JP3153531B2 - Direct spread receiver - Google Patents

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, the PN generator 114 and the orthogonal code generator 117 are supplied with timing signals for the respective paths 1 to K from the control unit 129 in the searcher unit 122 for estimating the 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.

[0007] In the searcher section 122, the baseband received signal is supplied to a PN generator 12 in a multiplier 123.
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 on 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 eliminating such multipath interference, there is an interference cancellation technique.
For example, Wada et al., "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. The 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 the value is 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 one user's path 1 in the multiplier 140 and spread, thereby despreading with a time delay of 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 with respect to 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-described 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
₁ (k), the PN code PN ₁ (k), and the orthogonal code WS ₁ (k) of one user have a time delay in order to compensate for the processing delay in the Rake receiving unit 121 and the interference 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 7 is a combining determining unit. A base station 10
1. In the B base station 161, the same transmission data is put in the user channel of the C slave station 102, spread with the spreading code (the same PN code with offset time) of each base station, and transmitted. In rake receiving section 2 for despreading the direct spread signal from base station A, the baseband received signal is transmitted to rake receiving section 12 shown in FIGS.
Similarly to 1,146, 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,
The rake receiving unit 3 that despreads the directly spread signal from the B base station performs despreading 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 7 matches 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, and then performs path combining on these 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 the spread signals are transmitted directly from the two base stations at the same time, the number of multipaths is doubled as a result, and the interference component due to the correlation between the multipaths increases. 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 the 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, 8 is A
A maximum power path detector 9 for the direct spread signal from the base station, and a maximum power path detector 9 for the direct spread signal from the B base station. Reference numeral 171 denotes an interference canceller that removes an interference component of a direct spread reception signal from the A base station, and 172 denotes an interference canceller that removes an interference component of a direct spread reception signal from the B base station.

In the interference canceller 171, 173
Reference numeral 174 denotes an interference replica generation unit for the direct spread signal of the user channel C from the A base station, 174 denotes an interference replica generation unit for the direct spread signal of the user channel D from the A base station, 17
5 is an interference replica generator for a direct spread signal of a pilot channel from the A base station, 176 is an adder, 177 is A
A despreader of a user channel C in the power up path P _A of the direct spread signal from the base station. In the interference canceller 172, reference numeral 178 denotes an interference replica generator for a direct spread signal of the user channel C from the B base station;
Is an interference replica generator for the direct spread signal of the user channel E from the B base station; 180 is an interference replica generator for the direct spread signal of the pilot channel from the B base station;
81 denotes an adder, 182 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.

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. Interference replica generators 173, 17
4. The interference replica generation units 178 and 179 respectively
This is similar to the one-user interference replica generator 135 shown in FIG. On the other hand, the interference replica generation unit 175,
Numeral 180 is similar to the pilot replica interference replica generator 135 _p shown in FIG. 11, and despreading units 177 and 182 are similar to the despreading unit 137 for the path P shown in FIG. Output the despread signal immediately before the data determination.

The maximum power path detectors 8 and 9 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 a baseband received signal amplitude of a pilot channel in each path and a reference signal representing a carrier phase with respect to a reference frequency signal, and is output from the control unit 129 of the searcher unit 122 shown in FIG. These are the same as the reference signals W (1) to W (K). However, for each of the direct spread signal from the A base station and the direct spread signal from the B base station, the maximum power path P _A ,
By detecting P _B , the power maximum paths P _A , P _B
Each user channel C of the despread signal of
And the data determination is performed.

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.

[0039]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems. In soft hand-off and the like, a multi-stream of a direct spread signal of the same data simultaneously transmitted from a plurality of transmitting stations is disclosed. It is an object of the present invention to provide a direct spread receiver that reduces mutual interference components due to paths.

