JP2000353985A - Direct spread receiver and direct spread transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direct spread receiving device which allows reducing the interfering components of mutual multi-paths of direct spread signals simultaneously transmitted from a plurality of system transmission antennas for reducing the effect of Rayleigh fading. SOLUTION: In this direct spread receiving device, an antenna having the power maximum path Px is selected as an antenna X according to the impulse responses of reception signals from antennas A and B whose offset time of spreading codes are different from each other. An interference canceller 5 virtually generates the direct spread reception signals of paths other than a path Px whose power is the maximum from the antenna X and the direct spread reception signals of plural paths from the antenna other than the antenna X 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 and a direct-spread transmitter used in a Division Multiple Access system or the like.

[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 a base station, 1
02 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. It is code-multiplexed, directly spread by being multiplied by a PN signal from a PN generator 108 in a multiplier 104, multiplied (modulated) by a reference frequency signal (carrier) of a reference frequency oscillator 109 in a multiplier 105, and transmitted. Antenna 1
06.

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-described DS-CDMA system, if the number of multipaths is small, deterioration of transmission performance can be prevented only by Rake reception. However, C slave station 102
When moving while being mounted on a car or the like, there is a problem of Rayleigh fading. FIG. 15 is a schematic explanatory diagram for explaining Rayleigh fading. 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 and 162 are adjacent paths, 163 is a path and 1
64 is a reflector. In some cases, the C slave station 102 is moving, and the reflector 164 exists near the C slave station 102. In such a case, there are a number of paths whose delay times hardly change, as illustrated as the close paths 161 and 162. The reception frequencies of a plurality of direct spread signals taking these paths slightly shift due to Doppler shift. The direction and magnitude of the frequency shift vary depending on the position of the reflector 164 and the like. These plurality of close paths 162 and 163 are regarded as one path 163 as a set of close paths. Such a path 16
The direct-sequence received signal of 3 has been subjected to Rayleigh fading. When receiving Rayleigh fading, while the C slave station 102 is moving, the received electric field strength greatly changes, and a point occurs at which the level drops to a level that cannot be received many times.
Therefore, the following system is proposed as a method of reducing the influence of Rayleigh fading.

FIG. 16 is a schematic configuration diagram of a transmission antenna diversity system for reducing the influence of Rayleigh fading. In the figure, the same parts as those in FIGS. 7, 8, and 15 are denoted by the same reference numerals, and description thereof will be omitted. Two transmission devices are provided, and the transmission antennas are 106A and 106B. The path from the antenna 106A to the C slave station 102 is 1
The path from 63A and the antenna 106B to the C slave station 102 is 163B. These are paths as a set of adjacent paths. When the distance between the transmitting antennas 106A and 106B is several wavelengths away, Rayleigh fading becomes independent. As a result, the point in time when the received electric field strength of the direct spread signal taking the path 163A falls,
The point in time when the received electric field strength of the direct spread signal taking B falls is independent. Therefore, in C slave station 102, if the direct spread signals transmitted from a plurality of systems of antennas 106A and 106B are simultaneously received and combined, the bit error rate of the received data is reduced and the transmission quality is improved. For that purpose, it is necessary for the direct spread receiver of the C slave station 102 to receive the paths 163A and 163B separately. In the illustrated example, the base station 101, for each line PN (Pseudo random Noise) code PN _A, are at different offset time PN _B (phase difference).

FIG. 17 is an explanatory diagram of a direct spread signal transmitted from two antennas. Transmission antenna 106A
And the transmission system of the transmission antenna 106B are:
The transmission data is spread-modulated using the same PN code,
PN code PN _A of each strain, PN _B, because it has a predetermined offset time from a predetermined reference time for each antenna (retardation), start timing of the signs are different from each other. The C slave station 102 can separate and receive the direct spread signals transmitted from the antennas 106A and 106B based on the offset time of the received pilot signal from the reference time of the PN signal. In addition,
Code length of the PN code (in the case of IS95, 2 ¹⁵ bits) long enough for, the time difference between the start timing mentioned above,
The path (path as a set of adjacent paths) is set to be longer than the delay time difference between the direct wave and the reflected wave. Therefore, the multipath from antenna 106A and the multipath from antenna 106B are received separately from each other. Further, in order to separate direct spread signals transmitted from a plurality of base stations, the offset time of the same PN code is made different. Therefore, the PN code P
N _A and _P BN need to be different from the offset time of other base stations. For example, the time difference is shorter than the offset time difference of the PN code between the base stations, but is longer than the multipath delay time. However, since the same PN code is used, the configurations of the transmitting-side spreading section and the receiving-side despreading section are simplified.

