KR100605981B1 - System, method, and computer program product for transmission diversity - Google Patents

Abstract

The present invention provides a transmission diversity system, a beam selection method, a spreading code allocation method, and a program thereof, which can reduce waste of signal power and can prevent occurrence of interference between a plurality of beams. In the transmission diversity method of the present invention, a transmission pair allocates a transmission signal to a beam space of a multi-beam and transmits the beam, and estimates a channel for each beam received at the reception side to maximize the sum of the channel estimates. In the beam selection method of selecting, when a power difference of each channel estimate value in the corresponding beam pair is larger than a predetermined value, one single beam is selected from the corresponding beam pair.

Transmit Diversity, Beam, Array Antenna

Description

System, method, and computer program for transmit diversity {SYSTEM, METHOD, AND COMPUTER PROGRAM PRODUCT FOR TRANSMISSION DIVERSITY}             

1 is a block diagram of a closed loop beam selector in a mobile station according to a first embodiment of the present invention;

2 is a block diagram of a base station according to the first embodiment of the present invention;

3 is a conceptual diagram for explaining two-dimensional diffusion;

4 is a conceptual diagram illustrating a spreading code generation process and spreading code allocation in the case of selecting two beams in the first embodiment of the present invention;

FIG. 5 is a conceptual diagram for explaining a spreading code generation process and spreading code allocation in the case of selecting a single / multi beam in the first embodiment of the present invention; FIG.

6 is a block diagram of a mobile station according to the first embodiment of the present invention;

7 is a conceptual diagram for explaining a spreading code generation process and spreading code allocation for a user signal and a pilot signal when two beams are selected in the first embodiment of the present invention;

8 is a block diagram of a spread signal frame in the first embodiment of the present invention;

9 is a graph showing the beam pattern of the low side lobe fixed multi-beam in the first embodiment of the present invention;

10 is a block diagram of a closed loop beam selector in a mobile station according to a second embodiment of the present invention;

11 is a block diagram of a base station according to a second embodiment of the present invention;

12 is a conceptual diagram illustrating a time beam space transmit diversity processing procedure at a base station;

13 is a block diagram of a conventional transmit diversity system;

14 is a block diagram of a conventional inter-beam time diversity system for time-oriented OFDM-CDM;

15 is a block diagram of a receiver in a conventional inter-beam time diversity system for time-oriented OFDM-CDM;

16 is a configuration diagram of a two beam selector with a conventional closed loop;

17 is a conceptual diagram for explaining allocation to a diffusion region of a conventional construction coding output;

18 is a conceptual diagram for explaining a relationship between a user position and a beam inverse when the angle spread is wide;

19 is a conceptual diagram for explaining a relationship between a user position and a beam area when the angle spread is narrow; And

20 is a conceptual diagram illustrating an example in which two users each use two beams and share one beam.

The present invention provides a transmit diversity system, a transmit diversity method, and a program using orthogonal frequency-division multiplexing code-division multiplexing (OFDM-CDM) for two-dimensional spreading in a time direction and a frequency direction. In particular, the present invention relates to a transmission antenna array and a time-space transmission diversity system used in a mobile communication system.

FIG. 13 is a space-time proposed by SM Alamouti (“a simple transmit diversity technique for wireless communications” IEEE Journal on Selected Areas In Communications, Vol. 16, No. 8, pp.1451-1458, October 1998). It is a figure for demonstrating the space-time transmit diversity technique using a code | symbol.

As shown in FIG. 13, in the transmission diversity technique of Alamouti, when the transmission symbols are s ₁ and s ₂ , the orthogonal space-time encoding matrix of two rows and two columns is represented by Equation 1 below.

At time 1, transmission signal s ₁ is transmitted from antenna # 1 and transmission signal s ₂ is simultaneously transmitted from antenna # 2. At time 2, -s ₂ ^* is transmitted from antenna # 1 and s ₁ ^* is simultaneously transmitted from antenna # 2.

At present, antenna # 1 as the channel response to the terminal h ₁ from and, if the antenna # 2 referred to the channel response to the terminal h ₂ the received signal at time 1 and time 2, r ₁ and r2 are each equation (2) And (3).

r ₁ = h ₁ s ₁ + h ₂ s ₂

r _{2 =} -h ₁ s ₂ ^* + h ₂ s ₁ ^*

On the receiving side the channel response from the antenna # 1 using the channel response h ₂ h ₁ from the antenna # 2 to perform decoding, and decoding the received signal is expressed as shown in each of the following (4) and equation (5).

Each of the transmission signals s ₁ and s ₂ can be detected from the decoded received signal, and the maximum ratio synthesis of h ₁ and h ₂ can be realized.

On the other hand, Figures 14 to 16 (M. Fujii, "Beamspace-Time transmit diversity for Time-domain spreading OFDM-CDM systems," IEICE Trans.on Communications, Vol. E86-b, No. 1 proposed by Fuji , pp. 344-351, January 2003). FIG. 3 illustrates a transmission diversity technique for improving transmission characteristics through selecting an optimal beam.

In the transmission diversity technique using the optimal beam selection, the base station uses a fixed multi-beam and estimates the channel response from each beam on the mobile station side to calculate the power (in the multi-carrier, the power value in each subcarrier is added. ), Selects two beams in which the sum of channel response powers from two adjacent beams is maximum and returns the beam index to the base station. In this technique, the transmission side constructs and transmits a transmission signal using two or two orthogonal construction encoding matrices, and allocates construction encoding output to two beams designated by the mobile station. In addition, the signal weighted by the beamforming array weight vector is spread using OFDM-CDM, which spreads only in the time direction, and then multiplexed with other user signals.

On the other hand, on the receiving side, by despreading in the time direction, all signals other than the user are suppressed and the desired signal is decoded.

Fig. 17 introduces allocation to the spreading region of the construction coded output in the existing time space transmit diversity. In the construction coder, the transmission data is space-coded, and then two spatial coding outputs [s ₁ , s ₂ ] and [-s ₂ ^* , s ₁ ^* ] in the spatial direction are sequentially beam-beam steering vectors W _b1 and W _b2 , respectively. Beam steering is multiplexed in the adder.

In this time direction, two adder outputs s ₁ W _b1 + s ₂ W _b2 and -s ₂ ^* W _b1 + s ₁ ^* W _b2 are diffused in two diffusion regions (2SF _Time ) in the time direction.

Therefore, in order to maintain orthogonality between codes in the despreading in the time direction, it is necessary to limit the spreading rate so that it is not affected by the channel fluctuation in the time direction.

In this construction code, the channel response needs to be invariant according to the time slot length of several symbols output in the time direction. Therefore, it is necessary to design so as not to be fluctuated in time direction over two diffusion regions. Therefore, there is a problem that transmission characteristics are deteriorated when the spreading ratio in the time direction is suppressed to a predetermined value or less and the number of users to be accommodated is limited due to the limiting spreading rate, or when the spreading time is influenced by two spreading regions.

In the method of selecting the two beams, as shown in FIG. 18, when the user is located between the beams, the beam diversity gain can be obtained, thereby improving transmission characteristics.

However, when the user is located near the maximum gain of the beam and the angular spread of the radio wave is narrow as compared to the beam width, as shown in FIG. 19, although the beam gain can be obtained, the signal transmitted from one beam is practically used even though several beams are used. There is a problem that only the mobile station reaches and wastes the signal power distributed to the other beams.

In addition, in the above-described time-space transmission diversity technique, since the spreading signal is spread only in the time direction, all signals other than the self-user signal are suppressed in the despreading of the receiving side. For example, if different users use different beam pairs and share another same beam, they will interfere with each other when decoding space-time codes, so that all other users' signals will be suppressed by despreading in the time direction. It is set as the structure which prevents occurrence.

However, in two-dimensional spreading in both the time direction and the frequency direction, when the construction code is decoded, in partial despreading in the time direction in the two-dimensional spreading region, interference of construction coding allocated to several beams sharing one beam is shared. There is a problem that can not be suppressed. As shown in FIG. 20, when beam # 1 and beam # 2 are used for user # 1 and beam # 2 and beam # 3 are used for user # 2, a signal transmitted to user # 1 is transmitted (s ₁ , s _2). ), The signal transmitted to user # 2 is called (s ₃ , s ₄ ), and the channel response at the mth subcarrier from beam # 1 and beam # 2 to user # 1 is h _{m, 1} , h _{m, 2} , respectively. In this case, the received signal at the m th subcarrier is represented by Equations 6 and 7 below.

r _{m, 1} = h _{m, 1} s ₁ + h _{m, 2} s ₂ + h _{m, 2} s ₃

The signals decoded using the channel responses h _{m, 1} and h _{m, 2} with respect to the received signals r _{m, 1} and r _{m, 2} may be represented by Equations 8 and 9, respectively.

In Equations 8 and 9, interference components occur in the second and third terms on the right side.

In other words, in the case of spreading only in the time direction, the spreading code is used within the range in which the channel response can be regarded as invariant, so that other user signals can be suppressed through despreading and no interference component is generated.

However, in two-dimensional spreading, the partial correlation between spreading codes is not necessarily zero in each subcarrier. Therefore, the above-mentioned interference component is generated, and since the decoding component and the response component (| h _{m, 1} | ² + | h _{m, 2} | ² ) of the self-user signal are different, the interference component is completely removed even when synthesized in the frequency direction. The problem is that you can't.

The present invention has been devised to solve the above problems, and its object is to provide excellent immunity to frequency selectivity and time variation of channel in a transmit diversity technique using multi-beam and construction codes for two-dimensional spread OFDM-CDM. The present invention provides a transmit diversity system, a transmit diversity method, and a program thereof.                         

In order to achieve the above object, the invention described in claim 1 is a transmission diversity system comprising a transmitter for allocating a transmission signal in the beam space of the multi-beams and a receiver for estimating a channel for each beam to be received. A first selecting means for selecting a beam pair in which the sum of the powers of the channel estimates is maximum, and selecting one single beam from the beam pair when the power difference of each channel estimate value in the beam pair is larger than a predetermined value. It is characterized by including two selection means.

In the invention according to claim 2, in the invention according to claim 1, the second selecting means includes the absolute power of the channel estimate value from the beam pair when the power difference of each channel estimate value in the beam pair is larger than a predetermined value. A single beam having a maximum value is selected.

In addition, the invention described in claim 3 is a transmission diversity system in which a transmission signal is time-coded in a transmission side, and the construction coded output is spread in a time direction and a frequency direction, and the spread output is allocated to a beam space of a multi-beam. When a single beam used by one user is the same as one of the multi beams used by another user, or one of the multi beams used by the user and one of the multi beams used by the other user is the same And a code assignment means for allocating a spread code whose partial correlation is zero in the time direction spread.

