KR100889748B1 - Apparatus and Method of Inter-Cell macro-diversity for providing Broadcast/Multicast Service using multi-antenna - Google Patents

Abstract

The present invention provides an apparatus and method for transmitting macrodiversity for providing a broadcast / multicast service in a wireless cellular communication system.

The apparatus and method for transmitting a macrodiversity according to the present invention apply a spatial multiplexing using multiple antennas within a cell, and apply a method for obtaining additional diversity between adjacent cells or base stations, thereby receiving a terminal received at a cell boundary. Diversity as well as signal-to-noise ratio of a signal can be increased to increase cell coverage for a particular data rate or to reduce transmit power.

Here, additional diversity applied between cells or base stations includes a method of changing an antenna for transmitting the same information between cells and a cyclic delay diversity method.

Broadcast / multicast, macrodiversity, physical channel, coding block

Description

Apparatus and Method of Inter-Cell macro-diversity for providing Broadcast / Multicast Service using multi-antenna}

1 is a diagram illustrating an internal configuration of an OFDM-based simultaneous transmission / reception apparatus for broadcast / multicast service in a conventional wireless cellular communication system.

2 is a diagram illustrating three cell groups of adjacent cells transmitting the same broadcast packet data according to an exemplary embodiment of the present invention.

3 is a structural diagram illustrating a cyclic delay diversity transmission technique in a conventional multi-antenna communication system.

4 is a block diagram illustrating an internal configuration of a macrodiversity transmitting apparatus having multiple transmission antennas according to an exemplary embodiment of the present invention.

5 is a block diagram illustrating an internal configuration of an OFDM modulator to which cyclic delay diversity of a transmitting apparatus according to an embodiment of the present invention is applied.

6 is a block diagram illustrating an internal configuration of a macrodiversity transmitting apparatus having multiple transmission antennas according to another exemplary embodiment of the present invention.

7 is a diagram illustrating an operation example of an antenna switching unit of a transmitting apparatus according to another exemplary embodiment of the present invention.

8 to 13 are block diagrams illustrating an internal configuration of a macrodiversity transmission apparatus having multiple transmission antennas according to another exemplary embodiment of the present invention.

14 is a flowchart illustrating a method for transmitting macrodiversity by the transmitter of FIG. 4 according to an embodiment of the present invention.

15 is a flowchart illustrating an operation of an OFDM modulator to which cyclic delay diversity of a transmitting apparatus is applied according to an embodiment of the present invention.

16 to 21 are flowcharts illustrating a method for transmitting macrodiversity by a transmitting apparatus according to another exemplary embodiment of the present invention.

FIG. 22 is a block diagram illustrating an internal configuration of a receiving apparatus having multiple receiving antennas according to an exemplary embodiment of the present invention.

23 is a flowchart illustrating an operation of a receiving apparatus having multiple receiving antennas according to an exemplary embodiment of the present invention.

24 and 25 are block diagrams illustrating an internal configuration of a macrodiversity transmission apparatus having multiple transmission antennas according to another exemplary embodiment of the present invention.

FIG. 26 is a block diagram illustrating an internal configuration of a receiving apparatus having multiple receiving antennas according to another exemplary embodiment of the present invention.

The present invention relates to an apparatus and method for transmitting macrodiversity for providing broadcast / multicast service by multiple transmission antennas. More particularly, the present invention relates to a cell boundary when providing a broadcast / multicast service in a wireless cellular communication system. The present invention relates to an apparatus and method for transmitting macrodiversity capable of obtaining additional diversity between cells or base stations in order to improve reception quality of a terminal in a mobile station.

Since the broadcast / multicast service is simultaneously provided to multiple users in a cell, users with poor reception quality at the cell boundary often determine overall system performance and determine data rates. Therefore, it is very important to improve the communication quality of the cell edge user. For this purpose, the quality of the cell edge user can be improved through a technique of simultaneously using broadcast / multicast data from several adjacent cells, that is, base stations.

The most basic broadcast / multicast service method is to generate and transmit the same OFDM information in multiple cells or base stations. In this case, in order to estimate a channel for the sum of several base station signals received by the terminal, each base station generates the same pilot and inserts the same pilot at the same position of the OFDM symbol and transmits it (3GPP2 C30-20040823-060, "Detailed description of the enhanced"). BCMCS transmit waveform description, "Aug. 2004). There is also a method of separately estimating the pilot of each base station.

1 is an example of an OFDM-based simultaneous transmission and reception apparatus for a broadcast / multicast service in a conventional wireless cellular communication system.

Referring to FIG. 1, the transmitting device 100 is included in the first base station 120, the second base station 121, and the third base station 122, respectively, and the receiving device 130 is included in the terminal 150. .

The first base station 120, the second base station 121, and the third base station 122 are each located in adjacent cells, and transmit data corresponding to a broadcast / multicast service to the terminal 150. The terminal 150 receives data from each base station to receive a broadcast / multicast service.

The apparatus 100 transmits a channel encoder 101, a modulator (or symbol mapper) 102, a pilot generator 104, and an OFDM modulator 103. Include. For convenience of explanation, the following description will be made from the perspective of the transmitting apparatus of the first base station, which is common to the second and third base stations.

The channel encoder 101 channel-codes the broadcast / multicast data common to the first base station 120, the second base station 121, and the third base station 122 in the same channel coding scheme. The modulator 102 generates the data symbol sequence X (K) by mapping the channel coded data to corresponding modulation symbols. Pilot generator 104 generates a pilot symbol sequence. The pilot symbol sequence is generated in common to the first base station 120, the second base station 121, and the third base station 122 so that the terminal 150 can estimate a channel for the received signal consisting of the sum of the base station signals. The generated pilot symbol is inserted at the same position of the OFDM symbol. The OFDM modulator 103 performs OFDM modulation on the data symbol string and the pilot symbol string to transmit them to the radio channels 170, 171, and 172.

The reception device 130 of the user terminal 150 includes an OFDM demodulator 131, a channel estimator 133, a symbol demodulator 132, and a channel decoder ( 134).

The OFDM demodulator 131 converts a received signal obtained by combining several base station signals into a corresponding received symbol Y (K) in the frequency domain. The channel estimator 133 estimates a channel using a pilot symbol included in the received signal. The symbol demodulator 132 demodulates the received symbol using the channel estimation result. The channel decoder 134 restores the original transmitted data based on the demodulated result.