FIG. 18 is a block diagram showing an example of the base station 101 in the system shown in FIG. In the figure, the same parts as those in FIGS. 8 and 16 are denoted by the same reference numerals, and description thereof will be omitted. Reference numeral 165 denotes a delay unit, and the PN generator 10
And generating a PN code PN _B by causing the PN code PN _A output from the 8 by a predetermined time. Transmission data output from the code multiplexing unit 103 in the multiplier 104A is spread by the PN code PN _A, the multiplier 104
B is spread by the PN code PN _B. The spread signal is multiplied by the reference frequency signal in multipliers 105A and 105B, respectively, and two transmission antennas 1
05A and 105B.

As described above, the effect of multipath fading can be reduced by transmitting a spread signal directly from one base station using a plurality of antennas. However, since a plurality of direct spreading signals are transmitted at the same time, as a result, the number of multipaths is multiplied, and interference components due to correlation between the multipaths increase. Therefore, it is preferable to apply the above-described interference cancellation technique. FIG.
If the interference canceller shown as 0 is applied as it is, the following configuration is obtained.

FIG. 19 is a block diagram of a direct spread receiver of a slave station used in the system shown in FIG. Here, for simplicity of description, it is assumed that the base station 101 shown in FIG. 15 transmits data only to two users, a C slave station 102 and a D slave station (not shown). In the figure, the same parts as those in FIG. 16 are denoted by the same reference numerals, and description thereof will be omitted. In the figure, reference numeral 2 denotes an R for despreading a directly spread signal from the antenna 106A (hereinafter, simply referred to as "antenna A").
The ake receiving unit 3 performs despreading of a direct spread signal from the antenna 106B (hereinafter, simply referred to as “antenna B”).
The ake receiving unit, 4 is a delay unit, 171 is an interference canceller that removes the interference component of the direct spread received signal from the antenna A, and 172 is the interference canceller that removes the interference component of the direct spread received signal from the antenna B. Reference numeral 32 denotes a combination determining unit, reference numeral 177 denotes a maximum power path detector of the direct spread signal from the antenna A, and reference numeral 178 denotes a maximum power path detector of the direct spread signal from the antenna B.

In the interference canceller 171, 6 is an interference replica generator for the direct spread signal of the user channel C from the antenna A, 7 is an interference replica generator for the direct spread signal of the user channel D from the antenna A, and 8 is the antenna. interference replica generation unit of the direct spread signal of the pilot channel from the a, 173 is an adder, 174 is a despreading unit of the user channel C in the power up path P _a of the direct spread signal from the antenna a. Interference canceller 17
In 9, 9 is an interference replica generation unit for a direct spread signal of a user channel C from antenna B, 10 is an interference replica generation unit for a direct spread signal of a user channel D from antenna B, and 11 is a pilot channel from antenna B. interference replica generation unit of the direct sequence signal, 175 is an adder, 176 is a despreading unit of the user channel C in the power up path P _B of the direct spread signal from the antenna B.

In the rake receiving section 2 for despreading the direct spread signal from the antenna A, the baseband received signal is transmitted to the rake receiving sections 121 and 1 shown in FIGS.
Similar to 46, the PN code PN _A synchronized with the start timing of the PN code PN _A to be used in the transmission system on the antenna A
, And data is determined by synchronous detection, and the initial received data of the user channels C and D are output. On the other hand, in the Rake receiving unit 3 for despreading the directly spread signal from the antenna B, the rake signal is despread based on the PN code PN _B synchronized with the start timing of the PN code PN _B used in the transmission system of the antenna B, and the data is determined. Then, it outputs the initial reception data of the user channels C and D. The delay unit 4 includes the delay unit 13 shown in FIGS.
Similarly to 2, the baseband direct-spread reception signal is delayed according to 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 perform the pilot replica interference replica generator 13 shown in FIG.
5 are those similar to _p. The despreading units 171 and 176
This is the same as the despreading unit 137 for the path P shown in FIG. 11, but outputs a despread signal 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 antenna A, a direct spread signal from the antenna B, and each individual power up path P _A, by detecting the P _B, the maximum power path P _A, despread signal P _B Each user channel C of
The combination determination section 32 performs data determination by combining. A block corresponding to the searcher unit 122 shown in FIG. 10 is included in the Rake receiving unit 2 for despreading the direct spread signal from the antenna A and the Rake receiving unit 3 for despreading the direct spread signal from the antenna B. The illustration is omitted.