[0040]

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. The direct spreading signals transmitted from the respective transmitting stations each have the same data in a user channel set in the direct spreading receiving apparatus, and include an impulse response estimating unit, a path selecting unit, and an initial data. Output means, interference cancellation means corresponding to each of the transmitting stations, and has a path combination determination means,
The impulse response estimation means 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 reception signal, and the path selection means estimates the impulse response. The initial data output means, based on the direct spread reception signal, outputs initial reception data for each transmission station, based on The corresponding interference canceling means, based on the initial reception data, respectively, from the corresponding transmitting station, at least one path excluding the path where the power is maximum, and from the other transmitting stations that do not correspond. Generating at least one interference replica in at least one path of By despreading the subtracted signal with respect to the path having the maximum power from the corresponding transmitting station, a despread signal corresponding to the transmitting station is output. After the despread signal corresponding to the station is path-combined, the data is determined, and at least the received data of the user channel set in the direct spread receiver is output. Therefore, when direct spread signals of the same data are simultaneously transmitted from a plurality of base stations, it is possible to reduce interference components due to multipath from any of the base stations. By combining the despread signal for the path with the highest power from each transmitting station, data determination can be made for the path with the highest power from each transmitting station, and the input signal level during data determination is prevented from lowering. In addition, the bit error rate can be reduced. 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 that can be identified by a spreading code, wherein each of the transmitting stations The direct spread signals transmitted from the respective have the same data in the user channel set in the direct spread receiver, impulse response estimation means, path selection means, initial data output means, a plurality of stages An interference canceller corresponding to each transmitting station, and having a plurality of stages of path combining determining means, wherein the impulse response estimating means is based on a direct spread received signal, based on the direct spread signal transmitted from each transmitting station. Estimate impulse responses for multiple paths,
The path selecting means selects a path having the maximum power for each of the transmitting stations based on the estimated impulse response, and the initial data output means controls the transmitting station based on the direct spread reception signal. Separately, output the initial reception data, the interference canceller corresponding to the first-stage transmission station, based on the initial reception data, from the corresponding transmission station, except for the path with the maximum power, At least one path, and at least an interference replica in at least one path from the other transmitting station that does not correspond to at least generate, and a signal obtained by subtracting the interference replica from the direct spread received signal, from the corresponding transmitting station. Despreading for the path where the power is maximum, outputs a first-stage despread signal corresponding to the transmitting station, Of the path combination judging means, after the despread signal of the first stage corresponding to the transmission station passes synthesis,
By performing the data determination, the first-stage reception data is output, and the interference cancellers corresponding to the transmission stations in the second and subsequent stages respectively receive, based on the reception data in the preceding stage, a signal from the corresponding transmission station. Generating at least one interference replica in at least one path excluding the path where the power is maximum, and at least one path from the non-corresponding other transmitting station, and subtracting the interference replica from the direct spread received signal. The spread signal is despread for the path where the power from the corresponding transmitting station has the maximum power, so that a despread signal corresponding to the transmitting station is output. After performing path synthesis on the despread signal of the stage corresponding to the transmitting station, the data is determined, and the received data of the stage is output. The received data includes a reception 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 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 spreading code, wherein each of the transmitting stations includes The direct spread signals transmitted from the respective devices have the same data in the user channel set in the direct spread receiver, and include a plurality of sequences of impulse response estimation units, a plurality of sequences of path selection units, and initial data. An output unit, an interference canceling unit corresponding to the transmitting station of a plurality of sequences, a path combining unit of a plurality of sequences, and a sequence combining determining unit, and the impulse response estimating unit of the plurality of sequences is an antenna corresponding to the plurality of sequences. Receiving the direct spread signal at, based on the direct spread received signal in each sequence, Estimating impulse responses for a plurality of paths of the direct spreading signal transmitted from each of the transmitting stations, the path selecting means of the plurality of sequences, based on the estimated impulse responses in the respective sequences, Selecting a path having the maximum power for each transmitting station in each sequence, the initial data output means based on the direct spread received signal in each sequence, for each transmitting station, for each sequence, Or, output the initial reception data common to each of the series, the interference cancellation means corresponding to the transmitting station of the plurality of series, respectively, based on the initial reception data, in each of the series, At least one path excluding the path with the maximum power from the transmitting station; And generating at least an interference replica in at least one path from the other uncorresponding transmitting station, and subtracting the interference replica from the direct-spread received signal in the respective sequence to obtain a corresponding signal in the respective sequence. By performing despreading on the path where the power from the transmitting station is maximum, a despread signal corresponding to the transmitting station is output, and the path combining means of the plurality of sequences is
Outputting a path-combined despread signal obtained by path-combining the despread signal corresponding to the transmitting station in each of the sequences, wherein the sequence combination determining means performs sequence combination on the path-combined despread signal in each of the sequences. By outputting data, at least the received data of the user channel set in the direct-sequence receiving apparatus is output. Therefore, by the diversity configuration of the receiving side,
In addition to the functions and effects 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 spreading code, wherein each of the transmitting stations includes: The direct spread signals transmitted from the respective devices have the same data in the user channel set in the direct spread receiver, and include a plurality of sequences of impulse response estimation units, a plurality of sequences of path selection units, and initial data. Output means, an interference canceller corresponding to each transmission station of a plurality of sequences in a plurality of stages, a path combining means of a plurality of sequences in a plurality of stages, and a sequence combining determination means of a plurality of stages, the impulse response estimation means of the plurality of sequences, ,
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 series, based on the estimated impulse response in the respective series, based on the path in each of the transmission station in each of the power is the maximum power Selecting, the initial data output means outputs, based on the direct spreading reception signal in each of the sequences, initial reception data for each of the transmission stations, for each of the sequences, or common to the respective sequences. And the first
The interference cancellers corresponding to the transmitting stations of the plurality of stages at the stages, respectively, based on the initial reception data, in the respective sequences, from the corresponding transmitting station,
At least one path excluding the path where the power is maximized, and at least an interference replica in at least one path from the other non-corresponding transmitting station is generated, and the direct-sequence received signal in the respective sequence is used to generate the replica. Outputting a first-stage despread signal corresponding to the transmitting station by despreading the signal from which the interference replica has been subtracted for a path in which the power from the corresponding transmitting station in the respective sequence is the maximum. And the first
The path combining means of the plurality of stages outputs a first-stage path-combined despread signal obtained by path-combining a first-stage despread signal corresponding to the transmitting station in each of the sequences. The sequence combination determination means of (1) outputs the received data of the first stage by performing data determination after performing the sequence synthesis on the path-combined despread signal of the first stage in each of the sequences, and outputs the received data of the second stage and thereafter. The interference cancellers corresponding to the transmitting stations of the plurality of sequences, respectively, based on the received data of the preceding stage output by the preceding sequence combining determining means, in the respective sequences, from the corresponding transmitting station, Generating at least one interference replica on at least one path excluding the path having the highest power and at least one path from the uncorresponding other transmitting station; A signal obtained by subtracting the interference replica from the direct spread received signal in respective series,
By despreading the path in which the power from the corresponding transmitting station in each of the series is maximized, a despread signal of the corresponding stage corresponding to the transmitting station is output, and the plurality of second and subsequent stages are output. The path combining means for a sequence outputs a path combined despread signal of the stage obtained by performing a path combination of the despread signal of the stage corresponding to the transmitting station in each of the sequences, and outputs the sequence combined signal of the second stage and thereafter. The determination unit outputs the received data of the corresponding stage by performing data determination after performing the sequence synthesis of the path combined despread signal of the corresponding stage in the respective sequences, and the received data of the final stage is at least the direct received data. This includes the reception data of the user channel set in the spread 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.