In the invention according to claim 4, in the invention according to claim 3, the code assignment means uses a spreading code whose partial correlation is zero in the time direction spread for a plurality of users using the same beam pair. It is further characterized by the assignment.

In addition, the invention as set forth in claim 5 is characterized in that, in a receiver for receiving a signal allocated to the beam space of the multi-beams and estimating a channel for each beam, first selecting means for selecting a beam pair in which the sum of the powers of the channel estimates is maximum And second selecting means for selecting one single beam from the beam pair when the power difference of each channel estimate value in the beam pair is larger than a predetermined value.

In addition, the invention described in claim 6 receives a channel estimation value from a receiver that receives a signal allocated to the beam space of the multi-beams and estimates a channel for each beam, and selects a beam pair whose power sum of the channel estimate is maximum. And first selecting means and second selecting means for selecting one single beam from the beam pair when the power difference of each channel estimated value is larger than a predetermined value in the beam pair.

In addition, the invention as set forth in claim 7 is a transmitter which constructs and encodes a signal, spreads its construction encoded output in a time direction and a frequency direction, and transmits the spread output in a beam space of a multi-beam. In the case where the single beam is the same as one of the multi-beams used by other users, or when one of the multi-beams used by the user is the same as the one of the multi-beams used by the other user, the partial in the time direction spread And code allocation means for allocating a spreading code whose correlation is zero.

In the invention according to claim 8, in the invention according to claim 7, the code assignment means assigns a spreading code whose partial correlation is zero in the time direction spread to a plurality of users using the same beam pair. Characterized in that.

The invention described in claim 9 further includes a beam pair in which the transmission side allocates a transmission signal to the beam space of the multi-beams and transmits the signal, and estimates the channel for each beam received at the reception side to maximize the sum of the powers of the channel estimates. In the beam selection method for selecting, when a power difference of each channel estimate value in the corresponding beam pair is larger than a predetermined value, one single beam is selected from the corresponding beam pair.

In the invention according to claim 10, in the invention according to claim 9, when the power difference of each channel estimate value in the beam pair is larger than a predetermined value, the absolute value of the power of the channel estimate value from the beam pair is maximum. It is characterized by selecting a single beam.

In addition, the invention described in claim 11 is a transmission diversity system in which a transmission signal is time-coded in the transmission side, the construction-coded output is spread in the time direction and the frequency direction, and the spread output is allocated to the beam space of the multi-beam. When one beam used by one user is the same as one of the multi beams used by another user, or when one beam of the multi beams used by the user is the same as one beam of the multi beam used by another user, And a spreading code of which partial correlation is 0 in the time-direction spreading.

In addition, the invention described in claim 12 is a transmission diversity system in which a transmission side is time-coded in a transmission signal, spreads its construction coded output in a time direction and a frequency direction, and transmits the spread output in a beam space of a multi-beam. And a spreading code in which each partial correlation is zero in the time-direction spreading to a plurality of users using the same beam pair.

In addition, the invention described in claim 13 is a receiver for receiving a signal allocated to the beam space of the multi-beams and estimating a channel for each beam, the process of selecting a beam pair in which the sum of the powers of the channel estimates is maximum, and When the power difference of each channel estimate value in a beam pair is larger than a predetermined value, it is a beam selection program for causing a receiver to perform the process of selecting one single beam from the corresponding beam pair.

In addition, the invention described in claim 14 receives a channel estimate value from a receiver that receives a signal allocated to the beam space of the multi-beams and estimates a channel for each beam, and selects a beam pair for which the sum of the powers of the channel estimates is maximum. The process and the beam selection program for causing the transmitter to perform a process of selecting one single beam from the beam pair when the power difference of each channel estimate value in the beam pair is larger than a predetermined value.

In addition, the invention described in claim 15 is a transmitter which constructs and encodes a signal, spreads its construction encoded output in a time direction and a frequency direction, and allocates the spread output to a beam space of a multi-beam to transmit. When the single beam and one of the multi-beams used by other users are the same, or when one of the multi-beams used by the user and the one of the multi-beams used by the other user are the same, the time-direction spreading Is a spreading code assignment program for causing a transmitter to perform a process of assigning a spreading code whose partial correlation is zero in the.

According to the invention described in claim 16, in the transmitter according to claim 15, a process of assigning a spreading code of which partial correlation is 0 in the time-direction spreading to a plurality of users using the same beam pair is performed. It is a spread code assignment program for further execution.

In the invention described in claim 17, the transmission diversity system constructs and encodes a transmission signal on the transmitting side, spreads the construction encoded output in the time direction and the frequency direction, and allocates the spread output to the beam space of the multi-beam to transmit in the spatial direction. Beam allocation means for allocating the construction coding output of the multiple beams to the multiple beams, and spreading code assignment means for allocating the construction coding output in the time direction to the various spreading codes in the same spreading region.

In the invention described in claim 18, in the invention described in claim 17, the beam allocation means selects a beam pair in which the sum of powers of channel estimates for each beam received by the receiver is maximum, and estimates each channel in the beam pair. When the power difference is greater than a predetermined value, one single beam is selected from the corresponding beam pair, and the construction encoding output in the spatial direction is allocated.

In the invention described in claim 17, in the invention described in claim 17, the spreading code assignment means is used when one beam used by one user and one beam of multiple beams used by another user are the same or used by one user. If one beam of the multi-beams and one of the multi-beams used by different users are the same, it is characterized in that the spreading code of the partial correlation is assigned to 0 in the same spreading region.

In the invention described in claim 18, in the invention described in claim 18, the spreading code assigning means is classified into a beam pair that does not interfere with a beam pair that does not interfere with each other, and groups and spreads the beam pair selected by the beam allocation means. In the time-direction spreading layer of the code tree, a spreading code having a two-dimensional spreading rate branching from another branch is assigned to another beam pair group.

In the invention according to claim 21, in the invention according to claim 19, the spreading code allocation means is classified into a beam pair that does not interfere with a beam pair that does not interfere with each other for the beam pair selected by the beam allocation means, and is grouped. In the time-direction spreading layer of, a spreading code having a two-dimensional spreading rate branching from another branch is allocated to another beam pair group.

In the invention described in claim 22, in the invention according to claim 18, the spreading code assigning means is a two-dimensional spreading rate branching from another branch in a time-direction spreading layer of a spreading code tree with respect to one single beam selected by the beam assigning means. It is characterized by assigning a spreading code of.

The invention as set forth in claim 23 is the invention as set forth in claim 19, wherein the spreading code assigning means is a two-dimensional spreading rate branching from another branch in a time-directional spreading rate layer of a spreading code tree for one single beam selected by the beam assigning means. It is characterized by assigning a spreading code of.

According to the invention of claim 24, in the transmission diversity, the transmission side constructs and encodes a transmission signal, spreads the construction encoded output in the time direction and the frequency direction, and allocates the spread output to the beam space of the multi-beam. It is characterized in that the coding output is allocated to the multiple beams of the multi-beams, and the construction coding output in the time direction is allocated to the different spreading codes in the same spreading region.

In the invention described in claim 25, in the invention according to claim 24, when the power difference of each channel estimate is greater than a predetermined value in a beam pair in which the sum of the channel estimates for each beam received by the receiver is maximum, the beam It is characterized by selecting one single beam from the pair and allocating the construction coding output in the spatial direction.

The invention according to claim 26 is, in the invention according to claim 24, in the case of the same beam as one of a single beam used by one user and a multi beam used by another user, or one of a multi beam used by one user. In the same spreading region, a spreading code having a partial correlation of 0 is allocated when the beam of the same beam and one of the multi-beams used by different users are the same.

The invention according to claim 27 is, in the invention according to claim 25, in the case of one of a single beam used by one user and a multi beam used by another user, or one of a multi beam used by one user. In the same spreading region, a spreading code having a partial correlation of 0 is allocated when the beam of the same beam and one of the multi-beams used by different users are the same.

In the invention according to claim 25, in the invention according to claim 25, the beam pairs with the maximum power sum of the channel estimates are classified into beam pairs that do not interfere with each other and beam pairs that do not interfere. In the directional spreading layer, a spreading code having a 2D spreading rate branching from another branch is allocated to another beam pair group.

The invention according to claim 29 is classified according to the invention according to claim 26 into groups of beam pairs that do not interfere with each other and beam pairs that do not interfere with each other for the beam pair at which the sum of powers of the channel estimates is maximum. In the directional spreading layer, a spreading code having a 2D spreading rate branching from another branch is allocated to another beam pair group.

The invention according to claim 30 is classified according to the invention according to claim 27 into beam pairs that do not interfere with each other and beam pairs that do not interfere with each other for the beam pair with the maximum power sum of the channel estimates. In the directional spreading layer, a spreading code having a two-dimensional spreading rate branching from another branch is allocated to another beam pair group.

The invention as set forth in claim 31 is characterized in that, in the invention as set forth in claim 25, a spreading code having a two-dimensional spreading rate branched from another branch in the time-direction spreading layer of the spreading code tree is assigned to the single beam selected. .

The invention according to claim 32 is characterized in that, in the invention according to claim 26, a spreading code having a two-dimensional spreading rate branched from another branch in the time-direction spreading layer of the spreading code tree is assigned to the selected single beam. do.

The invention as set forth in claim 33 is characterized in that, in the invention as set forth in claim 27, a spreading code having a two-dimensional spreading rate branched from another branch in the time-direction spreading layer of the spreading code tree is assigned to the single beam selected. .                         

According to the invention described in claim 34, in the transmission diversity in which the transmission side constructs and encodes a transmission signal, spreads the construction encoded output in the time direction and the frequency direction, and allocates the spread output to the beam space of the multi-beam,

And a communication program for executing a process of allocating space-time coded outputs to multiple beams of the multi-beams and a process of allocating time-spaced space-time coded outputs to different spreading codes in the same spreading region.

In the invention described in claim 34, the invention described in claim 34, wherein the power difference of each channel estimate is greater than a predetermined value in a beam pair in which the sum of the channel estimates for each beam received by the receiver is maximum. And a communication program for executing a process of selecting one single beam from a pair and allocating the construction coding output in the spatial direction.

The invention according to claim 36 is, in the invention according to claim 34, in the case where one beam is identical to a single beam used by one user and a multi beam used by another user, or one of the multi beams used by one user. In the case where one beam and one of the multi-beams used by different users are the same, it is a communication program for executing a process of assigning a spreading code of which partial correlation is 0 in the same spreading region.