In the above-described configuration, initial reception data is obtained in advance from the direct spread signals from the antennas A and B,
Based on the initial received data, a direct spread reception signal of a path from the same antenna excluding the power maximum path is virtually generated and used as an interference replica. This interference replica is subtracted, and the power maximum path is inverted again. By the configuration of spreading, the interference component of the direct spread reception signal of the maximum power path due to the direct spread reception signal of another path from the same antenna is reduced. PN used by the transmission system of antenna A
The code and the PN code used by the transmission system of the antenna B are:
As shown in FIG. 17, it can be identified by the offset time, but there is mutual correlation. Therefore, the despread signal of the maximum power path P _A also includes an interference component due to the direct spread signal of the path from the antenna B becoming an interference signal, while the despread signal of the maximum power path P _B includes: An interference component caused by the direct spread signal of the path from the antenna A becoming an interference signal is also included. However, the configuration described above does not reduce interference components between paths from these different antennas A and B.

[0039]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is intended to reduce the influence of Rayleigh fading and to reduce the direct spread signal transmitted simultaneously from a plurality of transmission antennas. It is an object of the present invention to provide a direct spread receiver that reduces mutual interference components due to multipath and a direct spread transmitter that reduces the influence of Rayleigh fading.

[0040]

According to the first aspect of the present invention, a plurality of direct spread signals transmitted from a plurality of transmission antennas and identifiable by a spreading code can be simultaneously transmitted. A direct spread receiving apparatus for receiving, wherein each of the plurality of direct spread signals has the same PN with a different offset time based on the same transmission data.
Code is spread as the spreading code, impulse response estimation means, path selection means, initial data output means, and interference cancellation means, the impulse response estimation means, based on the direct spread received signal Estimating impulse responses for a plurality of paths of the direct spread signal transmitted from the transmitting antenna, and the path selecting unit, based on the estimated impulse responses, among the plurality of paths, the power is maximum. And the initial data output means outputs initial receive data for each of the transmitting antennas based on the direct spread received signal, and the interference canceling means outputs power based on the initial receive data. From the transmitting antenna with the largest path, the path with the largest power was removed At least one path and at least an interference replica in at least one path from the other transmitting antennas are 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, at least the received data of the user channel set in the direct spreading receiver is output. Therefore, it is possible to prevent an increase in bit error rate due to Rayleigh fading due to transmission antenna diversity using a plurality of transmission antennas.
Increase in the number of multipaths due to transmit antenna diversity,
Further, interference components due to mutual interference of multipaths from a plurality of transmission antennas can be reduced by the interference canceling means. Despite receiving spread signals directly from multiple transmission antennas, one of them
Since despreading and data determination are performed only for one maximum power path from one transmitting antenna, the configuration for despreading and data determination is simplified. Since the same PN code is used and a plurality of systems are identified based on the difference in offset time, the configuration 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 a plurality of direct spread signals transmitted from a plurality of systems of transmitting antennas and distinguishable by a spreading code. Wherein each of the plurality of direct spread signals is obtained by spreading the same PN code having a different offset time as the spread code based on the same transmission data. Output means, and a plurality of stages of interference cancellers, the impulse response estimating means, based on the direct spread received signal, estimates the impulse response to a plurality of paths of the direct spread signal transmitted from the transmitting antenna , The path selecting means, based on the estimated impulse response, Of the paths, a path having the maximum power is selected, and the initial data output means outputs initial reception data for each of the transmission antennas based on the direct spread reception signal, and the first stage interference canceller includes: Based on the initial received data, from the transmitting antenna having the path with the largest power, at least one path excluding the path with the largest power, and at least one path from the other transmitting antennas Generate at least an interference replica in the path, despread the signal obtained by subtracting the interference replica from the direct spread received signal for the path having the maximum power, and determine the data to output the first-stage received data. The interference cancellers in the second and subsequent stages respectively select a path in which the power becomes maximum based on the received data in the previous stage. From the transmitting antenna to generate at least one path except for the path where the power is maximum, and at least one interference replica in at least one path from the other transmitting antennas, the direct spread received signal from the The signal from which the interference replica is subtracted is despread for the path where the power is maximum, and the data is determined to output the received data of the corresponding stage. This includes the reception data of the set user channel. 