JP2000353983A - Direct spread receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direct spread receiver reducing the interference of mutual multi-paths due to direct spread signals simultaneously transmitted from a plurality of transmitting stations in the soft hand off or the like. SOLUTION: In this direct spread receiver, a base station having a path Px whose power is the maximum is selected as an X base station according to the impulse responses of reception signals from A and B base stations. An interference canceller 5 virtually generates the direct spread reception signals of paths other than the path Px whose power is the maximum from the X base station and the direct spread reception signals of all the paths from the base station other than the X base station as an interference replica based on initial reception data, and removes the virtually generated signals from the received direct spread signal, and outputs the inverse spread signal of a user channel C of the path Px whose power is the maximum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a DS-CDMA (Direct Sequence Code) using a pilot channel.
The present invention relates to a direct-spread receiver used for a Division Multiple Access system.

[0002]

2. Description of the Related Art As a DS-CDMA system, a CDMA cellular telephone system (TIA) standardized in North America.
IS95). In this system, in a downlink, a pilot symbol is inserted into a pilot channel and transmitted, and a receiving side detects a carrier phase based on a received signal of the pilot channel and performs synchronous detection. FIG. 7 is a diagram illustrating a configuration of a downlink in the DS-CDMA system. 101 is an A base station,
102 is a C slave station. FIG. 8 is a schematic configuration diagram of a transmission device of a base station in a DS-CDMA system. In code multiplexing section 103, transmission data 1 to N of user channels of users 1 to N and data set to all 1s for pilot channels are assigned with orthogonal codes generated in orthogonal code generator 107, respectively. The signal is code-multiplexed, directly spread by being multiplied by a PN signal from a PN generator 108 in a multiplier 104, and multiplied (modulated) by a reference frequency signal (carrier) of a reference frequency oscillator 109 in a multiplier 105, and transmitted. The signal is transmitted from the antenna 106.

FIG. 9 is a schematic configuration diagram of a receiving device of a slave station in a DS-CDMA system. Receiving antenna 11
The signal received by 0 is multiplied by the sine wave reference frequency signal of the reference frequency oscillator 112 in the multiplier 111 to be converted into a baseband reception signal. DS-CD
As a feature of the demodulator of the MA system, a Rake reception method is adopted. Since the signal transmitted from the base station reaches the receiving antenna 110 through a plurality of paths, the received signal is a signal obtained by combining a plurality of signals having different amplitudes, carrier phases, and delay times. In the Rake reception method, the baseband reception signal is despread to be separated into reception signals of path 1 to path K and subjected to maximum ratio combining (Rake combining) into one impulse response. / N characteristics are improved.

[0004] A baseband received signal is output to a rake receiving section 121 and a searcher section 122. The baseband received signal is input to _K fingers 118 _{1 to} 118 K in Rake receiving section 121.
Each of the fingers 118 _{1 to} 118 _K is a demodulator for the _{first to K-} th paths, respectively. In the illustrated example, signals of up to K paths can be received. Each finger 118 _{1 -1}
18 _K have the same configuration.

[0005] The received signal of the baseband is multiplied by a multiplier 113.
Is multiplied by the PN code output from the PN generator 114 to obtain PN synchronization.
This C slave station 10 output from the orthogonal code generator 117
2 is multiplied by the orthogonal code of the user channel and the integrator 1
At 16, the received signal of the user channel of the C slave station 102 is despread by being integrated over one symbol period. From the fingers 118 _{1 to} 118 _K , the C slave stations 10 on the corresponding paths _{1 to K}
The despread received signals of the two user channels are output to the combining circuit 119.

Here, a timing signal for each of the paths 1 to K is supplied to the PN generator 114 and the orthogonal code generator 117 from a control unit 129 in the searcher unit 122 for estimating an impulse response. As a result, the PN generator 114 and the orthogonal code generator 117 output the PN code and the orthogonal code synchronized with the PN code and the orthogonal code of the corresponding paths 1 to K, respectively.

In the searcher section 122, the baseband received signal is supplied to a multiplier 123 by a PN generator 12.
4 is multiplied by the PN code output from the P.4, and is multiplied by the orthogonal code of the pilot channel output from the orthogonal code generator 126 in the multiplier 125 to separate the pilot channel received signal. Next, the integrator 127
Represents a received signal amplitude of a baseband of a pilot channel in a certain path k and a phase (carrier phase) with respect to a reference frequency signal through a filter 128 which integrates one symbol and further performs averaging for a plurality of symbols. The reference signal W (k) is generated and the control unit 12
9 is output. W (k) is a complex number, and k = 1 to K. As paths 1 to K, the path with the larger power is K
Are selected.

In the control unit 129, the PN generator 12
The timing of the PN generator 124 is controlled so that the PN code 4 is code-synchronized with the received signal, and the timing of the orthogonal code generator 126 is controlled so that the orthogonal code of the orthogonal code generator 126 is code-synchronized with the received signal. Control unit 12
Reference numeral 9 divides the time to generate K reference signals W (k) for K fingers. Also, by dividing the time, Rak
PN of K fingers 118 ₁ - 118 _K of e receiver 121
A timing signal is output to generator 114 and orthogonal code generator 117.

In the synthesizing circuit 119, each finger 1
Signals of user channels of the C slave station 102 from 181 to 118 _K are based on reference signals W (k) obtained from pilot channel reception signals of the paths _{1 to K} , respectively.
, The synchronous detection is performed by removing the phase offset of the received signal of the user channel of the C slave station 102, and the Rake combination is performed. The rake-combined received signal is decoded by the decoding unit 120,
Desired data of the user channel of the C slave station 102 is output.

As described above, by estimating the impulse response of each path k using the despread received signal of the pilot channel through which known data is transmitted, the phase offset of the received signal of each path k can be calculated. Has been removed. Although not shown, the multiplier 1 shown in FIG.
Numeral 11 denotes two actually provided, and a signal received by the receiving antenna 110 is also multiplied by a quadrature reference frequency signal orthogonal to the reference frequency signal to receive two series of baseband signals in phase and orthogonal to the reference frequency signal. Signal (usually
(Represented by complex numbers). The subsequent processes are individually performed on the two sequences, and the combining circuit 119 synchronously detects the two sequences as an in-phase component and a quadrature component with respect to the phase of the reference frequency signal (carrier).

Generally, high-speed data transmission is performed using DS-CDM.
When the A system is used, the chip rate naturally increases as the data rate increases. As the chip rate increases, the amount of interference due to multipath increases. When the number of multipaths increases, deterioration of transmission performance can no longer be prevented by the Rake reception method. When a signal obtained by combining the arriving waves of paths 1 to K with a time delay is received, when the arriving wave of a certain path k is despread, the arriving waves of the other paths with a time delay become interference signals. Therefore, the impulse response of a certain path k includes an interference component generated by cross-correlation with an incoming wave of another path. Therefore, if the impulse responses of the paths 1 to K are rake-combined, the transmission performance deteriorates.

As a first conventional technique for removing such multipath interference, there is an interference cancellation technique.
For example, Wada et al. And one other "B5-140 DS-CDMA"
A study of a multi-user multi-stage interference canceller in a system ", IEICE Society Conference (19988.9). Such an interference canceller (hereinafter referred to as prior art) is disclosed in the present application. A person has filed an application as Japanese Patent Application No. 10-236777.

First, an accurate impulse response is estimated using a pilot channel or the like. K paths having a large amplitude are selected, and their values are set to W (k) (k = 1 to K). The path P having the maximum amplitude value is selected. 1
The rake reception data is input to the first-stage interference canceller, and the output data of the previous-stage interference canceller is input to the second and subsequent interference cancellers. Further, an interference replica for each user is generated using a spreading code and W (k) for each path other than the maximum power path P. By subtracting interference replicas of all users from the received signal, despreading is performed on path P, and data for all users is detected. That is, W (k) is estimated in advance, and information on radio wave propagation is fixed after the estimation.