As described above, when the same information is transmitted from a plurality of cells to simply receive an added signal, the received signal-to-noise ratio (SNR) increases only the average value and does not increase the diversity order. That is, in the conventional scheme, the reception power of data symbols constituting one encoded packet is likely to be weakly received at the same time by fading, and thus there is a high probability of packet error.

In addition to the energy gain between cells, several methods for obtaining diversity gain between cells have been proposed. Firstly, in the description of the ETRI including the inventor of the present invention, when there is only one antenna for each cell, space-time coding is applied between cells, and the number of chunks of the coding block is divided into which blocks to transmit to which antenna. Apply differently to each chunk to obtain additional intercell diversity. When there are two or more antennas per cell, a space-time encoding is applied in a cell, and a method of applying an antenna combination combination differently between cells by dividing coding blocks between cells.

See also other papers (Hyunseok Oh, Sungsoo Kim, Sang-Hyo Kim, and Min-Goo Kim, "Novel transmit diversity techniques for broadcast services in cellular networks," Proceeding of VTC 2005 Spring, Stockholm, Sweden, May-June 2005.) In some embodiments, a space-time encoding is applied in a cell and an additional diversity gain is obtained through cyclic delay diversity (CDD) between cells.

The technical problem to be achieved by the present invention is to apply spatial multiplexing using multi-antenna in the cell in order to improve the reception quality of the terminal at the cell boundary when providing a broadcast / multicast service in a wireless cellular communication system, adjacent cells Or to provide additional diversity between base stations.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

In accordance with an aspect of the present invention, there is provided a macrodiversity transmission apparatus for providing a broadcast / multicast service using multiple transmission antennas according to a predetermined modulation scheme. A modulator for mapping to modulation symbols to generate a symbol sequence; A spatial multiplexer for spatially multiplexing the symbol strings to generate parallel frequency axis symbol strings; And an OFDM modulator for cyclically delaying each of the frequency axis symbol strings in a time domain and outputting the result to a corresponding transmission antenna.

More preferably, each of the frequency axis symbol strings is divided into two or more symbol blocks, and each of the frequency axis symbol strings is output to the OFDM modulator in correspondence with each of the transmission antennas according to a preset pattern in the symbol block unit. An antenna switching unit may further include.

In accordance with an aspect of the present invention, there is provided a macrodiversity transmission apparatus for providing a broadcast / multicast service using multiple transmission antennas according to a predetermined modulation scheme. A modulator for mapping to modulation symbols to generate a symbol sequence; A spatial multiplexer for spatially multiplexing the symbol strings to generate parallel frequency axis symbol strings; A diversity encoder which generates code symbol strings by diversity encoding each of the frequency axis symbol strings; And an OFDM modulator for cyclically delaying each of the code symbol sequences in a time domain and outputting the result to a corresponding transmission antenna.

More preferably, each of the coded symbol strings is divided into two or more symbol blocks, and each of the coded symbol strings is output to the OFDM modulator in correspondence with each of the transmission antennas according to a predetermined pattern in the symbol block unit. It may further include a switching unit.

According to an aspect of the present invention, there is provided a macrodiversity transmitter for providing a broadcast / multicast service using multiple transmission antennas according to a preferred embodiment of the present invention. A modulator for mapping to modulation symbols to generate a symbol sequence; A spatial multiplexer for spatially multiplexing the symbol strings to generate parallel frequency axis symbol strings; An antenna switching unit for dividing each of the frequency axis symbol strings into at least two symbol blocks, and outputting each of the frequency axis symbol strings corresponding to each of the transmission antennas according to a predetermined pattern in the symbol block unit; And an OFDM modulator for inverse Fourier transforming each of the frequency axis symbol strings output in the symbol block unit and outputting the inverse Fourier transforms to the corresponding transmission antennas.

In accordance with an aspect of the present invention, there is provided a macrodiversity transmission apparatus for providing a broadcast / multicast service using multiple transmission antennas according to a predetermined modulation scheme. A modulator for mapping to modulation symbols to generate a symbol sequence; A spatial multiplexer for spatially multiplexing the symbol strings to generate parallel frequency axis symbol strings; A diversity encoder which generates code symbol strings by diversity encoding each of the frequency axis symbol strings; An antenna switching unit for dividing each of the code symbol strings into at least two symbol blocks and outputting each of the code symbol strings corresponding to each of the transmission antennas according to a predetermined pattern in the symbol block unit; And an OFDM modulator for inverse Fourier transforming each of the code symbol strings output in the symbol block unit and outputting the inverse Fourier transform to the corresponding transmission antenna.

In accordance with an aspect of the present invention, there is provided a method for transmitting macrodiversity using multiple transmission antennas, the method comprising: (a) mapping channel-coded input data to modulation symbols according to a preset modulation scheme; Generating heat; (b) spatially multiplexing the symbol strings to generate parallel frequency axis symbol strings; And (c) cyclically delaying each of the frequency axis symbol strings in a time domain and outputting the same to the corresponding transmission antenna.

More preferably, after step (b), dividing each of the frequency axis symbol strings into at least two symbol blocks; And outputting each of the frequency axis symbol strings corresponding to each of the transmission antennas according to a preset pattern in the symbol block unit.

In accordance with an aspect of the present invention, there is provided a method for transmitting macrodiversity using multiple transmission antennas, the method comprising: (a) mapping channel-coded input data to modulation symbols according to a preset modulation scheme; Generating heat; (b) spatially multiplexing the symbol strings to generate parallel frequency axis symbol strings; (c) diversity coding each of the frequency axis symbol strings to generate code symbol strings; And (d) cyclically delaying each of the code symbol strings in a time domain and outputting the same to the corresponding transmission antenna.

More preferably, after the step (c), dividing each of the code symbol strings into at least two symbol blocks; And outputting each of the code symbol strings corresponding to each of the transmission antennas according to a preset pattern in units of the symbol block.

In accordance with an aspect of the present invention, there is provided a method for transmitting macrodiversity using multiple transmission antennas, the method comprising: (a) mapping channel-coded input data to modulation symbols according to a preset modulation scheme; Generating heat; (b) spatially multiplexing the symbol strings to generate parallel frequency axis symbol strings; (c) dividing each of the frequency axis symbol strings into at least two symbol blocks, and outputting each of the frequency axis symbol strings corresponding to each of the transmission antennas according to a preset pattern in the symbol block unit; And (d) inverse Fourier transforming each of the frequency axis symbol strings output in the symbol block unit and outputting each of the corresponding transmission antennas.

