JPH11266226A - Interference cancellation apparatus and method applied to CDMA communication system - Google Patents

Abstract

(57) [Summary] An object of the present invention is to shorten the calculation time of ranking processing and reduce the hardware scale and power consumption. SOLUTION: When transmission rate information for each user is known, in multipliers 2A1 to 2AK (K is the number of users), known transmission rate information for each user supplied from a base station control unit and a known requirement. Multiplied by the quality information, the sorting circuit 3 estimates the received power from the result of the multiplication, determines the ranking among the users, gives the ranking information to the first stage 4, and gives the first stage 4 to the final stage 6. The interference removal is performed sequentially up to.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interference canceling apparatus and a method applied to a communication system using a code division multiple access (CDMA) system for improving interference canceling characteristics in multipath transmission.

[0002]

2. Description of the Related Art In the CDMA system, different spreading codes are assigned to each user, and all users can simultaneously share the same frequency band for communication using the spreading codes. In this case, the signal of another user becomes an interference signal due to the cross-correlation of the spreading code assigned to each user. Therefore, mutual interference increases with an increase in the number of users, and reception characteristics deteriorate. As a technique for reducing the interference caused by the cross-correlation, a multi-stage serial interference canceller method (hereinafter, referred to as a serial interference canceller method) has been studied.

In the serial interference canceller system, transmission data is temporarily determined in descending order of received power, and an interference signal replica is generated on the receiving side based on the temporarily determined data.
By subtracting the interference signal replica from the received signal, the signal power to interference power ratio (SI
R) to improve reception characteristics.

According to this technique, in order to reduce the influence of the tentative decision error or the residual interference component on interference cancellation,
A loop that repeats the above-described operation several times by the user is required. Therefore, the above technique is called a serial interference canceller. In this serial interference canceller, it is necessary to perform channel estimation with high accuracy in order to reproduce an interference signal replica. For this purpose, a frame configuration in which pilot symbols are inserted into information data is used. The operation of performing channel estimation using the frame configuration is included in the above loop for interference cancellation. That is, the accuracy of channel estimation is improved by sequentially performing channel estimation for each stage.

FIGS. 16 and 17 show, for example, a C-type to which a conventional serial canceller, that is, an interference canceller shown in IEICE Technical Report RCS95-50 is applied.
A DMA receiving system is shown. As shown in FIGS. 16 and 17, the conventional CDMA receiving system has a sorting circuit 3, K (natural number) first stage to final stage 4, 5 to 6, and (K-1) delay circuits 7 , 8
…, K matched filters (MF) 20A1 to 20A
An interference elimination device having K and K level detectors 21A1 to 21AK, a decoding circuit 9, an SIR measurement block 10, and a TPC bit generator 11 are provided.

[0006] The sorting circuit 3 determines and sorts the ranking of the users (# 1 to #K) in descending order of the received signal level. First to last stage 4,5-6
Are connected in series to generate an interference signal replica based on the received signal, and sequentially perform interference cancellation according to the ranking. When outputting the received signal to the second stage 5 and subsequent stages, the delay circuits 7, 8,... Delay the interference signal replica generation processing time in the stages up to the previous stage. The decoding circuit 9 performs deinterleaving and Viterbi decoding based on the data decision values DJ1 to DJK output from the final stage 6.

[0007] The SIR determination block 10 determines the SIR based on each of the data determination values DJ1 to DJK output from the final stage 6. TPC bit generator 11
Determines a TPC bit value based on each determination result of the SIR determination block 10 and a target SIR prepared in advance. Here, the TPC bit indicates data transmitted to a mobile station on a downlink transmission signal. Matched filters (MF) 20A1 to 20AK detect correlation values for each user from the received signal and output level detectors 21A1 to 21AK.
21AK are matched filters 20A1 to 20A, respectively.
The level of the received signal is detected from the correlation value for each user detected by the AK and output to the sorting circuit 3 at the subsequent stage.

In each stage, a first stage 4 includes delay circuits 4A2, 4A3 to 4AK, and a subtractor 4B.
2, 4B3 to 4BK and first to Kth processing units 4C1, 4C2 to 4CK. Delay circuit 4A
2, 4A3 to 4AK input the received signal as it is as an error signal, and delay the output by the interference signal replica generation processing time of all the users whose processing order is earlier in the same stage. The subtractors 4B2, 4B3 to 4BK are
The processing order is first, and all interference signal replicas of users other than the user are subtracted from the output (received signal) of the delay circuit at the preceding stage and output.

The first to Kth processing units 4C1, 4C2
The 4CK performs despreading, channel estimation using pilot symbols, RAKE combining, and identification based on the received signals of the users ranked in descending order of the received signal level, and reproduces the interference signal replica. The output (interference signal replica) of each of the first to Kth processing units 4C1 and 4C2 to 4CK is not limited to the same stage, and also for the subsequent stages, the interference among the user-corresponding subtracters whose processing order is delayed. Supplied for everything that needs a replica.

Here, the received signal will be described. FIG.
FIG. 8 shows a frame configuration in which pilot symbols are inserted into information data. One frame is composed of pilot symbols, TPC symbols, and data symbols. One pilot block has a configuration in which the leading pilot symbol of the next block is added to the one frame, and its range includes a change before and after due to a phase shift as shown in FIG.

Next, the operation of the above CDMA receiving system will be described. FIGS. 16 and 17 show a case where the number of users is K (K is a natural number). Received signals are matched filters 20A1-2 corresponding to each user.
Input to 0AK. Each matched filter 20A1-2
At 0AK, a correlation value for each user is obtained, and the level detectors 21A1 to 21AK at the subsequent stage measure the received signal level for each user. Level detectors 21A1-21
When the received signal level of each user is measured by AK,
The measurement result is output to the sorting circuit 3. In the sorting circuit 3, the ranking is performed in descending order of the received signal level based on the input measurement result, and the transmission data is provisionally determined in that order.

An interference canceling unit including a plurality of stages (the first stage 4 to the final stage 6) is connected in series at the subsequent stage of the sorting circuit 3, and interference cancellation is sequentially performed at each stage. First, interference removal is performed from the first stage 4. In the first stage 4,
The first processing unit 4C1 is assigned to processing of a user signal (received signal) having the highest received signal level. When the user signal is input to the first processing unit 4C1, despreading, channel estimation using pilot symbols, RAKE combining and identification determination are performed therein.

Further, the decision value obtained in this way is re-spread for each path using the estimated value of the fluctuation of the transmission path, and an interference signal replica of the user signal having the highest received signal level is generated. This interference signal replica is supplied as an output of the first processing unit 4C1 to all the other processing units 4C2 to 4CK that are to be subsequently processed in the same stage. That is, the interference signal replica output from the first processing unit 4C1 is used for generating an interference signal replica with a user signal having a lower received signal level than the present user signal. At this time, it is used to generate an interference signal replica from a received signal of another user.

Here, the relationship between pilot symbols and data symbols used for channel estimation will be described. In each of the stages 4, 5 and 6, interference removal processing and interference signal replica generation are performed for each pilot block (see FIG. 18). For the data symbols between the pilot symbols, the estimated received fading complex envelope at the pilot symbol is interpolated, and for the data symbols outside the pilot symbol, the estimated received fading complex envelope at the pilot symbol is extrapolated, A received fading complex envelope at the data symbol position is determined. Thus, the second processing unit 4C of the first stage 4
2 is assigned to the user with the second highest received signal level.

The received signal is delayed by the delay circuit 4A2 by the processing delay of the first processing unit 4C1. Thereafter, the first user interference signal replica obtained by the first processing unit 4C1 by the subtractor 4B2 is subtracted from the received signal delayed by the delay circuit 4A2, and the output signal is input to the second processing unit 4C2. In the second processing unit 4C2, the same processing as in the above-described first processing unit 4C1 is performed, and an interference signal replica of the second user is output.

The third processing unit 4C3 of the first stage 4 is assigned to the user having the third highest received signal level. In the case of the third user, the received signal is delayed by the delay circuit 4A3 by the processing delay of the first and second processing units 4C1 and 4C2. Next subtractor 4
In B3, the interference signal replica of the first user and the interference signal replica of the second user are subtracted from the delayed received signal. The calculation result is the third processing unit 4C3
And the first and second processing units 4C described above.
The same processing as in 1, 4C2 is performed, and an interference signal replica of the third user is output. By repeating such an operation up to the K-th user, the interference signal replica generation processing in the processing units 4C1 to 4CK corresponding to all the users in the first stage 4 is completed.

Thereafter, in the second stage 5, an interference signal replica generation process is again performed on the received signals of all the users. The received signal is supplied to the second stage 5 after being delayed by the delay circuit 7 for the time required for the entire processing of the first stage 4. In the subtractor 5B1 after the delay circuit 7, the interference signal replicas of the second user, third user,..., Kth user in the first stage 4 are subtracted from the received signal (received pilot block). The calculation result is the first
The interference signal replica of the first user in the second stage 5 is output by being input to the processing unit 5C1 and performing the same processing as in each processing unit of the first stage 4.

The received signal delayed by the delay circuit 7 is further input to the subtracter 5B2 of the second stage 5 by the processing delay of the first processing unit 5C1 by the delay circuit 5A2. From signals, the interference signal replicas of the third to Kth users of the first stage 4 and the second
The interference signal replica of the first user in stage 5 is subtracted. The calculation result is input to the second processing unit 5C2, and an interference signal replica of the second user in the second stage 5 is generated.

