-M-KH, 104-M-1 to 104-M-KL outputs demodulated signals of high-rate and low-rate user signals.

Interference estimator 103—1-1—103—1—KH, ···, 103—M—1–103—M—KH and 104—1-1—104—1—KL, ··· , 104-M-1 to 104-M-KL are 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 111-1-11-N inputs the interference cancellation residual signal for each antenna at the preceding stage and despreads to antenna i. The multipliers 12—1 to 12—N weight the antenna by multiplying the outputs of the despreading means 11—1 to 11—N by weights wl to wN.

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. The adder 15 adds the output of the adder 13 and the output of the multiplier 14.

The detector 16 demodulates the output of the adder 15 using the transmission path estimation value in units of paths (# 1 to #L). The detector 16 is composed of a transmission path estimating means 17, a complex conjugate means 18, and a multiplier 19, and performs synchronous detection and demodulation and weights for realizing maximum ratio combining of a plurality of paths (# 1 to #L). Has the role of performing

The adder 20 combines the outputs of the detector 16 for each pass (# 1 to #L). The determiner 21 determines the output of the adder 20. The multiplier 22 multiplies the output of the decision unit 21 by the transmission path estimation value for each path (# 1 to #L) to generate a symbol replica of the current stage, 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. Multiplier 25-1-25—N is a complex conjugate weight w obtained by normalizing the weight used for antenna weighting to the output of multiplier 24 by the number of antennas. Multiply by 1 * / N to wN * / N.

The spreading means 26-1 to 26-N spreads the output of the multipliers 25-1 to 25-N for each antenna. Adder 2 7— 1 to 2 7— N is each path of spreading means 2 6— 1 to 26—N

The outputs of (# 1 to #L) are added for each antenna.

Here, the first stage interference estimator 10 3--1—1 to 1 to 10 3—1— KH, 10 4-1-1 to 10 4— 1-KL is the residual noise of each previous antenna. An antenna reception signal is input as a signal, and 0 is used as a symbol replica corresponding to the same user signal at the previous stage.

The final stage interference estimator 10 3— M—1 to 10 3— M—KH, 10 4— M—1 to 10 4 -M- KL uses only the demodulated signal output from the adder 20. Output and do not perform subsequent interference estimation processing. In the final stage, the process of updating the interference cancellation residual signal is not performed. As the weights wl to wN 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 factors to be multiplied by the multiplier 14 and the multiplier 24 are, for example, 11 (1—hi) m−1 (hi is a real number less than 1; You. These coefficients have the effect of relaxing the interference elimination operation. Instead of removing all the interference components in the first stage, the interference components are gradually eliminated in multiple stages.

In other words, in the first stage where the channel estimation error and the decision symbol error are large, the interference cancellation operation is relaxed to suppress the interference cancellation error, and the transmission channel estimation error and the decision symbol error are improved. It is possible to optimize the interference elimination characteristics at the same time. In particular, in a parallel type multi-user receiver, this interference weight control is very effective, and various methods can be considered for weighting the interference weight control.

In the conventional multi-user receiving apparatus described above, spatio-temporal interference is removed without distinction for each user signal having a different transmission rate, and uniform excellent reception quality can be realized for each user signal. Since the number of despreading means and spreading means occupying a large part of the processing amount in the interference estimator increases in proportion to the number of antennas, The scale becomes huge.

DISCLOSURE OF THE INVENTION:

The present invention has been made in view of the above-mentioned problems in the prior art, and has as its object to provide a multi-user receiving apparatus capable of obtaining a large interference removing effect with a relatively small apparatus scale. Is to do.

To achieve the above object, according to a first aspect of the present invention, there are provided a plurality of antennas for receiving a plurality of code division multiplex access signals, wherein the plurality of code division multiplexes received by the plurality of antennas are provided. A multi-user receiving apparatus that demodulates an access if signal and cancels interference between the plurality of code division multiple access signals, wherein a predetermined condition among the plurality of code division multiple access signals is satisfied. No.