FIG. 10 is a basic block diagram of the prior art. This is a case where a code-multiplexed channel sharing one PN code is composed of one user channel (one user) and one pilot channel. On the other hand, FIG. 9 shows a case in which a plurality of code-multiplexed user channels (users) sharing one PN code are used, so that the premise is slightly different. explain.

In this basic configuration, the impulse response is estimated, the reference signal W (k) representing the impulse response is fixed, and the rake receiving section 121 detects the output data DR. In addition, the power maximum path detector 131
Selects the path P having the maximum power based on the reference signal W (k). In the interference canceller 133, R
The data output from the ake receiving unit 121 is used as initial reception data to generate a signal before performing synchronous detection and despreading on a path other than the path P where the power is maximum, and based on known data of a pilot channel. Then, in the paths other than the path P where the power is maximized, the signals of the pilot channels before despreading are generated, these are used as interference replicas, and the interference replica is subtracted from the received signal to obtain the path where the power is maximized. The data is detected again by performing despreading and synchronous detection on P again. In this manner, the bit error rate is improved by removing the interference that is a cause of the deterioration of the received signal quality.

In searcher section 122 shown in FIG. 9, K paths having large power obtained by despreading the pilot channel received signal are selected, and reference signal W ( k) (k = 1 to
K) is output. Maximum power path detector 1 shown in FIG.
31 selects a path P having the maximum power from the reference signal W (k), and outputs the value of P to the interference canceller 133.

FIG. 13 is an explanatory diagram of the operation of the interference canceller 133 shown in FIG. The signal transmitted from the base station 101 passes through a plurality of paths and is received as a combined signal of signals having different delay times. The upper diagram shows an impulse response by multipath. A path P having the maximum power is selected, and a baseband received signal before performing synchronous detection and despreading on another path is virtually generated based on the determination data and pilot channel data, and is subtracted. Received signal
Despreading is performed on the path P having the maximum power, and an impulse response having no interference component is detected as shown in the lower part.

The path P having the maximum power has a small ratio including an interference component, and the paths other than the path P are estimated to be mainly interference components. Then, the Rake receiving unit 12
The tentative data DR of one user channel of one user output from 1 is used as an initial value, and a signal before performing synchronous detection and despreading is generated from this by performing reverse signal processing. At the same time, it generates a previous signal of the pilot channel to be despread based on a known data D _p of the pilot channel. Thus, the path P
, An interference replica in paths 1 to K is generated. Then, by subtracting all the interference replicas of path 1 to path K excluding path P from the baseband received signal,
The received signal is a baseband reception signal of almost only path P.

Therefore, the interference canceller 133 has an R
Output data DR one communication channel that is output from the ake receiver 121, and, using known data D _p of the pilot channel, without path P of maximum power K
Generate an interference replica of one path. Then, despreading is performed again on the path P for the baseband reception signal obtained by removing the interference replica from the baseband reception signal. In this way, it is possible to perform despreading on a baseband received signal substantially the same as when it is assumed that only an incoming wave of a single path P has been received.
As a result, reception data DC of the user channel from which the interference component due to the cross-correlation of the path is removed is obtained. In addition,
The delay unit 132 compensates for a processing delay inside the Rake receiving unit 121 and the interference canceller.

FIG. 11 is an internal configuration diagram of the interference canceller 133 shown in FIG. The interference replica generation unit 135 for one user generates interference replicas for K-1 paths, excluding the path P, for the only user channel used by only one user. Further, the pilot channel interference replica generating unit 135 _p generates interference replicas for the K−1 paths excluding the path P for the pilot channel.

FIGS. 12A and 12B show interference replica generators 135 and 135 shown in FIG. 11, respectively.
It is an internal block diagram of p. Regarding the interference replica generation unit 141 ₁ for path 1, the data DR output from the rake reception unit 121 is output to the multiplier 138 by the path 1.
Is multiplied by the reference signal W ₁ (1)
The carrier phase and amplitude of the path 1 are returned to the signal before the synchronous detection, which has the signal point phase and amplitude added. Next, the PN for pass 1 is
The code PN ₁ (1) is further multiplied by the orthogonal code WS ₁ (1) for the path 1 of one user in the multiplier 140 and spread, thereby despreading with the time delay of the path 1. The signal is returned to the baseband received signal before the transmission, and an interference replica of path 1 is generated. Same configuration as that of the interference replica generation unit 141 ₁ for the path 1 is located 1 K-piece with the exception of the path P, these K-1 pieces of signals are added by the adder 142, the output signal path P Excluded are the output signals of the interference replicas of paths 1 to K.

Here, W ₁ (k) (k = _{1 to} K, k = P
9) is the reference signal output by the control unit 129 shown in FIG. 9, and PN ₁ (k) (except k = _{1 to} K, k = P) is the reference signal shown in FIG.
PN code and orthogonal code WS ₁ (k) (k = _{1 to} K, k) output from the PN generator 114 of the finger 118 _k shown in FIG.
= Excluding P) is based on orthogonal code, one user orthogonal code generator 117 of the finger 118 _k outputs shown in FIG. However, as shown in FIG.
Processing delay in e receiving section 121, interference canceller 13
3. The time delay is adjusted in consideration of the processing delay inside 3.
W ₁ (k), PN ₁ (k), and WS ₁ (k) correspond to the control unit 129, PN generator 114, and orthogonal code generator 117 described above.
Can be produced by providing a delay unit similar to the delay unit 132 for each of the outputs of.

In the interference replica generator 135 _p for the pilot channel shown in FIG. 12B, the known data D _p of the pilot channel is added to the multiplier 13.
At 8, the signal is multiplied by the reference signal W ₁ (1) for path 1 to become a signal having the signal point phase and amplitude given the carrier phase and amplitude of path 1.
Next, PN ₁ (1) which is a PN code for path 1 in multiplier 139, and orthogonal code WS for pilot channel path 1 in multiplier 140
_By being multiplied by ₁ (p, 1) and spreading, respectively, the baseband reception signal having the time delay of path 1 before being despread is returned to generate an interference replica of path 1. Figure 12 similarly to (a), the same configuration as the interference replica generation unit 141 ₁ for the path 1 is located 1 K-piece with the exception of path P, these K-1 pieces of signal adders 1
42, the output signal becomes the output signal of the interference replica of the paths 1 to K excluding the path P.

Here, W ₁ (k) (k = _{1 to} K, k = P
9) is the reference signal output by the control unit 129 shown in FIG. 9, and PN ₁ (k) (except k = _{1 to} K, k = P) is the reference signal shown in FIG.
The PN code (the PN generator 114 of the finger 118 _k) output from the PN generator 124 of the searcher unit 122 shown in FIG.
), The orthogonal code WS
₁ (p, k) (excluding k = 1 to K, k = P) is based on the orthogonal code of the pilot channel output from the orthogonal code generator 126 of the searcher unit 122 shown in FIG. However, processing delay in the Rake receiving unit 121,
The time delay is adjusted in consideration of the processing delay inside the interference canceller 133. W ₁ (k), PN ₁ (k), WS ₁
(P, k) corresponds to the control unit 129 and the PN generator 12 described above.
4, by providing a delay unit similar to the delay unit 132 at each output of the orthogonal code generator 126.

Returning to FIG. 11, the description will be continued. In the adder 136, the output signal of the interference replica 135 is subtracted from the delayed baseband reception signal, and the result is input to the despreading unit 137 for the path P. The despreading unit 137 for this path P is the same as the finger unit 1 shown in FIG.
18 the same structure as the finger portion of the path P during ₁ - 118 _K. That is, the reference signal W for the path P
₁ (P), a PN code for the path P, PN ₁ (P),
And one user's orthogonal code WS for path P
_{Using 1} (P), the baseband received signal from which the interference replica has been deleted is subjected to despreading for the path P, and data is determined.