The third user is given a second stage 5
Of the third processing unit 5C3. This third
In the case of a user, the received signal is delayed by the delay circuit 5A3 by the processing delay of the first and second processing units 5C1 and 5C2. In the next subtractor 5B3, the interference signal replica of the first user and the second
The user's replica of the interference signal is subtracted. The calculation result is input to the third processing unit 5C3, where the same processing as in the first and second processing units 5C1 and 5C2 is performed, and the interference signal replica of the third user is output. By repeating such an operation up to the K-th user, the first to K-th corresponding to all users in the second stage 5
The interference signal replica generation processing in the processing units 5C1 to 5CK is completed.

The processing is the same in the third and subsequent stages, and the processing in the final stage 6 will be described last. Also in the final stage 6, interference signal replica generation processing is performed again on the received signals of all users.
In the final stage 6, the received signal is supplied to delay circuits 7, 8,.
-1), and is supplied after being delayed by the time required for the entire processing of the first to K-1st stages. Final stage 6
Subtracter 6B1 subtracts the interference signal replicas of all users other than the first user from the received signal (received pilot block) delayed in the previous stage. The calculation result is the first
The interference signal replica of the first user in the final stage 6 is output by being input to the processing unit 6C1 and performing the same processing as the above-described processing units.

The received signal delayed in the preceding stage is further input to the subtractor 6B2 of the final stage 6 by the delay circuit 6A2 after being delayed by the processing delay of the first processing unit 6C1. Interference signal replicas of all users other than two users are subtracted. The operation result is input to the second processing unit 6C2, and the final stage 6
, A second user interference signal replica is generated.

Then, the third user receives the final stage 6
Of the third processing unit 6C3. This third
In the case of a user, the received signal is delayed by the delay circuit 6A3 by the processing delay of the first and second processing units 6C1 and 6C2. In the next subtractor 6B3, the interference signal replicas of all users other than the third user are subtracted from the delayed received signal. The calculation result is input to the third processing unit 6C3, where the same processing as in the first and second processing units 6C1 and 6C2 is performed, and a third user interference signal replica is output. By repeating such an operation up to the K-th user, the first stage to the K-th processing units 6C1 to 6C1 corresponding to all users in the final stage 6
The interference signal replica generation processing in 6CK is completed.

As described above, in each stage, the characteristic is improved by subtracting the interference signal replica of another user already generated in the previous stage from the received signal, so that the higher the further to the subsequent stage, the higher the characteristics. Channel estimation accuracy can be obtained. Therefore, in the final stage 6 described above, an output with the highest channel estimation accuracy, that is, data determination values DJ1 to DJK after the interference removal processing are obtained. The final stage 6 includes a decoding circuit 9 and an SIR
The measurement block 10 is connected, and the decoding circuit 9
Judgment value DJ for each user output from final stage 6
Deinterleaving and Viterbi decoding are performed based on 1 to DJK to obtain decoded data.

The data judgment values DJ1 to DJK are also supplied to the SlR measurement block 10, where the SIR of the received signal is measured for each user based on the data judgment values DJ1 to DJK of each user. SIR measurement block 1
The SIR of each user measured at 0 is output to a TPC bit generator 11 where the measured SI of the SIR
R is compared with a target SlR prepared in advance.
As a result, for a user having a measured SIR exceeding the target SIR, T is instructed to reduce the transmission power at the mobile station.
A PC bit is generated while the measured S below the target SIR
For a user having an IR, a TPC bit is generated to instruct the mobile station to increase the transmission power. The user-specific TPC bits generated in this manner are transmitted to the corresponding mobile station in a downlink transmission signal. The above processing is performed for each pilot block.

[0025]

Since the conventional interference canceller is configured as described above, the effect of the interference cancellation by the serial interference canceller is not limited to each of the stages 4, 5... 6 shown in FIGS. , It depends on from which user the despreading, channel estimation and interference replica generation processing are performed in order. Therefore, conventionally, in order to obtain the order, prior to the processing for each stage, the received signal powers of all the users are measured, ranking is given to the user having the largest measured value, and the order is obtained according to the ranking result. Was.

On the other hand, the measurement of the SIR used for the transmission power control has been performed based on the reception signal determination result of each user after all the interference cancellation processings have been completed. In other words, the received signal power measurement unit used for ranking has only the purpose of ranking. However, if the received signal power measurement unit uses the ranking process as its only application, the measurement of the received signal power and the ranking process based on it take a great deal of time. However, there is a problem that the hardware scale is increased and the power consumption is increased. Also, as shown in FIGS. 16 and 17, a received signal power measurement block is configured by matched filters 20A1 to 20AK and level detectors 21A1 to 21AK, and a measurement error of the received signal power is reduced due to mutual interference between users. There was a fear that it would grow.

According to the present invention, there is provided a CDM capable of shortening the calculation time of ranking processing and reducing the hardware scale and power consumption in order to solve the above-mentioned conventional problems.
An object of the present invention is to obtain an interference elimination device and a method applied to an A communication system.

[0028]

Means for Solving the Problems The above-mentioned problems are solved,
In order to achieve the object, an interference canceling apparatus applied to a CDMA communication system according to the present invention is applied to a CDMA communication system in which transmission rate information for each user is known, and users are sequentially assigned according to a given ranking between users. An interference canceling apparatus for canceling interference between the plurality of users is characterized by comprising ranking determining means for determining a ranking between users based on known transmission rate information for each user.

According to the present invention, when transmission rate information for each user is known, the ranking between users is determined based on the known transmission rate information for each user. Configuration is unnecessary,
As a result, it is possible to shorten the calculation time of the ranking process and reduce the hardware scale and power consumption.

An interference canceller applied to a CDMA communication system according to the next invention is applied to a CDMA communication system in which both transmission rate information and required quality information for each user are known, and ranking between users is given arbitrarily. In the interference canceling apparatus for sequentially canceling interference between users according to the above, a ranking determining means for determining a ranking between users based on known transmission rate information for each user and known required quality information is provided.

According to the present invention, when transmission rate information for each user is known, ranking between users is determined based on known transmission rate information for each user and known required quality information. This eliminates the need for a configuration for measuring the received signal power, thereby shortening the calculation time of the ranking process and reducing the hardware scale and power consumption.

An interference canceller applied to a CDMA communication system according to the next invention is applied to a CDMA communication system in which transmission rate information for each user is unknown, and sequentially inter-users according to a given ranking between users. In an interference canceller that performs interference cancellation, a plurality of interference cancellers that are connected by at least the number of stages corresponding to the number of users, perform interference cancellation based on a ranking arbitrarily given in each stage, and detect transmission rate information, And ranking updating means for updating an arbitrary ranking used in the next stage interference removing means based on the transmission rate information detected by each interference removing means.

According to the present invention, when transmission rate information for each user is unknown, interference removal is performed based on a ranking arbitrarily given in each stage at least by the number of stages corresponding to the number of users, and the transmission rate information is determined. To detect
Arbitrary rankings used in the next stage are updated based on the transmission rate information detected in each stage, eliminating the need to measure the received signal power even if the transmission rate information for each user is unknown. Accordingly, it is possible to shorten the calculation time of the ranking process and reduce the hardware scale and the power consumption.

An interference canceller applied to the CDMA communication system according to the next invention has a CDMA system in which transmission rate information for each user is unknown and required quality information is known.
Applied to a communication system, in an interference canceling device that sequentially cancels interference between users according to an arbitrarily given ranking between users, is connected by at least the number of stages corresponding to the number of users, and is based on an arbitrarily given ranking at each stage. A plurality of interference canceling means for performing interference canceling and detecting transmission rate information, and an arbitrary interference canceling means used in the next stage based on the transmission rate information detected by each of the interference canceling means and known required quality information. Ranking updating means for updating the ranking.

According to the present invention, when the transmission rate information for each user is unknown, at least the number of stages corresponding to the number of users performs interference cancellation based on a ranking arbitrarily given in each stage, and the transmission rate information To detect
Since any ranking to be used in the next stage is updated based on the transmission rate information detected in each stage and the known required quality information, the received signal power can be reduced even if the transmission rate information for each user is unknown. There is no need for a configuration to measure,
As a result, it is possible to shorten the calculation time of the ranking process and reduce the hardware scale and power consumption.

An interference canceller applied to a CDMA communication system according to the next invention is applied to a CDMA communication system in which a case where transmission rate information for each user is unknown and a case where the transmission rate information is known are mixed, and a user who is arbitrarily given a transmission rate information In an interference canceling apparatus for successively canceling interference between users according to the ranking between them, the interference canceling apparatus is connected at least by the number of stages corresponding to the number of users, performs interference cancellation based on a ranking arbitrarily given in each stage, and detects transmission rate information A plurality of interference canceling means; a ranking determining means for determining a ranking among users based on known transmission rate information for each user; and a next stage interference canceling apparatus based on the transmission rate information detected by each of the interference canceling means. A ranking updating means for updating an arbitrary ranking used by the means, and when the transmission rate information is known, Serial Select ranking determining means used, whereas, wherein the transmission rate information is provided with a selection means for selecting and using the ranking update means when unknown.