One signal group is subjected to antenna directivity control and interference removal by a multi-user interference canceller, and the antenna directivity of a second signal group of the plurality of code division multiple access signals that does not satisfy the above condition is determined. Provided is a multi-user receiver configured to perform interference cancellation only by sex control.

According to a second aspect of the present invention, there are provided a plurality of antennas for receiving a plurality of code division multiplex access signals, wherein the plurality of code division multiplex access signals received by the plurality of antennas are demodulated and the plurality of antennas are received. A multi-user receiving apparatus that removes interference between code-division multiplexed access signals, wherein a first signal group satisfying a preset condition among the plurality of code-division multiplexed access signals is provided. Means for performing antenna directivity control and interference cancellation using 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 above condition. And a multi-user receiving device comprising:

According to a third aspect of the present invention, there are provided a plurality of antennas for receiving a plurality of code division multiplex access signals, wherein the plurality of code division multiplex access signals received by the plurality of antennas are demodulated and the plurality of antennas are received. A multi-user receiving apparatus for performing interference cancellation processing at a plurality of stages on each of the code division multiplex access signals to remove interference. A second one satisfying a preset condition of the plurality of code division multiple access signals;

For one signal group, 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 previous stage are input, and at each stage of the interference cancellation processing, Each user signal is received and demodulated with an antenna directivity unique to the user signal, and a current-stage symbol replica is generated and transmitted to the next stage. Spreading is performed on the difference between the current-stage symbol replica power and the previous-stage symbol replica. The signal is converted for each antenna and output, and the output signal is subtracted from the interference cancellation residual signal for each preceding antenna to update the interference cancellation residual signal for each antenna at the current stage to perform interference cancellation. An interference removal residual for each antenna, in which each signal of the first signal group is removed at least once from a second signal group that does not satisfy the above condition among the plurality of code division multiplexed access signals. Signal And force, to each user signal multiuser receiving device configured to perform interference cancellation by receiving and demodulating a unique antenna directivity is provided.

According to a fourth aspect of the present invention, there are provided a plurality of antennas for receiving a plurality of code division multiplex access signals, demodulating the plurality of code division multiplex access signals received by the plurality of antennas, and A multi-user receiving apparatus for performing interference cancellation processing at a plurality of stages on each of the code division multiplex access signals, thereby satisfying a preset condition among the plurality of code division multiplex access signals. Inputting the interference cancellation residual signal for each antenna obtained by the interference cancellation processing at the previous stage and the symbol repetition power corresponding to the same user signal at the previous stage to the first signal group, Means for receiving and demodulating each user signal with an antenna directivity specific to each user signal at the stage, 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. A spread signal relating to the difference from the symbol replica at the preceding stage is converted and output for each antenna, and the output signal is subtracted from the interference cancellation residual signal for each antenna at the preceding stage to obtain an interference cancellation residual for each antenna at the current stage. Means for performing the interference removal by updating signals; and each signal of the first signal group is compared with a second signal group of the plurality of code division multiple access signals that does not satisfy the condition. Antenna directivity unique to each user signal by inputting the interference cancellation residual signal for each antenna that has been eliminated at least once And a means for performing the interference removal by receiving and demodulating the multi-user signal.

According to a fifth aspect of the present invention, there are provided a plurality of antennas for receiving a plurality of code division multiplex access signals, wherein the plurality of code division multiplex access signals received by the plurality of antennas are demodulated and the plurality of antennas are received. A multi-user receiver that removes interference at multiple stages for each code-division multiplexed access signal, corresponding to the interference cancellation residual signal for each antenna obtained by the interference cancellation process at the previous stage and the same user signal at the previous stage Symbol replicas to be received, and at each stage of the interference removal processing, receive and demodulate each user signal with antenna directivity unique to each user signal, generate a symbol replica of the current stage, and transmit it to the next stage. An interference estimating unit that converts and outputs a spread signal related to a difference between a current-stage symbol replica and the preceding-stage symbol replica for each antenna; The output of the interference estimating unit of each stage of each signal of the first signal group is subtracted for each antenna from the signal obtained by delaying the interference cancellation residual signal by a predetermined value by the delay unit, and the output of each of the current stage antennas is subtracted. A first subtractor for updating the interference removal residual signal, corresponding to each stage of each signal of the first signal group that satisfies a preset condition among the plurality of code division multiplexed access signals. 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 corresponding to each signal of the second signal group that does not satisfy the condition, Provided is a multi-user receiving apparatus including a demodulation unit that receives and demodulates and outputs the signal with antenna directivity unique to the signal.