The invention according to claim 37 is, in the invention according to claim 35, wherein a single beam used by one user and a multi beam used by another user are the same, or a multi beam used by one user. In the case where one beam and one of the multi-beams used by different users are the same, it is a communication program for executing a process of assigning a spreading code of which partial correlation is 0 in the same spreading region.

In the invention described in Claim 38, the process and spreading code tree in the invention according to Claim 35 are classified into beam pairs that do not interfere with each other and beam pairs that do not interfere with each other for the beam pair with the maximum power sum of the channel estimates. And a communication program for executing a process of allocating a spreading code of a two-dimensional spreading rate branching from another branch in a time direction spreading rate layer to another beam pair group.

The invention as set forth in claim 39 is a process and a spreading code tree in the invention as set forth in claim 36, wherein the beam pair with the maximum power sum of the channel estimates is classified into a beam pair that does not interfere with each other and a beam pair that does not interfere with each other. And a communication program for executing a process of allocating a spreading code of a two-dimensional spreading rate branching from another branch in a time direction spreading rate layer to another beam pair group.

In the invention described in claim 35, in the invention described in claim 35, a process for assigning a spreading code having a two-dimensional spreading rate branched from another branch in a time-direction spreading rate layer of a spreading code tree is performed for the selected single beam. Characterized in that the communication program for.

According to an aspect of the present invention, there is provided a invention of claim 36, wherein, in the invention of claim 36, a process of assigning a spreading code having a two-dimensional spreading rate branched from another branch in the time-direction spreading layer of the spreading code tree is executed. Characterized in that the communication program for.

Hereinafter, a time beam space transmission diversity system according to embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a block diagram showing the configuration of a time beam space transmission diversity system according to the first embodiment.

The time beam space transmission diversity system according to the first embodiment of the present invention is composed of a mobile station (transceiver) 1 and a base station (transceiver) 2. As shown in Fig. 1, the time beam space transmission diversity system according to the first embodiment of the present invention employs a closed loop beam selection method.

The mobile station 1 includes an antenna 10, a switch 11, channel estimators 12-1 to 12-4, power calculators 13-1 to 13-4, and adders 14-1 to 14-4. And a closed loop beam selector consisting of a maximum detector 15, a power difference comparator 17, and a single / multi beam selector 18.

The antenna 10 receives a plurality of beams # 1 to # 4 emitted from the transmit array antenna 20 (see FIG. 1) of the base station 2 and outputs the received signals to the switch 11. It radiates the selection beam index (described later) input from the switch 11.

The switch 11 outputs a received signal input from the antenna 10 to the channel estimators 12-1 to 12-4 and simultaneously outputs a selection beam index input from the power comparator 17 to the antenna 10. do. In addition, switching of the input / output processing of the switch 11 is made according to a control command from a controller (not shown).

The fast Fourier transformer 60 receives the input of the received signal from the antenna 10, down converts the signal, removes the guard interval (GI) from the received signal, converts it to a subcarrier signal using an FFT, and channels for beams # 1 to # 4. Output to estimators 12-1 to 12-4.

The channel estimators 12-1 to 12-4 despread the received signal input from the switch 11 with respective spreading codes for each subcarrier to remove the modulation component of the pilot signal, and estimate the channel response ( Output to the power calculator (13-1 ~ 13-4).

The power calculators 13-1 to 13-4 calculate channel response powers input from the channel estimators 12-1 to 12-4 and sum them in all subcarriers to estimate the power from each beam and adder 14 -1 ~ 14-4). That is, the power calculator 13-1 outputs the power estimation value P ₁ of the beam # 1 to the adders 14-1 and 14-4. The power calculator 13-2 also outputs the power estimation value P ₂ of the beam # 2 to the adders 14-1 and 14-2. The power calculator 13-3 also outputs the power estimation value P ₃ of the beam # 3 to the adders 14-2 and 14-3. The power calculator 13-4 also outputs the power estimated value P ₄ of the beam # 4 to the adders 14-3 and 14-4.

The adders 14-1 to 14-4 each add the power estimates P _{1 to} P _{4 of} the beams # 1 to # 4 inputted from the power calculators 13-1 to 13-4, respectively. Output to the detector 15. That is, the adder 14-1 receives the power estimation values P ₁ and P ₂ of the beams # 1 and # 2 and outputs the power addition values P ₁ + P ₂ to the maximum detector 15. The adder 14-2 receives the power estimation values P ₂ and P _{3 of the} beams # 2 and # 3 and outputs the power addition value P ₂ + P ₃ to the maximum detector 15. The adder 14-3 receives the power estimation values P ₃ and P _{4 of the} beams # 3 and # 4 and outputs the power addition value P ₃ + P ₄ to the maximum detector 15. In addition, the adder 14-4 receives the power estimation values P ₄ and P ₁ of the beams # 4 and # 1 and outputs the power addition value P ₄ + P ₁ to the maximum detector 15.

The maximum detector 15 receives an input of power addition values P ₁ + P ₂ , P ₂ + P ₃ , P ₃ + P ₄ , and P ₄ + P ₁ , and compares each of the power additions to determine a maximum power addition. The power pair comparator 16 outputs the power value of the multiple beams indicated by the beam pair index and the beam pair index.

Here, the beam pair index is a combination of the power addition value and the corresponding beam. For example, when the power addition value P ₁ + P ₂ is the maximum, the combination of the corresponding beam becomes (beams # 1, # 2). The beam pair index is similarly defined for other power addition values.

In addition, the power value of the multiple beams indicated by the beam pair index is the power value of the multiple beams corresponding to the beam pair index output by the maximum detector 15. For example, the beam pair index output by the maximum detector 15 is (beam In the case of # 1 and # 2), the power values of the plurality of beams corresponding to the corresponding beam pair index are the power estimation values P1 and P2.

The power difference comparator 17 receives an input of a beam pair index and a power value of a plurality of beams indicated by the beam pair index, compares the difference between the power values of the plurality of beams with a predetermined threshold value, and compares the comparison result with a single / multi beam. Output to selector 18.

The single / multi beam selector 18 receives input of a comparison result of the difference in power values of the multiple beams indicated by the beam pair index, selects a single beam or a multi beam, and outputs the selected beam index to the switch 11. .

That is, when the difference in power is greater than a predetermined threshold, the single / multi beam selector 18 selects only the beam having a greater power than the plurality of beams indicated by the beam pair index, and the beam when the difference in power is smaller than the predetermined threshold. All the plurality of beams indicated by the pair index are selected.

2 is a block diagram illustrating a configuration of a base station according to the first embodiment of the present invention.

As shown in FIG. 2, the base station 2 includes a transmit array antenna 20, an error correction encoder 21, a mapper 22, an interleaver 23, a construction encoder 24, and an antenna branch 25-. 1-25-n, where n is a natural number.

The error correction encoder 21 receives input of transmission data, performs error correction encoding, and outputs the result to the mapper 22.

The mapper 22 receives the input of the error-correction-coded transmission data, maps it to a modulation constellation, and outputs it to the interleaver 23.

The interleaver 23 receives the input of the mapped data in order to spread the burst error, changes the data order, and outputs the data to the construction encoder 24.

The construction encoder 24 encodes the output signal of the interleaver 23 using the two-row orthogonal construction coding matrix represented by Equation 1 above, and assigns it to the beam indicated by the selection beam index received from the mobile station 1. Output

In the first embodiment of the present invention, when the selective beam indexes are beams # 1 and # 2, construction coding outputs are allocated to beams # 1 and # 2, and corresponding antenna branches 25-1 to 25-n are assigned. Output

Each antenna branch 25-1-25-n has a multiplexer 30, a block S / P converter 31, a two-dimensional spreader (32-1-32-m, m is a natural number), and multiple user signal multiplexes. It consists of a firearm 33, a pilot signal multiplexer 34, and a fast inverse Fourier transformer (= IFFT + GI) 35.

The multiplexer 30 receives the construction encoding output allocated by the construction encoder 24 to the beam indicated by the selection beam index, and multiplexes a plurality of beams to output to the block S / P converter 31. For example, in the present embodiment, the multiplexer 30 multiplexes the two beams (beams # 1 and # 2) by multiplying the array weights of the transmission array antenna 20 by construction coded transmission symbols.

The block S / P converter 31 receives inputs of multiplexed beam construction coded transmission symbols for a plurality of beams, performs serial-to-parallel conversion for each symbol, and outputs the two-dimensional spreaders 32-1 to 32-m, respectively. do.

The two-dimensional spreaders 32-1 to 32-m receive inputs of the serial-to-parallel beam-space-coded transmission symbols and allocate them to the spreading segments as shown in FIG. 3, and use the Walsh code in each spreading segment. Two-dimensional spreading in the frequency direction is performed and output to another user signal multiplexer 33.

At this time, as shown in FIG. 3, the two-dimensional spreading segment is set with a spreading region based on the number of OFDM symbols SF _{time in the time} direction and the number of subcarriers SF _{Freq in the} frequency direction. As the spreading code, a spreading code of spreading _time SF _Time x SF _Freq (time spreading rate x frequency spreading rate) allocated from the spreading code assignment controller 26 is used. In addition, the two-dimensional spreaders 32-1 to 32-m first diffuse in the time direction on the first subcarrier, and then repeat the spreading process in which the adjacent subcarriers further spread in the time direction. Perform two-dimensional spreading in the frequency direction.

The other user signal multiplexer 33 receives an input of a beam construction coded transmission symbol spread in two dimensions in a time direction and a frequency direction, and multiplexes the output signal to a pilot signal multiplexer 34.

The pilot signal multiplexer 34 spreads the pilot signal for each beam in the time direction, and further multiplexes the spread data multiplexed by other users to the fast inverse Fourier transformer 35.

The fast inverse Fourier transformer 35 converts into a time domain signal using a fast inverse Fourier transform (IFFT). In addition, the guard interval GI is added to up-convert to the carrier frequency and output to the transmission array antenna 20.

The transmit array antenna 20 is composed of a plurality (n) of antennas corresponding to each antenna branch 25-1 to 25-n, and a fast inverse Fourier of each antenna branch 25-1 to 25-n. A plurality of transmission signals input from the converter 35 are radiated.

The spreading code allocation controller 26 is used when the single beam used by one user and the one beam among the multi beams used by the other user are the same or the other beam is used by the other user and one of the multi beams used by one user. If one of the multi-beams is the same, a spreading code having a partial correlation of 0 is assigned in time spreading, or spreading in which the partial correlation is 0 in time spreading for a plurality of users using the same beam pair. A code is assigned and output to each of the two-dimensional spreaders 32-1 to 32-m.