According to the present invention, when the transmission rate information for each user is unknown and known, the transmission rate information is based on a ranking arbitrarily given in each stage, at least by the number of stages corresponding to the number of users. Performs interference cancellation and detects transmission rate information, determines the ranking between users based on the known transmission rate information for each user when the transmission rate information is known, and when the transmission rate information is unknown, Arbitrary ranking used in the next stage is updated based on the transmission rate information detected in each stage, so the received signal power is measured whether the transmission rate information for each user is unknown or known This eliminates the need for such a configuration, thereby shortening the calculation time of the ranking process and reducing the hardware scale and power consumption.

An interference canceller applied to a CDMA communication system according to the next invention is a CDMA communication system in which transmission rate information for each user is unknown and known, and required quality information is known. And an interference canceller that sequentially removes interference between users according to an arbitrary ranking between users, is connected at least by the number of stages corresponding to the number of users, and cancels interference based on the ranking arbitrarily given in each stage. And a plurality of interference canceling means for detecting transmission rate information, ranking determining means for determining a ranking between users based on known transmission rate information and known required quality information for each user, and each of the interference removing means To be used in the next stage interference canceling means based on the transmission rate information detected in step 1 and the known required quality information. A ranking updating means for updating a desired ranking, and selecting and using the ranking determining means when transmission rate information is known, while selecting and using the ranking updating means when transmission rate information is unknown And selecting means.

According to the present invention, when the transmission rate information for each user is unknown and known, the transmission rate information is based on a ranking arbitrarily given in each stage by at least the number of stages corresponding to the number of users. Performs interference cancellation and detects transmission rate information, and determines the ranking between users based on known transmission rate information and known required quality information for each user when the transmission rate information is known. When the information is unknown, an arbitrary ranking used in the next stage is updated based on the transmission rate information detected in each stage and the known required quality information, so that the transmission rate information for each user is unknown. This eliminates the need for a configuration for measuring the received signal power, even if it is known, thereby shortening the calculation time of the ranking process and reducing the hardware scale and It is possible to reduce the cost of power.

In the interference canceling apparatus applied to the CDMA communication system according to the next invention, the ranking determining means multiplies the known transmission rate information for each user by the known required quality information, and calculates the user-specific information based on the calculation result. It is characterized in that the ranking between users is determined by estimating the received power.

According to the present invention, the known transmission rate information for each user is multiplied by the known required quality information, and the received power is estimated for each user from the calculation result to determine the ranking between users. In addition, the required quality can be improved in accuracy.

In the interference removing apparatus applied to the CDMA communication system according to the next invention, the ranking updating means multiplies transmission rate information detected by each interference removing means for each user with known required quality information. The method is characterized in that the received power is estimated for each user from the calculation result and the ranking between users is updated.

According to the present invention, the transmission rate information detected at each stage for each user is multiplied by the known required quality information, and the received power is estimated for each user based on the calculation result, thereby updating the ranking between users. As a result, the required quality can be significantly improved in accuracy.

[0044] The interference canceller applied to the CDMA communication system according to the next invention is characterized in that the leading interference canceller stores the previous ranking and uses it as the current ranking.

According to the present invention, in the first stage of interference removal, the previous ranking is used, so that there is no significant difference in ranking, and required interference removal can be realized.

In the interference cancellation apparatus applied to the CDMA communication system according to the next invention, the first interference cancellation means increases the ranking of the user when there is a user whose ranking is not stored in the previous ranking. It is characterized by being determined as a ranking.

According to the present invention, when there is a user whose ranking is not stored in the previous ranking, the ranking of this user is determined as the maximum ranking. Removal can be achieved.

[0048] The interference canceller applied to the CDMA communication system according to the next invention is characterized in that the leading interference canceller stores the previous ranking and uses it as the current ranking.

According to the present invention, in the interference canceller capable of determining and updating the ranking, the previous ranking is used in the first-stage interference cancellation.
There is no significant shift in ranking, and it is possible to achieve the required interference removal.

[0050] In the interference canceling apparatus applied to the CDMA communication system according to the next invention, the leading interference canceling means is arranged such that when the selecting means selects the ranking determining means, the ranking determined by the ranking determining means is selected. And when the selection means selects the ranking updating means, the stored last ranking is followed.

According to the present invention, in the first stage, if the transmission rate information is known, the determined ranking is selected and interference is removed, while if the transmission rate information is unknown, the previous ranking is used. Is selected to perform interference elimination, so that it is possible to realize required interference elimination by using an optimal ranking as appropriate.

[0052] In the interference canceling apparatus applied to the CDMA communication system according to the next invention, the leading interference canceling means increases the ranking of the user when there is a user whose ranking is not stored in the previous ranking. It is characterized by being determined as a ranking.

According to the present invention, in the interference canceling apparatus capable of determining and updating the ranking, when there is a user whose ranking is not stored in the previous ranking, the ranking of this user is determined as the maximum ranking. , So there is no ranking omission for users,
It is possible to achieve the required interference cancellation.

The interference canceling apparatus applied to the CDMA communication system according to the next invention determines a ranking for each user based on the level of the received signal when a signal not subjected to transmission power control is received. Level ranking determining means for determining the level ranking.

According to the present invention, when a signal for which transmission power control is not performed is received, the ranking is determined for each user based on the level of the received signal. It is not necessary to measure the received signal power for the signal to be performed, which makes it possible to shorten the calculation time of the ranking process and reduce the power consumption.

The interference cancellation method applied to the CDMA communication system according to the next invention is applied to a CDMA communication system in which both transmission rate information and required quality information for each user are known, and according to an arbitrary user ranking. In an interference cancellation method for sequentially canceling interference between users, a first step of multiplying known transmission rate information for each user by known required quality information, and estimating received power for each user from a calculation result of the first step And a second step of determining a ranking between users.

According to the present invention, when the transmission rate information for each user is known, the ranking between users is determined based on the known transmission rate information for each user and the known required quality information. In addition, the processing for measuring the received signal power is not required, and thus the calculation time for the ranking processing can be shortened.

The interference cancellation method applied to the CDMA communication system according to the next invention is a CDMA system in which transmission rate information for each user is unknown and required quality information is known.
In an interference cancellation method applied to a communication system and sequentially canceling interference between users in accordance with an arbitrary ranking between users, a plurality of interference cancellation stages are connected by at least the number of stages corresponding to the number of users, and the interference of each stage is A first stage for performing interference cancellation based on a ranking arbitrarily given in the cancellation stage and detecting transmission rate information;
And a second step of updating an arbitrary ranking used in the next interference cancellation stage based on the transmission rate information detected in the first step and the known required quality information,
It is characterized by including.

According to the present invention, when the transmission rate information for each user is unknown, at least the number of stages corresponding to the number of users performs interference cancellation based on a ranking arbitrarily given in each stage, and the transmission rate information To detect
Based on the transmission rate information detected in each stage and the known required quality information, an arbitrary ranking used in the next stage is updated, so that even if the transmission rate information for each user is unknown, the received signal power can be reduced. Eliminates the need for measurement
This makes it possible to reduce the calculation time of the ranking process.

The interference cancellation method applied to the CDMA communication system according to the next invention is a CDMA communication system in which the case where the transmission rate information for each user is unknown and the case where the transmission rate information is known are mixed, and the required quality information is known. And an interference canceling method for sequentially canceling interference between users according to an arbitrary ranking between users, wherein a plurality of interference canceling stages are connected by at least the number of stages corresponding to the number of users, and the interference canceling stage of each of the stages is connected. A first step of performing interference cancellation based on a ranking arbitrarily given and detecting transmission rate information, and, based on known transmission rate information for each user and known required quality information when the transmission rate information is known. A ranking between users is determined, and when the transmission rate information is unknown, the transmission rate information detected in the first step is determined. And wherein the containing a second step of updating any ranking used in the next stage of interference cancellation stage, the based on the known required quality information.

According to the present invention, when the transmission rate information for each user is unknown and known, the transmission rate information is based on a ranking arbitrarily given in each stage at least by the number of stages corresponding to the number of users. Performs interference cancellation and detects transmission rate information, and determines the ranking between users based on known transmission rate information and known required quality information for each user when the transmission rate information is known. If the information is unknown, a step of updating an arbitrary ranking to be used in the next stage based on the transmission rate information detected in each stage and the known required quality information is performed, so that the transmission rate information for each user is unknown. Even if it is known, the process of measuring the received signal power is not required, thereby making it possible to shorten the calculation time of the ranking process.

[0062]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an interference canceling apparatus and method applied to a CDMA communication system according to the present invention will be described below in detail with reference to the accompanying drawings. Embodiment 1 FIG. First, the configuration will be described. In the first embodiment described below, the number of users is K as in the conventional case. FIGS. 1 and 2 are block diagrams showing a configuration example of a CDMA receiving system to which an interference canceller according to Embodiment 1 of the present invention is applied. In FIG. 1A, reference numeral 1A denotes a CDMA receiving system of Embodiment 1 of the present invention. Is shown. This C
As shown in FIGS. 1 and 2, the DMA receiving system 1A includes, for example, multipliers 2A1 to 2AK, a sorting circuit 3, K (natural number) first stage to final stage 4, 5 to 6, and (K− 1) an interference canceller having delay circuits 7, 8,..., A decoding circuit 9, an SIR measurement block 1
0 and a TPC bit generator 11.