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 a plurality of direct spread signals transmitted from a plurality of systems of transmitting antennas and capable of identifying the system by a spreading code. Wherein the plurality of direct spread signals are obtained by spreading the same PN code having a different offset time as the spreading code based on the same transmission data, respectively. Path selecting means, initial data output means, interference canceling means for a plurality of sequences, and sequence combining determining means, the impulse response estimating means for the plurality of sequences, the direct spread signal with a receiving antenna corresponding to the plurality of sequences. Receiving, based on the direct spread received signal in each sequence, in each said sequence, And estimating impulse responses for a plurality of paths of the direct spread signal transmitted from the receiving antenna, and the path selecting means of the plurality of sequences, based on the estimated impulse responses in the respective sequences, the respective sequences Out of the plurality of paths, a path having the maximum power is selected, and the initial data output unit is configured to perform a transmission for each of the transmission antennas based on the direct spread reception signal in each of the sequences. Or, outputting the initial received data common to each of the series, the interference cancellation means of the plurality of series, respectively, based on the initial received data, in each of the series, the path in which the power is maximum, At least excluding the path where the power is maximum from the transmitting antenna having One path and at least an interference replica in at least one path from the other transmitting antenna are generated, and a signal obtained by subtracting the interference replica from the direct spread received signal in the respective sequence is used in the respective sequence. By despreading the path where the power is maximum, a despread signal is output, and the sequence combination determination unit performs sequence determination on the despread signal in each of the sequences, and then performs data determination to determine at least It outputs received data of the user channel set in the direct spread receiver. 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 spreading receiving apparatus for simultaneously receiving a plurality of direct spreading signals transmitted from a plurality of transmitting antennas and distinguishable by a spreading code. Wherein the plurality of direct spreading signals are respectively spread based on the same transmission data using the same PN code having a different offset time as the spreading code, and a plurality of sequences of impulse response estimating means; A path selection unit, an initial data output unit, a plurality of stages of interference cancellers in a plurality of stages, and a plurality of stages of sequence combination determination units, and the plurality of sequences of impulse response estimation units are reception antennas corresponding to the plurality of sequences. Receiving the direct-spread signal, based on the direct-spread received signal in each sequence, The impulse response for a plurality of paths of the direct spread signal transmitted from the transmission antenna is estimated, and the path selection means of the plurality of sequences is configured based on the estimated impulse responses in the respective sequences. From among the plurality of paths in each sequence, a path having the maximum power is selected, and the initial data output unit is configured to transmit, based on the direct spread reception signal in each sequence, the transmission antenna, Outputting initial reception data for each sequence or common to the respective sequences;
The plurality of stages of interference cancellers at each stage, based on the initial received data, except for the path from the transmitting antenna having the path with the maximum power in each of the sequences, 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 antennas, and generating a signal obtained by subtracting the interference replica from the direct spread received signal in the respective sequence. The first stage despread signal is output by despreading the path in which the power in the sequence is maximum, and the first stage demultiplexing determination means outputs the first stage despread signal in each of the sequences. After the signals are synthesized in series, the data is determined, and the received data of the first stage is output. The interference cancellers of the plurality of sequences are based on the received data of the preceding stage output by the preceding-stage sequence combining determining unit, respectively, in each of the sequences, from the transmitting antenna having a path where the power is maximum, Generating at least one interference replica in at least one path excluding the path having the highest power, and at least one path from the other transmission antenna, and generating the interference replica from the direct spread reception signals in the respective sequences. By despreading the subtracted signal with respect to the path where the power in each of the series is maximized, a despread signal of the stage is output,
The sequence combination determination means in the second and subsequent stages, after performing sequence synthesis on the despread signals of the respective stages in the respective sequences, output data received by the corresponding stage, and The data includes at least received data of the user channel set in the direct spread receiving apparatus. Therefore, with the multi-stage configuration, in addition to the function and effect of the invention described in claim 3,
More reliable interference cancellation can be performed.