FIG. 4 is a conceptual diagram illustrating a spreading code allocation method by the spreading code allocation controller, grouping users who currently use beam pairs # 1 and # 2 and users who use beam pairs # 3 and # 4. Assume that A is a group B, and a user who uses beam pairs # 2 and # 3 and a user who uses beam pairs # 4 and # 1. When the path angle spread from the base station to each terminal is appropriately narrow, in case of other beam pairs in the same group, the signals allocated respectively by the beam separation do not interfere with each other. In addition, since the same two beams are used for a plurality of users in the same beam pair, an interference component does not occur when decoding a space-time code.

Meanwhile, as described above (see Equations 8 and 9), interference components occur between users belonging to other groups.

Accordingly, a plurality of nodes (nodes) having the same spreading ratio (see section X in FIG. 4) having the same time-direction spreading for beams used by the same group as the Walsh-based spreading code tree shown in FIG. 4 to suppress the interference component. In a node, a spreading code corresponding to a leaf generated at each node is allocated, and a beam generated by another group is generated at a node in the root direction rather than a spreading rate in a time direction without assigning a spreading code generated at the same node. Allocates another spreading code for the leaf.

In this case, in FIG. 4, the user belongs to the group A, that is, the user who uses the beam pairs # 1 and # 2 and the user who uses the beam pairs # 3 and # 4 as shown in the beam index, the time direction. In a plurality of nodes where the spreading rate of spreading (see section X in FIG. 4) is the same, 32-bit spreading codes 0 to 15 which are leaves generated from the nodes X ₁ , X ₂ , X ₃ , and X ₄ are allocated (FIG. 4). A), users belonging to group B, i.e. users using beam pairs (# 2, # 3) and users using beam pairs (# 4, # 1), are created on the same nodes as other groups A Without assigning the spreading codes 0 to 15, a plurality of spreading codes corresponding to a leaf generated at a node or a root in the root direction rather than a spreading rate in the time direction, that is, a spreading rate of the time spreading (see part X in FIG. 4) are the same. in the node, each node _{X 5, X 6, X 7} , the leaf of 32 bits generated by the X ₈ OK It assigns a code 16 to 32 (see the part B in Fig. 4).

FIG. 5 is a diagram for describing a spreading code allocation method in the case of selecting a single beam and a multi-beam. As shown in the beam selection classification, each group A to C is a group A and B to which a multi-beam is allocated. In this case, it is assumed that a single beam is classified into a group C to which the single beam is allocated.

At this time, as described above, no interference occurs between users in the same group. However, interference components occur as described above (see Equations 8 and 9) between users belonging to different groups.

Therefore, in such a group, as in the Walsh-based spreading code tree shown in FIG. 5, for the beams used by the same group, time-diffusion spreading ratios (see Y in FIG. 5) are generated from each node in the same node. Spreading codes are assigned, and for the beams used by different groups, the spreading codes generated from the same nodes are not assigned, but the other spreading codes, which are leaves generated from the node portions which are rooted in the root direction rather than the time spreading ratio, are allocated.

In this case, in FIG. 5, 32, the user belonging to the group A, that is, the user who uses the beam pairs # 1 and # 2 and the user who uses the beam pairs # 3 and # 4, as shown in the beam index, are 32. Allocate bit spreading codes 0-11 (see part A of FIG. 5) and use beam pairs (# 4, # 1) with users belonging to group B, i.e., users who use beam pairs (# 2, # 3). 32-bit spreading codes 12 to 23 are assigned (see section B of FIG. 5) to a user who belongs to group C, that is, a user who uses beam # 1, a user who uses beam # 2, and a beam # 32-bit spreading codes 24 to 31 are allocated to the user using 3 and the user using beam # 4 (see part C in FIG. 5).

In this case, the spreading codes generated from the nodes (nodes) are preferentially assigned to the users using the same beam pairs so that interference between spreading codes does not easily occur during synthesis in the frequency direction.

For example, in the example of FIG. 4, when a plurality of users select the same beam pairs # 1 and # 2, the spreading ratio of time spreading (see part X in FIG. 4) is different for beams used by the same group. Spreading codes 0 to 15 are selected because the spreading codes generated from the respective nodes are allocated in the same plurality of nodes. At this time, another spreading code generated from each of a plurality of nodes having the same spreading rate in time direction is additionally allocated. For example, first, spreading codes 0, 4, 8, and 12 are used first, and spreading codes 2, 6, 10, and 14 are sequentially assigned as the number of users increases.

The mobile station 1 further includes a fast Fourier transformer 60, time direction despreaders 61-1 through 61-n, and channel estimators 62-1, 2 through 62-n, 2n as shown in FIG. The construction decoders 63-1 to 63-n, the frequency direction synthesizers 64-1, 2 to 64-n, 2n, the block P / S converter 65, the deinterleaver 66, A construction decoder composed of an error correction decoder 67 is provided. The fast Fourier transformer 60 receives the input of the received signal from the antenna 10, down-converts it, removes the guard interval from the received signal, and converts it into a subcarrier signal by using an FFT. -n) and output to the channel estimators 62-1,2 to 62-n, 2n.

The channel estimators 62-1, 2 to 62-n, and 2n remove the modulated phase components of the pilot signal with respect to the despread signal and estimate the channel response to construct the estimation result. )

The time direction despreaders 61-1 to 61-n receive input of a subcarrier signal and receive a replica of the pilot signal from each transmit antenna using the pilot signal, the spread code for the pilot signal, and the obtained channel estimate. And subtract the received pilot signal replica from the Fourier transformed received subcarrier signal, and inversely in the time direction with respect to the received subcarrier signal subtracted from this pilot signal using a spreading code assigned to the user. Perform diffusion.

The construction decoders 63-1 to 63-n receive a subcarrier signal using a spreading code used by the user for the signal after time direction despreading which the despreaders 61-1 to 61-n output. Despread and perform construction decoding using the channel estimate. The frequency direction synthesizers 64-1, 2 to 64-n, and 2n receive construction decoding outputs from the construction decoders 63-1 to 63-n, synthesize them in the frequency direction, and output them to the block S / P converter 65. .

The block P / S converter 65 outputs to the deinterleaver 66 a block parallel / serial conversion of the synthesized signal synthesized by the frequency direction synthesizers 64-1, 2 to 64-n, and 2n.

The deinterleaver 66 receives the output signal of the block P / S converter 65 and reverses data order to the error correction decoder 67 as opposed to the interleaver 23. The error correction decoder 67 receives the output signal of the deinterleaver 66 and error corrects to obtain reproduction data.

Referring to the accompanying drawings, the operation of the time beam space transmission diversity system according to the first embodiment of the present invention will be described.

As shown in FIG. 1, when beams # 1 to # 4 are radiated from the array antenna 20 of the base station 2, the plurality of beams # 1 to # 4 from which the antenna 10 is radiated from the mobile station 1 side. It receives and outputs to the channel estimators 12-1 to 12-4 through the switch 11. The channel estimators 12-1 to 12-4 despread the input signal and estimate the channel response to the power calculators 13-1 to 13-4. The fast Fourier transformer 60 located between the switch 11 and the channel estimators 12-1 to 12-4 receives an input signal from the antenna 10 through the switch 11 and down converts the received signal. The guard interval (GI) is removed from the signal, converted to a subcarrier signal using an FFT, and output to the channel estimators 12-1 to 12-4 for beams # 1 to # 4.

The power calculators 13-1 to 13-4 estimate the power from each beam by calculating input channel response powers and adding them to all subcarriers, and adjacent to each of the adders 14-1 to 14-4. The sum of the channel response powers from the two beams is calculated and output to the maximum detector 15.

The maximum detector 15 receives the input of the power sum, compares the respective power sums, and outputs power values of the plurality of beams indicated by the beam pair index and the beam pair index to the power difference comparator 16 for the power sum determined as the maximum. do. This selects two beams in which the sum of channel response powers from two adjacent beams is maximum.

The power difference comparator 16 calculates a channel response power difference corresponding to the two selected beams and outputs to the single / multi beam selector 17 whether the difference is less than or equal to a predetermined threshold. That is, the power difference comparator 16 receives an input of a beam pair index and a power value of a plurality of beams indicated by the beam pair index, compares the difference between the power values of the plurality of beams with a predetermined threshold value, and compares the comparison result with a single / multi. Output to the beam selector 17.

The single / multi beam selector 17 selects two beams when the power difference calculated by the power difference comparator 16 is less than or equal to a predetermined threshold, and uses only the beam having the greater power when the power difference is greater than or equal to a predetermined threshold. Select one beam. That is, the single / multi beam selector 17 receives an input of a comparison result of the difference between the power values of the multiple beams indicated by the beam pair index, selects the single beam or the multi beam, and selects the selected beam index through the antenna 11 through the switch 11. Output as (10). The antenna 10 returns the beam index to the base station 2.

Subsequently, the base station 2 performs error correction encoding on the transmitted data, maps them to modulated signal points, randomizes the transmission order by the interleaver, and performs construction encoding using the above-described two-row orthogonal construction coding matrix. The construction encoding output is allocated to two beams designated by the selection beam index received from the mobile station 1.

In this case, when the beam designated by the mobile station 1 is one beam, that is, when the selection beam index indicates that the single beam is selected, the two beams are the same beam and are used unified. Therefore, in this case, the beam pair is used in the form of (# 1, # 1), (# 2, # 2), (# 3, # 3), and (# 4, # 4).

Therefore, when a pilot signal orthogonal to each beam is assigned to each beam, or when the pilot signal is spread with a spreading code orthogonal to each other and multiplexed, the mobile station 1 (receiving side) can estimate the channel response from each beam. The effect can be obtained.

The mobile station 1 can also obtain the effect of knowing in which beam area it is located by calculating the power of the channel estimate.

In addition, in the present embodiment, since the base station 2 allocates two-row, two-column construction encoding output to two adjacent beams or a single beam, the mobile station 1 (receiving side) adds the sum of the channel estimates from the adjacent beams. By calculating the power, it is possible to obtain an effect of detecting an index of two adjacent beams in which the sum of power is maximum.

It is also possible to specify that only one beam is to be used when the channel response power difference from the two beams selected by the mobile station 1 is large. In this case, the selection beam index (= beam selection information) is conveyed to the base station 2 in uplink. Therefore, the base station 2 can obtain the effect of knowing the beams to be allocated to each mobile station 1.