The difference between the CDMA receiving system 1A and the conventional CDMA receiving system shown in FIGS. 16 and 17 is that the conventionally used matched filters 20A1 to 20A1 are used.
20AK and level detectors 21A1 to 21AK are replaced by multipliers 2A1 to 2A2 instead of the reception signal power measurement block.
This is the part where AK is adopted. The multipliers 2A1-2A
K is connected to a base station controller (not shown). The multipliers 2A1 to 2AK supply a known required Eb / I0 (corresponding to an S / N ratio per information bit) indicating a required quality from the base station control unit and transmission rate information predetermined for each user. Then, the required Eb / I0 information is multiplied by the transmission rate information for each user, and the calculation result is output to the sorting circuit 3 at the subsequent stage. The required Eb / I0 is
It means Eb / I0 necessary for a data error or a frame error to be equal to or less than a specified value.

In the CDMA receiving system 1A, the configuration (multiplier 2A1) preceding the sorting circuit 3
2AK), the configuration is the same as that of the conventional configuration described above, and a description thereof will be omitted.

Next, the operation of the CDMA receiving system 1A will be described. Parts that overlap with the related art will be described in a simplified manner. First, prior to communication, data exchange required for communication is performed between a base station (not shown) and a mobile station corresponding to the number of users “K”. At that time, transmission rate information of each user is given to the base station. Can be Therefore, this CD
The transmission rate information of the received signal input to the MA receiving system 1A is known. Here, the known transmission rate information means that the transmission rate information does not change during communication and is constant. On the other hand, unknown transmission rate information means that the transmission rate information is not constant, such as when the transmission rate information fluctuates between image communication and voice communication during communication.

The transmission rate information acquired by the base station controller at the beginning of communication and the predetermined required Eb /
The l0 information is output to multipliers 2A1-2AK. In multipliers 2A1-2AK, [required Eb / I required for each user based on the input transmission rate information and required Eb / 10 information.
0] × [transmission rate] is calculated. The calculation result is output to the sorting circuit 3 at the subsequent stage for each user.
As described in the conventional example, the sorting circuit 3 estimates the received power from the calculation result and determines the ranking in the order of the user having the highest level.

In the first stage 4, channel estimation and interference signal replica generation processing for each user are executed based on the ranking information obtained as described above. Thereafter, the same processing as in the fourth stage is performed from the second stage 5 to the final stage 6. In each stage, the procedure of the provisional data determination for each user is the same as in the conventional example, and the details thereof are omitted.

In the above operation, the difference from the conventional operation is that when transmission power control is performed so that Eb / I0 at the time of demodulation becomes a target value, the reception signal power of the corresponding user is ideally controlled by the transmission power control. [Eb / I
0] × [transmission rate], the required Eb / 10
If the transmission rate information is known, the received signal power can be estimated within the range of the transmission power control error.

In this case, for users having the same required Eb / 10 and the same transmission rate information, the power is estimated to be the same, but ranking between the same powers is performed at random. Due to the configuration of interference elimination, even if a power measurement system is included, measurement errors due to mutual interference are included. is there.

Next, the overall operation will be functionally described. FIG. 3 is a flowchart functionally explaining the operation of the first embodiment. When a received signal is input in step S101, a value of [required Eb / I0] × [transmission rate] is obtained for each user in subsequent step S102. Then, a ranking process is performed in step S103. By this ranking process, the order of the user signals is determined in descending order from the calculation result of step S102. In step S104, the process proceeds to the first stage 4, and in the next step S105, channel estimation and interference replica generation processing for each user are performed.

Further, in step S106, the process proceeds to the next stage, that is, the second stage 5. In the second stage 5 as well, the channel estimation and interference replica generation processing of each user are performed as in the case of the first stage 4. Thus, Step S105 to Step S1
07 is repeatedly executed, and when the process proceeds to the final stage 6 in step S106, the next step S107
In, the shift to the final stage 6 is confirmed, and the process shifts to step S108 without returning to step S105. This time, in this step S108, channel estimation and interference signal replica generation for each user are performed, and finally data determination is performed. As a result, data determination values DJ1 to DJK for each user are obtained.

As described above, according to the first embodiment, when the required Eb / 10 of the received signal and the transmission rate information are known, the value of [required Eb / I0] × [transmission rate] is obtained. So that the ranking process is performed,
The received signal power measurement system is omitted. For this reason, the ranking calculation time can be shortened, and the hardware scale and power consumption can be reduced. In addition, since there is no reception power measurement block, ranking can be performed without including a measurement error of reception signal power due to mutual interference between users.

Embodiment 2 By the way, in the first embodiment described above, the ranking processing in the case where the required Eb / 10 of the received signal and the transmission rate information are known has been described. However, the present invention is not limited to this, and the present invention is not limited to this. As in the second embodiment, ranking may be performed even when the required Eb / 10 is known and the transmission rate information is unknown.

First, the configuration will be described. Also in the second embodiment described below, the number of users is K as in the first embodiment. FIGS. 4 and 5 are block diagrams showing an example of the configuration of a CDMA receiving system to which the interference canceller according to Embodiment 2 of the present invention is applied.
1B shows a CDMA receiving system according to the second embodiment. As shown in FIGS. 4 and 5, the CDMA receiving system 1B has, for example, multipliers 2A1 to 2AK, a sorting circuit 3, and K (natural number) first stages to final stages 14, 15 to 16, (K -1) an interference canceller having delay circuits 7, 8,... And switches 17, 18, a decoding circuit 9, an SIR measurement block 10, and T
A PC bit generator 11 is provided.

In the second embodiment, since the transmission rate information becomes unknown, it is necessary to internally generate the transmission rate information in the interference canceller of the CDMA receiving system 1B. Therefore, the following parts are different from the CDMA receiving system 1A of the first embodiment described above. That is, the multipliers 2A1 to 2AK do not receive the transmission rate information from the base station control unit (not shown), but the first stages 14 and 15
... The transmission rate information for the next stage from the stage immediately before the final stage 16 is received via the switch 17. A switch 1 is connected between the inputs of the multipliers 2A1-2AK and the outputs of the stages 14, 15-16.
7 are connected, and a multiplier 2 is connected in accordance with the processing in each stage.
The input sources of A1 to 2AK are appropriately switched. A switch 18 is connected to the output of the sorting circuit 3 and the input of each of the stages 14, 15 to 16, so that the output destination of the sorting circuit 3 is appropriately switched according to the processing in each stage.

Further, the first stage 14 is connected to the first stage ranking estimating block 13 for providing provisional ranking information. The first stage ranking estimating block 13 estimates the ranking with reference to the ranking information stored in the memory 12,
The ranking information is provided to the first block 14 as temporary ranking information. The memory 12 has a history function of storing ranking information obtained every time transmission power control is performed for each pilot block.

In the second embodiment, since the transmission rate information obtained in the preceding stage determines the ranking to be used in the subsequent stage, the first stages 14, 15 to 16 include the above-described first stage. 1 stage 4,5
6 includes a partly different configuration. For each stage, the first stage 14 comprises delay circuits 14A2, 14A3
To 14AK, subtracters 14B2, 14B3 to 14BK, first to Kth processing units 14C1 and 14C2 to 14C
K is provided. Delay circuits 14A2, 14A3 to 14A
K and the subtractors 14B2, 14B3 to 14BK
Description is omitted because it is the same as the conventional one. In addition, the first to Kth
The processing units 14C1 and 14C2 to 14CK are similar to the above-described first embodiment in the process of reproducing the replica of the interference signal, except that they detect the transmission rate information based on the received signal and output it to the switch 17. Form 1
Is different from

The second stage 15 to the final stage 1
6 is the same as the first stage 14, and the description is omitted. However, in FIG.
Are represented in the 10s. In particular, the first to Kth processing units 16C1 and 16C2 of the final stage 16
In 16CK, transmission rate information is not detected. This is because there is no subsequent stage, and it is not necessary to determine ranking using transmission rate information.

The CDMA receiving system 1B is the same as the above-described conventional configuration except for the difference between the above-described first embodiment and the conventional configuration, and the difference between the first embodiment and the first embodiment. I do.

Next, the operation of the CDMA receiving system 1B will be described. Parts that overlap with the related art will be described in a simplified manner. In the first stage 14, since the transmission rate information of the user is unknown, it is impossible to obtain an accurate ranking from the input received signal. The ranking estimation at this time is performed in the first stage ranking estimation block 13. In the ranking block 13 for the first stage, the ranking information stored in the memory 12 is used for the user signal having the ranking information of the previous pilot block. Because of the possibility, the highest ranking is given.

In each of the first to Kth processing units 14C1 to 14CK of the first stage 14, channel estimation and interference signal replica generation are performed for each user according to the ranking determined in this way, and at the same time, the data symbol Is detected. The transmission rate information may be explicitly included or detected by blind detection. Regarding blind detection, Electronics Let as Document 1
ters (Vol. 32, No. 2, Sept., 19)
96) and Document 2 at the IEICE National Convention (1997 Society Conference B-5-43).

Reference 1 discloses a method of using an error detection code when intermittent transmission is performed by changing the number of transmission symbols during transmission of less than the maximum number of frame bits. In the case of performing repetition and continuous transmission at a power outage, the transmission data modulation signal is encoded by a hierarchical repetition code, and detection is performed using a metric when the reception side decodes the repetition code assuming each rate. The method is shown.