This output data is data of one user whose transmission performance is improved by eliminating interference due to cross-correlation. The above-mentioned reference signal W ₁ (P), PN code PN
₁ (P) and one user's orthogonal code WS ₁ (P)
The reference signal W of the path excluding the path P described above
_{Like the 1} (k), the PN code PN ₁ (k), and the orthogonal code WS ₁ (k) of one user, a time delay is provided for compensating for a processing delay in the Rake receiving unit 121 and interference is caused. The time delay is adjusted in consideration of the processing delay inside the canceller 133.

FIG. 14 shows a code sharing one PN code.
The multiplexed channels have N user channels and
Prior art block consisting of one pilot channel
FIG. And interference for multiple users
The canceller is an interference canceller 151 of the 1st to Mth stages.₁~
151_MAre connected in cascade. This specific example
In this case, a plurality of interference
Operate the canceller to eliminate interference, and furthermore,
To operate the negotiation canceller,
Data is detected. First stage interference canceller 15
1₁Is the data D output from the Rake receiving unit 146.
Input R (1) to DR (N) as likely data
And the known data D of the pilot channel _p
To confirm that the interference signal has been canceled.
Data DC (1,1) to DC (1, N).

[0028] The second and subsequent stages, the output data from the preceding stage interference canceller with becomes the input data of the interference canceller of the next stage, also known data D _p of pilot channels is input. Each of the interference cancellers 151 _{1 to} 151 _{M at} any stage has a maximum power path detector 131 (FIG. 1).
0) is fixedly selected as the maximum power path. In addition, among the interference cancellers of each stage, 1 to
For the (M-1) th stage interference cancellers 151 _{1 to} 151 _M-1, it is necessary to output data of users 1 to N including data of the own station (for example, user 1). That is, the interference cancellers 151 ₁ to 151 in the _first to (M−1) stages
For 51M _-1 , despreading units for users 1 to N are required. The preceding is an explanation of the prior art relating to the interference canceller.

In the above description, the direct spread signal received by C slave station 102 is transmitted from one base station. However, at the time of soft handoff, the C slave station 102 simultaneously receives the direct spread signals transmitted from two or more base stations. FIG. 15 is an explanatory diagram of downlink soft handoff. In the figure, the same parts as those in FIG. 7 are denoted by the same reference numerals, and description thereof will be omitted. 161 is a B base station. In the DS-CDMA system, when the C slave station 102 moves from one cell to another cell,
When the C slave station 102 is located at the border of the cell, the A base station 10
1 and the B base station 161 simultaneously perform soft handoff control while transmitting the same data to the C slave station 102 via the user channel.

FIG. 16 is an explanatory diagram of direct spread signals transmitted from a plurality of base stations. The A base station 101 and the B base station 161 spread-modulate transmission data with a common PN code, and each PN code has a predetermined offset time (phase difference) for each base station from a predetermined reference time. Therefore, the start timings of the codes are different from each other. The C slave station 102 identifies the base station that transmitted the received direct spread signal based on the offset time from the reference time of the PN code of the received pilot signal. Since the code length of the PN code is sufficiently long, the time difference between the start timings described above is set longer than the delay time difference between the direct wave and the reflected wave between the multipaths. Therefore,
The multipath from the A base station 101 and the multipath from the B base station 161 can be detected separately from each other.

FIG. 17 is an explanatory diagram showing an example of the block configuration of the receiver at the time of soft handoff. In the figure,
2 is Rake for despreading the direct spread signal from the A base station.
A receiving unit 3 is a Rake receiving unit for despreading a direct spread signal from the B base station, and a combining determining unit 32 is provided. A base station 1
In the 01 and B base stations 161, the same transmission data is put in the user channel of the C slave station 102, and spread with the spreading codes (PN codes with time offsets) of the respective base stations and transmitted. In Rake receiving section 2 for despreading the directly spread signal from base station A, the baseband received signal is transmitted to Rake receiving sections 121 and 1 shown in FIGS.
Similarly to 46, the despreading is performed based on the PN code synchronized with the start timing of the PN code used by the A base station. However, unlike the Rake receiving unit shown in FIG. 9, the I and Q components immediately before the data determination are output instead of executing up to data determination by synchronous detection. Similarly, in the Rake receiving unit 3 for despreading the direct spread signal from the B base station, the signal is despread based on the PN code synchronized with the start timing of the PN code used by the B base station.

FIG. 18 is an explanatory diagram of the operation of the combination judging section shown in FIG. The combining determination unit 32 adjusts the carrier phases of the despread signals from the A base station and the B base station based on the pilot channels of both despread signals,
These are combined in a path to determine data. Even at a cell boundary where the received signal strength is reduced by such soft handoff, transmission data can be received without interruption by combining direct spread signals from both base stations after despreading. However, since two base stations transmit a direct spreading signal simultaneously, as a result,
The number of multipaths is doubled, and interference components due to mutual correlation between multipaths are increasing. Therefore, if Rake reception is simply performed or a direct spread signal from two base stations is combined as in the related art, the transmission performance may be rather deteriorated. Therefore, it is preferable to apply the interference cancellation technique at the time of the soft handoff described above. If the interference canceller shown in FIG. 10 is applied as it is, the configuration will be as follows.

FIG. 19 is an explanatory diagram showing an example of a block configuration at the time of soft handoff of a direct sequence receiver having an interference canceller. Here, in order to simplify the description, the A base station 101 shown in FIG.
It is assumed that the system transmits data only to two users of the D slave station (not shown) and the B base station 161 transmits data only to two users of the C slave station 102 and the E slave station (not shown). In the figure, the same parts as those in FIG. 17 are denoted by the same reference numerals, and description thereof will be omitted. However, Rake receiving section 2 for despreading the direct spread signal from A base station and Rake receiving section 3 for despreading the direct spread signal from B base station are shown in FIG.
7 has a different output stage, and the Rake shown in FIG.
As in the case of the unit 121, an output whose data has been determined by synchronous detection is output as initial reception data. 4 is a delay unit, 171
Is an interference canceller for removing the interference component of the direct spread received signal from the A base station, and 172 is an interference canceller for removing the interference component of the direct spread received signal from the B base station.

In the interference canceller 171, 6 is A
An interference replica generator for the direct spread signal of the user channel C from the base station, 7 is an interference replica generator for the direct spread signal of the user channel D from the A base station, and 8 is a direct spread signal of the pilot channel from the A base station. interference replica generation unit, 173 an adder, 174 is a despreading unit of the user channel C in the power up path P _a direct spread signal from the a base station. In the interference canceller 172, 9 is an interference replica generator for the direct spread signal of the user channel C from the B base station, 10 is an interference replica generator for the direct spread signal of the user channel E from the B base station, and 11 is the B base station. An interference replica generator for a direct spread signal of a pilot channel from a station;
6 is a despreading unit of the user channel C in the power up path P _B of the direct spread signal from the base station B. 177 is a power maximum path detector for the direct spread signal from the A base station, 1
Reference numeral 78 denotes a power maximum path detector for the direct spread signal from the B base station.

The delay unit 4 includes a delay unit 132 shown in FIG.
Similarly to the above, the baseband direct-spread reception signal is delayed in accordance with the processing delay of the rake reception unit, the interference replica generation unit, and the like. The interference replica generators 6 and 7 and the interference replica generators 9 and 10 are the same as the interference replica generator 135 for one user shown in FIG. On the other hand, the interference replica generators 8 and 11 generate the pilot replica interference replica generator 135 shown in FIG.
_The despreading units 171 and 176 are the same as the despreading units 137 and 176 for the path P shown in FIG. 11, but output despread signals immediately before data determination.