In addition, when beams are allocated to each of groups A and B as shown in the classification of the beam pairs shown in FIG. 7, for example, a spreading code having a spreading rate of twice the spreading ratio of time spreading is allocated to the pilot signal. Suppose, for a beam used by the same group as the Walsh-based spreading code tree shown in FIG. 7, the spreading ratio of the time-direction spreading (see Z in FIG. 7) is the same from a plurality of nodes (nodes). Allocates a spreading code corresponding to the generated leaf.

In this case, by assigning a spreading code having a spreading rate twice that of the spreading in the time direction spreading, 16-bit spreading codes 1 'to 4' are allocated to pilot signals other than the user signals of groups A and B.

The construction coded two symbol sequences are steered to the beam designated by the mobile station among the multi-beams, and then beam multiplexed. In addition, the beam multiplexed symbol sequence is allocated to spreading segments after being serially converted in each transmit antenna branch.

In each spreading segment, the Walsh code is used to spread in two dimensions in the time direction and the frequency direction, and multiplexed with other user signals. The spreading code used at this time uses a spreading code available according to the beam pair used as shown in FIG. In addition, each beam pilot signal is also spread in the time direction with a spreading code having a spreading rate twice that of the spreading in the time direction, and multiplexed with spread data.

At this time, as shown in FIG. 8, different user signals and pilot signals are spread and multiplexed in each spreading area SF _Time x SF _Freq in an Ns symbol x Nc subcarrier area.

The subcarrier signal is orthogonal frequency division multiplexed using a fast inverse Fourier transform (IFFT) to convert to a time domain signal, a guard interval (GI) is added, and then phase-converted to a carrier frequency through a transmission array antenna 20. Transmit (see beam pattern of the fixed multi-beam shown in FIG. 9).

The mobile station 1 (receiving side) converts the received signal into a received subcarrier signal using fast Fourier transform and despreads in the time direction by using a spreading code assigned a beam pilot signal in each subcarrier. Then, by removing the modulation component of the pilot signal from the despread signal, the channel estimate value from the beam is obtained.

In addition, the spreading code assigned by the user is used to despread the signal component causing interference by despreading in the time direction, and thereafter, construction decoding is performed to synthesize the frequency component. The despread signal is deinterleaved to perform error correction decoding to obtain a reproduction bit sequence.

As described above, user signals that share one and the same beam and also use different beam pairs in the allocation of spreading codes cause mutual interference when decoding construction codes. To solve this problem, branching from the same node is performed. If the spreading codes are allocated as described above using the property that partial correlations are zero with each other, signals from users interfering with each other can be suppressed by time direction despreading at the receiver. Therefore, the effect that interference does not occur at the time of decoding construction code can be obtained.

In addition, in the allocation of spreading codes, different spreading codes are allocated to users using the same beam pair as far as possible from each of a plurality of nodes in which the spreading ratio of the time spreading is the same. For example, by first using spreading codes 0, 4, 8, and 12, and sequentially spreading the spreading codes 2, 6, 10, and 14 as the number of users increases, another user is assigned by time-oriented despreading at the receiver. I can suppress it. As a result, inter-code interference may not be easily generated during synthesis in the frequency direction.

As described above, according to the time beam space transmission diversity system of the present embodiment, construction code decoding in a transmission method using a combination of a transmission multi-beam array and construction coding in an OFDM-CDM system using two-dimensional spreading The spreading code is assigned on the transmitting side to suppress the signal causing interference in time direction despreading on the receiving side, thereby obtaining the effect of preventing interference. As a result, it is possible to improve the transmission characteristics and contribute to the performance improvement of the system.

In addition, in the time beam space transmission diversity system of the present embodiment, an example of the case where the mobile station 1 determines the selection beam index from the power estimation value and the base station 2 performs allocation control of spreading codes based on this is described. The present invention is not limited to this. That is, it is also possible to calculate the power estimation value at the mobile station 1 side and transmit it to the base station 2, and determine the selection beam index from the power estimation value at the base station 2 side to perform allocation control of the spreading code.

The mobile station 1, the transmitter and the receiver of the base station 2 have a computer system therein. The above-described series of processing procedures for construction coding processing, construction decoding processing, and beam index selection processing are stored in a computer-readable recording medium in the form of a program, and the processing is performed by the computer reading and executing the program.

That is, each processing means and processing unit provided in the transmitter 1 and the receiver of the mobile station 1, the base station 2, and the like are processed by the central processing unit such as a CPU by reading the program into a main memory device such as a ROM or a RAM. It is realized by executing the calculation process.

The computer readable recording medium refers to a magnetic disk, magneto-optical disk, CD-ROM, DVD-ROM, semiconductor memory, and the like. It is also possible to send this computer program to a computer by means of a communication line and have the computer which has received it execute the program.

Hereinafter, a time beam space transmission diversity system according to a second embodiment of the present invention will be described with reference to the accompanying drawings.

10 is a block diagram showing the configuration of a time beam space transmission diversity system according to a second embodiment of the present invention.

The time beam space transmission diversity system according to the second embodiment of the present invention is composed of a mobile station (transceiver) 1 and a base station (transceiver) 2 as in the first embodiment, and employs a closed loop beam selection method.

The mobile station 1 includes an antenna 10, a switch 11, a channel estimator 12-1 to 12-4, a power calculator 13-1 to 13-4 and an adder 14-1 to 14-4. And a closed loop beam selector consisting of a maximum detector 15, a beam pair selector 16, a power difference comparator 17, and a single / multi beam selector 18.

The antenna 10 receives a plurality of beams # 1 to # 4 radiated from the transmit array antenna 20 (see FIG. 1) of the base station 2, and outputs the corresponding received signals to the switch 11. Emits a select beam index (to be described later) input from switch 11.

The switch 11 outputs a received signal input from the antenna 10 to the channel estimators 12-1 to 12-4 and outputs a selection beam index input from the single / multi beam selector 18. Output for 10). Switching of the input / output processing of the switch 11 is made in accordance with a control command from a controller (not shown).

The fast Fourier transformer 60 receives the input of the received signal from the antenna 10, down converts the signal, removes the guard interval from the received signal, converts it to a subcarrier signal using an FFT, and estimates the channel for beams # 1 to # 4. Output to (12-1 ~ 12-4).

The channel estimators 12-1 to 12-4 despread the subcarrier reception input from the fast Fourier transformer 60 with respective spreading codes to remove modulation components of the pilot signal and estimate the channel response (to be described later). Output to the power calculator (13-1 to 13-4).

The power calculators 13-1 to 13-4 calculate the power of the channel response input from the channel estimators 12-1 to 12-4, sum them in all subcarriers, estimate the power in each beam, and adder. (14-1 to 14-4), and outputs to the beam pair selector 16. That is, the power calculator 13-1 outputs the power estimated value P ₁ of the beam # 1 to the adders 14-1 and 14-4 and the beam pair selector 16. The power calculator 13-2 also outputs the power estimation value P ₂ of the beam # 2 to the adders 14-1 and 14-2 and the beam pair selector 16. The power calculator 13-3 also outputs the power estimated value P ₃ of the beam # 3 to the adders 14-2 and 14-3 and the beam pair selector 16. The power calculator 13-4 also outputs the power estimated value P ₄ of the beam # 4 to the adders 14-3 and 14-4 and the beam pair selector 16.

The adders 14-1 to 14-4 add power estimates P _{1 to} P ₄ of beams # 1 to # 4 input from the power calculators 13-1 to 13-4, respectively, and output the maximum detector 15. do. Specifically, the adder 14-1 receives inputs of the power estimation values P ₁ and P ₂ of the beams # 1 and # 2 and outputs the power addition value P ₁ + P ₂ to the maximum detector 15. In addition, the adder 14-2 receives inputs of the power estimation values P ₂ and P ₃ of the beams # 2 and # 3 and outputs the power addition value P ₂ + P _{3 to the} maximum detector 15. In addition, the adder 14-3 receives inputs of the power estimation values P ₃ and P ₄ of the beams # 3 and # 4 and outputs the power addition value P ₃ + P ₄ to the maximum detector 15. The adder 14-4 receives inputs of the power estimation values P ₄ and P ₁ of the beams # 4 and # 1 and outputs the power addition value P ₄ + P ₁ to the maximum detector 15.

The maximum detector 15 receives inputs of the power addition values P ₁ + P ₂ , P ₂ + P ₃ , P ₃ + P ₄ , and P ₄ + P ₁ , compares the respective power additions, and determines the maximum power addition. The beam pair index is output to the beam pair selector 16 for the value.

Here, the beam pair index is a combination of the power addition value and the corresponding beam. For example, when the power addition value P ₁ + P ₂ is the maximum, the combination of the corresponding beam becomes (beam # 1, # 2). The beam pair index is similarly defined for the other power addition values.

The beam pair selector 16 receives inputs of the power estimates P _{1 to} P ₄ from the power calculators 13-1 to 4 and inputs of the beam pair indexes to the maximum detector 15 so that the beam pair index and the beam pair index are The power values of the various beams represented are output to the power difference comparator 17.

The power values of the various beams indicated by the beam pair index are the power pair values corresponding to the beam pair indexes output by the maximum detector 15. For example, the beam pair index output by the maximum detector 15 is (beam # In the case of 1, # 2), the power values of the various beams corresponding to the corresponding beam pair indexes are the power estimates P ₁ and P ₂ .

The power difference comparator 17 receives an input between the beam pair index and the power values of the multiple beams indicated by the beam pair index, and compares the power value difference of the corresponding multiple beams with a predetermined threshold to compare the result of the comparison with the single / multi beam selector ( 18).

The single / multi beam selector 18 receives an input of a result of comparing power values of the multiple beams indicated by the beam pair index, selects a single beam or a multi beam, and outputs a selection beam index to the switch 11. That is, when the difference in power value is larger than a predetermined threshold, the single / multi beam selector 18 selects only beams having a large power value from several beams indicated by the beam pair index, and the beam pair when the difference in power value is smaller than a predetermined threshold value. Select all the multiple beams indicated by the index.

11 is a block diagram illustrating a configuration of a base station according to the second embodiment of the present invention.

As shown in FIG. 11, the base station 2 includes a transmit array antenna 20, an error correction encoder 21, a mapper 22, an interleaver 23, a construction encoder 24, and an antenna branch 25-1 through. 25-n; n is a natural number), and a spreading code allocation control section 26 is provided.

The error correction encoder 21 receives the input of the transmission data, performs error correction encoding, and outputs it to the mapper 22.

The mapper 22 receives the input of the error correction coded transmission data, maps it to modulation constellation, and outputs it to the interleaver 23. Since the interleaver 23 spreads the burst error, the interleaver 23 receives the input of the mapped data, reverses the order of the data, and outputs it to the construction encoder 24.