The required Eb / I0 is generally known, and is supplied from a base station control unit (not shown).
In the AK, multiplication is performed using the transmission rate information sent from the first stage 14 via the switch 17 and the required Eb / I0 information. In the sorting circuit 3, the rankings of the users are determined in the descending order of the value of [required Eb / 10] × [transmission rate] by the multipliers 2A1 to 2AK. The ranking information of the ranking result is transmitted to the second stage 15 by switching the output destination of the switch 18. In the second stage 15, processing is performed based on the transmitted ranking information, and transmission rate information of each user is newly detected.

Then, as in the previous time, the multipliers 2A1-2
In the AK, multiplication is performed using the transmission rate information sent from the second stage 15 via the switch 17 and the required Eb / 10 information, and the sorting circuit 3 calculates [required Eb / 10] × [transmission rate]. The ranking of the user is determined in the descending order of the value of. In the next stage, processing is performed based on the ranking result. Thereafter, the transmission rate information is updated for each stage, and the ranking processing is repeatedly executed. In the final stage 16, the processing is performed based on the ranking information determined from the transmission rate information of the immediately preceding stage. Fig. 1 shows the procedure for temporary data determination for each user.
2 is the same as the conventional example of FIG. 2, and the description thereof is omitted here. As described above, the further the stage is, the more the interference removing effect is increased, and the accuracy of detecting the transmission rate information is also improved, so that the removing effect is increased.

Next, the overall operation will be functionally described. FIG. 6 is a flowchart illustrating the operation according to the second embodiment. In step S201, a received signal is input. In subsequent step S202, it is determined whether or not there is previous pilot block ranking information with reference to the memory 12. As a result, when there is ranking information, the process proceeds to step S203, where the previous ranking information is used. On the other hand, when there is no ranking information, the process proceeds to step S204, where the user signal has the maximum ranking. Is attached.

The above step S203 or step S2
When the ranking is determined in 04, the process proceeds to the first stage 14 in the subsequent step S205. Further, in step S206, channel estimation, interference signal replica generation and transmission rate detection are performed for each user, and in subsequent step S207,
The value of [required Eb / I0] × [transmission rate] is obtained for each user. Then, in step S208, the ranking is determined based on the calculation result.

Thereafter, in step S209, the process proceeds to the second stage 15, and the next step S210
It is determined whether or not the current stage is the final stage 16. At this time, if the current stage is the final stage 16, the process proceeds to step S211 and channel estimation, interference signal replica generation, and data determination are performed for each user. Since the determination of the ranking based on the transmission rate information is unnecessary after the last stage, the process of detecting the transmission rate information becomes unnecessary. On the other hand, if the current stage is not yet the final stage, the process returns to step S206, and thereafter, a loop process from step S206 to step S210 is performed until the final stage 16 is determined in step S210.

As described above, according to the second embodiment, the required Eb / 10 of the received signal is known, and
If the transmission rate information is unknown, the ranking processing is performed with reference to the previous pilot block. Therefore, in this case, similarly to the first embodiment, the received signal power measurement system is omitted. You. For this reason, the ranking calculation time can be shortened, and the hardware scale and power consumption can be reduced.

Embodiment 3 By the way, in Embodiments 1 and 2 described above, the required Eb / 10 of all the users and the transmission rate information are known or the required Eb /
Although the ranking process in the case where / 10 is known and the transmission rate information is unknown has been described, the present invention is not limited to any one of such cases, and the known required Eb /
In the case of I0, ranking may be performed even when there are mixed users with known transmission rate information and unknown transmission rate information.

First, the configuration will be described. Also in the third embodiment described below, the number of users is K as in the first and second embodiments. 7 and 8 are block diagrams showing a configuration example of a CDMA receiving system to which the interference canceling device according to the third embodiment of the present invention is applied. In FIG. 7, reference numeral 1C denotes a CDMA receiving system of the third embodiment. Is shown. This CDMA receiving system 1C is configured as shown in FIG.
And as shown in FIG. 8, for example, the multipliers 2A1-2
AK, sorting circuit 3, K (natural number) first to final stages 14, 15 to 16, (K-1) delay circuits 7, 8,..., Switches 17, 18, and switches 19A1 to 19AK. It has an interference canceller, a decoding circuit 9, an SIR measurement block 10, and a TPC bit generator 11.

The CDMA receiving system 1C has the base configuration described in the second embodiment. In the third embodiment, the case where the transmission rate information is known and the case where the transmission rate information is unknown are mixed. Therefore, the case where the transmission rate information supplied from the base station control unit (not shown) is used and the case where the transmission rate information is There are two cases: internally generating transmission rate information in the interference canceller. For this purpose, the switches 19A1 to 19AK are newly incorporated by combining the configurations of the first and second embodiments.

Specifically, the switches 19A1 to 19AK
Connects the output of the switch 17 (transmission rate information) and the output of the base station controller (transmission rate information),
One of the outputs is connected to the inputs of multipliers 2A1-2AK. Accordingly, the supply source of the transmission rate information to the multipliers 2A1-2AK (the base station controller / first stages 14, 15,..., 16) (not shown) is the switch 19A1-1.
It is switched appropriately by 9AK.

Next, the operation of the CDMA receiving system 1C will be described. Portions that overlap with the related art and the above-described second embodiment will be described in a simplified manner. In the first stage 14, since the transmission rate information of the user is unknown,
It is impossible to obtain an accurate ranking from the input received signal. The ranking estimation at this time is performed in the first stage ranking estimation block 13. In the ranking block 13 for the first stage, the ranking information stored in the memory 12 is used for the user signal having the ranking information of the previous pilot block. Because of the possibility, the highest ranking is given.

In each of the first to Kth processing units 14C1 to 14CK of the first stage 14, channel estimation and interference signal replica generation are performed for each user in accordance with the ranking determined in this way, and at the same time, the data symbol Is detected and transferred to the next switches 19A1 to 19AK via the switch 17.

At this time, in the ranking for the next generation of the interference signal replica, the known transmission rate information supplied from the base station control unit is used for the user whose transmission rate information is known. The transmission rate information detected in the first stage 14 of the preceding stage is used for a user whose is unknown. At this time, either one of the known transmission rate information and the unknown transmission rate information is selected by the switches 19A1 to 19AK for each user. Since the required Eb / I0 is generally known and supplied from a base station control unit (not shown), the multipliers 2A1 to 2AK transmit the transmission rate information transmitted from the first stage 14 through the switches 19A1 to 19AK and the required Eb / I0. Multiplication is performed using the Eb / I0 information.

In the sorting circuit 3, the multiplier 2
The user ranking is determined in the descending order of the value of [required Eb / 10] × [transmission rate] by A1 to 2AK. The ranking information of the ranking result is switch 1
8 is transmitted to the second stage 15 by switching the output destination. In the second stage 15, processing is performed based on the transmitted ranking information, and transmission rate information of each user is newly detected.

The transmission rate information detected in the second and subsequent stages 15 is also supplied to multipliers 2A1-2AK depending on whether known transmission rate information is supplied from the base station controller. Is determined. That is, the use or non-use of the transmission rate information detected in each stage is determined for each user by switching the switches 19A1 to 19AK.

Next, the overall operation will be functionally described. FIG. 9 is a flowchart illustrating the operation according to the third embodiment. In the following description, only portions different from the above-described second embodiment will be described. Also in the third embodiment, as in the above-described second embodiment, step S
In step 201 to step S206, channel estimation for each user is performed in the first stage by ranking determination,
Interference signal replica generation and transmission rate (transmission rate information) detection are performed.

Then, in the next step S301, it is determined whether or not the transmission rate (transmission rate information) is known for each user. As a result, if the transmission rate information is known, the process proceeds to step S302, where a known value is adopted as the transmission rate value, while if the transmission rate information is unknown, the process proceeds to step S302.
The process proceeds to 303, where the transmission rate information measurement value detected in the interference removal processing by the preceding stage is used as the transmission rate value. Thereafter, as in the above-described second embodiment, the ranking is determined in steps S207 to S209, and the process proceeds to the next stage.

Thereafter, a loop process including steps S301 to S303 (steps S206 to S303) is performed until the process proceeds to the final stage in step S210.
Step S210) is repeatedly executed, and the data determination value DJ1 is determined in step S211 by shifting to the final stage.
~ DJK is required.

As described above, according to the third embodiment, even in the case where the transmission rate information is known and the unknown user are mixed at the time of the known required Eb / I0, the above-described embodiment is performed. As in the first and second embodiments, the received signal power measurement system is omitted. For this reason, the ranking calculation time can be shortened, and the hardware scale and power consumption can be reduced.

Embodiment 4 In the first to third embodiments described above, a case has been described in which the reception power can be estimated from the transmission rate information and the required Eb / I0 by the transmission power control. However, the present invention is not limited to this, and will be described below. As in the fourth embodiment, ranking may be performed even when a signal for which transmission power control is not performed is included. Therefore, a high-speed packet signal is an example of a signal for which transmission power control is not performed. That is, since high-speed transmission is performed in a short time, communication ends before transmission control is performed without performing closed-loop control. Assuming such a case, in the following Embodiment 4, an example of an interference canceller that can cope with a packet signal will be described.