The maximum power path detectors 177 and 178 are similar to the maximum power path detector 131 shown in FIG. The inputted reference signal _{W (1 A) ~W (K} A), W
_{(1 B) ~W (K B} ) is the received signal amplitude of the baseband pilot channel in each pass, and a reference signal representing the carrier phase with respect to the reference frequency signal,
This is similar to the reference signals W (1) to W (K) output from the control unit 129 of the searcher unit 122 shown in FIG. However, direct spread signal from the A base station, for each of the direct spread signal from the base station B individually power up path P _A, by detecting the P _B, the maximum power path P
_A, each user channel C of the despread signal P _B, synthesized will perform data determined in the synthesis determining unit 7.

A block corresponding to the searcher unit 122 shown in FIG. 10 is a Rake receiving unit 2 for despreading a direct spread signal from the A base station, and a Rake receiving unit 3 for despreading a direct spread signal from the B base station. Are not shown in the figure. Note that the user channel C in the direct spread signal from the A base station and the user channel C in the direct spread signal from the B base station are not necessarily the same user channel number. Therefore, in the code multiplexing section 103 of each base station shown in FIG. 8, the same orthogonal code is not always allocated and code-multiplexed.

In the above-described configuration, initial received data is obtained in advance from the direct spread signals from the respective base stations, and based on the initial received data, the direct spread received signals of the paths from the same base station excluding the path with the largest power are used. Is virtually generated as an interference replica, the interference replica is subtracted, and the maximum power path is despread again. The interference component to the direct spread received signal is reduced. PN code used by A base station 101 and B base station 16
The PN code used by 1 can be identified by the offset time as shown in FIG. 16, but has a mutual correlation. Thus, despread signal of maximum power path P _A is
The direct spread signal of the path from the B base station 161 includes an interference component due to becoming an interference signal, while the despread signal of the power maximum path P _B includes the direct spread signal of the path from the A base station. An interference component due to becoming a signal is also included. The configuration described above does not reduce interference components between paths of these different base stations.

The problem of mutual interference between paths of different base stations as described above is not limited to soft handoff.
This will be described with reference to FIG. A base station 101 and C slave station 1
02, a user channel is set, while a user channel is not set between the B base station 161 and the C slave station 102. Such a situation occurs before the soft handoff control is started or after the soft handoff control is finished. Also, originally, in the C slave station 102, the A base station 101 and the B
The received signal level of the direct spread signal from the base station 161 is
A similar situation occurs when both are large. Even in such a situation, since the direct spread signals are simultaneously transmitted from the two base stations, the number of multipaths is doubled, and the interference component due to the correlation between the multipaths increases. . Therefore, as in the past, simply rake
When reception is performed, the transmission performance may be deteriorated. However, an interference canceller as in the prior art does not have a configuration for canceling even an interference component between paths of different base stations.

[0040]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and has a relatively simple structure in a soft handoff or the like, and has a relatively simple structure, and is capable of simultaneously transmitting signals directly from a plurality of transmitting stations. It is an object of the present invention to provide a direct spread receiver that reduces mutual interference components due to multipath of a signal.

[0041]

According to the present invention, there is provided a direct spread receiving apparatus for simultaneously receiving direct spread signals transmitted from a plurality of transmitting stations identifiable by a spread code. An impulse response estimating means, a path selecting means, an initial data output means, and an interference canceling means, wherein the impulse response estimating means, based on a direct spread received signal, Estimating impulse responses for a plurality of paths of the spread signal, and the path selecting means, based on the estimated impulse responses, among the plurality of transmitting stations, a path having a maximum power from a predetermined transmitting station. Selecting, the initial data output means, based on the direct spread reception signal, outputs the initial reception data for each transmitting station, The interference canceling unit is configured to determine, based on the initial reception data, at least one path from the predetermined transmitting station excluding a path at which the power is maximum, and at least one path from another transmitting station. At least an interference replica is generated, and a signal obtained by subtracting the interference replica from the direct spread reception signal is despread for a path where the power is maximum, and by performing data determination, it is set to at least the direct spread reception apparatus. It outputs the received data of the user channel. Accordingly, even when a plurality of transmitting stations are simultaneously transmitting direct spread signals, interference components due to multipath from any of the transmitting stations can be reduced. Furthermore, since the spread signal is directly received from a plurality of transmitting stations, the despreading and data determination are performed only for one maximum power path from one of the transmitting stations. The configuration for despreading and data determination is simplified. The interference canceling means may be a single-stage interference canceller or a multi-stage interference canceller.

According to a second aspect of the present invention, there is provided a direct spread receiving apparatus for simultaneously receiving direct spread signals transmitted from a plurality of transmitting stations identifiable by a spread code, comprising: , Path selection means, initial data output means, and a plurality of stages of interference cancellers, the impulse response estimation means, based on the direct spread received signal, a plurality of the direct spread signals transmitted from each transmitting station Estimate the impulse response to the path, the path selecting means, based on the estimated impulse response, from the plurality of transmitting stations, from a predetermined transmitting station, select the path with the maximum power, The initial data output means outputs initial reception data for each transmitting station based on the direct spread reception signal, Canceller, based on the initial reception data, from the predetermined transmission station, at least one path the power without path with the maximum and,
Generating at least an interference replica in at least one path from the other transmitting station, despreading a signal obtained by subtracting the interference replica from the direct spread reception signal for a path having the maximum power, and determining data. Thus, the first stage received data is output, and the second and subsequent stages of the interference cancellers remove the path from the predetermined transmitting station, at which the power becomes maximum, based on the received data at the preceding stage. At least one path, and at least an interference replica in at least one path from the other transmitting station is generated, and a signal obtained by subtracting the interference replica from the direct spread received signal is used for a path having the maximum power. By despreading and judging the data, the received data of the corresponding stage is output, and the received data of the final stage is reduced. Also it is intended to include the received data of the user channels set to the direct sequence receiver. Therefore, with the multi-stage configuration, more reliable interference cancellation can be performed in addition to the operation and effect of the first aspect of the present invention.

According to a third aspect of the present invention, there is provided a direct spread receiving apparatus for simultaneously receiving direct spread signals transmitted from a plurality of transmitting stations identifiable by a spread code, wherein a plurality of series of impulse signals are provided. Response estimation means, a plurality of sequences of path selection means, initial data output means, a plurality of sequences of interference cancellation means, and a sequence combination determination means, the plurality of sequences of impulse response estimation means,
The direct spreading signal is received by an antenna corresponding to the plurality of streams, and a plurality of paths of the direct spreading signal transmitted from each transmitting station in each of the streams based on the direct spreading reception signal in each of the streams. Estimate the impulse response to the, the path selection means of the plurality of sequences, based on the impulse response estimated in the respective sequences, out of the plurality of transmission stations in the respective sequences, from a predetermined transmission station The path having the maximum power is selected, and the initial data output means, based on the direct sequence reception signal in each of the sequences, for each of the transmitting stations, for each of the sequences, or for each of the Outputs the initial received data common to the series, and the interference canceling means of the plurality of series, respectively, On the basis of the initial reception data, in each of the sequences, from the predetermined transmitting station, at least one path excluding the path where the power is maximum, and in at least one path from the other transmitting stations. At least generating an interference replica, a signal obtained by subtracting the interference replica from the direct spread reception signal in each of the sequences, by despreading the path in which the power in each of the sequences is the maximum, a despread signal. Outputting the sequence combination determining means, after performing sequence combination of the despread signals in the respective sequences, by performing data determination to output at least received data of a user channel set in the direct spreading receiving apparatus. It is. Therefore, due to the diversity configuration on the receiving side, in addition to the function and effect of the first aspect of the present invention, it is hardly affected by fading fluctuation.
The interference canceling means may be a single-stage interference canceller or a multi-stage interference canceller.