In accordance with an aspect of the present invention, there is provided a method for transmitting macrodiversity using multiple transmission antennas, the method comprising: (a) mapping channel-coded input data to modulation symbols according to a preset modulation scheme; Generating heat; (b) spatially multiplexing the symbol strings to generate parallel frequency axis symbol strings; (c) diversity coding each of the frequency axis symbol strings to generate code symbol strings; dividing each of the code symbol strings into at least two symbol blocks and outputting the code symbol strings corresponding to each of the transmission antennas according to a preset pattern in the symbol block unit; And (e) inverse Fourier transforming each of the coded symbol strings output in the symbol block unit and outputting the inverse Fourier transform to the corresponding transmission antenna.

In order to achieve the above technical problem, the present invention is characterized by providing a computer-readable recording medium having recorded thereon a program for executing a macrodiversity transmission method using multiple transmission antennas in a computer.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the same elements among the drawings are denoted by the same reference numerals and symbols as much as possible even though they are shown in different drawings. In the following description of the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted or briefly described.

In a wireless cellular communication system providing a broadcast / multicast service of the present invention, physically adjacent cells that transmit the same broadcast / multicast data are divided into two or more cell groups.

FIG. 2 is a diagram illustrating neighboring cells transmitting the same broadcast packet data divided into three cell groups according to an embodiment of the present invention.

(210),

(220),

(230)으로 나누고 있다. 이러한 셀 계획은 장치로 구현되어 수행될 수도 있으며 관리자에 의해 관념적으로 수행되어 각 기지국에 설정될 수도 있다. 전자의 구현 방법의 예로는, OFDM 셀룰러 시스템을 총괄하는 장치에 장착되어 상기 장치가 그룹화를 수행하는 방법, 모든 기지국 또는 일부 기지국에 장착되어 각 기지국들이 연동하여 그룹화를 수행하는 방법을 들 수 있다. 후자의 구현 방법으로는, 본 발명에 의한 OFDM 셀룰러 시스템을 구축하는 때에, 시스템 관리자가 상술한 그룹화 과정을 수행하여 각 기지국 장치에 셀 그룹 정보를 설정하는 방법을 예로 들 수 있다. 다만 전술한 방법은 일 예에 불과하므로 반드시 이에 한정되는 것은 아니고, 본 발명의 기술 분야에서 이용할 수 있는 다양한 방법으로 수행될 수 있을 것이다.Referring to FIG. 2, three groups of adjacent cells 200 transmitting the same broadcast / multicast data are shown.

(210),

220,

Divided by (230). Such cell planning may be implemented by a device and may be performed by an administrator and conceptually set by each base station. Examples of the former implementation method may include a method installed in a device that manages an OFDM cellular system and performing grouping, and a method in which all base stations or some base stations are connected to each other to perform grouping. As the latter implementation method, for example, a method of setting cell group information in each base station apparatus by performing a grouping process as described above by a system administrator when constructing an OFDM cellular system according to the present invention. However, the above-described method is only an example and is not necessarily limited thereto, and may be performed by various methods that may be used in the technical field of the present invention.

The present invention applies spatial multiplexing using multiple antennas within a cell and improves the reception quality of a user at a cell boundary when providing a broadcast / multicast service in a wireless cellular communication system. It is to provide a method for obtaining additional diversity.

As one method for this, by varying the antennas transmitting the same information between cells in the coding block, diversity in the coding block can be given to the signal coupled at the terminal receiving end. In addition, it is also possible to increase the diversity in the coding block by applying an intentional cyclic delay diversity using different cyclic delay values between cells. The coding block represents a set of all symbol sequences obtained by channel coding data to be transmitted.

That is, in order to apply spatial multiplexing to the entire antenna or part of the antenna in each cell, and to obtain additional diversity of the data stream used for the inter-cell coupling, the antenna combining combination may be changed in the coding block. Cyclic delay diversity can be given.

3 is a structural diagram of a transmission system illustrating a cyclic delay diversity transmission scheme. Cyclic delay diversity is called cyclic delay diversity, circular delay diversity, cyclic shift diversity, circular shift diversity, or the like. Here, cyclic delay diversity ("Multicarrier delay diversity modulation for MIMO systems," IEEE Transactions on Wireless Communications, vol. 3, no. 5, Sep. 2004, pp. 1756-1763.) Transmits the same signal to all transmit antennas. However, different circular delay values are inserted for each antenna.

Referring to FIG. 3, for example, transmission antenna 1 301 of a transmitting apparatus has a delay value of 0, transmission antenna 2 302 has a delay value of τ ₁ , and transmission antenna 3 203 has a τ _{2 value} . In addition to the delay value, the transmission antenna N 30N can be artificially added frequency diversity using multiple antennas by inserting a delay value of τ _N-1 . This is indicated by the diversity gain in the coding block.

The cyclic delay value according to the present invention is preferably set within the maximum delayable time to obtain the maximum diversity performance, and may give the same value for the antennas in one cell, or for the antennas in one cell. You can give different values. In addition, when considering the aforementioned cell group, it is preferable to apply the same cyclic delay value to cells in the same cell group. However, different delay values may be set for all cells. The cyclic delay value may be updated periodically.

Meanwhile, a method of changing the antenna coupling combination in the coding block is as follows.

As illustrated in FIG. 2, in an environment in which physically adjacent cells transmitting the same broadcast / multicast data are divided into two or more cell groups, a physical channel serving as a channel coding unit is divided into two or more partial regions. In order to obtain diversity in an encoding block, antenna combining combinations are different for each of the partial regions. Cells in each cell group may transmit data through an antenna in a predetermined pattern, where the pattern indicates which packet stream data is sent to which antenna.

As an example, consider an example of applying spatial multiplexing in which two transmit antennas exist for each cell belonging to three cell groups (cell group 0, cell group 1, and cell group 2), and different data streams are transmitted for each antenna. . The antenna numbers of the cell group 0 are 1 and 2, and the antenna numbers of the cell groups 1 and 2 are also referred to as 1 and 2 as well.