According to a fifth aspect of the present invention, there is provided a direct spread transmitting apparatus for transmitting a direct spread signal using at least one of a plurality of transmission antennas, comprising: a spreading means, an output means, And communication mode control means, wherein the communication mode control means has a normal mode and a soft handoff mode, and the spreading means is controlled by the communication mode control means, and in the normal mode, the same transmission data , A plurality of directly spread signals are generated by spreading the same PN code having a different offset time as a spreading code, and in the soft handoff mode, the PN code having a predetermined offset time is determined based on the transmission data. Generating one direct-spread signal by spreading using the spreading code; , Controlled by the communication mode control means, in the normal mode, output the plurality of direct spreading signals to the plurality of transmission antennas, respectively, in the soft handoff mode, the one direct spreading signal , To one of the plurality of transmission antennas. Therefore, in the normal operation mode, due to the transmission antenna diversity of the transmission antennas of a plurality of systems, on the direct spreading receiver side,
It is possible to prevent the bit error rate from increasing due to Rayleigh fading. On the other hand, at the time of soft handoff operation in which the number of multipaths increases, by not performing transmission antenna diversity, by suppressing the increase in the number of multipaths, on the direct spreading receiver side,
It is possible to eliminate the possibility that the bit error rate is increased by the increase of the interference component. Since the same PN code is used and a plurality of systems are identified based on the difference in offset time, the configuration is simplified.

[0045]

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, the same parts as those in FIG. 1 is an initial data output unit, 5 is an interference canceller corresponding to the antenna X, and 14 is a maximum power path detector. 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, R which despreads the direct spread signal from antenna A
The output of the ake receiving unit 2 and the output of the rake receiving unit 3 for despreading the direct spread signal from the antenna B are output to one interference canceller 5 corresponding to the spreading code of the system of the antenna X. Here, the antenna X is the impulse response of the signal received from the antenna A and the antenna B
In the set of impulse responses of the received signal from
This is an antenna having a path Px at which the power is maximized. The path Px is selected by a power maximum path detector 14 described later.

[0047] In the Rake receiver 2 for despreading direct sequence signal from the antenna A, in FIG. 2, as shown as an impulse response of a received signal from the antenna A, including power up path P _A Multiple paths 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 the cross-correlation between the paths from the antenna A, but also interference due to the cross-correlation with the path from the antenna B. Similarly, in Rake receiving section 3 for despreading the direct spread signal from antenna B, as shown in FIG. 2, as shown as an impulse response of the signal received from antenna B, it includes power maximum path P _B. A plurality of paths are separated and detected, and include interference due to cross-correlation with the path from antenna A and interference due to cross-correlation between paths from antenna B.

Now, assuming that the antenna X is the antenna A, the interference canceller 5 becomes an interference canceller corresponding to the antenna A. Maximum power path P _A from antenna _A
The direct spread received signals of the other paths except for the above, and the direct spread received signals of all the paths from the antenna B are virtually generated as interference replicas based on the initial received data, and are generated from the direct spread received signals. Remove. More specifically, the interference replica of the other paths except power up path P _A from antenna A, in the interference replica generation unit 6, 7 and 8 corresponding to the direct spreading the received signal from antenna A, FIG. 10 to 12 and FIG.
₁ (k), PN ₁ (k), WS ₁ (n, k), WS ₁ (p,
k). In addition, interference replicas of all paths of the direct spread received signal from antenna B are output to antenna replica generation units 9, 10 and 11, respectively.
Corresponding to a direct spread signal received from the W ₁ (k), PN
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 antenna X is the antenna B, the interference canceller 5 becomes an interference canceller corresponding to the antenna B, and the direct spread reception signals of the other paths except the maximum power path P _B from the antenna B; Antenna A
Are generated virtually as interference replicas based on the initial received data, and are removed from the direct spread received signals. On top of that, to output the maximum power path P _B, despread signal of a user channel C assigned to C slave station 102 from the antenna B.
More specifically, the interference replicas of all the paths of the direct spread received signal from antenna A are compared with W ₁ (k) corresponding to the direct spread received signal from antenna A in interference replica generators 6, 7, and 8. ), PN ₁ (k), WS ₁ (n,
k), WS ₁ (p, k). On the other hand, the interference replicas of the other paths except for the maximum power path P _B of the direct spread received signal from the antenna B are output to W ₁ corresponding to the direct spread received signal from the antenna B in each of the interference replica generators 9, 10, and 11. (K), PN ₁ (k), W
It is generated using the signals of S ₁ (n, k) and WS ₁ (p, k).

The adder 12 subtracts these interference replicas from the baseband direct-spread received signal delayed by the delay unit 4 to obtain the antennas A and A.
A direct spread received signal is obtained in which any interference signal on the path from antenna B has been removed. For users channel C at the maximum power path Px of the direct spread received signal, and despreading a direct spreading the received signal from the antenna X, by data determination, a user channel C of the power up path P _X without causing interference components Are obtained, and data is determined by an internal determination unit and received data is output, similarly to the despreading unit 137 for the path P shown in FIG.