According to a fourth aspect of the present invention, there is provided a direct spread receiving apparatus for simultaneously receiving direct spread signals transmitted from a plurality of transmitting stations identifiable by a spread code, comprising a plurality of series of impulse signals. Response estimating means, plural-sequence path selecting means, initial data output means, plural-stage plural-sequence interference canceller, and plural-stage sequence combining determining means, and the plural-sequence impulse response estimating means comprises Receiving the direct spread signal with an antenna corresponding to a sequence, and based on the direct spread received signal in each sequence, in each of the sequences, impulse for a plurality of paths of the direct spread signal transmitted from each of the transmitting stations. Responses are estimated, and the path selection means of the plurality of sequences is configured to estimate the response of each of the sequences. Based on the pulse response, among the plurality of transmitting stations in each of the series, a path from a predetermined transmitting station that maximizes the power is selected, and the initial data output unit performs the direct processing in each of the series. Based on the spread reception signal, for each of the transmitting stations, for each of the sequences, or, output initial reception data common to each of the sequences, the first stage of the multiple sequence interference canceller, On the basis of the initial reception data, in each of the sequences, from the predetermined transmitting station, at least one path excluding the path where the power is maximum, and in at least one path from the other transmitting stations. Generating at least an interference replica and subtracting the interference replica from the direct spread received signal in the respective sequence By despreading the signal in the path where the power in each of the sequences is the maximum, thereby outputting a first-stage despread signal. After serially combining the first-stage despread signal, the data is determined, and the first-stage received data is output.
The interference cancellers of the plurality of sequences in the second and subsequent stages are configured such that the power from the predetermined transmitting station in each of the sequences is based on the received data in the previous stage output by the sequence combining determination means in the previous stage. At least one interference replica in at least one path excluding the maximum path and at least one path from the other transmitting station are generated, and the interference replica is subtracted from the direct sequence reception signal in each of the sequences. By despreading the signal on the path where the power in each of the sequences is maximum, a despread signal of the stage is output, and the sequence combination determination means of the second and subsequent stages, After the sequence synthesis of the despread signal of the stage, the data is determined, and the received data of the stage is output. The received data are those including the received data of the user channels set to at least the direct sequence receiver. Therefore, with the multi-stage configuration, more reliable interference cancellation can be performed in addition to the operation and effect of the invention described in claim 3.

According to a fifth aspect of the present invention, in the direct spreading receiving apparatus according to any one of the first to fourth aspects, the direct spreading signal transmitted from each of the transmitting stations is: In each case, a user channel is set between the direct-sequence receiving device, and has the same data in the user channel, and the path selecting means, based on the estimated impulse response, A transmitting station having a path with the maximum power from a plurality of transmitting stations is defined as the predetermined transmitting station. Therefore, in soft handoff and the like, data determination can be performed for the path with the highest power, so that the bit error rate can be reduced.

According to a sixth aspect of the present invention, in the direct spread receiver according to any one of the first to fourth aspects, at least one of the direct spread signals transmitted from each of the transmitting stations is provided. One is that a user channel is set between the direct-sequence receiving device and the device,
The path selection means sets one of the transmitting stations, in which a user channel is set to the direct spreading receiver, as the predetermined transmitting station. Therefore, data can be determined for the path having the largest power among the paths from the transmitting station to which the user channel is set, so that the bit error rate can be reduced.

[0047]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a first embodiment of a direct sequence receiver according to the present invention at the time of soft handoff. In the figure, FIG.
The same parts as those in FIG. 19 are denoted by the same reference numerals, and description thereof will be omitted. 1 is an initial data output unit, 5 is an interference canceller corresponding to the X base station, and 14 is a maximum power path detector. FIG.
FIG. 2 is a schematic explanatory diagram of an interference canceling operation in the direct sequence receiver of FIG. 1.

In this embodiment, the internal configuration of initial data output unit 1 is the same as the configuration shown in FIG.
However, Ra which despreads the direct spread signal from the A base station
The output of the ke receiver 2 and the output of the rake receiver 3 for despreading the direct spread signal from the B base station are output to one interference canceller 5 corresponding to the X base station. Here, the X base station is a base station having a path Px with the maximum power in the set of the impulse response of the signal received from the A base station and the impulse response of the signal received from the B base station. The path Px is selected by a power maximum path detector 14 described later.

[0049] In the Rake receiver 2 for despreading direct sequence signals from the A base station, in FIG. 2, as shown as an impulse response of the received signal from the A base station, including the power up path P _A Are separated and detected. At this time, an interference component due to cross-correlation is also included, and this interference component is a factor that causes an error in data determination. This interference component includes not only interference due to cross-correlation between paths from the base station A, but also B
Includes interference due to cross-correlation with the path from the base station. Similarly, in the Rake receiving unit 3 for despreading the direct spread signal from the B base station, as shown in FIG. 2, as shown as an impulse response of the signal received from the B base station, the power maximum path P _B Are separated and detected, and include interference due to cross-correlation with the path from the A base station and interference due to cross-correlation between the paths from the B base station.

Now, assuming that the X base station is the A base station, the interference canceller 5 becomes an interference canceller corresponding to the A base station. Direct spread received signal other paths except power up path P _A from A base station, and a direct spread reception signals of all paths from the base station B as interference replicas, virtually based on the initial data received And remove it from the direct spread received signal. More specifically, the interference replica of the other paths except power up path P _A from A base station, the interference replica generation unit 6,
8, W ₁ (k), P ₁ shown in FIGS. 10 to 12 and 14 corresponding to the direct spread reception signal from the A base station.
It is generated using signals of N ₁ (k), WS ₁ (n, k), and WS ₁ (p, k). Further, interference replicas of all the paths of the direct spread received signal from the B base station are output to the interference replica generators 9, 10, 11 in W ₁ (k), PN corresponding to the direct spread received signal from the B base station. ₁ (k), WS
₁ (n, k) and WS ₁ (p, k). In this case, without excluding even the power up path P _B, it generates an interference replica.

On the other hand, when the X base station is the B base station,
Interference canceller 5 becomes an interference canceller corresponding to the B base station, direct spread received signal other paths except power up path P _B from the base station B, and direct sequence reception of all paths from A base station Signals as interference replicas
It is virtually generated based on the initial received data and is removed from the direct spread received signal. Then, a despread signal of the user channel C assigned to the C slave station 102 on the maximum power path P _B from the B base station is output. More specifically, the interference replicas of all the paths of the direct spread received signal from the A base station are converted into W signals corresponding to the direct spread received signal from the A base station in each of the interference replica generators 6, 7, and 8.
₁ (k), PN ₁ (k), WS ₁ (n, k), WS ₁ (p,
k). On the other hand, the interference replicas of the other paths except the power maximum path P _B of the direct spread received signal from the B base station are the interference replica generators 9, 10, and 10.
11, W ₁ (k), PN ₁ (k), WS ₁ (n, k), WS corresponding to the direct spread reception signal from the B base station
₁ is generated using the (p, k) signal.

The adder 12 subtracts these interference replicas from the baseband direct-spread reception signal delayed by the delay unit 4 to obtain the base stations A and B.
A direct spread received signal is obtained in which any interference signals on the path from the base station have been removed. For users channel C in the power up path P _X in the direct spreading the received signal, and despreading a direct spreading the received signal from the X base station, by the data determination, the maximum power path P _X without causing interference components A despread signal of user channel C is obtained,
Similar to the despreading unit 137 for the path P shown in FIG. 11, the data is determined by the internal determination unit and the received data is output.