That is, in a CDMA system in which multiple user signals with different transmission powers are multiplexed, user directivity control is performed on user signals with high transmission power and interference cancellation is performed by a multiplier interference canceller, and user signals with low transmission power are removed. By performing interference elimination only with antenna directivity control, a large interference elimination effect can be obtained with a relatively small device scale.

In particular, in a CDMA system that multiplexes a plurality of user signals with different transmission rates from each other, the multi-user interference canceller removes the interference of user signals in the same direction and high-speed rate that cannot be removed by antenna directivity control. By low By giving priority to the interference of the high-rate user signal with respect to the high-rate user signal, excellent interference cancellation performance can be easily realized.

According to the present invention having the above aspects, the present invention includes a plurality of antennas for receiving a plurality of code division multiplex access signals, demodulates a plurality of code division multiplex access signals received by the plurality of antennas, and a plurality of code division In a multi-user receiving apparatus that performs interference cancellation for multiple access signals in a plurality of stages, an antenna direction for a first signal group that satisfies a preset condition among a plurality of code division multiplexed 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 the second signal group that does not satisfy the conditions among multiple 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.

The above as well as many objects, aspects, and advantages of the present invention will be described with reference to the following detailed description, which illustrates, by way of example, preferred embodiments in accordance with the principles of the invention and the accompanying drawings. This will reveal who is skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. 1 is a block diagram showing a configuration example of a conventional multi-user receiving apparatus, FIG. 2 is a block diagram showing a configuration of a multi-user receiving apparatus according to an embodiment of the present invention, and FIG. 3 is a high-speed rate shown in FIG. FIG.

FIG. 4 is a block diagram showing the configuration of the demodulation unit for the low-rate user signal shown in FIG. 2, and

FIG. 5 is a block diagram showing a configuration of a multi-user receiving apparatus according to another embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 2 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 one embodiment of the present invention performs conventional multi-user spatio-temporal interference cancellation on a high-rate user signal, and shifts a low-rate user signal to the final stage of a high-rate user signal. Only the antenna directivity control is performed using the interference cancellation residual signal as an input, that is, a signal in which the high-rate user signal is removed from the received signal.

In a CDMA system where multiple user signals with different transmission rates are multiplexed, the number of high-rate user signals is small, but the influence of the interference is large. Conversely, the effect of low-rate user signal interference is small, but large. Therefore, in the multi-user receiving apparatus according to one embodiment of the present invention, by omitting the operation of the multi-user interference canceller for each low-rate user signal, it is possible to minimize the decrease in the interference removal performance, thereby reducing the processing amount. It can be significantly 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), when antennas 1-1 to 1-N receive a CDMA signal, a high-rate user signal is transmitted. Output to the interference estimation unit (IEU: Interference Estimation Unit) 3-1-1-3 -1-KH of the first stage interference cancellation processing unit 2-1.

M (M is an integer equal to or greater than 2) Interference cancellation processing unit 2-1 to 2— When M is formed, the noise estimation unit for each stage in a high-rate user signal 3-1 to 1 to 3—1 -KH, ···, 3— M— :! ~ 3—M—KH inputs 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 each user in each stage of the interference cancellation processing. It receives and demodulates the signal with its own antenna directivity, generates a symbol replica of the current stage, and transmits it to the next stage.

At the same time, the interference estimator 3-1-1 to 3-1-KH,..., 3_M-1 to 3-M-KH Convert and output for each antenna.