The construction encoder 24 encodes an output signal of the interleaver 23 using an orthogonal construction coding matrix of two rows and two columns as shown in Equation 1 above, and allocates the beams indicated by the selection beam index received by the mobile station 1 Output In the second embodiment of the present invention, for example, when the selection beam index is (beams # 1, # 2), the construction encoding outputs are assigned to the beams # 1, # 2 and the corresponding antenna branches 25-1 to 25-n. )

The antenna branches 25-1 to 25-n are multiplexers 30, S / P converters 31, 32-1 and 2, and two-dimensional diffusers 33-1, 2 to 33-m, and 2m, respectively. (m is a natural number), a multiplexer 34, other user signal multiplexers 35, a pilot signal multiplexer 36, and a fast inverse Fourier transformer (= IFFT + GI) 37.

The multiplexer 30 receives the input of the construction encoding output allocated by the construction encoder 24 to the beams of the selected beam index, and multiplexes multiple beams and outputs them to the block S / P converter 31. For example, in the second embodiment, the multiplexer 30 multiplexes two beams (beams # 1, # 2) by multiplying the construction coded transmission symbols by the array weight at the transmission array antenna 20.

The S / P converter 31 receives an input of a beam construction coded transmission symbol multiplexed on several beams, performs serial-to-parallel conversion every two symbols, and outputs the S / P converters 32-1 and 2. These two output signals correspond to the time direction output signals of the construction encoder 24. The S / P converters 32-1 and 2 convert the two output signals from the S / P converters 32-1 and 2 in parallel and in parallel to the number of spreading segments, respectively. 33-m, 2m) The two-dimensional spreaders 33-1, 2 to 33-m, and 2m receive inputs of serial / parallel transformed beam construction coded transmission symbols, assign them to spreading segments as shown in FIG. 3, and use a Walsh code in each spreading segment. Two-dimensional spread in the direction and frequency direction and output to the multiplexer (34).

In this case, as shown in FIG. 3, a spread region is set according to the number of OFDM symbols SFTime in the segment and the number of subcarriers SFFreq in the frequency direction. As a spreading code, a spreading code having a spreading ratio SFTime x SFFreq (time spreading rate x frequency spreading ratio) assigned by the spreading code assignment controller 26 is used. In addition, the two-dimensional spreaders 33-1, 2 to 33-m, and 2m first spread in the time direction on the first subcarrier and then spread in the time direction on the neighboring subcarriers, and then repeat the time direction and frequency. Two-dimensional diffusion in the direction is performed.

The multiplexers 34-1 to m multiplex two symbols in the time direction of each of the two-dimensional spreaders 33-1, 2 to 33-m, and 2m in the same diffusion region, and other user signal multiplexers 35. Output to For example, the multiplexer 34-1 multiplexes two symbols in the time direction output from the two-dimensional spreaders 33-1 and 2 in the same spreading region and outputs them to the other user signal multiplexer 35.

The other user signal multiplexer 35 receives an input of a beam construction coded transmission symbol spread in two dimensions in the time direction and the frequency direction, and multiplexes it among several users, and outputs it to the pilot signal multiplexer 36.

The pilot signal multiplexer 36 spreads the pilot signal for each beam in the time direction and further multiplexes it with other user multiplexed spread data and outputs it to the fast inverse Fourier transformer 37.

The fast inverse Fourier transformer 37 converts into a time domain signal using a fast inverse Fourier transform (IFFT). The guard interval GI is added and phase-transformed to a carrier frequency and output to the transmission array antenna 20.

The transmit array antenna 20 is composed of a number (n) of antennas corresponding to each antenna branch 25-1 to 25-n, and a fast inverse Fourier of each antenna branch 25-1 to 25-n. The transmitter 37 emits various transmission signals.

The spreading code allocation controller 26 is the same as the beam of the single beam used by the user and one of the multi beams used by the user, or the beam of one of the multi beams used by the user and the multi beam used by the other users. If it is equal to the beam of 1, either assign a spreading code whose partial correlation is zero in time spreading, or assign a spreading code whose partial correlation is 0 in time spreading to multiple users using the same beam pair. Outputs 2D diffuser 33-1, 2 ~ 33-m, 2m respectively.

Allocation of Spreading Codes As shown in FIG. 4, a user using a current beam pair (# 1, # 2) and a user using a beam pair (# 3, # 4) are referred to as a group A, and a beam pair (# 2, # 3) A user using the A and a user using the beam pairs # 4 and # 1 are referred to as a group B.

When the path angle spread from the base station to each terminal is appropriately narrow, signals allocated to beam separation in different beam pairs within the same group do not interfere with each other. In addition, since the same two beams are used for multiple users in the same beam pair, interference components do not occur when decoding a space-time code.

On the other hand, as mentioned above (see Equations 8 and 9) among users belonging to different groups, interference components occur.

Therefore, for the beams used by the same group, such as the Walsh-based spreading code tree as shown in FIG. 4, to suppress the interference component, the spreading rate of the time-direction spreading (see X in FIG. 4) at the same node (node) In this case, the spreading code corresponding to the leaf (leaf) generated at each nodal point is allocated, and the spreading code generated at the same nodal point is not allocated to beams used by different groups, so that the node in the root direction is larger than the diffusion rate in the time direction diffusion. Allocates a different spreading code, corresponding to the leaf created at the point.

In this example, as shown in FIG. 4, the spreading ratio of time spreading is applied to a user belonging to group A, that is, a user using beam pairs # 1 and # 2 such as a beam index and a user using beam pairs # 3 and # 4. Allocate 32-bit spreading codes 0 to 15, which are leaves generated at each node X ₁ , X ₂ , X ₃ , and X ₄ at the same node (see part X in FIG. 4) (see part A in FIG. 4). ), Users in group B (users using beam pairs (# 2, # 3) and users using beam pairs (# 4, # 1)) have spread codes 0 to 15 generated at the same node as other group A No other spreading code, i.e., the diffusion rate of the time direction diffusion (see part X in FIG. 4) corresponding to the node generated at the root or root (root) rather than the diffusion rate of the time direction diffusion, without assigning 32-bit spreading code 16 to 3, a leaf generated at each node X ₅ , X ₆ , X ₇ , and X ₈ at point 2 is allocated (see part B of FIG. 4).

In other words, in the spreading code allocation controller 26, spreading codes are assigned based on the following rules.

1) Another group assigns a spreading code that is generated in another branch in the spreading code of the time direction spreading.

2) Two spreading codes used for the same user allocate spreading codes generated at different branches for the spreading rate of the time spreading.

3) The other user using the same beam pair is assigned a code if there is a spreading code generated from another branch in the time spreading spreading rate.

4) Users belonging to different beam pairs in the same group may use the same spreading code without the assignment constraint.

On the other hand, the mobile station 1, as shown in Figure 6, the fast Fourier transformer 60, the time direction despreaders (61-1 to 61-n), channel estimators (62-1, 2 to 62-n, 2n) ), Construction decoders 63-1 to 63-n, frequency direction synthesizers 64-1, 2 to 64-n, 2n, block P / S converter 65, deinterleaver 66, and error correction decoder The construction decoder which consists of 67 is provided.

The fast Fourier transformer 60 receives the input of the received signal from the antenna 10, downconverts it, removes the guard interval from the received signal, converts it to a subcarrier signal using an FFT, and uses a time direction despreader 61-1 to 61. -n) and output to channel estimators 62-1, 2-62-n, 2n.

The channel estimators 62-1, 2-62-n, and 2n remove the modulated phase components of the pilot signal with respect to the despread signal, estimate the channel response, and estimate the result of the construction decoders 61-1 through 61-. output to n).

The time direction despreaders (61-1 to 61-n) receive the input of the subcarrier signal and generate a pilot signal reception replica at each transmit antenna using a pilot signal, a spread signal for the pilot signal, and the obtained channel estimate, and perform a Fourier transform. The received pilot signal replica is subtracted from one received subcarrier signal, and the received subcarrier signal subtracted from this pilot signal is despread in the time direction using a spreading code assigned to the user.

The construction decoders 63-1 to 63-n receive the received subcarrier signal using a spreading code used by the user for the signal after the time direction despreading which the despreaders 61-1 to 61-n respectively output. Despread and perform construction decoding using channel estimates.

The frequency direction synthesizers 64-1, 2 to 64-n, and 2n receive construction decoding outputs from the construction decoders 63-1 to 63-n, synthesize them in the frequency direction, and transmit them to the block S / P converter 65. Output

The block P / S converter 65 performs block parallel / serial conversion of the synthesized signal synthesized by the frequency direction synthesizers 64-1, 2 to 64-n, and 2n and outputs the deinterleaver 66.

The deinterleaver 66 receives the output signal of the block P / S converter 65, reverses the order of data as opposed to the interleaver 23, and outputs the data to the error correction decoder 67.

The error correction decoder 67 receives the output signal of the deinterleaver 66 and corrects the error to obtain reproduction data.

Hereinafter, an operation of a time beam space transmission diversity system according to a second embodiment of the present invention will be described with reference to the accompanying drawings.

12 is a diagram illustrating a time beam space transmit diversity processing procedure in the base station 2 of the time beam space transmit diversity system according to the second embodiment of the present invention.

As shown in FIG. 10, when the beams # 1 to # 4 are emitted from the array antenna 20 of the base station 2, the mobile station 1 receives various beams # 1 to # 4 from which the antenna 10 is radiated and switches ( 11) and outputs them to the channel estimators 12-1 to 12-4. Despread the received signals input from the channel estimators 12-1 to 12-4 to estimate the channel response and output the power to the power calculators 13-1 to 13-4.

The power calculators 13-1 to 13-4 calculate the power of the input channel response, sum them in all subcarriers, average them, estimate the power in each beam, and add adjacent units in the adders 14-1 to 14-4. The sum of the powers of the channel responses in the two beams is calculated and output for the maximum detector 15.

The maximum detector 15 receives the input of the power sum, compares the respective power sums, and outputs the power values of the beams represented by the beam pair index and the beam pair index to the power difference comparator 16 for the power sum determined as the maximum. do. In this way, the two beams are selected in which the sum of the channel responses in the two adjacent beams is maximum.

The power difference comparator 16 calculates the power difference of the channel response corresponding to the two selected beams and outputs to the single / multi beam selector 17 whether the difference is less than or equal to a certain threshold. That is, the power difference comparator 16 receives the input of the beam pair index and the power values of the multiple beams indicated by the beam pair index, compares the power value difference of the corresponding multiple beams with a predetermined threshold, and compares the comparison result with the single / multi beam selector. Output for (17).