In the normal operation other than the soft handoff, the operation can be performed with the block configuration shown in FIG. However, assuming that a base station to which no user channel is set is, for example, a B base station, blocks 23, 9, 10, 1 for processing a direct spread reception signal from the B base station.
Operation 1 may be stopped. Alternatively, the total number of paths that can be processed as a whole may be increased by using these blocks for processing the paths of the A base station to which the user channel is set. Note that, in other embodiments to be described later, a similar configuration can be adopted during a normal operation other than the soft handoff.

FIG. 3 shows a second embodiment of the direct sequence receiving apparatus according to the present invention.
FIG. 3 is a block diagram illustrating soft handoff for explaining the embodiment. 17, FIG. 19, FIG.
The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. 21 is a receiving antenna, 22 is a multiplier, 23 is a reference frequency oscillator, and 34 is a synthesis determination unit. In this embodiment, there are two types of receivers. In order to distinguish between the first and second receivers, the reference numerals and reference symbols have a
Or, a subscript “b” is added.

Two systems of receiving antennas are also provided for diversity. For example, two receiving antennas are provided at a distance (space diversity). Or 2
Two identical directional antennas are provided with different antenna orientations (angle diversity). Alternatively, antennas with different directivities are used (angle diversity). The directional characteristics and installation conditions of these antennas are
A single antenna or a combination of two or more antennas may be used.

The different receiving antennas 21a, 21a
The signal received by 1b is multiplied by sine wave reference frequency signals of reference frequency oscillators 23a and 23b in multipliers 22a and 22b, and is converted into a baseband direct spread reception signal. The reference frequency oscillators 13a and 13b are:
A sine wave reference frequency signal having the same frequency is output. The reference frequency oscillators 23a and 23b may share one reference frequency oscillator. This baseband direct spread received signal is Rak which despreads the direct spread signal from the A base station.
e, which are despread in the receiving units 2a and 2b, data is determined, and the user channels C and
The received data of D is output as initial received data. On the other hand, the baseband direct-spread reception signals are Rake receivers 3a and 3b that despread the direct-spread signal from the B base station.
The received data of the user channels C and E transmitted from the B base station are despread and data determined, and are output as initial received data.

The two-series interference cancellers 5a and 5b
On the basis of the initial reception data described above, the signals pass through the delay units 4a and 4b.
Of the interfering signal contained in the directly spread signal
Generate a replica and subtract this replica from the direct spread signal
And the maximum power path P_Xa, P _XbUser Chan in
Despreading the channel C, the despreading with reduced interference components
Output scattered signal. As each interference canceller 5a, 5b
Uses the interference canceller 5 shown in FIG.
You. However, unlike the interference canceller shown in FIG.
The despread signal immediately before data determination is output. In addition,
Maximum power path P in series a_XaBase station Xa having
And the maximum power path P in the sequence b_XbBase station X having
b may be different. Interference cancellers 5a, 5
The output of b is input to the combination determination unit 24. Composition judgment unit
Reference numeral 24 denotes a sequence after synthesizing the despread signal for each sequence.
The received data is output by performing data determination.

Two antennas 21a and 21b
Are independent. That is, they are receiving different multipath fading. For this reason, there is a high possibility that a direct spread signal without an output decrease due to fading fluctuation can be received from one of them, so that it is resistant to fading fluctuation. Also, what affects the noise of the two systems of receivers is the antenna 21
The multipliers 22a and 22b convert the signals a and 21b into baseband direct spread signals. If there are two receivers, the noise is independent for each receiver. Therefore, the influence of noise is averaged as compared with the case of one system. An interference canceller is used based on a baseband signal to which independent noise has been added to a received signal that has undergone independent multipath fading, and the output signals of the two systems are combined and determined. It becomes a receiving device that is superior to the performance of the interference canceller of the system alone.

FIG. 4 is an explanatory diagram of the operation of synthesizing two streams in the synthesizing judgment section 24 shown in FIG. FIG. 4 (a)
FIG. 4 is an explanatory diagram of a synthesizing function, and FIG. The in-phase component (I phase) and the quadrature component (Q phase) of the despread signal output from the interference canceller 5a of the first receiver (system a) are set to (V _1i , V _1q ), and the second receiver ( The in-phase and quadrature components of the despread signal output from the interference canceller 14b of the system b) are (V _2i , V _2q ), and the in-phase and quadrature components of the sequence combined signal are (V _0i , V _0q ).

The sequence synthesized signal is obtained by:
Each is created by adding weights W _t1 and W _t2 . That is, V _{0i =} V _1i * W _t1 + V _2i * W _t2 V _{0q =} V _1q * W _t1 + V _2q * W _t2 . Here, the weight W _t1, W _t2, for ^{_{example, W t1 = (V 1i 2}} + V 1q 2) / {(V 1i + V 2i) 2 + (V 1q + V
_2q) ² ｝ ^1/2 W _t2 = (V _2i ² ₊ V _2q ² ) / ｛(V _{1i +} V _2i ) ² + (V _{1q +} V
_2q) ² ｝ ^1/2 .

[0061] Alternatively, as the weight _{W t1, W t2, W t1} = (V 1i 2 + V 1q 2) 1/2 / {(V 1i + V 2i) 2 + (V
^{_{1q + V 2q) 2} 1/2}} W t2 = (V 2i 2 + V 2q 2) 1/2 / {(V 1i + V 2i) 2 + (V
_{1q +} V _2q) ² ｝ ^1/2 . Note that the value of each denominator is the length of a vector obtained by adding the respective path synthesized signals. As shown in FIG. 4B, in the case of four-phase modulation, data is determined based on which quadrant on the IQ phase plane the above-mentioned sequence combined signal (V _0i , V _0q ) is located, and the received data is output. Is done. In the above description, the weighting in combining the outputs of the two receivers has been described. However, the combining is performed using the same weighting also in the path combining in the combining determining unit 32 in FIG.

FIG. 5 is a block diagram showing a third embodiment of the direct spread receiver according to the present invention. In the drawing, the same parts as those in FIGS. 17, 19, 1, and 3 are denoted by the same reference numerals, and description thereof is omitted. Reference numeral 31 denotes a delay unit for compensating for a delay in processing time in the initial data output unit 1, the combination determination unit 32, and the interference canceller 5. 3
Reference numeral 2A denotes a path combination determination unit corresponding to the A base station, and 32B denotes a path combination determination unit corresponding to the B base station.

In this embodiment, rake receiving sections 2a and 2a for despreading a direct spread signal from base station A
b, Rake for despreading the direct spread signal from base station B
The receiving units 3a and 3b output a despread signal corresponding to an impulse response of the initial reception data at a stage immediately before obtaining the initial reception data. The path combining determination unit 32A corresponding to the A base station performs sequence combining of the despread signal of the path corresponding to the A base station in each of the sequences, and then performs data determination. Output the initial received data. On the other hand, the path combining determination unit 32B corresponding to the B base station performs sequence combining of the despread signal of the path corresponding to the B base station in each of the sequences, and then performs data determination to determine the B base station. Outputs the initial reception data from the station. As described above, it is more appropriate to perform the two-system synthesis determination individually for the initial data output units 1a and 1a for the own system.
The initial received data becomes more reliable than using the output of b. This initial received data is the interference canceller 5a,
By being input to 5b, the output data of the combination determination unit 24 becomes more reliable.

In each of the above embodiments, a one-stage interference canceller is used. Although not shown, as shown in FIG. 14, the interference canceller can be cascadedly operated in a multi-stage configuration (multi-stage). The second and subsequent interference cancellers use the output of the preceding stage as initial reception data. Further, in a two-system receiver configuration,
It can have a multi-stage configuration.

FIG. 6 is a block diagram of a fourth embodiment of the direct sequence receiver according to the present invention. In the drawing, the same parts as those in FIGS. 17, 19, 1, and 3 are denoted by the same reference numerals, and description thereof is omitted. However, the one-stage interference cancellers 5a and 5b shown in FIG. 3 output despread signals of only the user channel C of the C slave station, and the combining determination unit 124 outputs the received data of the user channel C of the C slave station. It should have output only. However, in the multistage configuration of this embodiment, the interference cancellers 5a and 5b output despread signals of all user channels, and the combining determination unit 24 converts the received data of all user channels into the initial data of the next stage. By using the received data, interference replicas of all user channels are generated in the next stage so that interference components can be reduced.