Delay device 5—1—1 to 5—1—N,…, 5— (M-1) —1 to 5— (M—1) —N is the received signal Estimation unit 3—1 1 1 33—1—KH,…, 3—M—Delay until the processing result of 1—3—M—KH is output. Subtractor 6—1—1 to 6—1—N,..., 6— (M—1) -1-6- (M−1) −1N is an interference estimator for each signal of each user signal. 1— 1 to 3— 1— ΚΗ, ···,

3— Μ— Reduce the output of 1 to 3_Μ_ΚΗ for each antenna to obtain the interference cancellation residual signal for each antenna at the current stage. Last-stage interference estimator 3— Μ— :! ~ 3-Μ-ΚΗ output the demodulated signal of each high-speed user signal.

Also, the demodulation unit (DEM: Demodulation unit) for low-rate user signals 4-1 to 4-1-1 KL is for each antenna obtained by the M-1 stage interference cancellation processing for the high-rate user signal. And outputs the demodulated signal of each user signal at a low speed rate by receiving the demodulated interference cancellation residual signal and receiving and demodulating the antenna directivity unique to each user signal.

Fig. 3 shows the interference estimators 3-1-1 to 3-1-1 KH, ..., 3-M-1-3-M-KH at each stage in the high-rate user signal shown in Fig. 2. FIG. 4 is a block diagram showing a configuration, which is the same as the above-described conventional example. In FIG. 3, the interference estimating units 3-1-1-1-1-KH,..., 3-M-1-3-M-KH at each stage in a high-rate user signal Interference estimator for high-rate and low-rate user signals 103—1-1—: L 03—1—KH,. ~ 103—M—KH, 104-1—1—: L 04—1—KL,..., 104—M—1—104—M—KL has the same configuration as multiple M 1 to #L), and a plurality of path unit processing units are provided corresponding to multipath transmissions consisting of

Despreading means 11-1 to I-1N receive the interference cancellation residual signal for each antenna at the preceding stage and perform despreading for each antenna. The multipliers 12-1 to 12-N perform antenna weighting by multiplying the outputs of the despreading means 11-1 to 11-1N by weights wl to wN.

The detector 16 uses the output of the adder 15 as the transmission path estimate for each path (# 1 to #L). And demodulate. 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). Has the role of performing

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. The multiplier 25-1-25-N multiplies the output of the multiplier 24 by complex conjugate weights w 1 * / N to wN * / N obtained by normalizing the weight used in the antenna weighting by the number of antennas.

The spreading means 26-1 to 26-N spread the output of the multiplier 25-1-25-1N for each antenna. Adder 27- 1 to 27- -N is each path of diffusion means 26- 1 to 26-N

The outputs of (# 1 to #L) are added for each antenna.

Here, the first-stage interference estimator 3-1—1 1 to 3_1—KH receives the antenna reception signal as the interference cancellation residual signal for each antenna in the previous stage, and outputs 0 as a symbol replica corresponding to the same user signal in the previous stage. Is used. The final-stage interference estimator 3—M—1 to 3-—M-KH outputs only the demodulated signal output from the adder 20, and does not perform the subsequent interference estimation processing. In the final stage, the process of updating the interference cancellation residual signal is not performed.

As the weights wl to wN 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 multiplier 14 and the multiplier 24 are, for example, eleven (1 −) m−1 (that is, a real number equal to or less than 1, m is an integer of 2 or more and M or less) and hi.

FIG. 4 is a demodulation unit 41 for the low-rate user signal shown in FIG. 4 is a block diagram illustrating a configuration of 4_KL. FIG. In FIG. 4, 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 51-1-51-1N inputs the interference cancellation residual signal for each antenna obtained by the M-1 stage interference cancellation processing for the high-rate user signal, and performs despreading for each antenna. The multipliers 52—1 to 52—N weight the output of the despreading means 51-1-51—N with the antenna.

The adder 53 is a multiplier 52—! ~ 52—N output is synthesized. 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 ίΓ′ίΓ signal.

Weights wl to wN to be multiplied to perform antenna directivity control use steering antenna weights and adaptive control weights determined separately based on the estimation of the direction of arrival of the user signal.