[0044]

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 A base station, and 6 is an interference canceller corresponding to the B base station. FIG. 2 is a schematic explanatory diagram of an interference canceling operation in the direct spread receiving apparatus of FIG.

In this embodiment, the internal configuration of the 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 receiving unit 2 is also output to the interference canceller 5, and Rake for despreading the direct spread signal from the B base station is performed.
The output of the receiving unit 3 is also output to the interference canceller 6.

[0046] 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.

The interference canceller 5 corresponding to the A base station
Direct spread received signal other paths except power up path P _A direct spread signal received from the A base station, and a direct spread reception signals of all paths from the base station B as interference replicas, the initial reception data Virtually generated based on the direct spread received signal. On top of that, the maximum power path P _A from A base station, and outputs the despread signal of a user channel C which is set to C slave station 102.

More specifically, with reference to FIG. 19 described above, the power maximum path P from the A base station 101 will be described.
The interference replicas of the other paths except _A correspond to the direct spread reception signals from the A base station in the interference replica generators 173, 174, and 175.
4, W ₁ (k), PN ₁ (k), WS ₁ (n,
k), WS ₁ (p, k). In addition, interference replicas of all paths of the direct spread signal from the B base station are output from interference replica generation units 178, 179, and 180.
, 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. In this case, without excluding even the power up path P _B, it generates an interference replica.