The single / multi beam selector 17 selects the two beams when the power difference calculated by the power difference comparator 16 is less than or equal to a predetermined threshold value, and uses only the beam having the larger power when the power difference calculated by the power difference comparator 16 is less than or equal to the predetermined threshold value. Select one beam. That is, the single / multi beam selector 17 receives an input of a result of comparing the power values of the multiple beams indicated by the beam pair indexes, and the single beam also selects the multi beams and sets the selection beam index via the switch 11 to the antenna ( Output to 10). The antenna 10 sends its beam index back to the base station 2.

Next, the base station 2 performs error correction encoding on the transmitted data, maps them to modulated signal points, randomizes the transmission order through the interleaver, and constructs the construction using the above-described two-row orthogonal construction coding matrix. The construction coded output is allocated to two beams designated by the selection beam index received by the mobile station 2.

That is, as shown in FIG. 12, the beamforming is performed by beam steering vectors of two beams having two streams [s ₁ , -s ₂ ^* ] and [s ₂ , s ₁ ^* ] of the construction coding output interposed in a direction in which the user is located. Conduct. If the beam indices of these two beams are b ₁ and b ₂ , the beam steering vectors for s ₁ and -s ₂ ^* can be expressed as Equation 10. For s ₂ and s ₁ ^* , the beam steering vector can be expressed by Equation 11. Beamforming is performed on the beam steering vectors of Equations 10 and 11 and multiplexed.

At time 1, a signal as shown in equation (12) is output, and at time 2, a signal as shown in equation (13) is output.

Here, each element of V corresponds to each antenna branch.

That is, V ₁ ^iA can be obtained at time 1 and V ₂ ^iA at time 2 for each antenna branch. These output signals V ₁ ^iA and V ₂ ^iA are serial-to-parallel converted, and V ₁ ^iA and V ₂ ^iA are spread using spreading codes c ₁ and c ₂ in antenna branch #iA and multiplexed in the same spreading segment.

In this case, when beams are allocated to groups A and B as shown in the beam pair classification of FIG. 7, for example, a spreading code having a spreading rate twice as large as the time spreading spreading rate is allocated to a pilot signal, the Walsh sequence as shown in FIG. For beams used by the same group, such as the spreading code tree of, the spreading rate (see section Z in Figure 7) of the time-direction spreading corresponds to the leaf (leaf) generated at each node at the same node (node) Assign code

In this case, since a spreading code having a spreading rate twice that of the time spreading spreading rate is allocated to the pilot signal, 16-bit spreading codes 1 'to 4' are allocated to pilot signals other than the user signals of groups A and B.

In other words, each spreading segment is spread in two dimensions in the time direction and the frequency direction using a Walsh code. The spreading code used at this time uses a spreading code that can be used according to the beam pair used as shown in FIG.

Then, in each subcarrier in the two-dimensional spreading region and other user signals obtained in the same manner, the pilot signal is spread and multiplexed with the user signal using various spreading codes orthogonal to the spreading code for spreading the user signal.

The frame signal generated in this way (see FIG. 8) is converted into a time domain signal using fast inverse Fourier transform (IFFT), a guard interval is added, and phase-converted to a carrier frequency to be transmitted simultaneously by all the array antenna elements (see FIG. 9). See beam pattern of fixed multi-beams).

The mobile station 1 (receiving side) converts the received signal into a received subcarrier signal using fast Fourier transform and despreads in the time direction with a spreading code assigned a beam pilot signal in each subcarrier. If the modulation component of the pilot signal is removed from the despread signal, the channel estimation value in the beam can be obtained.

In addition, the user spreads the signal component causing interference by despreading in the time direction with the assigned spreading code, and then performs construction decoding to synthesize it in the frequency direction. The despread signal is deinterleaved to decode error correction to obtain a reproduction bit sequence.

As described above, according to the time beam space transmission diversity system according to the second embodiment of the present invention, a construction code is used in a transmission scheme using a combination of a transmission multi-beam array and construction coding in an OFDM-COM system using two-dimensional spreading. In decoding, a spreading code is allocated at the transmitting side so that a signal causing interference can be suppressed in time direction despreading at the receiving side. Therefore, it is possible to prevent the occurrence of interference and to reduce the inter-code interference due to the frequency selectivity.

In addition, according to the time beam space transmission diversity system of the present embodiment, multiple symbols in the time direction of the construction coded output are spread by multiple spreading codes and multiplexed in the same spreading region so that they are not affected by the time variation through the Doppler frequency.

Therefore, transmission characteristics can be improved and system performance is greatly contributed.

In addition, according to the time beam space transmission diversity system of the present embodiment, the spatial direction output of the construction coder is allocated to the beam space, so that when the user is properly scattered in the multi-beams, all signals multiplexed to each mobile station are not reached. A user signal sharing a beam that the user is using arrives. This reduces the number of user signals that arrive and reduces inter-code interference.

In addition, in the conventional scheme, the time-domain output of the construction coder uses multiple spreading regions in the time direction. According to the time beam space transmission diversity system of the present embodiment, the time-directional output of the construction coder is assigned to multiple spreading codes and the same spreading is performed. Multiplexing within the domain increases the channel's immunity to time fluctuations.

That is, according to the time beam space transmission diversity system of the present embodiment, inter-code interference due to channel frequency selectivity, inter-code interference due to time variation of the channel, and deterioration in decoding characteristics of construction codes can be reduced.

According to the time beam space transmission diversity system of this embodiment, pilot signals orthogonal to each other are allocated to each beam. Alternatively, since a pilot signal is spread with multiple spreading codes that are orthogonal to each other, the channel response of each beam may be estimated at the receiver.

Therefore, the power of the channel estimates in each beam can be calculated to know in which beam area the mobile station is located.

In addition, since the base station allocates the construction encoding output of two rows and two columns to two adjacent beams or a single beam, the receiving side can calculate the sum of powers of channel estimates in the adjacent beams and detect the index of adjacent two beams with the maximum sum of powers. .

In the case where the power difference of the channel response in the selected two beams is large, when the transmission power is distributed to the two beams, the power allocated to the beam having the smallest reaching power is not effectively utilized, so that only one beam having a large reception power is used. The beam selection information is then sent back to the base station in uplink.

Thus, the base station can know the valid beam to be assigned to each mobile station.

Users who share another same beam and use another beam pair interfere with each other when decoding the construction code. Generation of Spreading Codes Since spreading codes branched from different branches in a code tree have a correlation of 0 in the partial correlation over spreading rates of different branches, if spreading codes are assigned according to the above assignment method, the signals of users who interfere with each other Since can be suppressed through time direction despreading at the receiver, there is an effect that no interference occurs when decoding the construction code.

In addition, since two spreading codes used by the same user are assigned codes having a two-dimensional spreading rate branched from different branches in the time spreading rate, space-time decoding is realized because the signals can be separated by time spreading.

The user can use the same beam pair in the allocation of the spreading code, so that the spreading code branched from the other branch can be allocated at the time spreading rate as much as possible to suppress other user signals by the time spreading at the receiver. In this case, there is an effect that interference between codes does not occur well.

The transmitters and receivers of the mobile station 1 and the base station 2 have a computer system therein.

The above-described sequence of processing for construction coding processing, construction decoding processing, and beam index selection processing is stored in a computer-readable recording medium in a program format. Is done.

That is, in the transmitter and receiver of the mobile station 1 and base station 2 described above, each processing means and processing unit reads the program into a main memory device such as a ROM or a RAM by a central processing unit such as a CPU, and processes and processes information. It is realized by executing the process.

The computer-readable recording medium herein refers to a magnetic disk, magneto-optical disk, CD-ROM, DVD-ROM, semiconductor memory, and the like. The computer program may be distributed to a computer via a communication line, and the computer receiving the distribution may execute the program.

As described above, in the present invention, a transmission pair allocates a transmission signal to a beam space of a multi-beam, transmits a beam pair, and estimates a channel for each beam received at a reception side to maximize the power sum of channel estimation values. In the beam selection method for selecting, when the power difference of each channel estimate value in the corresponding beam pair is larger than a predetermined value, since a single beam is selected from the corresponding beam pair, an effect of suppressing waste of signal power can be obtained. .

The present invention also provides a transmission diversity system in which a transmission side is time-encoded in a transmission signal, the time-frequency encoding is spread in a time direction and a frequency direction, and the spread output is allocated to a beam space of a multi-beam.

When a single beam used by one user and one of the multi beams used by another user are the same, or when one of the multi beams used by the user is the same as one of the multi beams used by the other user, Since a spreading code having a partial correlation of 0 is assigned in the time direction spreading, an effect of preventing interference between a plurality of beams can be obtained.

In addition, in the transmission diversity system in which the transmission side constructs and encodes a transmission signal, spreads the construction encoding output in the time direction and the frequency direction, and allocates the spread output to the beam space of the multi-beam, transmits the construction encoding output in the spatial direction. Is assigned to multiple beams of multi-beams, and time-spaced construction coding output is assigned to multiple spreading codes in the same spreading region, thereby reducing the inter-code interference due to the frequency selectivity and the time due to the Doppler frequency. Since it is not affected by fluctuations, it is possible to obtain an effect of improving transmission characteristics.