If antenna number 1 of cell group 0, antenna number 2 of cell group 1, and antenna number 1 of cell group 2, that is, the antenna combination for each cell group (1,2,1) send the same data stream (A), , Antenna number 2 of the remaining cell group 0, antenna number 1 of cell group 1, and antenna number 2 of cell group 2, that is, (2, 1, 2), which is a combination of antennas for each cell group, are identical. It is possible to send).

Thus, when dividing the coding block into four partial regions, (1,1,1), (2,2,1), (2,1,2), (1) for each partial region of the data stream A Antenna coupling combination can be changed in the same manner as (2,2), and (2,2,2), (1,1,2), (1,2, You can change the antenna coupling combination in the same way as (1), (2,1,1).

According to the method, the antenna transmission pattern is changed for each partial region in each cell, and the change in the antenna transmission pattern is also changed when the cell group is changed. If there is only one cell group, the antenna transmission pattern is the same for every cell and there is no additional inter-cell diversity gain. However, in the present invention, since the antenna transmission pattern is changed for two or more partial regions with two or more cell groups, the diversity gain Can be obtained. In this way, code symbols belonging to the channel coding block may have different channel characteristics.

Hereinafter, embodiments of the transmitting apparatus to which the method is applied according to the present invention will be described in detail. Meanwhile, those skilled in the art will fully appreciate that the symbols and symbol strings in the drawings are arbitrarily selected for convenience of description.

4 is a block diagram illustrating an internal configuration of a macrodiversity transmitting apparatus having multiple transmission antennas according to an exemplary embodiment of the present invention. 14 is a flowchart illustrating a macrodiversity transmission method by the transmission apparatus according to an embodiment of the present invention.

The transmission apparatus includes a channel encoder 410, a modulator 420, a spatial multiplexer 430, and an OFDM modulator 470, and includes multiple transmission antennas. The transmitting device is included in a base station in each cell of FIG. 2. The operation of each component of the transmitting apparatus will be described below with reference to FIG.

The channel encoder 410 performs channel encoding on the input data to be transmitted (S1410).

The modulator (or symbol mapper) 420 generates a serial symbol sequence S ₁ S ₂ S ₃ S ₄ S ₅ S ₆ S ₇ S ₈ by mapping the channel-coded input data to modulation symbols according to a preset modulation scheme. (S1420). The preset modulation scheme may be applied to various modulation schemes such as quadrature phase shift keying (QPSK), quadrature amplitude modulation (QAM), and the like.

The spatial multiplexer 430 spatially multiplexes the symbol string to generate frequency axis symbol strings S ₁ S ₂ S ₅ S ₆ and S ₃ S ₄ S ₇ S ₈ , which are parallel symbol strings in two columns of the frequency domain. (S1430).

Spatial multiplexing is a method of simultaneously transmitting different data from a transmitter to a receiver using multiple antennas. The above method has an advantage of increasing data capacity by increasing channel capacity.

The OFDM modulator 470 cyclically delays each of the frequency axis symbol strings in the frequency domain in the time domain to obtain cyclic delay diversity and outputs the cyclic delay diversity to the corresponding transmission antenna (S1440). The OFDM modulator 470 may be provided separately corresponding to each of the corresponding symbol strings.

The OFDM modulator 470 includes an inverse Fourier transform unit 510, a delay unit 520, and a guard interval insertion unit 530 as shown in FIG. 5. Referring to FIG. 15, which describes the operation of the OFDM modulator 470, an inverse Fourier transform unit (IFFT) 510 generates an inverse time-domain symbol string by performing inverse Fourier transform on each frequency-axis symbol string ( In operation S1510, the delay unit 520 performs a cyclic delay by giving a cyclic delay value to each inverse Fourier transformed time axis symbol string (S1520), and the guard interval insertion unit 530 inserts a guard interval in each cyclic delayed time axis symbol string ( S1530). As described with reference to FIG. 2, the cyclic delay value may be set in each cell group unit or cell unit, and a different cyclic delay value may be assigned to each of multiple transmission antennas in a cell. For example, the cyclic delay values set in transmission antennas 1 and 2 of cells belonging to cell group 1 may be d ¹ ₁ and d ¹ ₂ , respectively.

The output of the OFDM modulator may be transmitted by a corresponding physical transmit antenna, but may be transmitted through a virtual transmit antenna by performing a precoding that applies a precoding matrix in a precoder (not shown) (S1450). ).

6 is a block diagram illustrating an internal configuration of a macrodiversity transmitting apparatus having multiple transmission antennas according to another exemplary embodiment of the present invention. 16 is a flowchart for explaining a macrodiversity transmission method by the transmission apparatus according to another preferred embodiment of the present invention.

The transmitting apparatus includes a channel encoder 610, a modulator 620, a spatial multiplexer 630, an antenna switching unit 660, and an OFDM modulator 670, and includes multiple transmission antennas. The transmitting device is included in a base station in each cell of FIG. 2. Hereinafter, the operation of each component of the transmitting apparatus will be described with reference to FIG. 16, and description of contents overlapping with the above description will be omitted.

The channel encoder 610 performs channel encoding on the input data to be transmitted (S1610).

The modulator 620 generates a serial symbol sequence S ₁ S ₂ S ₃ S ₄ S ₅ S ₆ S ₇ S ₈ by mapping the channel-coded input data to modulation symbols according to a preset modulation scheme (S1620).

The spatial multiplexer 630 spatially multiplexes the symbol string to generate frequency axis symbol strings S ₁ S ₂ S ₅ S ₆ and S ₃ S ₄ S ₇ S ₈ , which are parallel symbol strings in two columns of the frequency domain. (S1630).

The antenna switching unit 660 divides each of the frequency axis symbol sequences S ₁ S ₂ S ₅ S ₆ and S ₃ S ₄ S ₇ S ₈ into at least two symbol blocks, and divides each of the frequency axis symbol sequences into the symbol. According to the pattern J previously set in units of blocks, the transmission is output to the OFDM modulator 670 corresponding to each of the transmission antennas (S1640). A symbol block is a part of a symbol string including a predetermined number of symbols by dividing a symbol string according to a predetermined antenna switching rule, and corresponds to a partial region of the channel-coded physical channel.