First, the configuration will be described. In the fourth embodiment described below, the number of users is K as in the first, second, and third embodiments. FIGS. 10 and 11 show C to which the interference canceller according to the fourth embodiment of the present invention is applied.
FIG. 3 is a block diagram illustrating a configuration example of a DMA receiving system, in which 1D denotes a CDMA receiving system according to the fourth embodiment. This CDMA receiving system 1
D is, for example, as shown in FIGS. 10 and 11, multipliers 2A1 to 2AK, sorting circuit 3, K (natural number) first stage to final stage 14, 15 to 1
6, (K-1) delay circuits 7, 8,..., Switch 17,
18, switches 19A1 to 19AK, matched filters 20A1 to 20AK, level detectors 21A1 to 21A
It includes an interference canceller having a K and user signal selection block 22, a decoding circuit 9, an SIR measurement block 10, and a TPC bit generator 11.

The CDMA receiving system 1D has the base configuration described in the third embodiment. In the fourth embodiment, a reception signal power measurement block is required for a packet signal for which transmission power control is not performed, as in the related art. Therefore, the matched filters 20A1 to 20A1 to 20A
K and level detectors 21A1 to 21AK are added. In the fourth embodiment, the ranking of a signal to be subjected to transmission power control can be determined from required [Eb / I0] × [transmission rate] without passing through a received signal power measurement block.

In that sense, the output of the level detectors 21A1 to 21AK and the multiplier 2 are provided before the sorting circuit 3.
A user signal selection block 22 connected to the outputs of A1 to 2AK is provided. The user signal selection block 22 selects which output is to be supplied to the sorting circuit 3 depending on whether the received signal is a packet signal or other signal (signal for which transmission power control is performed).

Next, the operation of the CDMA receiving system 1D will be described. It should be noted that only portions different from the related art and the above-described third embodiment will be described. In the case of a packet signal, the received packet signal is input to matched filters 20A1 to 20AK corresponding to each user. In each of the matched filters 20A1 to 20AK, a correlation value for each user is obtained, and the level detectors 21A1 to 21A1
The received signal level is measured for each user by 21AK. When the received signal level of each user is measured by the level detectors 21A1 to 21AK, the measurement result is sent to the sorting circuit 3 via the user signal selection block 22. In the sorting circuit 3, the ranking of the user is determined in the descending order of the received signal power value of the received power measurement block at the preceding stage.

[0107] The case of a signal for which transmission power control is performed instead of a packet signal will also be described. In the first stage 14, since the transmission rate information of the user is unknown, it is impossible to obtain an accurate ranking from the input received signal. The ranking estimation at this time is the first
This is performed in the stage ranking estimation block 13. In the first stage ranking block 13, the ranking information stored in the memory 12 is used for the user signal having the ranking information of the previous pilot block, and the maximum power is used for the user signal without such ranking information. Because of the possibility, the highest ranking is given.

In each of the first to Kth processing units 14C1 to 14CK of the first stage 14, channel estimation and interference signal replica generation are performed for each user according to the ranking determined in this way, and at the same time, the data symbol Is detected and transferred to the next switches 19A1 to 19AK via the switch 17.

At this time, in the ranking for the next generation of the interference signal replica, the known transmission rate information supplied from the base station control unit is used for the user whose transmission rate information is known. The transmission rate information detected in the first stage 14 of the preceding stage is used for a user whose is unknown. At this time, either one of the known transmission rate information and the unknown transmission rate information is selected by the switches 19A1 to 19AK for each user. Since the required Eb / I0 is generally known and supplied from a base station control unit (not shown), the multipliers 2A1 to 2AK transmit the transmission rate information transmitted from the first stage 14 through the switches 19A1 to 19AK and the required Eb / I0. Multiplication is performed using the Eb / I0 information. The multiplication results are sent to the sorting circuit 3 via the user signal selection block 22. In the sorting circuit 3, the [Required Eb] by the multipliers 2A1-2AK is used.
/ 10] × [transmission rate] The user ranking is determined in the descending order of the value.

Next, the overall operation will be functionally described. FIG. 12 is a flowchart illustrating the operation according to the fourth embodiment. In the following description, only portions different from the above-described third embodiment will be described. Also in the fourth embodiment, as in the above-described third embodiment, in steps S201 to S206, channel estimation, interference signal replica generation, and transmission rate (transmission rate information) for each user are determined in the first stage by ranking determination in the first stage. Detection is performed.

In the next step S401, it is determined for each user whether the signal is a packet signal. As a result, if the received signal is a packet signal, the process proceeds to step S402 to use the received signal power value for the ranking process. Thereafter, the process proceeds to step S208. On the other hand, if the received signal is not a packet signal but a signal for which transmission power control is not performed, the process proceeds to step S301, and it is further determined for each user whether transmission rate information is known. .

That is, in step S301, it is determined whether transmission rate information is known for each user. As a result, if the transmission rate information is known, the process proceeds to step S302, and a known value is adopted as the transmission rate value, while if the transmission rate information is unknown, the process proceeds to step S303. Then, the transmission rate information measurement value detected in the interference removal processing by the preceding stage is set as the transmission rate value. Thereafter, similarly to the above-described third embodiment, steps S207 to S207 are performed.
At 209, the ranking is determined, and the process proceeds to the next stage.

Thereafter, a loop process including steps S401 and S402 (step S20) is performed until the process shifts to the final stage in step S210.
6 to step S210) are repeatedly executed, and by shifting to the final stage, the data determination value D is determined in step S211.
J1 to DJK are required.

As described above, according to the fourth embodiment, the operation of the received signal power measurement block is limited to only the packet signal. Therefore, when receiving signals other than the packet signal, the first embodiment is used. As in the case of (1) to (3), it is possible to shorten the calculation time of the ranking and reduce the power consumption. Therefore, as a whole process, it is possible to minimize the calculation time of the ranking and the increase in power consumption as much as possible.

Embodiment 5 FIG. Now, according to the present invention, as in a fifth embodiment described below, the first to fifth embodiments described above.
4 may be realized by one circuit configuration. That is, when the transmission rate information is known, the operation of the above-described first embodiment may be realized, while when the transmission rate information is unknown, the operation of the above-described fourth embodiment may be realized. .

First, the configuration will be described. In the fifth embodiment described below, the number of users is K as in the first to fourth embodiments. FIGS. 13 and 14 are block diagrams showing a configuration example of a CDMA receiving system to which the interference canceling apparatus according to the fifth embodiment of the present invention is applied. In the drawings, reference numeral 1E denotes a CDMA receiving system of the fifth embodiment. Is shown. This CDMA receiving system 1E is configured as shown in FIG.
3 and FIG. 14, for example, the multiplier 2A1
~ 2AK, sorting circuit 3, K (natural number) first
Stage-Final stage 14, 15-16, (K-1)
, Switches 17, 18, switches 19A1 to 19AK, matched filters 20A1 to 20
An interference canceller having an AK, level detectors 21A1 to 21AK, a user signal selection block 22, and a switch 23, a decoding circuit 9, an SIR measurement block 10, and a TPC bit generator 11 are provided.

The CDMA receiving system 1E has the base configuration described in the fourth embodiment. In the fifth embodiment, the processing mode is set to the operation of the first embodiment or the operation of the fourth embodiment according to whether the transmission rate information is known or unknown. A switch 23 is provided. This switch 23
Are connected to the output of the first stage ranking estimating block 13 and the output of the switch 18, and are also connected to the first stage 14. Here, the switch 18 is different from the above-described switch 18 in a connection line with a newly added switch 23.

When the transmission rate information is known, the switch 23 provides the ranking information from the sorting circuit 3 to the first stage 14 in the operation mode according to the first embodiment. Is switched to the output of the switch 18. On the other hand, when the transmission rate information is unknown, the first stage ranking estimating block 13 sends the first stage 1
4 to provide ranking information to the first stage 14
Output to the first stage ranking estimating block 13
Switch to output.

Next, the operation of the CDMA receiving system 1E will be described. It should be noted that only portions different from the related art and the first to fourth embodiments will be described. For the input received signal, not a pilot signal, and
When both the required Eb / I0 and the transmission rate information are known, all the switches 19A1 to 19AK are switched to the output of the base station control unit. In this case, in the multipliers 2A1 to 2AK, the transmission rate information supplied from the base station control unit is supplied to the required Eb supplied from the base station control unit.
/ I0. Therefore, in the user signal selection block 22, the outputs of the multipliers 2A1-2AK are output to the sorting circuit 3.

In this sorting circuit 3, the multiplier 2A
In the result of multiplication of 1 to 2 AKs, the users are ranked in the order of the value, and the ranking information is stored in the
Is output to the switch 23 via the. The input of the switch 23 at that time has been switched to the switch 18,
The ranking information sent from the switch 18 is transmitted to the first stage 14. As described above, when the transmission rate information is known, in the first stage 14, [required E
Channel estimation and interference signal replica generation are performed in accordance with the ranking obtained by [b / I0] × [transmission rate]. Subsequent operations are the same as in the first embodiment,
The description is omitted.

When the transmission rate information is unknown when the required Eb / I0 is known for the input received signal, accurate ranking cannot be performed. Therefore, the input of the switch 23 is used for the first stage. The process is switched to the ranking estimation block 13. Therefore, the first stage 1
The ranking used in 4 is estimated. The operation in this case is in accordance with Embodiment 3 described above, and a description thereof will be omitted.