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. In the figure, the same parts as those in FIG. 19 and FIG. 21 is a receiving antenna, 22 is a multiplier, 23 is a reference frequency oscillator, and 24 is a synthesis judging 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 numerals are a or b
With a subscript.

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 21a, 21
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 23a and 23b
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 obtained by despreading the direct spread signal from antenna A to Ra.
The data is despread in the ke receivers 2a and 2b, data is determined, and the reception data of the user channels C and D transmitted from the antenna A is output as initial reception data. On the other hand, the baseband direct-spread reception signal is a Rake receiving unit 3 that despreads the direct-spread signal from antenna B.
The received data of user channels C and D transmitted from antenna B are output as initial received data after being despread in a and 3b and subjected to data determination.

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_XaAntenna Xa having
And the maximum power path P in the sequence b_XbAntenna with
Xb may be different. Interference canceller 5a,
The output of 5b is input to the combination determination unit 24. Combination judgment
The unit 24 performs the sequence synthesis of the despread signal for each sequence,
The received data is output by performing data determination.

The two antenna systems 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 the two streams in the synthesizing judging 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 .

[0058] 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 in the path combining in the combining determining unit 32 in FIG.

FIG. 5 is a block diagram of a third embodiment of the direct sequence receiver according to the present invention. In the figure, the same parts as those in FIG. 19, FIG. 1 and FIG. 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. 32A is a path combination determination unit corresponding to antenna A, and 32B is a path combination determination unit corresponding to antenna B.

In this embodiment, Rake receiving sections 2a, 2a for despreading the direct spread signal from antenna A
b, Rak for despreading the direct spread signal from antenna B
The e 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 combination determination unit 32A corresponding to the antenna A performs the sequence combination of the despread signal of the path corresponding to the antenna A in each sequence, and then performs data determination, thereby performing initial reception from the antenna A. Output data. On the other hand, the path combination determination unit 32B corresponding to the antenna B performs the sequence combination of the despread signal of the path corresponding to the antenna B in each of the sequences, and then performs data determination to determine the data from the antenna B. Outputs the initial reception data. Thus, 2
The determination of the combination of the streams makes the initial received data more reliable than the use of the outputs of the initial data output units 1a and 1b of the respective streams individually. By inputting the initial reception data to the interference cancellers 5a and 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 showing a fourth embodiment of the direct sequence receiver according to the present invention. In the figure, the same parts as those in FIG. 19, FIG. 1 and FIG. 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 antenna X having the maximum power path P _X.
Generate interference replicas of all detected paths except _X , cancel them, and for all detected multipaths in direct spread signals from antennas other than antenna X, generate interference replicas of all detected paths. Generate
I canceled this. However, for the detected multipath in the direct spread signal from the antenna X, only the interference replica of at least one path excluding the power maximum path P _X is generated and canceled, and Even if an interference replica of at least one path is generated and canceled for the detected multipath in the direct spread signal, the interference component is reduced according to the amount of cancellation.

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, 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 determination may be performed 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 direct spreading receiver described above 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 a pilot channel is also generated in a section of a pilot channel in which a received signal of a user channel does not exist. 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-described transmission antenna diversity system for reducing the influence of Rayleigh fading,
Since the number of multipaths is multiplied by a plurality of times, in an environment where a large number of multipaths originally exist, the ability to cancel interference must be enhanced. Therefore,
For example, it is suitable in an environment where there are no multipaths due to a small amount of radio wave reflectors, or at most a few waves. Alternatively, it is also suitable for a case where the chip rate of the spreading code is reduced because the transmission rate of the transmission data is low. In this case, the delay time difference between the multipaths is small compared to the cycle of one chip, and is included within one chip time. Therefore, the number of multipaths of a path as a set of adjacent paths decreases.

When the base station 101 performs a soft handoff operation of any of the slave stations including the C slave station 102, the other base stations simultaneously transmit a direct spread reception signal. At this time, the number of multipaths in the C slave station 102 is double that in the normal state. Therefore, the base station 101 stops the transmission antenna diversity described above and
Preferably, the transmission is from one antenna. Also,
Not only during the soft handoff operation, but also when a user channel is set up with one base station, but a direct spread signal is transmitted simultaneously from another base station that has not been set up with a user channel. It is preferable to stop transmission antenna diversity. In such a case, the direct spread receiving apparatus can operate even with the block configuration of FIG. However, if the system that does not transmit is antenna B, the operations of blocks 3, 9, 10, and 11 that process the direct spread reception signal from antenna B may be stopped. Alternatively, these blocks may be used for processing a path from another base station at the time of soft handoff or the like. In other embodiments, the same configuration can be adopted at the time of soft handoff and the like.