7 illustrates an example of a switching pattern of the antenna switching unit 660. Both a and b of FIG. 7 may be one channel coding block or may be one different channel coding block. In (a) of FIG. 7, symbol sequences (a ₁ a ₂ a ₃ a ₄ a ₅ a ₆ , b ₁ b ₂ b ₃ b ₄ b ₅ b ₆ ) input to the antenna switching unit are respectively a ₁ a ₂ / a ₃ a ₄ / a ₅ a ₆ , b ₁ b ₂ / b ₃ b ₄ / b ₅ b ₆ After dividing into blocks, the antenna is selected by switching in blocks so that the upper antenna is a ₁ a ₂ b ₃ b ₄ a ₅ a ₆ is transmitted, and the lower antenna is transmitting b ₁ b ₂ a ₃ a ₄ b ₅ b ₆ . 7 (b) shows a different switching pattern from (a), the symbol strings (a ₁ a ₂ a ₃ a ₄ a ₅ a ₆ , b ₁ b ₂ b ₃ b ₄ b ₅₎ input to the antenna switching unit b ₆ ) is divided into a ₁ a ₂ / a ₃ a ₄ a ₅ a ₆ , b ₁ b ₂ / b ₃ b ₄ b ₅ b ₆ , and then the antenna is selected through block-by-block switching. a ₁ a ₂ b ₃ b ₄ b ₅ b ₆ and the lower antenna transmits b ₁ b ₂ a ₃ a ₄ a ₅ a ₆ . When (a) and (b) belong to different cell groups, a ₁ is added to the upper antennas of the two cells, a ₅ is added to the upper antenna and the lower antenna of the two cells. Therefore, considering the sum of the symbols in the various cell groups, since the combination of antennas added for each symbol is different, diversity is increased in the code block.

The OFDM modulator 670 obtains cyclic delay diversity by cyclically delaying each of the frequency axis symbol strings in the time domain and outputs the cyclic delay diversity to the corresponding transmission antenna (S1650). The OFDM modulator 670 may be provided separately corresponding to each of the corresponding symbol strings. The OFDM modulator 670 includes an inverse Fourier transform unit 510, a delay unit 520, and a guard interval insertion unit 530 as shown in FIG. 5.

The output of the OFDM modulator may optionally be pre-encoded to form a virtual transmit antenna in the pre-encoder (not shown) (S1660).

8 is a block diagram illustrating an internal configuration of a macrodiversity transmitting apparatus having multiple transmission antennas according to another exemplary embodiment of the present invention. 17 is a flowchart for explaining a macrodiversity transmission method by the transmission apparatus according to another preferred embodiment of the present invention.

The transmission apparatus includes a channel encoder 810, a modulator 820, a spatial multiplexer 830, a diversity encoder 840, and an OFDM modulator 870, and includes multiple transmission antennas. The transmitting device is included in a base station in each cell of FIG. 2. Hereinafter, the operation of each component of the transmitting apparatus will be described with reference to FIG. 17, and description of contents overlapping with the above description will be omitted.

The channel encoder 810 performs channel encoding on the input data to be transmitted (S1710).

The modulator 820 generates a serial symbol sequence S ₁ S ₂ S ₃ S ₄ S ₅ S ₆ S ₇ S ₈ by mapping the channel-coded input data to modulation symbols according to a preset modulation scheme (S1720).

The spatial multiplexer 830 spatially multiplexes the symbol string to generate frequency axis symbol strings S ₁ S ₂ S ₅ S ₆ and S ₃ S ₄ S ₇ S ₈ , which are two parallel symbol strings in the frequency domain. (S1730).

The diversity encoder 840 generates code symbol sequences by applying diversity encoding by applying inversion and conjugation to each of the frequency axis symbol sequences (S1740). The frequency-axis symbol strings S ₁ S ₂ S ₅ S ₆ are diversity coded and code symbol strings S ₁ -S ^* ₂ S ₅ -S ^* ₆ and S ₂ S ^* ₁ S ₆ containing the same data information. S ^* ₅ ), and the frequency axis symbol string S ₃ S ₄ S ₇ S ₈ is diversity coded to include code symbol strings S ₃ -S ^* ₄ S _7- S ^* ₈ including the same data information. , S ₄ S ^* ₃ S ₈ S ^* ₇ ).

Diversity coding may be one of space time block coding (STBC) or space frequency block coding (SFBC). The diversity encoding has a merit that a diversity gain and an encoding gain can be obtained together by transmitting the same data. The diversity encoder 840 may be separately provided corresponding to each input symbol string.

The OFDM modulator 870 cyclically delays each of the code symbol strings in the time domain to obtain cyclic delay diversity and outputs the cyclic delay diversity to the corresponding transmission antenna (S1750). The OFDM modulator 870 may be separately provided corresponding to each of the corresponding symbol strings. The OFDM modulator 870 includes an inverse Fourier transform unit 510, a delay unit 520, and a guard interval insertion unit 530.

In the output of the OFDM modulator, pre-encoding may be selectively performed to form a virtual transmission antenna in the pre-encoder (not shown) (S1760).

9 is a block diagram showing an internal configuration of a macrodiversity transmitting apparatus having multiple transmission antennas according to another exemplary embodiment of the present invention. 18 is a flowchart for explaining a macrodiversity transmission method by the transmission apparatus according to another preferred embodiment of the present invention.

The transmission apparatus includes a channel encoder 910, a modulator 920, a spatial multiplexer 930, a diversity encoder 940, an antenna switching unit 960, and an OFDM modulator 970, and includes multiple transmission antennas. do. The transmitting device is included in a base station in each cell of FIG. 2. Hereinafter, the operation of each component of the transmitting apparatus will be described with reference to FIG. 18, and description of contents overlapping with the above description will be omitted.

The channel encoder 910 performs channel encoding on the input data to be transmitted (S1810).

The modulator 920 maps the channel-coded input data into modulation symbols according to a preset modulation scheme to generate a serial symbol sequence S ₁ S ₂ S ₃ S ₄ S ₅ S ₆ S ₇ S ₈ (S1820).

The spatial multiplexer 930 spatially multiplexes the symbol string to generate frequency axis symbol strings S ₁ S ₂ S ₅ S ₆ and S ₃ S ₄ S ₇ S ₈ , which are parallel symbol strings in two columns of the frequency domain. (S1830).