Next, the overall operation will be functionally described. FIG. 15 is a flowchart illustrating the operation according to the fifth embodiment. In the following description, only portions different from the above-described fourth embodiment will be described. In the fifth embodiment, when a received signal is input in step S201, it is determined in subsequent step S501 whether the transmission rate information of all users is known or unknown. As a result, if the transmission rate information of all users is known, the process proceeds to step S102. Then, as in the first embodiment, the final data determination values DJ1 to DJ are obtained through steps S102 to S108.
K is required.

On the other hand, if the transmission rate information of all users is unknown, the process proceeds to step S202. In this case, as in the above-described fourth embodiment, step S20
In step 2 to step S206, channel estimation, interference signal replica generation, and transmission rate (transmission rate information) for each user are determined in the first stage by ranking determination.
Detection is performed.

In the next step S401, it is determined whether or not the signal is a packet signal for each user. As a result, if the received signal is a packet signal, the process proceeds to step S402 to use the received signal power value for the ranking process. Thereafter, the process proceeds to step S208. On the other hand, if the received signal is not a packet signal but a signal for which transmission power control is not performed, the process proceeds to step S301, and it is further determined for each user whether transmission rate information is known. .

That is, in step S301, it is determined whether transmission rate information is known for each user. As a result, if the transmission rate information is known, the process proceeds to step S302, and a known value is adopted as the transmission rate value, while if the transmission rate information is unknown, the process proceeds to step S303. Then, the transmission rate information measurement value detected in the interference removal processing by the preceding stage is set as the transmission rate value. Thereafter, similarly to the above-described third embodiment, steps S207 to S207 are performed.
At 209, the ranking is determined, and the process proceeds to the next stage.

Thereafter, a loop process including steps S401 and S402 (step S20) is performed until the process shifts to the final stage in step S210.
6 to step S210) are repeatedly executed, and by shifting to the final stage, the data determination value D is determined in step S211.
J1 to DJK are required.

As described above, according to the fifth embodiment, since all the configurations of the first to fourth embodiments are covered, if the transmission rate information is known, [Required Eb / I0 ] × [transmission rate], the ranking process is performed, so that the ranking calculation time is reduced,
On the other hand, when the transmission rate information is unknown, it is possible to shorten the ranking calculation time and reduce the power consumption during reception other than the packet signal, similarly to the first to third embodiments described above. Become.

In the first to fifth embodiments described above,
The ranking process is performed based on the value of [required Eb / I0] × [transmission rate]. Of the required Eb / 10 and transmission rate information, the dominant element in the ranking result is transmission rate information. The required Eb / I0 varies within a range of 10 ⁻³ (for voice communication) to 10 ⁻⁶ (for data communication). However, in data communication, a high-precision error correction code is used. It does not fluctuate and does not make a significant difference in ranking. Therefore, ranking processing using only transmission rate information is also possible, which is effective in terms of simplification of the apparatus. In this case, in the flowcharts of FIGS. 3, 6, 9, 12, and 15, the ranking is performed only in the transmission rate value in steps S102 and S207.

Although the present invention has been described with reference to the first to fifth embodiments, various modifications are possible within the scope of the present invention, and these are not excluded from the scope of the present invention.

[0130]

As described above, according to the present invention,
When the transmission rate information for each user is known, the ranking between users is determined based on the known transmission rate information for each user, so that a configuration for measuring the received signal power is unnecessary, and There is an effect that an interference canceller applied to a CDMA communication system capable of shortening the calculation time of the ranking process and reducing the hardware scale and the power consumption can be obtained.

According to the next invention, when transmission rate information for each user is known, ranking between users is determined based on known transmission rate information for each user and known required quality information. Therefore, there is no need for a configuration for measuring the received signal power, thereby shortening the calculation time of the ranking process and reducing the hardware scale and the power consumption. Is obtained.

According to the next invention, when the transmission rate information for each user is unknown, at least the number of stages corresponding to the number of users performs interference cancellation based on the ranking arbitrarily given in each stage, and the transmission rate is reduced. Since information is detected and any ranking used in the next stage is updated based on the transmission rate information detected in each stage,
Even if the transmission rate information for each user is unknown, the configuration for measuring the received signal power is not required, thereby shortening the calculation time of the ranking process and reducing the hardware scale and power consumption. There is an effect that an interference canceling device applied to the CDMA communication system can be obtained.

According to the next invention, when the transmission rate information for each user is unknown, at least the number of stages corresponding to the number of users performs interference elimination based on a ranking arbitrarily given in each stage, and the transmission rate is reduced. Since information is detected and any ranking used in the next stage is updated based on the transmission rate information detected in each stage and the known required quality information, the transmission rate information for each user is unknown. However, there is no need for a configuration for measuring the received signal power, thereby reducing the calculation time of the ranking process and reducing the hardware scale and power consumption. Is obtained.

According to the next invention, when the transmission rate information for each user is unknown and unknown,
At least by the number of stages corresponding to the number of users, perform interference cancellation based on the ranking arbitrarily given in each stage and detect the transmission rate information, and if the transmission rate information is known, convert it to known transmission rate information for each user. Based on the transmission rate information detected at each stage, if the transmission rate information is unknown, the ranking between the users is updated based on the transmission rate information detected at each stage. It is not necessary to have a configuration for measuring the received signal power whether the transmission rate information is unknown or known, thereby shortening the calculation time of the ranking process and reducing the hardware scale and power consumption. This provides an effect that an interference canceller applied to a CDMA communication system that can perform the above operation is obtained.

According to the next invention, when the transmission rate information for each user is unknown and unknown,
At least the number of stages according to the number of users, perform interference cancellation based on the ranking arbitrarily given in each stage and detect the transmission rate information, and if the transmission rate information is known, the known transmission rate information for each user and The ranking between users is determined based on the known required quality information, while the optional used in the next stage based on the transmission rate information detected in each stage and the known required quality information when the transmission rate information is unknown. Since the ranking is updated, a configuration for measuring the received signal power is unnecessary even if the transmission rate information for each user is unknown or known, thereby shortening the calculation time of the ranking process, In addition, there is provided an effect that an interference canceller applied to a CDMA communication system capable of reducing hardware scale and power consumption can be obtained. That.

According to the next invention, the known transmission rate information for each user is multiplied by the known required quality information, and the received power is estimated for each user from the calculation result to determine the ranking between users. Therefore, there is an effect that an interference canceller applied to a CDMA communication system that can improve accuracy in required quality can be obtained.

According to the next invention, the transmission rate information detected at each stage for each user is multiplied by the known required quality information, and the received power is estimated for each user from the calculation result, thereby updating the ranking between users. The CDM can improve the accuracy of the required quality remarkably.
There is an effect that an interference canceling device applied to the A communication system can be obtained.

According to the next invention, in the first stage of interference cancellation, the previous ranking is used, so that there is no significant difference in ranking and CDMA capable of realizing required interference cancellation. There is an effect that an interference canceling device applied to a communication system can be obtained.

According to the next invention, when there is a user whose ranking is not stored in the previous ranking, the ranking of this user is determined as the maximum ranking. An effect is obtained that an interference canceling device applied to a CDMA communication system capable of realizing interference cancellation is obtained.

According to the next invention, in the interference canceling apparatus capable of determining and updating the ranking, the previous ranking is used in the first-stage interference canceling, so that a large difference in ranking is avoided. In addition, there is an effect that an interference canceller applied to a CDMA communication system capable of realizing required interference cancellation can be obtained.

According to the next invention, in the first stage, when the transmission rate information is known, the determined ranking is selected and interference is removed, and when the transmission rate information is unknown, the previous ranking is used. Since the interference is canceled by selecting the ranking, an effect is obtained that an interference canceller applied to a CDMA communication system capable of appropriately realizing the required interference cancellation using the optimum ranking is obtained. .

According to the next invention, in the interference canceling device capable of determining and updating the ranking, when there is a user whose ranking is not stored in the previous ranking, the ranking of this user is determined as the maximum ranking. As a result, there is an effect that an interference canceller applied to a CDMA communication system capable of realizing required interference cancellation without omission of ranking for a user can be obtained.

According to the next invention, when a signal for which transmission power control is not performed is received, the ranking is determined for each user based on the level of the received signal. It is not necessary to measure the received signal power for a signal on which the interference is removed, and thereby, the interference elimination device applied to the CDMA communication system capable of shortening the calculation time of the ranking process and reducing the power consumption is provided. The effect is obtained.

According to the next invention, when transmission rate information for each user is known, a step of determining a ranking between users based on known transmission rate information for each user and known required quality information is provided. This eliminates the need for the process of measuring the received signal power, thereby providing an effect of obtaining an interference elimination method applicable to a CDMA communication system that can shorten the calculation time of the ranking process.

According to the next invention, when the transmission rate information for each user is unknown, at least the number of stages corresponding to the number of users performs interference elimination based on a ranking arbitrarily given in each stage, and the transmission rate is reduced. Since information is detected and an arbitrary ranking used in the next stage is updated based on the transmission rate information detected in each stage and the known required quality information, the transmission rate information for each user is unknown. However, the process of measuring the received signal power is not required, thereby providing an effect of obtaining an interference elimination method applied to a CDMA communication system capable of shortening the calculation time of the ranking process.