FIG. 5 is a block diagram showing a configuration of a multi-user receiving apparatus according to another embodiment of the present invention. In FIG. 5, a multi-user receiving apparatus according to another embodiment of the present invention is a demodulation unit (DEM: Demodulation Unit) for low-speed user signals. Input the interference cancellation residual signal for each antenna obtained in the first stage interference cancellation processing, receive and demodulate with the antenna directivity unique to each user signal, and output the demodulated signal of each low-rate user signal The configuration is the same as that of the multi-user receiving apparatus according to the embodiment of the present invention except that the configuration is performed, and the same components are denoted by the same reference numerals. The operation of the same component is the same as that of the above-described embodiment of the present invention.

In the multi-user receiving apparatus according to an embodiment of the present invention, demodulation of a low-rate user signal is performed by inputting an interference cancellation residual signal for each antenna obtained by M−1-stage interference cancellation processing of a high-rate user signal. Therefore, there is a delay due to 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 and the device mounting method, and is generally not negligible. In the CDMA system, high-speed closed-loop transmission power control is used, so if there is a demodulation delay, its characteristics are greatly degraded.

Therefore, it is necessary to keep this delay as small as possible. Other embodiments of the present invention In this embodiment, as in the embodiment of the present invention, the multi-user space-time interference is removed for the high-rate user signal, and only the antenna directivity control is performed for the low-rate user signal. For the input, the interference cancellation residual signal for each antenna obtained by the interference cancellation processing at the first stage of the high-rate user signal is used.

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

It should be noted that, in addition to the configuration of the above-described embodiment of the present invention and other embodiments, an input for demodulation of a low-rate user signal can be obtained by interference removal processing of an arbitrary stage of a high-rate user signal. A configuration using the interference cancellation residual signal for each antenna 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 reception quality of each user signal is different or when the transmission power of each user signal is different for other reasons.

As described above, in a CDMA system in which a plurality of user signals having different transmission powers are multiplexed, the transmission power is large, the user signal is subjected to antenna directivity control and interference cancellation is performed by a multi-user interference canceller. By performing interference cancellation for only a small user signal using only the antenna directivity control, a large interference cancellation effect can be obtained with a relatively small equipment scale.

In particular, in a CDMA system that multiplexes a plurality of user signals with different transmission rates from each other, the multi-user interference canceller removes interference of high-rate user signals in the same direction that cannot be eliminated by antenna directivity control, thereby reducing the low-speed rate. Therefore, it is possible to preferentially suppress interference of a high-rate user signal with respect to another user signal, and it is possible to easily achieve excellent interference removal performance.

In addition, the demodulation delay can be reduced by demodulating the low-rate user signal with the interference cancellation residual signal obtained by the first-stage interference cancellation processing of the high-rate user signal as input.

Claims

The scope of the claims

1. A plurality of antennas for receiving a plurality of code division multiplex access signals, demodulation of the plurality of code division multiplex access signals received by the plurality of antennas, and interference with the plurality of code division multiplex access signals What is claimed is: 1. A multi-user receiver for canceling, wherein an antenna directivity control and a multi-user interference canceller for a first signal group satisfying a preset condition among the plurality of code division multiplex access signals are performed. A multi-user receiving apparatus configured to perform interference cancellation only on antenna directivity control for a second signal group among the plurality of code division multiple access signals that does not satisfy the condition. .

2. The first signal group is a signal group in which at least one of transmission power, transmission rate, and required reception quality is high, and the second signal group is the transmission power, the transmission rate, and the required signal quality. 2. The multi-user receiving apparatus according to claim 1, wherein at least one of the reception quality is a low signal group.

3. It has a plurality of antennas for receiving a plurality of code division multiple access signals, demodulates the plurality of code division multiple access signals received by the plurality of antennas, and interferes with the plurality of code division multiple access signals. What is claimed is: 1. A multi-user receiver for canceling, wherein an antenna directivity control and a multi-user interference canceller for a first signal group satisfying a preset condition among the plurality of code division multiplex access signals are performed. And a means for performing interference elimination only on antenna directivity control for a second signal group of the plurality of code division multiplexed access signals that does not satisfy the condition. User receiving device.

4. The first signal group is a signal group in which at least one of transmission power, transmission rate, and required reception quality is high, and the second signal group is the transmission power, the transmission rate, and the transmission rate. 4. The multi-user receiving apparatus according to claim 3, wherein at least one of the required reception quality is a low signal group.