The diversity encoder 940 generates code symbol strings by applying diversity encoding by applying inversion and conjugation to each of the frequency axis symbol strings (S1840).

The antenna switching unit 960 is a sequence of each symbol symbol (S ₁ -S ^* ₂ S ₅ -S ^* ₆ , S ₂ S ^* ₁ S ₆ S ^* ₅ , S ₃ -S ^* ₄ S ₇ -S ^* ₈ , OFDM modulator 970 by dividing S ₄ S ^* ₃ S ₈ S ^* ₇ ) into two or more symbol blocks, and corresponding to each of the transmission antennas according to a predetermined pattern J in the symbol block units. Output to step S1850).

The OFDM modulator 970 cyclically delays each of the code symbol sequences in time domain to obtain cyclic delay diversity and outputs the cyclic delay diversity to the corresponding transmission antenna (S1860). The OFDM modulator 970 may be separately provided corresponding to each of the corresponding symbol strings. The OFDM modulator 970 includes an inverse Fourier transform unit 510, a delay unit 520, and a guard interval insertion unit 530 as shown in FIG. 5.

The output of the OFDM modulator may optionally be pre-encoded to form a virtual transmit antenna in the pre-encoder (S1870).

FIG. 10 illustrates a transmission apparatus in which the pre-coder 1080 is further provided in the transmission apparatus of FIG. 9 according to another exemplary embodiment of the present invention. Since all components are identical to those of FIG. 9 except for the total encoder, detailed description thereof will be omitted.

 FIG. 11 is a block diagram illustrating an internal configuration of a macrodiversity transmitting apparatus having multiple transmission antennas according to another exemplary embodiment of the present invention. 19 is a flowchart for explaining a macrodiversity transmission method by the transmission apparatus according to another preferred embodiment of the present invention.

The transmitting apparatus includes a channel encoder 1110, a modulator 1120, a spatial multiplexer 1130, a copy unit 1150, an antenna switching unit 1160, an OFDM modulator 1170, and a pre encoder 1180. A transmitting antenna is provided. The transmitting device is included in a base station in each cell of FIG. 2. Hereinafter, the operation of each component of the transmitting apparatus will be described with reference to FIG. 19, and description of contents overlapping with the above description will be omitted.

The channel encoder 1110 performs channel encoding on the input data to be transmitted (S1910).

The modulator 1120 maps the channel-coded input data into modulation symbols according to a preset modulation scheme to generate a serial symbol sequence S ₁ S ₂ S ₃ S ₄ S ₅ S ₆ S ₇ S ₈ (S1920).

The spatial multiplexer 1130 spatially multiplexes the symbol string to generate frequency axis symbol strings S ₁ S ₂ S ₅ S ₆ and S ₃ S ₄ S ₇ S ₈ , which are two parallel symbol strings in the frequency domain. (S1930).

The copy unit 1150 copies each of the frequency axis symbol strings to generate frequency axis symbol string pairs (S1940). Since each pair of frequency-axis symbol strings has the same data information, it is difficult to obtain diversity gain by itself, but may be combined with cyclic delay diversity to obtain diversity gain. The copy unit 1150 may be provided separately corresponding to each of the corresponding symbol strings.

The antenna switching unit 1160 divides each frequency axis symbol string (a pair of S ₁ S ₂ S ₅ S ₆ , a pair of S ₃ S ₄ S ₇ S ₈ ) into two or more symbol blocks, and the frequency axis symbol Each of the columns is output to the OFDM modulator 1170 corresponding to each of the transmission antennas according to the pattern J preset in the symbol block unit (S1950). Here, the antenna switching unit 1160 may be selectively provided.

The OFDM modulator 1170 cyclically delays each of the frequency axis symbol strings in the time domain to obtain cyclic delay diversity and outputs the cyclic delay diversity to the corresponding transmission antenna (S1960). The OFDM modulator 1170 may be separately provided corresponding to each of the corresponding symbol strings. The OFDM modulator 1170 includes an inverse Fourier transform unit 510, a delay unit 520, and a guard interval insertion unit 530 as shown in FIG. 5.

The output of the OFDM modulator may be pre-encoded to form a virtual transmit antenna in the pre-encoder 1180 (S1970). Precoding can optionally be performed.

12 is a block diagram illustrating an internal configuration of a macrodiversity transmitting apparatus having multiple transmission antennas according to another exemplary embodiment of the present invention. 20 is a flowchart for explaining a macrodiversity transmission method by the transmission apparatus according to another preferred embodiment of the present invention.

The transmission apparatus includes a channel encoder 1210, a modulator 1220, a spatial multiplexer 1230, an antenna switching unit 1260, and an OFDM modulator 1270, and includes multiple transmission antennas. The transmitting device is included in a base station in each cell of FIG. 2. Hereinafter, the operation of each component of the transmitting apparatus will be described with reference to FIG. 20, and description of contents overlapping with the above description will be omitted.

The channel encoder 1210 performs channel encoding on the input data to be transmitted (S2010).

The modulator 1220 generates a serial symbol sequence S ₁ S ₂ S ₃ S ₄ S ₅ S ₆ S ₇ S ₈ by mapping the channel-coded input data to modulation symbols according to a preset modulation scheme (S2020).

The spatial multiplexer 1230 spatially multiplexes the symbol string to generate frequency axis symbol strings S ₁ S ₂ S ₅ S ₆ and S ₃ S ₄ S ₇ S ₈ , which are two parallel symbol strings in the frequency domain. (S2030).

The antenna switching unit 1260 divides each of the frequency axis symbol sequences S ₁ S ₂ S ₅ S ₆ , S ₃ S ₄ S ₇ S ₈ into two or more symbol blocks, and divides each of the frequency axis symbol sequences into the symbol. According to the pattern J previously set in units of blocks, the signal is outputted to the OFDM modulator 1270 in correspondence with each of the transmission antennas (S2040). By changing the antennas transmitting the same information between cells in block units within the coded channel, diversity can be given to signals coupled at the terminal receiving end.

The OFDM modulator 1270 converts each of the frequency-axis symbol strings by inverse Fourier transform into time-axis symbol strings in the time domain to perform OFDM modulation and output the result to the corresponding transmission antenna (S2050). The OFDM modulator 1270 may be separately provided corresponding to each of the corresponding symbol strings.