According to the next invention, when transmission rate information for each user is unknown and unknown,
At least the number of stages according to the number of users, perform interference cancellation based on the ranking arbitrarily given in each stage and detect the transmission rate information, and if the transmission rate information is known, the known transmission rate information for each user and The ranking between users is determined based on the known required quality information, while the optional used in the next stage based on the transmission rate information detected in each stage and the known required quality information when the transmission rate information is unknown. , The process of measuring the received signal power becomes unnecessary even if the transmission rate information for each user is unknown or known, thereby shortening the calculation time of the ranking process. There is an effect that an interference cancellation method applied to a CDMA communication system capable of performing the above can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a CDMA receiving system to which an interference canceller according to a first embodiment of the present invention is applied.

FIG. 2 is a block diagram illustrating a configuration example of a CDMA receiving system to which the interference canceller according to the first embodiment of the present invention is applied.

FIG. 3 is a flowchart illustrating an operation according to the first embodiment.

FIG. 4 is a block diagram illustrating a configuration example of a CDMA receiving system to which an interference canceller according to a second embodiment of the present invention is applied.

FIG. 5 is a block diagram illustrating a configuration example of a CDMA receiving system to which an interference canceller according to a second embodiment of the present invention is applied.

FIG. 6 is a flowchart illustrating an operation according to the second embodiment.

FIG. 7 is a block diagram illustrating a configuration example of a CDMA receiving system to which an interference canceller according to a third embodiment of the present invention is applied.

FIG. 8 is a block diagram showing a configuration example of a CDMA receiving system to which an interference canceller according to a third embodiment of the present invention is applied.

FIG. 9 is a flowchart illustrating an operation according to the third embodiment.

FIG. 10 is a block diagram illustrating a configuration example of a CDMA receiving system to which an interference canceller according to a fourth embodiment of the present invention is applied.

FIG. 11 is a block diagram illustrating a configuration example of a CDMA receiving system to which an interference canceller according to a fourth embodiment of the present invention is applied.

FIG. 12 is a flowchart illustrating an operation according to the fourth embodiment.

FIG. 13 is a block diagram illustrating a configuration example of a CDMA receiving system to which an interference canceller according to a fifth embodiment of the present invention is applied.

FIG. 14 is a block diagram illustrating a configuration example of a CDMA receiving system to which an interference canceller according to a fifth embodiment of the present invention is applied.

FIG. 15 is a flowchart illustrating an operation according to the fifth embodiment.

FIG. 16 shows a CD to which a conventional interference canceller is applied.
It is a block diagram showing an example of 1 composition of an MA receiving system.

FIG. 17 shows a CD to which a conventional interference removing device is applied.
It is a block diagram showing an example of 1 composition of an MA receiving system.

FIG. 18 is a diagram illustrating a pilot block.

[Explanation of symbols]

1A-1E CDMA receiving system, 2A1-2AK
Multiplier, 3 sorting circuit, 4,14 first stage, 5,15 second stage, 6,16 final stage, 7,8 delay circuit, 12 memory, 13 first stage estimation block, 17,18 switch, 19A1
１９19AK switch, 20A1-20AK matched filter, 21A1-21AK level detector, 22
User signal selection block, 23 switches.

Claims (17)

[Claims] 1. An interference cancellation apparatus which is applied to a CDMA communication system in which transmission rate information for each user is known, and sequentially cancels interference between users according to a given ranking between users. An interference canceller applied to a CDMA communication system, comprising a ranking determining means for determining a ranking between users based on rate information. 2. An interference cancellation apparatus which is applied to a CDMA communication system in which both transmission rate information and required quality information for each user are known, and sequentially cancels interference between users according to an arbitrary ranking between users. An interference canceller applied to a CDMA communication system, further comprising a ranking determining means for determining a ranking between users based on another known transmission rate information and known required quality information. 3. An interference cancellation apparatus applied to a CDMA communication system in which transmission rate information for each user is unknown, and sequentially canceling interference between users according to an arbitrary ranking between users. A plurality of interference cancellers connected by the number of stages and performing interference cancellation based on a ranking arbitrarily given in each stage and detecting transmission rate information, based on the transmission rate information detected by each interference cancellation unit, And a ranking updating means for updating an arbitrary ranking used in the interference removing means of the stage. An interference removing apparatus applied to a CDMA communication system, comprising: 4. An interference canceller that is applied to a CDMA communication system in which transmission rate information for each user is unknown and required quality information is known, and sequentially cancels interference between users according to an arbitrary ranking between users. In the apparatus, a plurality of interference canceling means connected at least by the number of stages corresponding to the number of users, performing interference cancellation based on a ranking arbitrarily given in each stage and detecting transmission rate information, and detecting by each of the interference canceling units And a ranking updating means for updating an arbitrary ranking used in the next stage interference removing means based on the obtained transmission rate information and the known required quality information. Removal device. 5. An interference canceling apparatus applied to a CDMA communication system in which a case where transmission rate information for each user is unknown and a case where the transmission rate information is known are known, and which sequentially cancels interference between users according to an arbitrary given ranking between users. A plurality of interference canceling means connected at least by the number of stages corresponding to the number of users, performing interference cancellation based on a ranking arbitrarily given in each stage and detecting transmission rate information, and known transmission rate information for each user. Ranking determining means for determining a ranking between users based on the, a ranking update means for updating an arbitrary ranking used in the next stage interference removal means based on the transmission rate information detected by each interference removal means, When the transmission rate information is known, the ranking deciding means is selected and used. Interference cancellation apparatus applied to a CDMA communication system characterized by comprising selection means for selecting and using the ranking update means when the unknown, the. 6. The present invention is applied to a CDMA communication system in which transmission rate information for each user is unknown and known, and the required quality information is known. An interference canceller that performs interference cancellation between at least as many stages as the number of users, performs interference cancellation based on a ranking arbitrarily given at each stage, and detects transmission rate information. Ranking determining means for determining a ranking between users based on known transmission rate information and known required quality information for each user; based on transmission rate information and known required quality information detected by each of the interference removing means Ranking updating means for updating an arbitrary ranking used in the next stage interference elimination means, and transmission rate information. And a selecting means for selecting and using the ranking determining means when is known, while selecting and using the ranking updating means when transmission rate information is unknown. Interference canceller applied to the system. 7. The ranking determining means multiplies known transmission rate information for each user by known required quality information, and estimates received power for each user from a calculation result to determine a ranking between users. An interference canceller applied to the CDMA communication system according to claim 2. 8. The ranking updating means multiplies transmission rate information detected by each of the interference removing means for each user by known required quality information, and estimates received power for each user based on a result of the calculation, thereby obtaining a ranking between users. 7. The CDM according to claim 4, wherein the ranking of the CDM is updated.
An interference canceller applied to the A communication system. 9. The CDMA system according to claim 3, wherein said first interference removing unit stores a previous ranking and uses it as a current ranking.
An interference canceller applied to a communication system. 10. The apparatus according to claim 9, wherein, if there is a user whose ranking is not stored in the previous ranking, the leading interference removing unit determines the ranking of the user as the maximum ranking. An interference canceller applied to a CDMA communication system. 11. The CDM according to claim 5, wherein the leading interference removing unit stores a previous ranking and uses it as a current ranking.
An interference canceller applied to the A communication system. 12. The method according to claim 1, wherein the leading interference removing unit is configured to execute the ranking updating unit according to the ranking determined by the ranking determining unit when the selecting unit selects the ranking determining unit. The apparatus according to claim 11, wherein the apparatus according to the previous ranking is stored. 13. The method according to claim 11, wherein, if there is a user whose ranking is not stored in the previous ranking, the leading interference removal unit determines the ranking of the user as the maximum ranking. An interference canceller applied to the CDMA communication system according to any one of the preceding claims. 14. The apparatus according to claim 1, further comprising a level ranking determining means for determining a ranking for each user based on a level of the received signal when a signal for which transmission power control is not performed is received. Item 14. An interference canceller applied to the CDMA communication system according to any one of Items 1 to 13. 15. An interference cancellation method applied to a CDMA communication system in which both transmission rate information and required quality information for each user are known, and sequentially canceling interference between users according to a given ranking of users, A first step of multiplying known transmission rate information by known required quality information; and a second step of estimating received power for each user from the calculation result of the first step and determining a ranking between users. An interference cancellation method applied to a CDMA communication system. 16. Interference cancellation which is applied to a CDMA communication system in which transmission rate information for each user is unknown and required quality information is known, and sequentially cancels interference between users according to an arbitrary given ranking between users. A first step in which a plurality of interference cancellation stages are connected by at least the number of stages corresponding to the number of users, wherein interference cancellation is performed based on a ranking arbitrarily given in each of the interference cancellation stages, and transmission rate information is detected. And a second step of updating an arbitrary ranking used in the next interference cancellation stage based on the transmission rate information detected in the first step and the known required quality information. An interference cancellation method applied to a CDMA communication system. 17. A CDMA communication system in which transmission rate information for each user is unknown and known, and the required quality information is known, and the users are sequentially assigned according to a given ranking between users. In the interference cancellation method of performing interference cancellation between the plurality of interference cancellation stages, at least the number of stages corresponding to the number of users are connected, and interference cancellation is performed based on a ranking arbitrarily given in each of the interference cancellation stages and transmitted. A first step of detecting rate information; determining a ranking among users based on known transmission rate information and known required quality information for each user when the transmission rate information is known; and when the transmission rate information is unknown. Based on the transmission rate information detected in the first step and the known required quality information, Interference cancellation method applied to the CDMA communication system and the second step, characterized in that it contains to update any rankings for use.