Reference numerals 41a and 41b denote delay units for compensating for processing delays in the first-stage interference cancellers 5a and 5b, the combination determination unit 24, and the second-stage interference cancellers 42a and 42b. Reference numerals 42a and 42b denote second-stage interference cancellers, which use the received data output from the first-stage combination determination unit 24 as initial received data, but have the same configuration as the interference cancellers 24a and 24b. . 43
Is a second-stage synthesis determination unit, which has the same configuration as the first-stage synthesis determination unit 24. Note that the interference cancellation of the pilot channel, similar to FIG. 14, is executed by generating an interference replica by entering the known data D _p of the pilot channel. 44a and 44b are delay units, and second-stage interference cancellers 42a and 42b;
Combination determination section 43, interference cancellers 45a and 45 at the final stage
b compensates for the processing delay inside. The interference cancellers 45a and 45b at the final stage need only output the despread signal of the user channel C of the C slave station, similarly to the interference cancellers 5a and 5b shown in FIG. Reference numeral 46 denotes a final-stage synthesis determination unit which, like the synthesis determination unit 24 shown in FIG. 3, only needs to output received data of the user channel C of the C slave station. In the illustrated example, the initial data output units 1a and 1b and the first-stage interference cancellers 5a and 5b
Although the configuration of the one-stage interference canceller shown in FIG. 3 is used as the configuration up to this point, the configuration shown in FIG. 5 may be used instead.

As each stage of the interference canceller cascades, the subsequent stage interference canceller cancels the interference based on the received data of the preceding stage, so that more reliable received data can be output. It is also possible to change the number of operation stages as appropriate, and to output reception data of the user channel C of the C slave station from the last operation stage. By reducing the number of operation stages, processing time and power consumption can be reduced. By detecting an error state by using a bit error rate detection means (not shown), and detecting this error state,
The number of operating stages may be adaptively controlled so as to obtain a certain reception quality.

In the above description, the interference canceller determines the maximum power path P _X for the detected multipath in the direct spread signal from the X base station having the maximum power path P _X.
Generate interference replicas of all detected paths except, cancel them, and for detected multipaths in direct spread signals from base stations other than X base station,
Interference replicas of all detected paths were generated and canceled. However, for the detected multipath in the direct spread signal from the X base station, only an interference replica of at least one path excluding the maximum power path P _X is generated and canceled, and the base other than the X base station is canceled. Even if an interference replica of at least one path is generated and canceled for the detected multipath in the direct spread signal from the station, the interference component is reduced according to the cancellation amount.

An interference replica of a certain path is
If generated based on the initial received data of all user channels and the known data of the pilot channel,
That is, by generating interference replicas of all communication channels, the interference component when direct spread received signal of this path, cheek completely would be canceled, and the direct spread received signal despread the power up path P _X Is greatly reduced. However, even if an interference replica is generated and canceled based on only the initial reception data of some user channels, for example, the initial reception data of the user channel of the own station, the interference component is reduced according to the cancellation amount. As described above, when the interference cancellation of only some of the interference signals is realized by the interference canceller having the multi-stage configuration, the path for generating the interference replica and its communication channel are arbitrarily determined for each stage. It is also possible.

In the above description, a two-system receiver configuration is used. However, a larger number of receiver configurations may be used, and data may be determined by performing sequence synthesis. Further, at least the receiving antenna is actually provided with a plurality of systems by, for example, sequentially switching the outputs of the receiving antennas of the plurality of systems by the selection switch means, but the succeeding processing blocks have only one actual processing block. Multiple signals may be multiplexed. In the above description, the initial reception data is output by the Rake combination. Instead, the baseband direct-spread reception signal is despread, and among them, the despread signal of the path P having the maximum power is determined. Then, a despreading unit that outputs this as initial reception data may be used.

In the above description, a configuration in which the same user data is transmitted from a plurality of base stations to the own station during soft handoff has been described. However, even when such soft handoff is not performed, when transmitting the same user data from a plurality of base stations to the own station at the same time,
Interference components can be reduced. Even in such a case, the direct-sequence receiving apparatus of the present invention can reduce the mutual interference components of the multipath of the direct-sequence signals transmitted from a plurality of base stations.

The direct spreading receiver described above can also be applied to W-CDMA (Wideband CDMA) having a pilot symbol section in a frame. In a W-CDMA system, a plurality of user channels are code-multiplexed, and a pilot symbol common to a plurality of user channels is inserted in a certain time interval, and an impulse response is estimated based on the pilot symbols. Outputs a reference signal W (k).

In W-CDMA, the section of the user channel and the section of the pilot channel are temporally different. However, if the multipath of the pilot channel enters the section of the user channel, the pilot channel becomes This will cause interference due to multipath cross-correlation on the user channel. Therefore, by using the pilot channel interference replica generation unit 135p shown in FIG. 11, interference due to the pilot channel can also be removed.

However, an interference replica of the pilot channel is generated even in a section of the pilot channel where no received signal of the user channel exists. If the interference replica component in the section of the pilot channel is large, it may become a noise component and the transmission quality may be degraded. Accordingly, the output of the pilot channel interference replica generation unit 135p shown in FIG. 11 is output to the adder 136 via a switch unit (not shown). This switch section is controlled by the control section 129 and supplies the replica replica of the pilot channel to the adder 136 only in the section of the user channel.

In the above description, the operation of the direct spreading receiver in soft handoff has been described. However, even in a situation where a user channel is set between one base station and a direct spread signal is simultaneously transmitted from another base station to which no user channel is set, the above-described direct spread receiving apparatus is used. Can be applied. In this case, the maximum power path is selected from the multipath from the base station in which the user channel is set between the direct power receiving apparatus and the direct power receiving apparatus. Further, not only in the case where the spread signal is directly transmitted from the base station to the slave station, but also in the case where the spread signal is directly transmitted from the arbitrary transmitting station to the receiving apparatus, when the same situation as described above occurs, the above-described direct spread signal is used. A spreading receiver can be applied.

[0076]

As will be apparent from the above description, the present invention has a relatively simple configuration for direct spreading transmitted from a plurality of transmitting stations at the same time in soft handoff between a plurality of base stations and slave stations. This has the effect of reducing mutual interference components due to signal multipath.

[Brief description of the drawings]

FIG. 1 is a block diagram at the time of soft handoff for explaining a first embodiment of a direct sequence receiving apparatus of the present invention.

FIG. 2 is a schematic explanatory diagram of an interference canceling operation in the direct spreading receiver of FIG. 1;

FIG. 3 is a block diagram at the time of soft handoff for explaining a second embodiment of the direct spread receiving apparatus of the present invention.

FIG. 4 is an explanatory diagram of an operation of synthesizing two sequences in the synthesis determination unit shown in FIG. 3;

FIG. 5 is a block diagram of a third embodiment of the direct sequence receiver according to the present invention.

FIG. 6 is a block diagram of a fourth embodiment of the direct sequence receiver according to the present invention.

FIG. 7 is a diagram illustrating a configuration of a downlink in a DS-CDMA system.

FIG. 8 is a schematic configuration diagram of a transmission device of a base station in a DS-CDMA system.

FIG. 9 is a schematic configuration diagram of a receiving device of a slave station in the DS-CDMA system.

FIG. 10 is a basic block configuration diagram of a prior art.

11 is an internal configuration diagram of the interference canceller shown in FIG.

12 is an internal configuration diagram of the interference replica generation unit shown in FIG.