The output of the OFDM modulator may optionally be pre-encoded to form a virtual transmit antenna in the pre-encoder (not shown) (S2060).

FIG. 13 is a block diagram illustrating an internal configuration of a macrodiversity transmitting apparatus having multiple transmission antennas according to another exemplary embodiment of the present invention. 21 is a flowchart for explaining a macrodiversity transmission method by the transmission apparatus according to another embodiment of the present invention.

The transmission apparatus includes a channel encoder 1310, a modulator 1320, a spatial multiplexer 1330, a diversity encoder 1340, an antenna switching unit 1360, and an OFDM modulator 1370, and includes multiple transmission antennas. do. The transmitting device is included in a base station in each cell of FIG. 2. Hereinafter, the operation of each component of the transmitter will be described with reference to FIG. 21, and descriptions of contents overlapping with the above description will be omitted.

The channel encoder 1310 performs channel encoding on the input data to be transmitted (S2110).

The modulator 1320 generates the serial symbol sequence S ₁ S ₂ S ₃ S ₄ S ₅ S ₆ S ₇ S ₈ by mapping the channel-coded input data into modulation symbols according to a preset modulation scheme (S2120). .

The spatial multiplexer 1330 spatially multiplexes the symbol string to generate frequency axis symbol strings S ₁ S ₂ S ₅ S ₆ and S ₃ S ₄ S ₇ S ₈ , which are parallel symbol strings in two columns of the frequency domain. (S2130).

The diversity encoder 1340 generates code symbol strings by applying diversity inversion and conjugation to each of the frequency axis symbol strings (S2140).

The antenna switching unit 1360 divides each code symbol string S ₁ S ₂ S ₅ S ₆ , S ₃ S ₄ S ₇ S ₈ into two or more symbol blocks, and divides each of the code symbol strings into the symbol block unit. In response to the preset pattern J, the signal is outputted to the OFDM modulator 1370 corresponding to each of the transmission antennas (S2150).

The OFDM modulator 1370 converts each of the code symbol strings by inverse Fourier transform into time-base symbol strings in the time domain to perform OFDM modulation and output the result to a corresponding transmission antenna (S2160). The OFDM modulator 1370 may be separately provided corresponding to each of the corresponding symbol strings.

The output of the OFDM modulator may optionally be pre-encoded to form a virtual transmit antenna in the pre-encoder (not shown) (S2170).

According to the present invention to which the antenna combination combination changing method and the cyclic delay diversity method are applied to obtain the additional diversity between cells, a pilot is generated and inserted into an OFDM modulated OFDM symbol for channel estimation at a receiving end.

In applying the additional diversity method between the two cells, it is necessary to consider the increased pilot overhead.

First, we look at how to change the antenna coupling combination. Within one partial region (symbol block described above), there is no additional pilot overhead as it is the same as the existing scheme which does not apply special techniques between cells. However, since interpolation for channel estimation is difficult to apply to symbols of the partial region boundary, an additional pilot may need to be inserted at the partial region boundary to overcome such performance degradation.

The pilot overhead in the inter-cell cyclic delay diversity scheme is discussed. In the cyclic delay diversity scheme, there is a difference in how much delay is given and in other words, how much frequency selectivity is provided. If the delay value is small and the frequency selectivity is small, it is considered as a general channel environment, and the pilot value added between cells is received and the channel is estimated to estimate the channel without additional overhead. However, if large frequency selectivity is obtained with a large delay value to increase frequency diversity, there is a need to estimate inter-cell or inter-cell group pilots, respectively. In this case, the overhead increases in multiples by the number of cell groups or cells to be estimated. As such, when pilots need to be sent many times, there is a way to increase the resource allocation itself for the pilot by multiples so that each pilot is allocated an orthogonal resource, and a group of cells or symbols in multiple pilot symbols without increasing the resource allocation for the pilot. There is a method of distinguishing by multiplying different codes for each cell. Both methods are a trade-off between channel estimation performance and resource consumption.

FIG. 22 is a block diagram illustrating an internal configuration of a reception apparatus having multiple reception antennas and receiving a broadcast / multicast service in an OFDM cellular system according to an embodiment of the present invention. 23 is a flowchart illustrating an operation of the receiving device according to an embodiment of the present invention. The receiving device is included in a terminal in each cell of FIG. 2. Hereinafter, an operation of each component of the reception device will be described with reference to FIG. 23, and descriptions of contents overlapping with the above description will be omitted.

The receiving apparatus includes an OFDM demodulator 2210, a channel estimator 2220, a symbol detector 2230, a spatial demultiplexer 2240, a demodulator 2250, and a channel decoder 2260, and includes multiple receiving antennas.

The OFDM demodulator 2210 performs Fourier transform on the same broadcast / multicast data signal received from each cell through multiple reception antennas to perform OFDM demodulation (S2310). The received signal is a signal generated and transmitted by each transmission antenna of each cell belonging to a plurality of cell groups generated by dividing adjacent cells according to a predetermined coding scheme. The predetermined coding scheme includes a coding scheme of the transmission apparatus according to the present invention.

The channel estimator 2220 extracts a pilot symbol from the OFDM demodulated received symbol strings to estimate a channel (S2320).

The symbol detector 2230 signals the symbol strings by applying an ML algorithm (Maximum Likelihood Detection Algorithm) to each of the channel estimated received symbol strings (S2330).

The spatial demultiplexer 2240 generates a series of received symbol strings by demultiplexing the received symbol strings to recover the spatial multiplexed received signal (S2340).

The demodulator (or symbol demapper) 2250 demodulates the received symbol according to the modulation scheme of the transmitting apparatus according to the present invention (S2350).

The channel decoder 2260 restores the original transmitted data based on the demodulated result (S2360).

Until now, a method of applying spatial multiplexing to multiple antennas, or applying some spatial multiplexing to various antennas and various diversity has been described. In this case, spatial multiplexing basically transmits a different data stream for each antenna, but this antenna may be a physical antenna or a virtual antenna that has been precoded. In addition, the data stream for each antenna may belong to the same coding block or may belong to different coding blocks.