Claims (41)

A transmission diversity system comprising a transmitter for assigning a transmission signal to a beam space of a multi-beam and a receiver for estimating a channel for each beam to be received, The receiver includes first selection means for selecting a beam pair in which the sum of powers of channel estimates is maximum; And second selecting means for selecting one single beam from the beam pair when the power difference of each channel estimate value in the beam pair is larger than a predetermined value. The method of claim 1, And the selecting means selects one single beam having a maximum absolute value of power of the channel estimate value from the beam pair when the power difference of each channel estimate value is larger than a predetermined value in the beam pair. City system. In a transmission diversity system in which a transmission signal is encoded by a transmission side, the construction encoded output is spread in a time direction and a frequency direction, and the spread output is allocated to a beam space of a multi-beam. When one beam of one user and the one of the multi-beams used by another user is the same, or when one of the multi-beams used by the user and one of the multi-beams used by the other user is the same And a code assigning means for assigning a spreading code of which partial correlation is zero in time-directional spreading. The method of claim 3, wherein And said code assigning means further allocates a spreading code of which partial correlation is zero in said time direction spreading to a plurality of users using the same beam pair. A receiver for receiving a signal allocated to a beam space of a multi-beam and estimating a channel for each beam, First selecting means for selecting a beam pair in which the sum of the powers of the channel estimates is maximum; And second selection means for selecting one single beam from the beam pair when the power difference of each channel estimate value in the beam pair is larger than a predetermined value. First selecting means for receiving a signal allocated to the beam space of the multi-beams, receiving a channel estimate from a receiver for estimating a channel for each beam, and selecting a beam pair for which the sum of the powers of the channel estimates is maximum; And second selecting means for selecting one single beam from the beam pair when the power difference of each channel estimate value in the beam pair is larger than a predetermined value. A transmitter which constructs and encodes a signal and spreads the constructive encoding output in a time direction and a frequency direction, and allocates the spreading output to a beam space of a multi-beam. When a single beam used by one user is the same as one of the multi beams used by another user, or when one beam of the multi beams used by the user is the same as one of the multi beams used by the other user. And code assignment means for assigning a spreading code whose partial correlation is zero in said time direction spreading. The method of claim 7, wherein And the code assignment means further assigns spreading codes of which partial correlation is zero in each of the time direction spreads for different users using the same beam pair. A beam selection method in which a transmitting side allocates a transmission signal to a beam space of a multi-beam and transmits the signal, and estimates a channel for each beam received at the receiving side, and selects a beam pair having a maximum sum of channel estimate values. And selecting a single beam from the beam pair when the power difference of each channel estimate value in the beam pair is larger than a predetermined value. The method of claim 9, And selecting a single beam having a maximum absolute value of power of the channel estimate value from the beam pair when the power difference of each channel estimate value is larger than a predetermined value in the beam pair. In a transmission diversity system in which a transmission signal is encoded by a transmission side, the construction encoded output is spread in a time direction and a frequency direction, and the spread output is allocated to a beam space of a multi-beam. When the single beam used by one user is the same as one of the multi beams used by another user, or when one beam of the multi beams used by the user is the same as one of the multi beams used by the other user, And spreading code in which partial correlation is 0 in the time direction spreading. In a transmission diversity system in which a transmission signal is encoded by a transmission side, the construction encoded output is spread in a time direction and a frequency direction, and the spread output is allocated to a beam space of a multi-beam. A spreading code allocation method according to claim 1, wherein spreading codes having partial correlations of 0 in the time-direction spreading are allocated to various users using the same beam pair. A receiver for receiving a signal allocated to the beam space of the multi-beams to estimate the channel for each beam, Processing for selecting a beam pair in which the sum of the powers of the channel estimates is maximum; A computer-readable recording medium having recorded thereon a beam selection program for causing a receiver to perform a process of selecting one single beam from the beam pair when the power difference of each channel estimate value in the beam pair is larger than a predetermined value. Receiving a signal allocated to the beam space of the multi-beams, receiving a channel estimate from a receiver for estimating a channel for each beam, and selecting a beam pair for which the sum of powers of the channel estimates is maximum; A computer-readable recording medium having recorded thereon a beam selection program for causing a transmitter to perform a process of selecting one single beam from the beam pair when the power difference of each channel estimate in the beam pair is larger than a predetermined value. A transmitter for constructing and encoding a signal, spreading the constructive encoding output in a time direction and a frequency direction, and allocating the spreading output to a beam space of a multi-beam. When the single beam used by one user is the same as one of the multi beams used by another user, or when one beam among the multi beams used by the user is the same as one beam among the multi beams used by the other user, A computer-readable recording medium having recorded thereon a spreading code assignment program for causing a transmitter to perform a process for assigning a spreading code whose partial correlation is zero in time-directional spreading. 16. A transmitter according to claim 15, wherein a computer having recorded thereon a spreading code assignment program for further executing a process of allocating spreading codes of which partial correlation is zero in the time-direction spreading for various users using the same beam pair Reversible Recording Media. In a transmission diversity system in which a transmission signal is constructively encoded by a transmission signal, the corresponding construction encoding output is spread in a time direction and a frequency direction, and the corresponding spread output is allocated to a beam space of a multi-beam. Beam allocation means for allocating spatial encoding output in the spatial direction to the multiple beams of the multi-beam; A transmission diversity system comprising spreading code assignment means for allocating time-domain constructional coding output to multiple spreading codes in the same spreading region. The method of claim 17, wherein the beam allocation means, Select a beam pair in which the sum of the channel estimates for each beam received by the receiver is maximum, and if a power difference of each channel estimate in the beam pair is larger than a predetermined value, select one single beam in the beam pair. And a transmission encoding output in the spatial direction. 18. The method of claim 17, wherein the spreading code allocation means is used when the single beam used by one user and the one beam of the multi-beams used by the other user are the same, or the other beam is different from one beam of the multi-beams used by one user. And if one of the multiple beams used is the same, a spreading code of which partial correlation is zero in the same spreading region is allocated. 19. The apparatus of claim 18, wherein the spreading code assignment means is: The beam allocating means classifies and groups the beam pairs that interfere with each other and the beam pairs that do not interfere with each other for the selected beam pair. Transmit diversity system, characterized in that it is assigned to a group. 20. The apparatus of claim 19, wherein the spreading code assignment means is: The beam allocating means classifies the selected beam pair into a pair of beam pairs that do not interfere with each other and a pair of beams that do not interfere with each other. Transmit diversity system, characterized in that it is assigned to a group. 19. The method of claim 18, wherein the spreading code assigning means assigns a spreading code having a two-dimensional spreading rate branching from another branch in a time-direction spreading layer of a spreading code tree to one single beam selected by the beam assigning means. Transmission diversity system. 20. The method of claim 19, wherein the spreading code assigning means assigns a spreading code having a two-dimensional spreading rate branching from another branch in the time-direction spreading layer of the spreading code tree to one single beam selected by the beam assigning means. Transmission diversity system. In the transmission diversity, the spatial encoding of the transmission signal is performed by constructing the transmission signal, spreading the construction encoding output in the time direction and the frequency direction, and allocating the diffusion output to the beam space of the multi-beam. And a plurality of beams in a time direction, and time-domain construction coding outputs are assigned to different spreading codes in the same spreading region. 25. The method of claim 24, wherein when a power difference of each channel estimate is greater than a predetermined value in a beam pair in which the sum of the channel estimates for each beam received by the receiver is maximum, one single beam is selected in the corresponding beam pair. And a transmission encoding output in the spatial direction. 25. The method of claim 24, wherein the same beam as one of a single beam used by one user and a multi beam used by another user, or a multiple beam used by another user and one beam of a multi beam used by one user. And a spreading code of which partial correlation is zero in the same spreading region when one of the beams is the same. The method of claim 25, wherein the same beam as one of the single beam used by one user and the multi-beam used by the other user, or the multi-beam used by the other user and one of the multi-beams used by one user. And a spreading code of which partial correlation is zero in the same spreading region when one of the beams is the same. 26. The method of claim 25, wherein the power sum of the channel estimates is classified into beam pairs that do not interfere with each other and beam pairs that do not interfere with each other for beam pairs that maximize, and branch from different branches in the time-direction spreading layer of a spreading code tree. A transmission diversity method comprising allocating a spreading code having a two-dimensional spreading rate to another beam pair group. 27. The method of claim 26, wherein the power sum of the channel estimates is grouped into beam pairs that do not interfere with each other and beam pairs that do not interfere with each other for beam pairs that maximize, and branch from different branches in the time-direction spreading layer of a spreading code tree. A transmission diversity method comprising allocating a spreading code having a two-dimensional spreading rate to another beam pair group. 28. The method of claim 27, wherein the power sum of the channel estimates is classified into beam pairs that do not interfere with each other and beam pairs that do not interfere with each other for beam pairs that maximize the branching, and branch from different branches in a time-direction spreading layer of a spreading code tree. A transmission diversity method comprising allocating a spreading code having a two-dimensional spreading rate to another beam pair group. 27. The method of claim 25, wherein a spreading code having a two-dimensional spreading rate branched from another branch in a spreading layer of a spreading code tree is allocated to the selected single beam. 27. The transmission diversity method of claim 26, wherein a spreading code having a two-dimensional spreading rate branched from another branch in a spreading layer of a spreading code tree is allocated to the selected single beam. 28. The method of claim 27, wherein a spreading code having a two-dimensional spreading rate branched from another branch in a spreading layer of a spreading code tree is allocated to the selected single beam. In transmission diversity, the transmission side constructs and encodes a transmission signal, spreads the construction encoded output in a time direction and a frequency direction, and allocates the spread output to a beam space of a multi-beam. A computer-readable recording medium having recorded thereon a communication program for executing a process of allocating space-time coded outputs to multiple beams of the multi-beams and a process of allocating time-spaced coded outputs to multiple spread codes in the same spreading region. . 35. The method of claim 34, wherein when the power difference of each channel estimate is greater than a predetermined value in the beam pair in which the sum of the channel estimates for each beam received by the receiver is maximum, one single beam is selected in the corresponding beam pair. A computer-readable recording medium having recorded thereon a communication program for executing a process of allocating space-time coded output in the spatial direction. 35. The method of claim 34, wherein the single beam used by one user and the one beam of the multi-beams used by the other user are the same, or the one beam used by the other user and the other beam used by the other user. A computer-readable recording medium having recorded thereon a communication program for executing a process of assigning a spreading code of which partial correlation is zero in the same spreading region when one of the multi-beams is the same. 36. The method of claim 35, wherein the single beam used by the one user and the one beam of the multi-beams used by the other user are the same, or the one beam used by the other user and the other beam used by the other user. A computer-readable recording medium having recorded thereon a communication program for executing a process of assigning a spreading code of which partial correlation is zero in the same spreading area when one of the multi-beams is the same. 36. The method of claim 35, wherein the processing of classifying and grouping beam pairs that interfere with each other and beam pairs that do not interfere with each other for the beam pair where the sum of the channel estimates is maximum is performed at different branches in the time-direction spreading layer of the spreading code tree. A computer-readable recording medium having recorded thereon a communication program for executing a process of assigning a diverging two-dimensional spreading spreading code to another beam pair group. 37. The processing according to claim 36, wherein the process of classifying and grouping beam pairs that interfere with each other and beam pairs that do not interfere with each other for the beam pair at which the sum of the channel estimates is maximum is performed at different branches in the temporal spreading layer of the spreading code tree. A computer-readable recording medium having recorded thereon a communication program for executing a process of assigning a diverging two-dimensional spreading spreading code to another beam pair group. 36. The computer readable recording medium according to claim 35, wherein a communication program for recording a communication program for executing a process of allocating a spreading code of a two-dimensional spreading rate branched from another branch in the time-directional spreading rate layer of a spreading code tree for the selected single beam. media. 37. The computer readable recording medium according to claim 36, wherein a communication program for recording a communication program for executing a process of allocating a spreading code of a two-dimensional spreading rate branched from another branch in a time-directional spreading rate layer of a spreading code tree for the selected single beam. media.

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