5. Equipped with a plurality of antennas for receiving a plurality of code division multiple access signals, A multi-user receiving apparatus for demodulating the code-division multiplexed access signals of the number of received signals received by the plurality of antennas and performing interference elimination processing on the plurality of code-division multiplexed access signals at a plurality of stages to remove interference. A first signal group satisfying a preset condition among the plurality of code division multiplexed access signals, and an interference removal residual signal for each antenna obtained by interference removal processing of a preceding stage and a preceding stage. And a symbol replica corresponding to the same user signal is received, demodulated and received at each stage of the interference removal processing with an antenna directivity unique to each user signal, and a symbol replica of the current stage is generated. The signal is transmitted to the next stage, and a spread signal relating to the difference between the current stage symbol replica and the previous stage symbol replica is converted and output for each antenna. The interference cancellation is performed by subtracting from the interference cancellation residual signal for each antenna in the stage and updating the interference cancellation residual signal for each antenna in the current stage, thereby satisfying the condition of the plurality of code division multiplexed access signals. Inputting the interference cancellation residual signal for each antenna from which each signal of the first signal group has been removed at least once for the second signal group that is not received, and receiving the user signal with an antenna directivity unique to each user signal A multi-user receiving apparatus configured to perform interference removal by demodulation.

6. The first signal group is a signal group in which at least one of transmission power, transmission rate, and required reception quality is high, and the second signal group is the transmission power and the transmission rate. 6. The multi-user receiving apparatus according to claim 5, wherein at least one of the required 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, wherein the plurality of code division multiplex access signals received by the plurality of antennas are demodulated, and a plurality of A multi-user receiving apparatus that performs interference cancellation processing at a stage and performs interference cancellation, wherein a first signal group that satisfies a preset condition among the plurality of code division multiplex access signals is provided at a stage preceding the first group. The interference removal residual signal for each antenna obtained by the interference removal processing and the symbol replica corresponding to the same user signal at the previous stage are input, and the antenna directivity specific to each user signal is obtained at each stage of the interference removal processing. Means for receiving and demodulating with Means for generating a precursor and transmitting the signal to the next stage; converting a spread signal relating to the difference between the current-stage symbol level power and the previous-stage symbol replica for each antenna, and outputting the output signal; and outputting the output signal to the preceding-stage antenna. Means for performing the interference cancellation by updating the interference cancellation residual signal for each antenna at the current stage by subtracting from the interference cancellation residual signal for each antenna, and satisfying the condition of the plurality of code division multiple access signals. For the second signal group, the interference signal of each antenna from which the snow signal of the first signal group has been removed at least once is input and received with an antenna directivity unique to each user signal. Means for removing the interference by demodulation.

8. The first signal group is a signal group in which at least one of transmission power, transmission rate, and required reception quality is high, and the second signal group is the transmission power and the transmission rate. 8. The multi-user receiving apparatus according to claim 7, 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 are demodulated, and a plurality of antennas are provided for the plurality of code division multiplex access signals. This is a multi-user receiver that performs interference cancellation at the stage, and inputs the interference cancellation residual signal for each antenna obtained by the interference cancellation process at the previous stage and the symbol replica corresponding to the same user signal at the previous stage. Receiving and demodulating each user signal with an antenna directivity unique to each user signal at each stage of the interference removal processing, generating a symbol replica of the current stage and transmitting it to the next stage, and transmitting the symbol replica of the current stage and the symbol replica of the previous stage. An interference estimating unit that converts a spread signal related to a difference from a symbol replica for each antenna and outputs the converted signal; Thus, the output of the interference estimating unit at each stage of each signal of the first signal group is subtracted for each antenna from the signal delayed by a predetermined value, thereby updating the interference removal residual signal for each antenna at the current stage. And one subtracter corresponding to each stage in each signal of a first signal group that satisfies a preset condition of the plurality of code division multiple access signals, Each antenna has at least one rejection of each signal. A demodulation unit for receiving the interference cancellation residual signal, receiving and demodulating the signal with an antenna directivity unique to each user signal, and outputting the demodulated signal corresponding to each signal of the second signal group that does not satisfy the above condition. Multi-user receiving device.