In the present invention, the spatial multiplexer is used after the channel encoder and the modulator for the application of the spatial multiplexing scheme. However, as shown in FIGS. 24 and 25, the spatial multiplexer is disposed in front of the channel encoder and the modulator. It may be implemented. That is, each of the spatial multiplexed input data is channel-coded and modulated by the channel encoder and the modulator to achieve intra-cell spatial multiplexing. In this case, a plurality of channel encoders and modulators may be designed to correspond to each of the data of the spatial multiplexed parallel. Since the following functions and operations are the same as the functions and operations of the above-described embodiments of the transmitting apparatus of the present invention, a detailed description thereof will be omitted.

When the transmission apparatuses of FIGS. 24 and 25 are applied, the reception apparatus may also be applied to the spatial demultiplexer after signal decoding by the demodulator and the channel decoder, as shown in FIG. 26. Likewise, a plurality of demodulators and channel decoders may be designed to correspond to each of input data. FIG. 26 is the same as the function and operation of the embodiment of the reception apparatus of the present invention described above, except that the spatial demultiplexing is performed by the spatial demultiplexer after the channel decoder and the demodulator.

Meanwhile, although the present invention exemplifies two parallel data generations by spatial multiplexing, it is possible to generate more parallel data depending on the number of transmission antennas of a base station and the number of reception antennas of a terminal. Those who have will know enough.

The invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. In addition, functional programs, codes, and code segments for implementing the present invention can be easily inferred by programmers in the art to which the present invention belongs.

So far, the present invention has been described with reference to preferred embodiments. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims.

Therefore, it will be understood by those skilled in the art that the present invention may be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

When providing a broadcast / multicast service based on OFDM in a wireless cellular communication system according to the present invention, a method of applying spatial multiplexing using multiple antennas in a cell and obtaining additional diversity between adjacent cells or base stations By applying, the diversity of the signal received by the terminal at the cell boundary as well as the diversity can be increased to increase cell coverage for a specific data rate and lower transmission power.

As a result, the reception quality of the UE located at the cell boundary can be improved.

Claims (52)

delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete In the macrodiversity transmission method using multiple transmission antennas, (a) generating a symbol sequence by mapping channel-coded input data to modulation symbols according to a preset modulation scheme; (b) spatially multiplexing the symbol strings to generate parallel frequency axis symbol strings; And (c) cyclically delaying each of the frequency axis symbol strings in a time domain and outputting the same to the corresponding transmission antenna; And a pattern for selecting a transmission antenna from which the frequency axis symbol strings are output in units of two or more cell groups that classify a plurality of physically adjacent cells. The method of claim 26, wherein after step (b), Dividing each of the frequency axis symbol strings into at least two symbol blocks; And outputting each of the frequency axis symbol strings corresponding to each of the transmission antennas according to a predetermined pattern in units of the symbol block. delete The method of claim 26, wherein after step (b), Copying each of the frequency axis symbol strings to generate frequency axis symbol string pairs; Dividing each of the frequency axis symbol strings inputted into the frequency axis symbol string pair into two or more symbol blocks; And And outputting each of the frequency axis symbol strings corresponding to each of the transmission antennas according to a predetermined pattern in units of the symbol block. delete The method of claim 26, And a cyclic delay value provided for the cyclic delay is set in units of cells or groups of cells. delete delete The method of claim 26, And a cyclic delay value provided for the cyclic delay is set in units of transmit antennas in a cell. The method of claim 26, and (d) performing precoding for virtual transmission antenna formation on the output of step (c). In the macrodiversity transmission method using multiple transmission antennas, (a) generating a symbol sequence by mapping channel-coded input data to modulation symbols according to a preset modulation scheme; (b) spatially multiplexing the symbol strings to generate parallel frequency axis symbol strings; (c) diversity coding each of the frequency axis symbol strings to generate code symbol strings; And (d) cyclically delaying each of the code symbol strings in a time domain and outputting them to a corresponding transmission antenna; And a pattern for selecting a transmission antenna from which the frequency axis symbol strings are output in units of two or more cell groups that classify a plurality of physically adjacent cells. The method of claim 36, wherein step (c) comprises: A method for transmitting macrodiversity, characterized by generating code symbol strings by either space time block coding (STBC) or space frequency block coding (SFBC). The method of claim 36, wherein after step (c), Dividing each of the code symbol strings into at least two symbol blocks; And outputting each of the code symbol strings corresponding to each of the transmission antennas according to a preset pattern in the symbol block unit. delete The method of claim 36, And a cyclic delay value provided for the cyclic delay is set in units of cells or groups of cells. delete delete The method of claim 36, And a cyclic delay value provided for the cyclic delay is set in units of transmit antennas in a cell. The method of claim 36, and (e) performing precoding for virtual transmission antenna formation on the output of step (d). The method of claim 38, and (e) performing precoding for virtual transmission antenna formation on the output of step (d). In the macrodiversity transmission method using multiple transmission antennas, (a) generating a symbol sequence by mapping channel-coded input data to modulation symbols according to a preset modulation scheme; (b) spatially multiplexing the symbol strings to generate parallel frequency axis symbol strings; (c) dividing each of the frequency axis symbol strings into at least two symbol blocks, and outputting each of the frequency axis symbol strings corresponding to each of the transmission antennas according to a preset pattern in the symbol block unit; And (d) inverse Fourier transforming each of the frequency axis symbol strings output in the symbol block unit and outputting each of the corresponding transmission antennas; And wherein the transmission antenna selection pattern is set in units of two or more cell groups that classify a plurality of physically adjacent cells. 47. The method of claim 46 wherein and (e) performing precoding for virtual transmission antenna formation on the output of step (d). In the macrodiversity transmission method using multiple transmission antennas, (a) generating a symbol sequence by mapping channel-coded input data to modulation symbols according to a preset modulation scheme; (b) spatially multiplexing the symbol strings to generate parallel frequency axis symbol strings; (c) diversity coding each of the frequency axis symbol strings to generate code symbol strings; dividing each of the code symbol strings into at least two symbol blocks and outputting the code symbol strings corresponding to each of the transmission antennas according to a preset pattern in the symbol block unit; And and (e) inverse Fourier transforming each of the coded symbol strings output in the symbol block unit to output the corresponding transmission antenna. And wherein the transmission antenna selection pattern is set in units of two or more cell groups that classify a plurality of physically adjacent cells. The method of claim 48, The diversity coding method is one of space time block coding (STBC) and space frequency block coding (SFBC). delete The method of claim 48, and (f) performing precoding for virtual transmission antenna formation with respect to the output of step (e). delete

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