[0073]

As is apparent from the above description, the direct spread receiving apparatus according to the present invention can reduce the influence of Rayleigh fading and can multiply direct spread signals transmitted simultaneously from a plurality of transmission antennas. There is an effect that mutual interference components due to paths are reduced. ADVANTAGE OF THE INVENTION The direct-sequence transmission apparatus of this invention has the effect that the bit error rate increase by Rayleigh fading can be prevented in the normal operation mode. On the other hand, at the time of the soft handoff operation, by suppressing an increase in the number of multipaths, there is an effect that it is possible to eliminate a possibility that the bit error rate is increased due to an increase in the interference component.

[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 a schematic explanatory diagram for explaining Rayleigh fading.

FIG. 16 is a schematic configuration diagram of a transmission antenna diversity system that reduces the influence of Rayleigh fading.

FIG. 17 is an explanatory diagram of a direct spread signal transmitted from two systems of antennas.

18 is a block diagram showing an example of a base station in the system shown in FIG.

FIG. 19 is a block diagram of a direct spreading receiver of a slave station used in the system shown in FIG. 16;

[Explanation of symbols]

1. Initial data output unit, 2 Rake receiving unit for despreading the direct spread signal from antenna A, 3 Rake receiving unit for despreading the direct spread signal from antenna B, 4 delay unit, 5 interference canceller corresponding to antenna X , 14
Maximum power path detector

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 5K022 EE02 EE35 5K059 CC03 CC07 CC09 DD35 DD39 EE02

Claims (5)