These interference replicas are added to the A base by subtracting these interference replicas from the baseband direct spread received signal delayed by the delay unit 4 in an adder similar to the adder 176 in FIG. A direct spread reception signal is obtained in which any interference signals on the paths from the station and the B base station are removed. For users channel C in the power up path P _A of the direct spread received signals, by despreading, the despread signal of a user channel C of the power up path P _A without causing interference component is obtained.

On the other hand, the interference canceller 6 corresponding to the B base station receives the direct spread reception signals of other paths except the power maximum path P _B of the direct spread reception signals from the B base station 161 and the A base station 101. Are virtually generated based on the initial received data using the direct spread received signals of all the paths as interference replicas and are removed from the direct spread received signals. Then, the maximum power path P from the B base station
_A despread signal of the user channel C set to the C slave station 102 of _B is output. Since a specific internal configuration can be obtained by replacing the base stations in the interference canceller 5 corresponding to the A base station, the description is omitted. The combining determination unit 7 combines the two despread signals with reduced interference components to determine the data of the user channel C, as in FIG.

During normal operation other than soft handoff, operation is possible even with the block configuration of FIG. However, if the base station on which the user channel is not set is, for example, a B base station, the operations of blocks 3, 5 (part), and 6, which process a direct spread reception signal from the B base station, 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 spread receiver 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. 11, a receiving antenna; 12, a multiplier; 13, a reference frequency oscillator; 14, an interference canceller; In this embodiment, there are two types of receivers. In order to distinguish between the first and second receivers, reference numerals and reference numerals are appended with a or b.

Two systems of receiving antennas are 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 11a, 1
The signal received by 1b is multiplied by sine wave reference frequency signals of reference frequency oscillators 13a and 13b in multipliers 12a and 12b, 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 13a and 13b 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.

Two-sequence interference cancellers 14a and 14b
Are based on the above-mentioned initial reception data,
b, a replica of the interference signal included in the direct spread signal delayed through b is generated, and this replica is subtracted from the direct spread signal to obtain the user channel C in the maximum power paths P _Aa and P _Ab and the maximum power paths P _Ba and P _Ba . It despreads the user channel C in P _Bb and outputs a despread signal with reduced interference components. As the interference cancellers 5a, 5b, 6a and 6b, a set of interference cancellers 5 and 6 shown in FIG. 1 are used for each stream, and their outputs are input to the combining determination unit 15. Combination judgment unit 15
First synthesizes the despread signal corresponding to the base station in the same manner as the synthesis determination unit 7 shown in FIG. However, although the combination determination unit 7 shown in FIG. 1 executes up to data determination, the combination determination unit 15 does not yet perform data determination.
Next, after the combined despread signal for each sequence is subjected to sequence combination, data determination is performed to output received data.

Two antennas 11a and 11b for each system
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 receivers is the antenna 11
multipliers 12a, 12b, etc., for converting a, 11b into a baseband direct spread signal. 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 15 shown in FIG. FIG. 4 (a)
FIG. 4 is an explanatory diagram of a synthesizing function, and FIG. 4B is an explanatory diagram of a determination function. Interference canceller 14a of first receiver (system a)
Component (I phase) and quadrature component (Q) of a path combined signal obtained by combining the despread signals corresponding to the base stations output from the base station.
_Is (V _1i , V _1q ), and the in-phase and quadrature components of the path combined signal obtained by combining the despread signal corresponding to the base station output from the interference canceller 14b of the second receiver (system b) are represented by ( 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 .

[0059] 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 systems of receivers has been described. However, in the above-described path combining, combining is performed using similar weighting.

FIG. 5 is a block diagram of a third 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. Reference numeral 21 denotes a delay unit, which is an initial data output unit, a combination determination unit 22, and an interference canceller 1
4 to compensate for a delay in processing time. 2
Reference numeral 2 denotes a combination determination unit.