13 is an explanatory diagram of the operation of the interference canceller shown in FIG.

FIG. 14 is a block diagram of a prior art in which a code-multiplexed channel sharing one PN code is composed of N user channels and one pilot channel.

FIG. 15 is an explanatory diagram of downlink soft handoff.

FIG. 16 is an explanatory diagram of direct spread signals transmitted from a plurality of base stations.

FIG. 17 is an explanatory diagram showing an example of a block configuration showing an operation of the receiver at the time of soft handoff.

FIG. 18 is an explanatory diagram of the operation of the combination determination unit shown in FIG. 17;

FIG. 19 is an explanatory diagram showing an example of a block configuration at the time of soft handoff of a direct sequence receiver having an interference canceller.

[Explanation of symbols]

1 initial data output unit, 2 rake receiving unit for despreading a direct spread signal from base station A, 3 rake receiving unit for despreading a direct spread signal from base station, 4 delay unit,
5 interference canceller corresponding to X base station, 14 maximum power path detector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K022 EE02 EE35 5K067 AA03 BB04 CC10 CC24 EE02 EE10 EE24 JJ54

Claims (6)

[Claims] 1. A direct spreading receiver for simultaneously receiving direct spreading signals transmitted from a plurality of transmitting stations identifiable by a spreading code, comprising: an impulse response estimating means, a path selecting means, an initial data output means, and An interference canceling unit, wherein the impulse response estimating unit estimates impulse responses for a plurality of paths of the direct spread signal transmitted from each of the transmitting stations, based on the direct spread received signal, Based on the estimated impulse response, from among the plurality of transmitting stations, from a predetermined transmitting station, select a path having a maximum power, the initial data output means, based on the direct spread received signal And outputting the initial reception data for each transmitting station. The interference canceling unit outputs the initial reception data based on the initial reception data. From a given transmitting station, at least one path excluding the path where the power is maximized, and at least one interference replica in at least one path from the other transmitting stations is generated, and from the direct spread received signal, By despreading the signal from which the interference replica has been subtracted for the path where the power is maximum, and performing data determination,
A direct-sequence receiving device, which outputs at least reception data of a user channel set in the direct-sequence receiving device. 2. A direct spread receiving apparatus for simultaneously receiving direct spread signals transmitted from a plurality of transmitting stations identifiable by a spreading code, comprising: an impulse response estimating means, a path selecting means, an initial data output means, and A plurality of stages of interference cancellers, wherein the impulse response estimating means estimates impulse responses for a plurality of paths of the direct spread signals transmitted from the respective transmitting stations, based on the direct spread received signals, Means, based on the estimated impulse response, from among the plurality of transmitting stations, from a predetermined transmitting station, to select a path having the maximum power, the initial data output means, the direct spread reception signal And outputs the initial reception data for each transmitting station based on the first reception data. Generating at least one interference replica from at least one path from the predetermined transmitting station except for the path having the highest power, and at least one path from the other transmitting stations; The signal obtained by subtracting the interference replica from the signal is despread for the path having the maximum power, and the data is determined, thereby outputting the first-stage received data. Based on the received data at the preceding stage, from the predetermined transmitting station,
At least one path excluding the path where the power is maximized, and at least one interference replica in at least one path from the other transmitting station is generated, and a signal obtained by subtracting the interference replica from the direct spread received signal is generated. By despreading the path with the maximum power and determining the data, the received data of the corresponding stage is output, and the received data of the last stage is at least the reception of the user channel set in the direct spread receiving device. A direct spread receiver comprising data. 3. A direct spreading receiver for simultaneously receiving direct spreading signals transmitted from a plurality of transmitting stations identifiable by spreading codes, comprising: a plurality of impulse response estimating means; a plurality of path selecting means; A data output unit, a plurality of sequences of interference canceling units, and a sequence combining determining unit, wherein the plurality of sequences of impulse response estimating units receive the direct spread signal with an antenna corresponding to the plurality of sequences, and each of the sequences Estimating impulse responses for a plurality of paths of the direct spread signal transmitted from each of the transmitting stations in the respective sequences, based on the direct spread reception signals in, the path selection means of the plurality of sequences, Based on the impulse response estimated in the sequence of Among the plurality of transmitting stations, a path from a predetermined transmitting station that maximizes power is selected, and the initial data output means, based on the direct spread reception signals in the respective streams, Separately,
For each of the sequences, or output initial reception data common to each of the sequences, the plurality of sequences of interference canceling means, based on the initial reception data, the predetermined in each of the sequences, And at least one interference replica in at least one path excluding the path with the highest power from at least one of the transmission stations and at least one path from the other transmission stations, and the direct spreading in the respective sequences is performed. By despreading the signal obtained by subtracting the interference replica from the received signal on the path where the power in each of the sequences is maximum, a despread signal is output. After performing sequence synthesis on the despread signal, at least the And outputs the received data of the user channels set to contact spread receiver apparatus, spread receiver device directly, characterized in that. 4. A direct spreading receiver for simultaneously receiving direct spreading signals transmitted from a plurality of transmitting stations identifiable by spreading codes, comprising: a plurality of impulse response estimating means; a plurality of path selecting means; A data output unit, a multi-stage interference canceller having a plurality of stages, and a multi-stage sequence combination determining unit, wherein the plurality of sequence impulse response estimating units receive the direct spread signal with an antenna corresponding to the plurality of sequences. And estimating impulse responses for a plurality of paths of the direct spread signals transmitted from the respective transmitting stations in the respective sequences, based on the direct spread reception signals in the respective sequences, and selecting the path in the plurality of sequences. Means, based on the impulse response estimated in the respective sequence, Among the plurality of transmitting stations in the series, from a predetermined transmitting station, select a path having the maximum power, the initial data output means, based on the direct spread received signal in each of the series, For each transmitting station,
Outputs initial reception data common to each of the sequences or to each of the sequences. The first-stage interference cancellers for the plurality of sequences each include:
On the basis of the initial reception data, at least one path from the predetermined transmitting station, excluding the path where the power is maximum, and at least one path from the other transmitting stations, in the respective streams. At least in the first stage by despreading a signal obtained by subtracting the interference replica from the direct spread received signal in each of the sequences on a path where the power in each of the sequences is maximized. The first-stage sequence combination determining means performs a sequence determination on the first-stage despread signal in each of the sequences, and then performs data determination to obtain the first-stage received data. The interference cancellers of the second and subsequent stages are respectively provided before and after the preceding stage output by the preceding sequence combining determination means. Interference in at least one path from the predetermined transmitting station, excluding the path with the highest power, and at least one path from the other transmitting station in the respective sequences based on received data By generating at least a replica and despreading the signal obtained by subtracting the interference replica from the direct spread received signal in each of the sequences, despreading the path where the power in each of the sequences is maximized, thereby despreading the stage. A signal, and the sequence combination determination means of the second and subsequent stages performs sequence determination on the despread signals of the stage in the respective sequences, and then performs data determination to output received data of the stage. The reception data at the last stage includes at least reception data of a user channel set in the direct-sequence reception device. Is Dressings, spread receiver device directly, characterized in that. 5. The direct spreading signal transmitted from each of the transmitting stations has a user channel set with the direct spreading receiving device and has the same data in the user channel. The path selection unit, based on the estimated impulse response, sets a transmitting station having a path where power from the plurality of transmitting stations is maximized as the predetermined transmitting station. The direct-sequence receiving device according to any one of claims 1 to 4. 6. At least one of the direct sequence signals transmitted from each of the transmitting stations has a user channel set with the direct sequence receiving apparatus, and the path selecting means includes: The direct spread receiving apparatus according to any one of claims 1 to 4, wherein one of the transmitting stations for which a user channel is set between the direct spread receiving apparatus and the direct spread receiving apparatus is the predetermined transmitting station.