[Claims] 1. A direct spread receiving apparatus for simultaneously receiving a plurality of direct spread signals transmitted from a plurality of systems of transmitting antennas and capable of identifying the system by a spreading code, wherein the plurality of direct spread signals are: Based on the same transmission data, the same PN code with a different offset time is spread as the spreading code, and has an impulse response estimation means, a path selection means, an initial data output means, and an interference cancellation means, The impulse response estimation means estimates impulse responses to a plurality of paths of the direct spread signal transmitted from the transmission antenna based on the direct spread reception signal, and the path selection means Based on the plurality of paths, select a path having a maximum power, The initial data output unit outputs initial reception data for each of the transmission antennas based on the direct spread reception signal, and the interference cancellation unit has a path where the power is maximum based on the initial reception data. Generating at least one interference replica in the at least one path excluding the path with the highest power from the transmission antenna and at least one path from the other transmission antennas, and generating the interference from the direct spread received signal; The signal from which the replica is subtracted is despread for the path with the maximum power, and the data is determined to output at least reception data of the user channel set in the direct spreading receiver. Spread receiver. 2. A direct spread receiving apparatus for simultaneously receiving a plurality of direct spread signals transmitted from a plurality of systems of transmitting antennas and identifying the system by a spreading code, wherein the plurality of direct spread signals are: The same PN code with a different offset time is spread as the spreading code based on the same transmission data, and includes an impulse response estimation unit, a path selection unit, an initial data output unit, and a multistage interference canceller. The impulse response estimating means estimates impulse responses for a plurality of paths of the direct spread signal transmitted from the transmitting antenna, based on the direct spread received signal, and the path selecting means estimates the impulse Based on the response, select the path with the highest power among the plurality of paths The initial data output means outputs initial reception data for each of the transmission antennas based on the direct spread reception signal, and the first stage interference canceller sets the power to be maximum based on the initial reception data. And generating at least interference replicas in at least one path from the transmitting antennas having at least one path excluding the path having the highest power and at least one path from the other transmitting antennas. 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, the power from the transmitting antenna having a path where the power is maximum, At least one path excluding the path where is the largest, and at least an interference replica in at least one path from the other transmission antenna is generated, a signal obtained by subtracting the interference replica from the direct spread received signal, By despreading the path having the maximum power and determining the data, the received data of the corresponding stage is output, and the received data of the final stage is at least the received data of the user channel set in the direct spreading receiver. A direct-sequence receiving device, comprising: 3. A direct spread receiving apparatus for simultaneously receiving a plurality of direct spread signals transmitted from a plurality of systems of transmission antennas and capable of identifying the system by a spreading code, wherein the plurality of direct spread signals are: Based on the same transmission data, the same PN code with a different offset time is spread as the spreading code, and a plurality of impulse response estimating means, a plurality of path selecting means, an initial data output means, a plurality of Interference canceling means, and having a sequence combination determining means, the plurality of impulse response estimating means receives the direct spread signal at the receiving antenna corresponding to the plurality of sequences, to the direct spread received signal in each sequence The direct spreading signals transmitted from the transmitting antennas in the respective sequences. Estimating impulse responses for a plurality of paths of the signal, the path selecting means of the plurality of streams, based on the impulse responses estimated in the respective streams, power of the plurality of paths in the respective streams, The initial data output means, based on the direct spread received signal in each of the sequences, for each of the transmission antennas, for each of the sequences, or common to each of the sequences The plurality of series of interference cancellation means, based on the initial received data, respectively, in each of the series, the power from the transmitting antenna having a path where the power is the maximum, And at least one path excluding the path where At least one interference replica in at least one path from the antenna, and despreads a signal obtained by subtracting the interference replica from the direct spread reception signal in the respective sequence for a path in which the power in the respective sequence is maximum. The sequence combination determining means performs sequence determination on the despread signals in the respective sequences, and then performs data determination to determine at least the user set in the direct spreading receiver. A direct spread receiving apparatus for outputting received data of a channel. 4. A direct spread receiving apparatus which receives simultaneously a plurality of direct spread signals transmitted from a plurality of systems of transmitting antennas and which can identify the system by a spread code, wherein the plurality of direct spread signals are: Based on the same transmission data, the same PN code with a different offset time is spread as the spreading code, and the plurality of sequences of impulse response estimation means, the plurality of sequences of path selection means, the initial data output means, and the plurality of stages are used. A plurality of sequence interference cancellers, and a plurality of stages of sequence combination determination means, the plurality of sequences of impulse response estimating means receive the direct spread signal with a receiving antenna corresponding to the plurality of sequences, and in each of the sequences Based on the direct spread received signal, in each of the sequences, before transmitted from the transmit antenna Estimating impulse responses for a plurality of paths of the direct spreading signal, the path selecting means of the plurality of sequences, based on the impulse responses estimated in the respective sequences, of the plurality of paths in the respective sequences. Among them, a path having the maximum power is selected, and the initial data output means is based on the direct spread reception signal in each of the streams, for each of the transmission antennas, for each of the streams, or for each of the streams. Output initial reception data common to the series, and the first-stage interference cancellers for the plurality of series respectively
Based on the initial received data, in each of the streams, at least one path excluding the path with the highest power from the transmitting antenna having the path with the highest power, and the other transmissions Generating at least an interference replica in at least one path from an antenna, despreading a signal obtained by subtracting the interference replica from the direct spread reception signal in the respective sequence, for a path in which the power in the respective sequence is maximum; By outputting the first-stage despread signal, the first-stage sequence-combining determination unit performs data determination after performing the first-stage despread signal in each of the sequences. , And outputs the received data of the first stage. The interference cancellers of the plurality of sequences in the second and subsequent stages respectively Based on the received data at the previous stage output by the sequence combination determining means, at least one of the transmission antennas having the path with the maximum power, excluding the path with the maximum power, in each of the sequences. One path and at least an interference replica in at least one path from the other transmitting antenna, and generating a signal obtained by subtracting the interference replica from the direct spread received signal in the respective sequence, the power in the respective sequence. By despreading the path having the maximum value, outputs the despread signal of the corresponding stage, and the sequence combination determination means in the second and subsequent stages performs sequence synthesis of the despread signal of the corresponding stage in the respective sequences. Thereafter, by performing data determination, the received data of the corresponding stage is output. Even without those including the received data of the user channels set to the direct spread receiving apparatus, spread receiver device directly, characterized in that. 5. At least one of a plurality of transmission antennas
A direct spreading transmission apparatus for transmitting a direct spreading signal by using one of: a spreading means, an output means, and a communication mode control means, wherein the communication mode control means has a normal mode and a soft handoff mode. The spreading unit is controlled by the communication mode control unit. In the normal mode, based on the same transmission data,
A plurality of direct spreading signals are generated by spreading the same PN code having different offset times as spreading codes. In the soft handoff mode, the PN code having a predetermined offset time is spread based on the transmission data. The output means is controlled by the communication mode control means, and in the normal mode, the plurality of direct spread signals are respectively transmitted to the plurality of systems. And transmitting the one direct spread signal to one of the plurality of transmission antennas in the soft handoff mode.