In this embodiment, the interference cancellers 14a and 14a are different from the second embodiment shown in FIG.
b, when outputting the initial reception data to the
In the same manner as above, the despread signal corresponding to the base station is synthesized,
Next, the sequences are combined and data is determined. Therefore, Rake for despreading the direct spread signal from the A base station
Rake receivers 3a and 3b, which despread the direct spread signals from B base stations, receive despread signals corresponding to the impulse response of the initial received data at a stage immediately before obtaining the initial received data. Output. As described above, the initial reception data becomes more reliable in the case of performing the combination determination of the two series than in the case of using the outputs of the initial data output units 1a and 1b of the own series individually. By inputting the initial reception data to the interference cancellers 14a and 14b, the output data of the combination determination unit 15 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 14a and 14b shown in FIG. 3 output a despread signal of only the user channel C of the C slave station, and the combining determination unit 15 outputs the reception 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 14a and 14b output despread signals of all user channels, and the combining determination unit 15 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 31a and 31b denote delay units for compensating for processing delays in the first-stage interference cancellers 14a and 14b, the combination determination unit 15, and the second-stage interference cancellers 32a and 32b. Reference numerals 32a and 32b denote second-stage interference cancellers, which use the received data output from the first-stage combining determination unit 15 as initial received data, but have the same configuration as the interference cancelers 14a and 14b. . 3
Reference numeral 3 denotes a second-stage synthesis determination unit, which has a configuration similar to that of the first-stage synthesis determination unit 15. 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. 34a and 34b are delay units, and the second-stage interference cancellers 32a and 32b
b, synthesis determination section 33, final-stage interference canceller 35a,
This is to compensate for the processing delay inside 35b. The interference cancellers 5a and 35b at the third final stage need only output a despread signal of only the user channel C of the child station C, similarly to the interference cancellers 14a and 14b shown in FIG. Reference numeral 36 denotes a final-stage combination determining unit, similar to the combination determining unit 15 shown in FIG. 3, which 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 canceller 1
Although the configuration of the single-stage interference canceller shown in FIG. 3 is used as the configuration up to 4a and 14b, 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 5 corresponding to the A base station determines the maximum power path P for the detected multipath in the direct spread signal from the A base station 101.
Generate interference replicas of all detected paths except _A , cancel them, and generate interference replicas of all detected paths for the detected multipaths in the direct spread signal from B base station 161. And canceled this. However, the multi-paths detected in a direct spread signal from the A base station 101, to cancel this by generating only interference replica of the at least one path except power up path P _A, and, B base station 161
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 CDMA, the interference component is reduced according to the amount of cancellation. In particular, for the multi-paths detected in a direct spread signal from the base station B 161, if canceling an interference replica of a power up path P _B, there is large reduction degree interference component. The same can be said for the interference canceller 6 corresponding to the B base station.

Further, 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, when the direct spread received signal of this path, cheek completely would be canceled, the maximum direct spread received signal power path P _A, despreading the P _B Will be 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.

The above-described direct spread receiver can 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, but when 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 user channel received signal exists. If the interference replica component in the section of the pilot channel is large, it may become a noise component, which may lower the transmission quality. 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, a configuration has been described in which the same user data is transmitted from a plurality of base stations to the own station during soft handoff. However, even when such soft handoff is not performed, when the same user data is transmitted from a plurality of base stations to the own station at the same time, the direct spread receiving apparatus of the present invention is transmitted from a plurality of base stations. In addition, it is possible to reduce the mutual interference component of the multipath of the directly spread signal. 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.

[0073]

As will be apparent from the above description, the present invention provides a method of soft handoff between a plurality of base stations and slave stations, etc., whereby mutual spreading of direct spread signals transmitted simultaneously from a plurality of transmitting stations by multipath is achieved. There is an effect that the interference component is reduced.

[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 synthesizing 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 A base station, 6 Interference canceller corresponding to B base station, 7 Combination determination unit, 8, 9
Maximum power path detector

Continuation of the front page (56) References JP-A-2000-68979 (JP, A) JP-A-2000-269931 (JP, A) JP-A-2000-353981 (JP, A) JP-A-2000-353982 (JP, A) JP 2000-353983 (JP, A) JP-A 2000-353985 (JP, A) JP-A 2000-353986 (JP, A) Proceedings of the 1998 IEICE Communication Society Conference 1, p. 454 (1998-9-7) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 1/69-1/713 H04J 13/00-13/06 H04B 1/10 H04B 7/02 H04B 7 / 08

Claims (4)

(57) [Claims] 1. A direct spread receiving apparatus for simultaneously receiving direct spread signals transmitted from a plurality of transmitting stations identifiable by a spreading code, wherein the direct spread signals transmitted from the respective transmitting stations are: The user channel set in the direct spreading receiver has the same data, and includes an impulse response estimating unit, a path selecting unit, an initial data output unit, an interference canceling unit corresponding to each of the transmitting stations, and a path combining unit. Having a determination means, the impulse response estimation means, based on the direct spread received signal, estimates impulse responses to a plurality of paths of the direct spread signal transmitted from each of the transmitting stations, the path selection means, Based on the estimated impulse response, a path having the maximum power for each transmitting station is selected. The initial data output means outputs the initial reception data for each of the transmitting stations based on the direct spread reception signal, and the interference canceling means corresponding to the transmitting station respectively responds based on the initial reception data. From the transmitting station, at least one path excluding the path where the power is the maximum, and at least one interference replica in at least one path from the other non-corresponding transmitting station is generated at least, 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 from the corresponding transmitting station is maximized, a despread signal corresponding to the transmitting station is output, and the path combining determination unit includes: After performing path synthesis on the despread signal corresponding to the transmitting station, by performing data determination, at least the A direct spread receiving apparatus for outputting received data of a set user channel. 2. A direct spread receiving apparatus for simultaneously receiving direct spread signals transmitted from a plurality of transmitting stations identifiable by a spreading code, wherein the direct spread signals transmitted from the respective transmitting stations are: A user channel set in the direct spreading receiver has the same data as the impulse response estimating means, path selecting means, initial data output means, interference cancellers corresponding to the transmitting stations in a plurality of stages, and a plurality of Having a stage path combining determination unit, wherein the impulse response estimation unit estimates impulse responses to a plurality of paths of the direct spread signal transmitted from each of the transmitting stations, based on the direct spread reception signal, The selecting means selects a path having the maximum power for each transmitting station based on the estimated impulse response. The initial data output means outputs initial reception data for each of the transmitting stations based on the direct spread reception signal, and an interference canceller corresponding to the transmitting station in the first stage outputs the initial reception data to the initial reception data, respectively. Based on at least one path from the corresponding transmitting station, excluding the path with the highest power, and at least one interference replica on at least one path from the other transmitting station that does not correspond, By despreading the signal obtained by subtracting the interference replica from the direct spread received signal for the path where the power from the corresponding transmitting station is the maximum, the first-stage despread signal corresponding to the transmitting station is obtained. The first-stage path combining determination means performs a path-combining of the first-stage despread signal corresponding to the transmitting station, and then performs data determination. And outputs the received data of the first stage, and the interference canceller corresponding to the transmitting station of the second and subsequent stages,
Based on the received data at the preceding stage, at least one path from the corresponding transmitting station excluding the path where the power is maximum, and at least one path from the non-corresponding other transmitting station. At least generating an interference replica in the above, the signal obtained by subtracting the interference replica from the direct spread received signal, by despreading the path where the power from the corresponding transmission station is the maximum, corresponding to the transmission station The path combining determination means in the second and subsequent stages performs path combining on the despread signal of the stage corresponding to the transmitting station, and then performs data determination to determine the received data of the stage. And the received data at the final stage includes at least the received data of the user channel set in the direct-sequence receiving device. That, spread receiver device directly, characterized in that. 3. A direct spread receiving apparatus for simultaneously receiving direct spread signals transmitted from a plurality of transmitting stations identifiable by a spreading code, wherein the direct spread signals transmitted from the respective transmitting stations are: It has the same data in the user channel set in the direct spreading receiver, and corresponds to a plurality of series of impulse response estimating means, a plurality of series of path selecting means, an initial data output means, and a plurality of series of transmitting stations. Interference canceling means, path combining means for a plurality of sequences, and sequence combining determining means, the impulse response estimating means for the plurality of sequences receives the direct spread signal with an antenna corresponding to the plurality of sequences, and each of the sequences The direct spreading transmitted from each transmitting station in the respective sequence based on the direct spreading received signal in Estimating impulse responses for a plurality of paths of the signal, the path selection means of the plurality of streams, based on the estimated impulse responses in the respective streams, power for each of the transmitting stations in the respective streams. Selecting the path that is the largest, the initial data output means, based on the direct sequence reception signals in the respective sequences, for each of the transmitting stations,
For each of the sequences, or, output initial reception data common to each of the sequences, the interference cancellation means corresponding to the transmission station of the plurality of sequences, respectively, based on the initial reception data, From the corresponding transmitting station in the sequence
At least one path excluding the path where the power is maximized, and at least an interference replica in at least one path from the other non-corresponding transmitting station is generated, and the direct-sequence received signal in the respective sequence is used to generate the replica. By despreading the signal from which the interference replica has been subtracted for the path where the power from the corresponding transmitting station in the respective sequence is maximum, a despread signal corresponding to the transmitting station is output, The path combining means for a sequence outputs a path combined despread signal obtained by performing a path combining on the despread signal corresponding to the transmitting station in each of the sequences, and the sequence combining determining means comprises the path combining unit for each of the sequences. After the sequence synthesis of the despread signal, at least the direct spreading receiver And it outputs the set reception data of the user channels are spread receiving apparatus directly, characterized in that. 4. A direct spread receiving apparatus for simultaneously receiving direct spread signals transmitted from a plurality of transmitting stations identifiable by a spreading code, wherein the direct spread signals transmitted from each of the transmitting stations are: A user channel set in the direct spreading receiver has the same data, and includes a plurality of series of impulse response estimation means, a plurality of series of path selection means, an initial data output means, and a plurality of stages of transmission stations of a plurality of series. An interference canceller corresponding to the above, a plurality of stages of path combining means of a plurality of stages, and a plurality of stages of sequence combining determining means, wherein the plurality of sequences of impulse response estimating means are directly spread by an antenna corresponding to the plurality of sequences. Receiving a signal and transmitting from each of the transmitting stations in the respective sequence based on the direct spread received signal in the respective sequence. Estimating impulse responses to a plurality of paths of the obtained direct spread signal, the path selection means of the plurality of sequences, based on the estimated impulse responses in the respective sequences, Selecting a path having the maximum power for each transmitting station, the initial data output means, based on the direct spread reception signals in the respective sequences, for each transmitting station,
For each of the sequences, or output initial reception data common to each of the sequences, interference cancellers corresponding to the plurality of transmission stations in the first stage corresponding to the transmission stations, respectively, based on the initial reception data ,
At least generating at least one interference replica in at least one path from the corresponding transmitting station in each of the sequences, excluding the path with the highest power, and at least one path from the other transmitting station that does not correspond. Then, the 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 from the corresponding transmitting station in each of the sequences is maximized,
A first-stage despread signal corresponding to the transmitting station is output. The first-stage path combining means of the plurality of streams outputs a first-stage despread signal corresponding to the transmitting station in each of the streams. Outputting a first-stage path-combined despread signal subjected to path combining, wherein the first-stage sequence-combination determining means performs a sequence determination on the first-stage path-combined despread signal in each of the series, and then performs data determination. By doing so, the first-stage reception data is output, and the interference cancellers corresponding to the plurality of series of transmission stations in the second and subsequent stages respectively receive the preceding-stage reception data output by the preceding-stage sequence combining determination means. Based on at least one path from the corresponding transmitting station, excluding the path with the highest power, in the respective sequences,
And at least one of the other non-corresponding transmitting stations.
At least one interference replica in one path, and subtracting the interference replica from the direct sequence reception signal in each of the sequences, the path in which the power from the corresponding transmitting station in each of the sequences is maximized. By despreading, the despread signal of the stage corresponding to the transmitting station is output, and the path combining means of the second and subsequent stages of the plurality of sequences is configured to correspond to the transmitting station in the respective sequences. Outputting a path-combined despread signal of the stage obtained by path-combining the despread signal of the stage; the sequence combination determination means of the second and subsequent stages converts the path-combined despread signal of the stage in each of the sequences into a sequence After the combining, the data is determined to output the received data of the corresponding stage, and the received data of the final stage is at least directly expanded. It is intended to include the received data of the user channels set to the receiver, spread receiver device directly, characterized in that.