10. The first signal group is a signal group in which at least one of transmission power, transmission rate, and required reception quality is high, and the second signal group is the transmission power, the transmission rate, and the transmission rate. 10. The multi-user receiving apparatus according to claim 9, wherein at least one of 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 an interference cancellation residual signal for each of the preceding antennas and performs inverse processing for each antenna. First despreading means for spreading, a first multiplier for weighting an output of the first despreading means with an antenna, and a first adder for synthesizing an output of the first multiplier A second multiplier for weighting a symbol replica corresponding to the same user signal at the preceding stage, and a second multiplier for adding an output of the adder and an output of the second multiplier. An adder, and a first detector that demodulates the output of the second adder using the path estimation value in path units are disposed in each of the plurality of path unit processing units, and A third adder that combines the outputs of the first detector, and a determiner that determines the output of the third adder. A third multiplier that is arranged in common with the plurality of path unit processing units, multiplies the output of the decision unit by the transmission path estimation value for each path, generates a symbol replica of the current stage, and outputs the replica 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, and the fourth A fifth multiplier that multiplies the output of the multiplier by a normalized complex conjugate of the weight used in the antenna weighting; a spreading unit that spreads the output of the fifth multiplier for each antenna; 10. The multi-user receiving apparatus according to claim 9, wherein a fourth adder for adding an output of each path for each antenna is provided in each of the plurality of path unit processing units.

12. The interference estimating unit includes a plurality of path unit processing units corresponding to a multipath propagation path including a plurality of paths, and receives the interference cancellation residual signal for each preceding antenna. A first despreading means for performing despreading every time, a first multiplier for weighting an output of the first despreading means with antenna weight, and a second demultiplexing means for synthesizing an output of the first multiplier. 1), a second multiplier for weighting the symbol replica corresponding to the same user signal at the preceding stage, and an output of the first adder and an output of the second multiplier. A second adder that performs demodulation by using a transmission path estimation value for each path, and a first detector that demodulates the output of the second adder to each of the plurality of path unit processing units. A third adder that combines the outputs of the first detector for each of the first and second detectors; and a determiner that determines the output of the third adder. A third multiplier for multiplying the output of the multiplier by the transmission path estimation value for each path to generate a symbol replica of the current stage and outputting the replica 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; and the fourth multiplication A fifth multiplier for multiplying the output of the multiplier by the complex conjugate of the weight used in the antenna weighting; a spreading unit for spreading the output of the fifth multiplier for each antenna; 10. The multi-user receiving apparatus according to claim 10, wherein a fourth adder for adding the output of each path for each antenna is provided in each of the plurality of path unit processing units.

13. The interference estimating unit corresponding to the first stage in each signal of the first signal group inputs an antenna reception signal as an interference cancellation residual signal for each antenna in the preceding stage, and corresponds to the same user signal in the preceding stage. The interference estimating unit corresponding to the last stage of each signal of the first signal group outputs only the demodulated signal which is the output of the third adder, and 0 12. The multi-user receiving apparatus according to claim 11, wherein the apparatus is configured not to perform processing.

14. The interference estimating unit corresponding to the first stage in each signal of the first signal group inputs an antenna reception signal as an interference cancellation residual signal for each antenna in the preceding stage, and corresponds to the same user signal in the preceding stage. The interference estimating unit corresponding to the last stage of each signal of the first signal group outputs only the demodulated signal which is the output of the third adder, and 0 It is noted that no processing is performed. 13. The multi-user receiving device according to claim 12, wherein:

15. The 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, and each signal of the first signal group. A second despreading means for inputting an interference cancellation residual signal for each antenna from which the 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 means A sixth multiplier, a fifth adder that synthesizes the output of the sixth multiplier, and a second adder that demodulates the output of the fifth adder using a channel estimation value on a path basis. A detector is disposed in each of the plurality of path unit processing units, and a sixth adder that combines the outputs of the second detector for each path is disposed in common with the plurality of path unit processing units. The multi-user receiving device according to any one of claims 9 to 14, characterized by: