EP1999861A1

EP1999861A1 - Apparatus and method of inter-cell macro-diversity for providing broadcast/ multicast service using multi-antenna

Info

Publication number: EP1999861A1
Application number: EP07715782A
Authority: EP
Inventors: Jae-Kyun Kwon; Jae-Young Ahn; Yun-Hee Kim; Sung-Kyo Kang
Original assignee: Electronics and Telecommunications Research Institute ETRI; Industry Academic Cooperation Foundation of Kyung Hee University
Current assignee: Electronics and Telecommunications Research Institute ETRI; Industry Academic Cooperation Foundation of Kyung Hee University
Priority date: 2006-03-24
Filing date: 2007-03-23
Publication date: 2008-12-10
Also published as: KR100889748B1; EP1999861A4; WO2007111449A1; KR20070096883A

Abstract

Provided are a macro-diversity transmission apparatus and method for providing a broadcast/multicast service using multiple transmitting antennas in a wireless cellular communication system. The apparatus and method apply spatial multiplexing using multiple antennas within a cell and obtain additional diversity among adjacent cells or base stations. Therefore, the signal-to-interference ratio (SIR) and diversity order of signals received by terminals at cell boundaries can be increased. Consequently, cell coverage for a particular data rate can be increased, and transmission power can be reduced. Here, additional diversity applied among cells or base stations includes a method of changing antennas transmitting the same information among cells and a cyclic delay diversity (CDD) method.

Description

APPARATUS AND METHOD OF INTER-CELL MACRO-DIVERSITY FOR PROVIDING BROADCAST/MULTICAST SERVICE USING MULTI-ANTENNA

TECHNICAL FIELD

The present invention relates to a macro-diversity transmission apparatus and m ethod for providing a broadcast/multicast service using multiple transmitting antennas, a nd more particularly, to a macro-diversity transmission apparatus and method which en able a wireless cellular communication system to obtain additional inter-cell or inter-bas e station diversity when providing a broadcast/multicast service, in order to enhance the received signal quality of terminals at cell boundaries.

BACKGROUND ART A broadcast/multicast service is simultaneously provided to a plurality of users wi thin a cell. Since users at the boundary of the cell have poor received signal quality, th ey often determine the performance and data transmission rate of the entire system. Accordingly, it is very important to improve the communication quality of users at the bo undary of the cell. One way of doing so is to simultaneously use broadcast/multicast d ata received from a number of base stations of other adjacent cells. In the most basic conventional broadcast/multicast service provision method, a n umber of cells or base stations generate and transmit the same orthogonal frequency di vision multiplexing (OFDM) signal with respect to the same data information. In this ca se, in order to enable a terminal to estimate a channel from the sum of a number of bas e station signals received, each base station generates the same pilot, inserts the pilot i nto the same position of an OFDM symbol, and transmits the OFDM symbol (refer to 3 GPP2 C30-20040823-060, "Detailed Description of the Enhanced BCMCS Transmit W aveform Description," Aug. 2004). The pilots of the base stations may also be estimat ed separately.

FIG. 1 illustrates an OFDM-based transmission/reception apparatus for providing a broadcast/multicast service in a conventional wireless cellular communication syste m.

Referring to FIG. 1 , first through third base stations 120 through 122 each includ e a transmission apparatus 100, and a terminal 150 includes a reception apparatus 130 The first through third base stations 120 through 122 are in adjacent cells and tra nsmit data corresponding to a broadcast/multicast service to the terminal 150. The ter minal 150 receives the data from each of the first through third base stations 120 throug h 122 in order to receive the broadcast/multicast service. The transmission apparatus 100 includes a channel encoder 101 , a modulator (o r symbol mapper) 102, a pilot generator 104, and an OFDM modulator 103. For conve nience, the following description will be made from the perspective of the first base stati on 120, and the same description holds true for the second and third base stations 121 and 122. The channel encoder 101 channel-encodes broadcast/multicast data, which is co mmon to the first through third base stations 120 through 122, using the same channel encoding method. The modulator 102 maps the channel-encoded data to a correspon ding modulation symbol and generates a data symbol sequence X(K). The pilot gener ator 104 generates a pilot symbol sequence. The same pilot symbol sequence is gene rated by each of the first through third base stations 120 through 122, so that the termin al 150 can estimate a channel for a received signal composed of the sum of a number of base station signals. Each pilot symbol of the pilot symbol sequence is inserted into the same position for an OFDM symbol of each base station. The OFDM modulator 103 OFDM-modulates the data symbol sequence and the pilot symbol sequence and tr ansmits the OFDM-modulated data symbol sequence and pilot symbol sequence to wir eless channels 170 through 172.

The reception apparatus 130 included in the terminal 150 includes an OFDM de modulator 131 , a channel estimator 133, a symbol demodulator 132, and a channel dec Oder 134. The OFDM demodulator 131 converts a received signal composed of the sum of a number of base station signals into a corresponding received symbol Y(K) in a freque ncy domain. The channel estimator 133 estimates a channel using a pilot symbol seq uence included in the received signal. The symbol demodulator 132 demodulates a re ceived symbol based on the result of the channel estimation. The channel decoder 13 4 restores the originally transmitted data.

If the received signal is simply the sum of the same data transmitted from a num ber of cells, as described above, the mean of the received signal-to-noise ratios (SNRs) increases while the diversity order does not increase. That is, in the conventional met hod, there is a high probability that the received power of data symbols included in an e ncoded packet will be simultaneously weaken due to fading. Therefore, packet errors are highly likely.

In addition to a method of obtaining an inter-cell energy gain, several methods of obtaining an inter-cell diversity gain have been suggested. One of the methods inclu des a technology suggested by the Electronics and Telecommunications Research lnsti tute (ETRI), to which the inventor of the present invention belongs. In this method, wh en each cell has one antenna, space-time coding is used between cells. Coding block s are divided into a number of bundles, and the row of a space-time coding matrix whic h is to be transmitted to each antenna is determined differently for each bundle of codin g blocks, thereby obtaining an additional inter-cell diversity gain. When each cell has t wo or more antennas, space-time coding is used within the cell. A method of dividing coding blocks and applying a different combination of antennas is used between cells. Another technology was suggested by Hyunseok Oh, Sungsoo Kim, Sanghyo Ki m and Mingoo Kum in a paper, entitled "Novel Transmit Diversity Techniques for Broad cast Services in Cellular Networks," Proceeding of VTC 2005 Spring, Stockholm, Swed en, May-June 2005. This technology applies space-time coding within a cell and appli es cyclic delay diversity (CDD) between cells in order to obtain an additional diversity ga in.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an OFDM-based transmission/reception apparatus for providing a broadcast/multicast service in a conventional wireless cellular communication syste m;

FIG. 2 illustrates three groups of adjacent cells transmitting the same broadcast/ multicast data according to an embodiment of the present invention;

FIG. 3 illustrates a cyclic delay diversity (CDD) transmission technique used by a conventional multi-antenna communication system;

FIG. 4 is a block diagram of a macro-diversity transmission apparatus including multiple transmitting antennas according to an embodiment of the present invention; FIG. 5 is a block diagram of an orthogonal frequency division multiplexing (OFD

M) modulator of the macro-diversity transmission apparatus of FIG. 4 to which CDD is a pplied according to an embodiment of the present invention; FIG. 6 is a block diagram of a macro-diversity transmission apparatus including multiple transmitting antennas according to another embodiment of the present inventio n;

FIG. 7 illustrates the operation of an antenna switching unit of the macro-diversit y transmission apparatus illustrated in FIG. 6 according to an embodiment of the presen t invention;

FIGS. 8 through 13 are block diagrams of a macro-diversity transmission apparat us including multiple transmitting antennas according to other embodiments of the pres ent invention; FIG. 14 is a flowchart illustrating a macro-diversity transmission method used by the transmission apparatus of FIG. 4 according to an embodiment of the present inventi on;

FIG. 15 is a flowchart illustrating the operation of an OFDM modulator of a macro -diversity transmission apparatus to which CDD is applied according to an embodiment of the present invention;

FIGS. 16 through 21 are flowcharts illustrating a macro-diversity transmission me thod used by a transmission apparatus according to other embodiments of the present i nvention;

FIG. 22 is a block diagram of a reception apparatus including multiple receiving a ntennas according to an embodiment of the present invention;

FIG. 23 is a flowchart illustrating the operation of the receiving apparatus of FIG. 22 according to an embodiment of the present invention;

FIGS. 24 and 25 are block diagrams of a macro-diversity transmission apparatus including multiple transmitting antennas according to other embodiments of the presen t invention; and

FIG. 26 is a block diagram of a reception apparatus including multiple receiving a ntennas according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Technical Goal of the Invention

The present invention provides a method of applying spatial multiplexing using m ultiple antennas within a cell and obtaining additional diversity between adjacent cells or base stations in order to enhance the received signal quality of terminals at cell bound aries, when a wireless cellular communication system provides a broadcast/multicast se rvice.

However, the objectives of the present invention are not restricted to the one set forth herein. The above and other objectives of the present invention will become mor e apparent to one of ordinary skill in the art to which the present invention pertains by re ferencing the detailed description of the present invention given below.

Technical Solution of the Invention

In order to achieve the technical goal of the invention, the present invention appli es spatial multiplexing using multiple antennas within a cell, and switches antennas whi ch transmit the same information, within a coding block between adjacent cells or base stations, or gives intentional cyclic delay diversity (CDD) using different circular delay va lues in order to obtain additional diversity, when a wireless cellular communication syste m provides a broadcast/multicast service.

Effect of the Invention

When a wireless cellular communication system provides a broadcast/multicast s ervice based on orthogonal frequency division multiplexing (OFDM) according to the pre sent invention, spatial multiplexing using multiple antennas is applied within a cell, and a method of obtaining additional diversity is applied between adjacent cells or base stati ons. Therefore, the signal-to-noise ratio (SNR) and diversity of signals received by ter minals at cell boundaries can be increased. Consequently, cell coverage for a particul ar data rate can be increased, and transmission power can be reduced, which in turn e nhances the received signal quality of the terminals at the cell boundaries.

BEST MODE FOR CARRYING OUT THE INVENTION

According to an aspect of the present invention, there is provided a macro-divers ity transmission apparatus using multiple transmitting antennas. The apparatus includ es a modulator mapping channel-encoded input data into modulation symbols accordin g to a preset modulation method, and generating a symbol sequence; a spatial multiple xer spatially multiplexing the symbol sequence and generating parallel frequency-axis s ymbol sequences; and an orthogonal frequency division multiplexing (OFDM) modulator cyclically delaying the frequency-axis symbol sequences in a time domain and outputti ng the cyclically delayed symbol sequences to respective transmitting antennas. The apparatus may further include an antenna switching unit dividing each of the frequency-axis symbol sequences into two or more symbol blocks, and outputting the f requency-axis symbol sequences respectively to the OFDM modulator toward the trans mitting antennas selected according to a preset pattern in units of symbol blocks. According to another aspect of the present invention, there is provided a macro- diversity transmission apparatus using multiple transmitting antennas. The apparatus i ncludes a modulator mapping channel-encoded input data into a modulation symbols a ccording to a preset modulation method, and generating a symbol sequence; a spatial multiplexer spatially multiplexing the symbol sequence and generating parallel frequenc y-axis symbol sequences; a diversity coder diversity-coding the parallel frequency-axis s ymbol sequences and generating code symbol sequences; and an OFDM modulator cy clically delaying the code symbol sequences in a time domain and outputting the cyclica Hy delayed code symbol sequences to respective transmitting antennas.

The apparatus may further including an antenna switching unit dividing each of t he code symbol sequences into two or more symbol blocks, and outputting the code sy mbol sequences respectively to the OFDM modulator toward the transmitting antennas selected according to a preset pattern in units of symbol.

According to another aspect of the present invention, there is provided a macro- diversity transmission apparatus using multiple transmitting antennas. The apparatus i ncludes a modulator mapping channel-encoded input data into modulation symbols ace ording to a preset modulation method and generating a symbol sequence; a spatial mul tiplexer spatially multiplexing the symbol sequence and generating parallel frequency-ax is symbol sequences; an antenna switching unit dividing each of the frequency-axis sy mbol sequences into two or more symbol blocks, and outputting the frequency-axis sym bol sequences respectively toward the transmitting antennas determined according to a preset pattern in units of symbol blocks; and an OFDM modulator performing an invers e fast Fourier transform (IFFT) on the frequency-axis symbol sequences output in units of symbol blocks and outputting the IFFTed symbol sequences to the respective corres ponding transmitting antennas. According to another aspect of the present invention, there is provided a macro- diversity transmission apparatus using multiple transmitting antennas. The apparatus i ncludes a modulator mapping channel-encoded input data into modulation symbols ace ording to a preset modulation method, and generating a symbol sequence; a spatial mu Itiplexer spatially multiplexing the symbol sequence and generating parallel frequency-a xis symbol sequences; a diversity coder diversity-coding the parallel frequency-axis sym bol sequences and generating code symbol sequences; an antenna switching unit dividi ng each of the code symbol sequences into two or more symbol blocks, and outputting t he code symbol sequences respectively toward the transmitting antennas selected acco rding to a preset pattern in units of symbol blocks; and an OFDM modulator performing an IFFT on the code symbol sequences output in units of symbol blocks and outputting the IFFTed code symbol sequences to the respective transmitting antennas.

According to another aspect of the present invention, there is provided a macro- diversity transmission method using multiple transmitting antennas. The method inclu des (a) mapping channel-encoded input data into modulation symbols according to a pr eset modulation method, and generating a symbol sequence; (b) spatially multiplexing t he symbol sequence and generating parallel frequency-axis symbol sequences; and (c) cyclically delaying the frequency-axis symbol sequences in a time domain and outputti ng the cyclically delayed symbol sequences to respective transmitting antennas. The method may further include, after operation (b), dividing each of the frequen cy-axis symbol sequences into two or more symbol blocks; and outputting the frequenc y-axis symbol sequences respectively toward the transmitting antennas selected accord ing to a preset pattern in units of symbol.

According to another aspect of the present invention, there is provided a macro- diversity transmission method using multiple transmitting antennas. The method inclu des (a) mapping channel-encoded input data into modulation symbols according to a pr eset modulation method, and generating a symbol sequence; (b) spatially multiplexing t he symbol sequence and generating parallel frequency-axis symbol sequences; (c) dive rsity-coding the parallel frequency-axis symbol sequences and generating code symbol sequences; and (d) cyclically delaying the code symbol sequences in a time domain an d outputting the cyclically delayed code symbol sequences to respective transmitting an tennas.

The method may further include, after operation (c), dividing each of the code sy mbol sequences into two or more symbol blocks; outputting the code symbol sequence s respectively toward the transmitting antennas selected according to a preset pattern i n units of symbol.

According to another aspect of the present invention, there is provided a macro- diversity transmission method using multiple transmitting antennas. The method inclu des (a) mapping channel-encoded input data into modulation symbols according to a pr eset modulation method, and generating a symbol sequence; (b) spatially multiplexing t he symbol sequence and generating parallel frequency-axis symbol sequences; (c) divi ding each of the frequency-axis symbol sequences into two or more symbol blocks, and outputting the frequency-axis symbol sequences respectively toward the transmitting a ntennas selected according to a preset pattern in units of symbol; and (d) performing an IFFT on the frequency-axis symbol sequences output in units of symbol blocks and out putting the IFFTed symbol sequences to the respective transmitting antennas.

According to another aspect of the present invention, there is provided a macro- diversity transmission method using multiple transmitting antennas. The method inclu des (a) mapping channel-encoded input data into modulation symbols according to a pr eset modulation method, and generating a symbol sequence; (b) spatially multiplexing t he symbol sequence and generating parallel frequency-axis symbol sequences; (c) dive rsity-coding the parallel frequency-axis symbol sequences and generating code symbol sequences; (d) dividing each of the code symbol sequences into two or more symbol bl ocks, and outputting the code symbol sequences respectively toward the transmitting a ntennas selected according to a preset pattern in units of symbol; and (e) performing an IFFT on the code symbol sequences output in units of symbol blocks and outputting th e IFFTed code symbol sequences to the respective transmitting antennas.

According to another aspect of the present invention, there is provided a comput er-readable recording medium on which a program for executing the macro-diversity tra nsmission method is recorded.

EMBODIMENTS

The present invention will now be described more fully with reference to the acco mpanying drawings, in which exemplary embodiments of the invention are shown. Th e invention may, however, be embodied in many different forms, and should not be con strued as being limited to the embodiments set forth therein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully conve y the concept of the invention to those skilled in the art. Like reference numerals deno te like elements in the drawings, and thus their description will not be repeated. A deta iled description might be omitted when it is determined that related prior art or the detail ed description of the structure may unnecessarily obscure the point of the present inven tion. In a wireless cellular communication system providing a broadcast/multicast servi ce according to the present invention, physically adjacent cells transmitting the same br oadcast/multicast data are divided into two or more groups.

FIG. 2 illustrates three groups of adjacent cells transmitting the same broadcast/ multicast data according to an embodiment of the present invention.

Referring to FIG. 2, the adjacent cells 200 transmitting the same broadcast/multi cast data are divided into the three groups ^ o (210), ^C i (220) and ^C 2 (230). Such a cell plan may be implemented and executed by a device. Alternatively, an administr ator may create the cell plan and set it in each base station. Examples of the former i mplementation method include a method of equipping the device with an apparatus, wh ich administrates an orthogonal frequency division multiplexing (OFDM) system, and pe rforming a grouping operation using the apparatus, and a method of equipping the devi ce with all or some base stations and performing the grouping operation using the base stations which are linked to one another. An example of the latter implementation met hod includes a method in which a system administrator performs the grouping operation when an OFDM cellular system according to the present invention is implemented and sets cell group information in each base station. However, the present invention is no t limited to the above examples, and the cell plan can be implemented using various me thods that can be used in the art to which the present invention pertains. In order to improve the received signal quality of users at cell boundaries when a wireless cellular communication system provides a broadcast/multicast service, the pr esent invention applies a space-time multiplexing method using multiple antennas withi n a cell and applies a method of obtaining additional diversity between adjacent cells or base stations. One method for obtaining additional inter-cell diversity is to switch antennas tran emitting the same information between cells within a coding block and to offer diversity t 0 signals to be sum up at a receiving end of a terminal, within the coding block. Anoth er method is intentional cyclic delay diversity (CDD) using a different circular delay valu e for each cell, thereby increasing the diversity within a coding block. The coding bloc k denotes symbol sequences obtained after data to be transmitted is channel-encoded.

That is, in each cell, spatial multiplexing may be used for all antennas or part of t he antennas. In addition, an antenna combination may be changed in a coding block or the cyclic delay diversity may be offered in order to obtain additional diversity for a da ta stream to be sum up at receiving end of a terminal.

FIG. 3 illustrates the structure of a transmission system using a CDD transmissio n technique. CDD may also be referred to as circular delay diversity, cyclic shift diversi ty, and circular shift diversity. The CDD technique ("Multicarrier Delay Diversity Modul ation for MIMO Systems," IEEE Transactions on Wireless Communications, vol. 3, no. 5, Sep. 2004, pp. 1756-1763) transmits the same signal to all transmitting antennas but inserts a different circular delay value for each antenna.

Referring to FIG. 3, delay values of zero, τ i, τ 2, and τ _{N 1} are respectively ins erted into the signals of first through N^th transmitting antennas 301 through 3ON of a tra nsmission apparatus. Therefore, frequency diversity can be intentionally added using multiple antennas. The frequency diversity results in diversity gain within a coding bloc k.

The circular delay value according to the present invention may be set within a m aximum period of time that can be delayed in order to obtain maximum diversity perfor mance. The same or different circular delay values may be given to antennas within a cell. When cell groups described above are taken into consideration, the same circula r delay value may be given to cells within the same group. Alternatively, all cells may h ave different delay values. The circular delay value may be periodically updated. A method of changing a combination of antennas within a coding block will now be described.

In an environment where physically adjacent cells transmitting the same broadca st/multicast data are divided into two or more groups as illustrated in FIG. 2, a physical channel, which is a channel-coding unit, is divided into two or more regions. In order t 0 obtain diversity in a coding block, the combination of antennas is varied for each regio n. Cells in each group can transmit data using antennas in a preset pattern. The pre set pattern indicates which packet stream data is to be transmitted to each antenna.

For example, each of the cells included in zeroth through second cell groups ma y have two transmitting antennas, and a spatial multiplexing method in which a different data stream is transmitted to each antenna may be used. The zeroth cell group may have first and second antennas, and the same may apply to the first and second cell gr oups.

In this case, if the first antenna of the zeroth cell group, the second antenna of th e first cell group and the first antenna of the second cell group, that is, an antenna com bination of (1 ,2,1), all transmit the same data stream (A), the remaining second antenna of the zeroth cell group, the first antenna of the first cell group and the second antenna of the second cell group, that is, an antenna combination of (2,1 ,2), can all transmit an other same data steam (B). Therefore, if a coding block is divided into four regions, the antenna combination can be changed to (1 ,1 ,1 ), (2,2,1 ), (2,1 ,2) and (1 ,2,2) for the four regions of the data str earn (A), and to (2,2,2), (1 ,1 ,2), (1 ,2,1 ) and (2,1 ,1 ) for the four regions of the data strea m (B).

The above method changes an antenna transmission pattern for each region in e ach cell. In addition, when a cell group is changed, the change of the antenna transmi ssion pattern is changed. If there is only one cell group, no additional inter-cell diversit y gain can be obtained, since all cells have the same antenna transmission pattern. H owever, in the present invention, there are two or more cell groups, and different antenn a transmission patterns are applied to two or more regions of a coding block, to provide the diversity gain. Consequently, code symbols in a channel coding block can have dif ferent channel characteristics.

A transmission apparatus using the above method according to the present inve ntion will now be described in detail. It will be fully understood by those of ordinary skil I in the art that symbols and symbol sequences illustrated in the drawings were arbitraril y selected for convenience of description.

FIG. 4 is a block diagram of a macro-diversity transmission apparatus including multiple transmitting antennas according to an embodiment of the present invention. F IG. 14 is a flowchart illustrating a macro-diversity transmission method used by the tran smission 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. The transmission apparatus is included in a base station within each cell illustrated in FIG. 2. The operation of each element of the transmission apparatus will now be described with reference to FIG. 14. The channel encoder 410 channel-encodes input data that is to be transmitted (o peration S1410).

The modulator (or symbol mapper) 420 maps the channel-encoded input data to a modulation symbol using a preset modulation method, and generates a serial symbol sequence S₁S₂S₃S₄S₅S₆S₇S₈ (operation S1420). The preset modulation method may be quadrature phase shift keying (QPSK), quadrature amplitude modulation (QAM), or t he like.

The spatial multiplexer 430 spatially multiplexes the serial symbol sequence SiS₂ S3S4S5S6S7S8 and generates frequency-axis symbol sequences SiS₂S₅S₆ and S₃S₄S₇S _8> which are two parallel symbol sequences in a frequency domain (operation S1430).

Spatial multiplexing is a method of simultaneously transmitting different data usin g multiple antennas to a receiving end from a transmitting end. Spatial multiplexing ca n increase channel capacity, which in turn increases the data rate.

The OFDM modulator 470 cyclically delays each of the frequency-axis symbol se quences SiS₂SsS6 and S3S4S7S8 in a time domain, thereby obtaining CDD, and outputs the cyclically delayed symbol sequences to the respective transmitting antennas (operat ion S1440). The number of the OFDM modulator 470 may be equivalent to that of par allel symbol sequences

The OFDM modulator 470 includes an inverse fast Fourier transform (IFFT) unit 510, a delay unit 520, and a guard interval insertion unit 530, as illustrated in FIG. 5. Referring also to FIG. 15, illustrating the operation of the OFDM modulator 470, the IFF T unit 510 performs an IFFT on each of the frequency-axis symbol sequences SiS₂SsS ₆ and S₃S₄S₇S₈ and generates time-axis symbol sequences in a time domain (operation S1510). The delay unit 520 cyclically delays each of the time-axis symbol sequences obtained after the IFFT by assigning a circular delay value to each of the time-axis sy mbol sequences (operation S1520). The guard interval insertion unit 530 inserts a gua rd interval into each cyclically delayed time-axis symbol sequence (operation S1530). As described above with reference to FIG. 2, the circular delay value may be set for eac h cell group or each cell. In addition, a different circular delay value may be given to e ach of multiple transmitting antennas in a cell. For example, circular delay values set f or the first and second transmitting antennas of the first cell group may respectively be d ₁ and d ₂.

An output of the OFDM modulator 470 may be transmitted through a correspondi ng physical transmitting antenna. Alternatively, the output may be precoded by a prec oder (not shown) using a precoding matrix, and transmitted through a virtual transmittin g antenna (operation S 1450).

FIG. 6 is a block diagram of a macro-diversity transmission apparatus including multiple transmitting antennas according to another embodiment of the present inventio n. FIG. 16 is a flowchart illustrating a macro-diversity transmission method used by th e transmission apparatus according to an embodiment of the present invention.

The transmission apparatus includes a channel encoder 610, a modulator 620, a spatial multiplexer 630, an antenna switching unit 660, and an OFDM modulator 670. The transmission apparatus also includes the multiple transmitting antennas. The tra nsmission apparatus is included in a base station within each cell illustrated in FIG. 2. The operation of each element of the transmission apparatus will now be described with reference to FIG. 16. However, what has already been described above will be omitt ed here. The channel encoder 610 channel-encodes input data that is to be transmitted (o peration S1610).

The modulator 620 maps the channel-encoded input data to a modulation symbo I using a preset modulation method and generates a serial symbol sequence S₁S₂S₃S₄ S₅S₆S₇S₈ (operation S 1620). The spatial multiplexer 630 spatially multiplexes the serial symbol sequence S-₁S₂

S₃S₄S₅S₆S₇S₈ and generates frequency-axis symbol sequences S₁S2S₅S₆ and S₃S₄S₇S ₈, which are two parallel symbol sequences in a frequency domain (operation S1630).

The antenna switching unit 660 divides each of the frequency-axis symbol seque nces SiS₂SsS₆ and S₃S₄S₇S₈ into two or more symbol blocks, and outputs the frequenc y-axis symbol sequences SiS₂S₅S₆ and S₃S₄S₇S₈ respectively to the OFDM modulator 670 toward the transmitting antennas selected according to a preset pattern(J) in units of symbol blocks (operation S1640). Each of symbol blocks into which a symbol sequ ence is divided according to a predetermined antenna-switching rule includes a predete rmined number of symbols and corresponds to each region of a physical channel which is channel-encoded described in FIG. 2.

FIG. 7 illustrates an example of a switching pattern of the antenna switching unit 660 of FIG. 6. Referring to FIG. 7, a and b may be a single channel coding block or dif ferent channel coding blocks. In (a), symbol sequences aia₂a₃a₄a₅a₆ and bib₂b₃b₄b₅b₆ input to the antenna switching unit 660 are divided into blocks of aia₂/a₃a₄/a₅a₆ and bio cks of b-ιb₂/b₃b₄/b₅b₆. Then, the switching unit 660 performs a switching operation in u nits of blocks and thus selects antennas. As a result, an upper antenna transmits a-ιa₂ b₃b₄a₅a₆, and a lower antenna transmits bib₂a₃a4b₅b6. Another switching pattern differ ent from that of (a) is illustrated in (b). In (b), symbol sequences aia2a₃a4a₅a6 and bφ₂ b₃b₄b₅b₆ input to the antenna switching unit 660 are divided into blocks of a-ιa2/a₃a4a₅a6 and blocks of bib₂/b₃b₄b5b6. Then, the switching unit 660 performs a switching operati on in units of blocks and thus selects antennas. As a result, an upper antenna transmi ts aia₂b₃b₄b₅b₆, and a lower antenna transmits bib₂a₃a4a₅a₆. If (a) and (b) patterns ap ply to different cell groups, for example, ai symbols from the upper antennas of each ce Il are added, and a₅ symbol from the upper antenna in one cell and a₅ symbol from the I ower antenna in another cell are added. Therefore, considering that symbols from a n umber of cell groups are added, a combination of antennas varies according to each sy mbol, and diversity is increased within a coding block.

The OFDM modulator 670 cyclically delays each of the symbol sequences in the time domain, thereby obtaining CDD, and outputs the cyclically delayed symbol sequen ces to the respective transmitting antennas (operation S 1650).

The number of the OFDM modulator 670 may be equivalent to that of parallel sy mbol sequences. As illustrated in FIG. 5, the OFDM modulator 670 includes an IFFT u nit 510, a delay unit 520, and a guard interval insertion unit 530. The output of the OF DM modulator 670 may selectively be precoded by a precoder (not shown) in order to f orm a virtual transmitting antenna (operation S1660).

FIG. 8 is a block diagram of a macro-diversity transmission apparatus including multiple transmitting antennas according to another embodiment of the present inventio n. FIG. 17 is a flowchart illustrating a macro-diversity transmission method used by th e transmission apparatus according to an embodiment of the present invention.

The transmission apparatus includes a channel encoder 810, a modulator 820, a spatial multiplexer 830, a diversity coder 840, and an OFDM modulator 870. The tran smission apparatus also includes the multiple transmitting antennas. The transmission apparatus is included in a base station within each cell illustrated in FIG. 2. The operat ion of each element of the transmission apparatus will now be described with reference to FIG. 17. However, what has already been described above will be omitted here.

The channel encoder 810 channel-encodes input data that is to be transmitted (o peration S1710).

The modulator 820 maps the channel-encoded input data to a modulation symbo I using a preset modulation method and generates a serial symbol sequence S₁S₂S₃S₄ S₅S₆S₇S₈ (operation S1720).

The spatial multiplexer 830 spatially multiplexes the serial symbol sequence SiS₂ S₃S₄S₅S₆S₇S₈ and generates frequency-axis symbol sequences SiS₂S₅S₆ and S₃S₄S₇S s, which are two parallel symbol sequences in a frequency domain (operation S1730). The diversity coder 840 diversity-codes the frequency-axis symbol seqαences Si S2S₅S₆ and S₃S4S₇Sβ by inverting and conjugating them, and generates code symbol se quences (operation S1740).

The frequency-axis symbol sequence SiS₂S₅S₆ is diversity-coded into code sym bol sequences Si-S^* ₂S₅-S^* ₆ and S₂S^*iS₆S^* ₅ including the same data information, and th e frequency-axis symbol sequence S₃S₄S₇S₈ is diversity-coded into code symbol seque nces S₃-S ₄S₇-S a and S₄S ₃SsS ₇ including the same data information.

Diversity coding may be space time block coding (STBC) or space frequency bio ck coding (SFBC). Diversity coding is a method of transmitting the same data. Both a diversity gain and a coding gain can be obtained through diversity coding. The numb er of the diversity coder 840 may be equivalent to that of parallel input symbol sequenc es.

The OFDM modulator 870 cyclically delays each of the code symbol sequences Si-S^* ₂S₅-S^* ₆, S₂S^*iS₆S^*5, S3-S^*4S₇-S^*8 and S₄S^* ₃S8S^*7 in a time domain, thereby obtainin g CDD₁ and outputs the cyclically delayed symbol sequences to the respective transmitt ing antennas (operation S1750). The number of the OFDM modulator 870 may be eq uivalent to that of paralle symbol sequences. As illustrated in FIG. 5, the OFDM modul ator 870 includes an IFFT unit 510, a delay unit 520, and a guard interval insertion unit 530. An output of the OFDM modulator 870 may selectively be precoded by a precod er (not shown) in order to form a virtual transmitting antenna (operation S1760).

FIG. 9 is a block diagram of a macro-diversity transmission apparatus including multiple transmitting antennas according to another embodiment of the present inventio n. FIG. 18 is a flowchart illustrating a macro-diversity transmission method used by th e transmission apparatus according to an embodiment of the present invention.

The transmission apparatus includes a channel encoder 910, a modulator 920, a spatial multiplexer 930, a diversity coder 940, an antenna switching unit 960, and an O FDM modulator 970. The transmission apparatus also includes the multiple transmittin g antennas. The transmission apparatus is included in a base station within each cell i llustrated in FIG. 2. The operation of each element of the transmission apparatus will now be described with reference to FIG. 18. However, what has already been describ ed above will be omitted here.

The channel encoder 910 channel-encodes input data that is to be transmitted (o peration S1810). The modulator 920 maps the channel-encoded input data to a modulation symbo I using a preset modulation method, and generates a serial symbol sequence SiS₂S₃S₄ S₅S₆S₇S₈ (operation S1820).

The spatial multiplexer 930 spatially multiplexes the serial symbol sequence S₁S₂ S₃S₄S₅S₆S₇S₈ and generates frequency-axis symbol sequences SiS₂S₅S₆ and S₃S₄S₇S s, which are two parallel symbol sequences in a frequency domain (operation S1830).

The diversity coder 940 diversity-codes the frequency-axis symbol sequences Si S₂S₅S₆ and S₃S₄S₇S₈ by inverting and conjugating them, and generates code symbol se quences Si-S^* ₂S₅-S^* ₆, S₂S^*iS₆S^* ₅, S₃-S^* ₄S₇-S^* ₈ and S₄S^* ₃S₈S^* ₇ (operation S1840). The antenna switching unit 960 divides each of the code symbol sequences SrS

^* ₂S₅-S^* ₆, S₂S^*iS₆S^* ₅, S₃-S^* ₄S₇-S^*s and S₄S^* ₃S₈S^* ₇ into two or more symbol blocks, and 0 utputs the code symbol sequences Si-S ₂S₅-S^* ₆, S₂S 1S₆S ₅, S₃-S ₄S₇-S^* ₈ and S₄S ₃S₈S^* ₇ respectively to the OFDM modulator 970 toward the transmitting antennas selected ac cording to a preset pattern(J) in units of symbol blocks (operation S1850). The OFDM modulator 970 cyclically delays each of the code symbol sequences i n a time domain, thereby obtaining CDD, and outputs the cyclically delayed symbol seq uences to the respective transmitting antennas (operation S1860). The number of the OFDM modulator 970 may be equivalent to that of parallel symbol sequences. As illus trated in FIG. 5, the OFDM modulator 970 includes an IFFT unit 510, a delay unit 520, a nd a guard interval insertion unit 530.

An output of the OFDM modulator 970 may selectively be precoded by a precod er (not shown) in order to form a virtual transmitting antenna (operation S1870).

FIG. 10 is a block diagram of a transmission apparatus according to another em bodiment of the present invention, wherein the transmission apparatus includes a preco der 1080 in addition to the elements of the transmission apparatus illustrated in FIG. 9. Since the elements of the transmission apparatus illustrated in FIG. 10 are identical to those of the transmission apparatus illustrated in FIG. 9 except for the precoder 1080, a detailed description thereof will not be repeated.

FIG. 11 is a block diagram of a macro-diversity transmission apparatus including multiple transmitting antennas according to another embodiment of the present inventio n. FIG. 19 is a flowchart illustrating a macro-diversity transmission method used by th e transmission apparatus according to an embodiment of the present invention.

The transmission apparatus includes a channel encoder 1110, a modulator 1120 , a spatial multiplexer 1130, a copier 1150, an antenna switching unit 1160, an OFDM modulator 1170, and a precoder 1180. The transmission apparatus also includes the multiple transmitting antennas. The transmission apparatus is included in a base stati on within each cell illustrated in FIG. 2. The operation of each element of the transmis sion apparatus will now be described with reference to FIG. 19. However, what has air eady been described above will be omitted here.

The channel encoder 1110 channel-encodes input data that is to be transmitted ( operation S1910).

The modulator 1120 maps the channel-encoded input data to a modulation symb ol using a preset modulation method and generates a serial symbol sequence SiS₂S₃S₄ S₅S₆S₇S₈ (operation S1920).

The spatial multiplexer 1130 spatially multiplexes the serial symbol sequence Si S₂S₃S₄S₅S₆S₇S₈ and generates frequency-axis symbol sequences S1S₂S₅S₆ and 8₃S₄S ₇S₈, which are two of parallel symbol sequences in a frequency domain (operation S193 0). The copier 1150 copies each of the frequency-axis symbol sequences S1S2S5S6 and S₃S₄S₇S₈ and generates pairs of frequency-axis symbol sequences (operation S19 40). Since each pair of frequency-axis symbol sequences has the same data informati on, it cannot obtain a diversity gain by itself. However, if CDD is also applied, it can ob tain a diversity gain. The number of the copier 1150 may be equivalent to that of parall el symbol sequences.

The antenna switching unit 1160 divides each of the frequency-axis symbol sequ ences (a pair of SiS₂S₅S₆ and a pair of S₃S₄S₇S₈) into two or more symbol blocks, and outputs the frequency-axis symbol sequences SiS₂S₅S₆ and S₃S₄S₇S₈ respectively to th e OFDM modulator 1170 toward the transmitting antennas selected according to a pres et pattern(J) in units of symbol blocks (operation S1950). The antenna switching unit 1 160 may selectively be implemented.

The OFDM modulator 1170 cyclically delays each of the frequency-axis symbol s equences SiS₂S₅S₆ and S₃S₄S₇S₈ in a time domain, thereby obtaining CDD, and output s the cyclically delayed symbol sequences to the respective transmitting antennas (oper ation S1960).

The number of the OFDM modulator 1170 may be equivalent to parallel symbol sequences. As illustrated in FIG. 5, the OFDM modulator 1170 includes an IFFT unit 5 10, a delay unit 520, and a guard interval insertion unit 530. An output of the OFDM m odulator 1170 may be precoded by the precoder 1180 in order to form a virtual transmitt ing antenna (operation S1970). Precoding may selectively be performed.

FIG. 12 is a block diagram of a macro-diversity transmission apparatus including multiple transmitting antennas according to another embodiment of the present inventio n. FIG. 20 is a flowchart illustrating a macro-diversity transmission method used by th e transmission apparatus according to an 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 1 270. The transmission apparatus also includes the multiple transmitting antennas. Th e transmission apparatus is included in a base station within each cell illustrated in FIG. 2. The operation of each element of the transmission apparatus will now be describe d with reference to FIG. 20. However, what has already been described above will be omitted here.

The channel encoder 1210 channel-encodes input data that is to be transmitted ( operation S2010).

The modulator 1220 maps the channel-encoded input data to a modulation symb ol using a preset modulation method and generates a serial symbol sequence S₁S₂S₃S₄ S₅S₆S₇S₈ (operation S2020).

The spatial multiplexer 1230 spatially multiplexes the serial symbol sequence Si S₂S₃S4S5S₆S₇S₈ and generates frequency-axis symbol sequences SiS₂S₅Se and S3S4S ₇Ss₁ which are two parallel symbol sequences in a frequency domain (operation S2030). The antenna switching unit 1260 divides each of the frequency-axis symbol sequ ences SiS₂S₅S₆ and S₃S₄S₇Ss into two or more symbol blocks, and outputs the frequen cy-axis symbol sequences SiS₂SsS₆ and S₃S4S7S8 respectively to the OFDM modulator 1270 toward the transmitting antennas selected according to a preset pattem(J) in unit s of symbol blocks (operation S2040). Since antennas transmitting the same informati on in each cell are switched with each other in units of blocks within an encoded chann el, diversity can be given to signals added by a receiving end of a terminal.

The OFDM modulator 1270 OFDM-modulates the frequency-axis symbol sequen ces by performing an IFFT on them and generating time-axis symbol sequences in a ti me domain, and outputs the time-axis symbols respectively to corresponding transmittin g antennas (operation S2050). The number of the OFDM modulator 1270 may be equ ivalent to parallel symbol sequences. An output of the OFDM modulator 1170 may selectively be precoded by a preco der (not shown) in order to form a virtual transmitting antenna (operation S2060).

FIG. 13 is a block diagram of a macro-diversity transmission apparatus including multiple transmitting antennas according to another embodiment of the present inventio n. FIG. 21 is a flowchart illustrating a macro-diversity transmission method used by th e transmission apparatus according to an embodiment of the present invention.

The transmission apparatus includes a channel encoder 1310, a modulator 1320

, a spatial multiplexer 1330, a diversity coder 1340, an antenna switching unit 1360, and an OFDM modulator 1370. The transmission apparatus also includes the multiple tra nsmitting antennas. The transmission apparatus is included in a base station within eac h cell illustrated in FIG. 2. The operation of each element of the transmission apparatu s will now be described with reference to FIG. 21. However, what has already been de scribed above will be omitted here.

The channel encoder 1310 channel-encodes input data that is to be transmitted ( operation S2110).

The modulator 1320 maps the channel-encoded input data to a modulation symb ol using a preset modulation method and generates a serial symbol sequence S-|S₂S₃S₄ S₅S₆S₇S₈ (operation S2120).

The spatial multiplexer 1330 spatially multiplexes the serial symbol sequence Si S₂S₃S4S₅S₆S₇S₈ and generates frequency-axis symbol sequences S₁S₂S₅S₆ and S₃S₄S ₇S₈, which are two of parallel symbol sequences in a frequency domain (operation S213 0).

The diversity coder 1340 diversity-codes the frequency-axis symbol sequences S ₁S₂S₅S₆ and S₃S₄S₇S₈ by inverting and conjugating them, and generates code symbol s equences (operation S2140).

The antenna switching unit 1360 divides each of the code symbol sequences int 0 two or more symbol blocks, and outputs the code symbol sequences respectively to t he OFDM modulator 1370 toward the transmitting antennas selected according to a pre set pattern(J) in units of symbol blocks (operation S2150). The OFDM modulator 1370 OFDM-modulates the code symbol sequences by pe rforming an IFFT on them and generating time-axis symbol sequences in a time domain

, and outputs the time-axis symbols respectively to corresponding transmitting antennas

(operation S2160). The number of the OFDM modulator 1370 may be equivalent to p arallel symbol sequences. An output of the OFDM modulator 1370 may selectively be precoded by a preco der (not shown) in order to form a virtual transmitting antenna (operation S2170).

As described above, a method of changing a combination of antennas and an int er-cell CDD technique are applied to the present invention in order to obtain additional i nter-cell diversity. Like the related art, the present invention generates a pilot and inse rts the pilot into an OFDM-modulated OFDM symbol so that a receiving end can estimat e a channel.

However, the above two methods of obtaining additional inter-cell diversity increa se a pilot overhead, which needs to be taken into consideration. In the case of the method of changing a combination of antennas, since no partic ular technique is applied between cells within a region (a symbol block described above ) as in the related art, no additional pilot overhead occurs. However, it is difficult to ap ply interpolation to symbols at the boundary of the region for channel estimation. Ther efore, it is necessary to insert an additional pilot into the boundary of the region in order to maintain performance.

A pilot overhead which may occur when the inter-cell CDD technique is used will now be described. The pilot overhead of inter-cell CDD technique varies according to t he size of a delay, i.e. frequency selectivity. If frequency selectivity is small due to a s mall delay value, it is determined that a current channel environment is normal. Theref ore, a channel can be estimated using a received pilot value, which is the sum of pilot v alues from each cell, without an additional overhead.

However, if a large frequency selectivity is obtained using a large delay value in order to increase frequency diversity, it is necessary to estimate a pilot of each cell or c ell group. In this case, the overhead increases by twice the number of cell groups or c ells. When several times as many pilots need to be transmitted, the resources allocat ed to each pilot may be doubled so that each pilot can be allocated orthogonal resource s. Alternatively, pilot symbols may be multiplied by a different code for each cell group or cell without increasing the resources allocated to each pilot. These two methods p rovide a trade-off between the performance of channel estimation and resource consu mption.

FIG. 22 is a block diagram of a reception apparatus included in an OFDM cellula r system according to an embodiment of the present invention, wherein the reception a pparatus includes multiple receiving antennas and receives a broadcast/multicast servic e. FIG. 23 is a flowchart illustrating the operation of the receiving apparatus according to an embodiment of the present invention. The reception apparatus is included in a t erminal within each cell illustrated in FIG. 2. The operation of each element of the rec eption apparatus will now be described with reference to FIG. 23. However, what has already been described above will be omitted here. The reception apparatus includes an OFDM demodulator 2210, a channel estim ator 2220, a symbol detector 2230, a spatial demultiplexer 2240, a modulator 2250, and a channel decoder 2260. The reception apparatus also includes the multiple receivin g antennas.

The OFDM demodulator 2210 performs an FFT on the same broadcast/multicast data signal received from a plurality of cells through the multiple receiving antennas, a nd thus OFDM-demodulates the broadcast/multicast data signal (operation S2310).

The broadcast/multicast data signal has been generated by each transmitting ap paratus according to a predetermined encoding method and then transmitted by each tr ansmitting antenna in each cell included in a plurality of cell groups into which adjacent cells are divided. The predetermined encoding method includes an encoding method used by the transmission apparatus according to the present invention.

The channel estimator 2220 extracts a pilot symbol from the symbol sequences of the OFDM-demodulated broadcast/multicast data signal and estimates channels (op eration S2320). The symbol detector 2230 applies a maximum likelihood (ML) detection algorith m to each of the received and channel-estimated symbol sequences, and signal-proces ses the symbol sequences (operation S2330).

The spatial demultiplexer 2240 demultiplexes the output of the symbol detector i n order to restore the spatially multiplexed broadcast/multicast data signal, and generat es serial symbol sequences (operation S2340).

The demodulator (or symbol demapper) 2250 demodulates the output of the spa tial demultiplexer according to the modulation method used by the transmission apparat us according to the present invention (operation S2350).

The channel decoder 2260 restores the originally transmitted data based on the demodulation result (operation S2360).

Until now, a method of applying spatial multiplexing to multiple antennas within a cell or a method of applying spatial multiplexing to some of the multiple antennas and a pplying various diversity technique to the remaining antennas have been described. Basically, spatial multiplexing denotes transmitting a different data stream to each a ntenna. In this case, the antenna may be a physical antenna or a precoded virtual ant enna. In addition, the different data streams for respective antennas may be included i n the same coding block or different coding blocks.

In the present invention, a spatial multiplexer is used after a channel encoder an d a modulator are used in order to apply spatial multiplexing. However, spatial multiple xing according to the present invention may be performed in a state where the spatial m ultiplexer is placed before the channel encoder and the modulator as illustrated in FIGS . 24 and 25. That is, spatially multiplexed input data is channel-encoded and modulate d respectively by the channel encoder and the modulator, thereby performing intra-cell spatial multiplexing. Here, the number of the channel encoder and the modulator may be equivalent to that of spatially multiplexed parallel data. The subsequent functions a nd operations of the reception apparatus are identical to those of the transmission appa ratus described above, and thus a detailed description thereof will be omitted.

When a transmission apparatus as illustrated in FIG. 24 or 25 is used, a receptio n apparatus may use a spatial demultiplexer after a demodulator and a channel decode r perform signal decoding as illustrated in FIG. 26. The number of the demodulator an d the channel decoder may be equivalent to that of receiving data. The function and o peration of the reception apparatus illustrated in FIG. 26 are identical to those of the rec eption apparatus described above, except that the spatial demultiplexer performs spatia I demultiplexing after the channel decoder and the demodulator perform signal decodin g, and thus a detailed description thereof will be omitted.

In the present invention, a case where two pieces of parallel data are generated t hrough spatial multiplexing has been described as an example. However, it will be full y understood by those of ordinary skill in the art that two or more pieces of parallel data can be generated according to the number of transmitting antennas of a base station a nd the number of receiving antennas of a terminal.

The invention can also be embodied as computer readable code on a computer r eadable recording medium. The computer readable recording medium is any data stor age device that can store data which can be thereafter read by a computer system. E xamples of the computer readable recording medium include read-only memory (ROM), random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, and carrier waves (such as data transmission through the Internet). T he 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 distri buted fashion. Also, functional programs, code, and code segments for accomplishing the present invention can be easily construed by programmers skilled in the art to whic h the present invention pertains.

While this invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that vari ous changes in form and detail may be made therein without departing from the spirit a nd scope of the invention as defined by the appended claims. The exemplary embodi ments should be considered in a descriptive sense only, and not for purposes of limitati on. Therefore, the scope of the invention is defined not by the detailed description of t he invention but by the appended claims, and all differences within the scope will be co nstrued as being included in the present invention.

Claims

1. A macro-diversity transmission apparatus using multiple transmitting antennas, t he apparatus comprising: a modulator mapping channel-encoded input data into modulation symbols accor ding to a preset modulation method, and generating a symbol sequence; a spatial multiplexer spatially multiplexing the symbol sequence and generating p arallel frequency-axis symbol sequences; and an orthogonal frequency division multiplexing (OFDM) modulator cyclically delayi ng the frequency-axis symbol sequences in a time domain and outputting the cyclically delayed symbol sequences to respective transmitting antennas.

2.

The apparatus of claim 1 , further comprising an antenna switching unit dividing e ach of the frequency-axis symbol sequences into two or more symbol blocks, and outp utting the frequency-axis symbol sequences respectively to the OFDM modulator towa rd the transmitting antennas selected according to a preset pattern in units of symbol b locks.

3.

The apparatus of claim 2, wherein a pattern in which the antenna switching unit s elects a transmitting antenna is set for each of two or more cell groups into which adja cent cells transmitting the common input data are divided.

4.

The apparatus of claim 1, further comprising: a copier copying the frequency-axis symbol sequences and generating pairs of fr equency-axis symbol sequences; and an antenna switching unit dividing each of the frequency-axis symbol sequences of the pairs into two or more symbol blocks, and outputting the frequency-axis symbol s equences respectively to the OFDM modulator toward the transmitting antennas selecte d according to a preset pattern in units of symbol blocks.

5.

The apparatus of claim 1 , wherein a pattern in which the antenna switching unit s elects a transmitting antenna is set for each of two or more cell groups into which adj acent cells transmitting the common input data are divided.

6.

The apparatus of claim 1 , wherein the OFDM modulator comprises: an inverse fast Fourier transform (IFFT) unit performing an IFFT on the frequenc y-axis symbol sequences and generating time-axis symbol sequences; a delay unit cyclically delaying the IFFTed time-axis symbol sequences by assign ing a circular delay value to each IFFTed time-axis symbol sequence; and a guard interval insertion unit inserting a guard interval into each cyclically delaye d time-axis symbol sequence.

7.

The apparatus of claim 6, wherein the circular delay value set for each of two or more cell groups into which the adjacent cells transmitting the common input data are divided.

8.

The apparatus of claim 6, wherein the circular delay value is set for each of the a djacent cells transmitting the common input data.

9. The apparatus of claim 6, wherein the circular delay value is set for each transmi tting antenna transmitting the input data in a cell.

10.

The apparatus of claim 1 , further comprising a precoder precoding an output of th e OFDM modulator in order to form a virtual transmitting antenna.

11.

A macro-diversity transmission apparatus using multiple transmitting antennas, t he apparatus comprising: a modulator mapping channel-encoded input data into modulation symbols accor ding to a preset modulation method, and generating a symbol sequence; a spatial multiplexer spatially multiplexing the symbol sequence and generating p arallel frequency-axis symbol sequences; a diversity coder diversity-coding the parallel frequency-axis symbol sequences a nd generating code symbol sequences; and an OFDM modulator cyclically delaying the code symbol sequences in a time do main and outputting the cyclically delayed code symbol sequences to respective transm itting antennas.

12.

The apparatus of claim 11 , wherein the diversity coder generates the code symb ol sequences through any one of space time block coding (STBC) or space frequency b lock coding (SFBC).

13.

The apparatus of claim 11 , further comprising an antenna switching unit dividing each of the code symbol sequences into two or more symbol blocks, and outputting the code symbol sequences respectively to the OFDM modulator toward the transmitting an tennas selected according to a preset pattern in units of symbol blocks.

14.

The apparatus of claim 13, wherein a pattern in which the antenna switching unit selects a transmitting antenna is set for each of two or more cell groups into which adj acent cells transmitting the common input data are divided.

15.

The apparatus of claim 11 , wherein the OFDM modulator comprises: an IFFT unit performing an IFFT on the code symbol sequences and generating t ime-axis symbol sequences; a delay unit cyclically delaying the IFFTed time-axis symbol sequences by assign ing a circular delay value to each IFFTed time-axis symbol sequence; and a guard interval insertion unit inserting a guard interval into each cyclically delaye d time-axis code symbol sequence.

16.

The apparatus of claim 15, wherein the circular delay value set for each of two or more cell groups into which the adjacent cells transmitting the common input data are divided.

17.

The apparatus of claim 15, wherein the circular delay value is set for each of the adjacent cells transmitting the common input data.

18.

The apparatus of claim 15, wherein the circular delay value is set for each trans mitting antennas transmitting the input data in a cell.

19.

The apparatus of claim 11 or 13, further comprising a precoder precoding an out put of the OFDM modulator in order to form a virtual transmitting antenna.

20. A macro-diversity transmission apparatus using multiple transmitting antennas, t he apparatus comprising: a modulator mapping channel-encoded input data into modulation symbols accor ding to a preset modulation method, and generating a symbol sequence; a spatial multiplexer spatially multiplexing the symbol sequence and generating p arallel frequency-axis symbol sequences; an antenna switching unit dividing each of the frequency-axis symbol sequences into two or more symbol blocks, and outputting the frequency-axis symbol sequences re spectively toward the transmitting antennas determined according to a preset pattern in units of symbol blocks; and an OFDM modulator performing an IFFT on the frequency-axis symbol sequence s output in units of symbol blocks and outputting the IFFTed symbol sequences to the r espective transmitting antennas.

21.

The apparatus of claim 20, further comprising a precoder precoding an output of the OFDM modulator in order to form a virtual transmitting antenna.

22.

A macro-diversity transmission apparatus using multiple transmitting antennas, t he apparatus comprising: a modulator mapping channel-encoded input data into modulation symbols accor ding to a preset modulation method, and generating a symbol sequence; a spatial multiplexer spatially multiplexing the symbol sequence and generating p arallel frequency-axis symbol sequences; a diversity coder diversity-coding the parallel frequency-axis symbol sequences a nd generating code symbol sequences; an antenna switching unit dividing each of the code symbol sequences into two o r more symbol blocks, and outputting the code symbol sequences respectively toward t he transmitting antennas selected according to a preset pattern in units of symbol block s; and an OFDM modulator performing an IFFT on the code symbol sequences output i n units of symbol blocks and outputting the IFFTed code symbol sequences to the resp ective transmitting antennas.

23.

The apparatus of claim 22, wherein the diversity coder generates the code symb ol sequences through any one of STBC or SFBC.

24.

The apparatus of claim 22, wherein a pattern in which the antenna switching unit selects a transmitting antenna is set for each of two or more cell groups into which adj acent cells transmitting the common input data are divided.

25.

The apparatus of claim 22, further comprising a precoder precoding an output of the OFDM modulator in order to form a virtual transmitting antenna.

26.

A macro-diversity transmission method using multiple transmitting antennas, the method comprising:

(a) mapping channel-encoded input data into modulation symbols according to a preset modulation method, and generating a symbol sequence;

(b) spatially multiplexing the symbol sequence and generating parallel frequency- axis symbol sequences; and

(c) cyclically delaying the frequency-axis symbol sequences in a time domain an d outputting the cyclically delayed symbol sequences to respective transmitting antenna S.

27.

The method of claim 26, further comprising after operation (b): dividing each of the frequency-axis symbol sequences into two or more symbol b locks; and outputting the frequency-axis symbol sequences respectively toward the transmit ting antennas selected according to a preset pattern in units of symbol.

28. The method of claim 27, wherein a pattern in which a transmitting antenna is sel ected is set for each of two or more cell groups into which adjacent cells transmitting th e common input data are divided.

29. The method of claim 26, further comprising after operation (b): copying the frequency-axis symbol sequences and generating pairs of frequency -axis symbol sequences; dividing each of the frequency-axis symbol sequences of the pairs into two or mo re symbol blocks; outputting the frequency-axis symbol sequences respectively toward the transmit ting antennas selected according to a preset pattern in units of symbol.

30.

The method of claim 29, wherein a pattern in which a transmitting antenna is sel ected is set for each of two or more cell groups into which adjacent cells transmitting th e common input data are divided.

31. The method of claim 26, wherein operation (c) comprises:

(c1 ) performing an IFFT on the frequency-axis symbol sequences and generatin g time-axis symbol sequences;

(c2) cyclically delaying the IFFTed time-axis symbol sequences by assigning a cir cular delay value to each IFFTed time-axis symbol sequence; and (c3) inserting a guard interval into each cyclically delayed time-axis symbol sequ ence.

32.

The method of claim 31 , wherein the circular delay value is set for each of two or more cell groups into which the adjacent cells transmitting the common input data are divided.

33.

The method of claim 31 , wherein the circular delay value is set for each of the ad jacent cells transmitting the common input data.

34.

The method of claim 31 , wherein the circular delay value is set for each transmitt ing antennas transmitting the input data in a cell.

35.

The method of claim 26, further comprising (d) precoding an output of operation (c) in order to form a virtual transmitting antenna.

36.

(a) mapping channel-encoded input data into modulation symbols according to a preset modulation method, and generating a symbol sequence; (b) spatially multiplexing the symbol sequence and generating parallel frequency- axis symbol sequences;

(c) diversity-coding the parallel frequency-axis symbol sequences and generating code symbol sequences; and (d) cyclically delaying the code symbol sequences in a time domain and outputtin g the cyclically delayed code symbol sequences to respective transmitting antennas.

37.

The method of claim 36, wherein in operation (c), the code symbol sequences ar e generated through any one of STBC or SFBC.

38.

The method of claim 36, further comprising after operation (c): dividing each of the code symbol sequences into two or more symbol blocks; outputting the code symbol sequences respectively toward the transmitting anten nas selected according to a preset pattern in units of symbol.

39.

The method of claim 38, wherein a pattern in which a transmitting antenna is sel ected is set for each of two or more cell groups into which adjacent cells transmitting th e common input data are divided.

40.

The method of claim 36, wherein operation (d) comprises: (d1 ) performing an IFFT on the code symbol sequences and generating time-axi s symbol sequences;

(d2) cyclically delaying the IFFTed time-axis symbol sequences by assigning a ci rcular delay value to each IFFTed time-axis symbol sequence; and

(d3) a guard interval insertion unit inserting a guard interval into each cyclically d elayed time-axis code symbol sequence.

41.

The method of claim 40, wherein the circular delay value is set for each of two or more cell groups into which the adjacent cells transmitting the common input data are divided.

42. The method of claim 40, wherein the circular delay value is set for each of the ad jacent cells transmitting the common input data.

43.

The method of claim 40, wherein the circular delay value is set for each transmitt ing antennas transmitting the input data in a cell.

44.

The method of claim 36, further comprising (e) precoding an output of operation (d) in order to form a virtual transmitting antenna.

45.

46.

(c) dividing each of the frequency-axis symbol sequences into two or more symb ol blocks, and outputting the frequency-axis symbol sequences respectively toward the t ransmitting antennas selected according to a preset pattern in units of symbol; and (d) performing an IFFT on the frequency-axis symbol sequences output in units o f symbol blocks and outputting the IFFTed symbol sequences to the respective transmit ting antennas.

47.

The method of claim 46, further comprising (e) precoding an output of operation (d) in order to form a virtual transmitting antenna.

48.

(c) diversity-coding the parallel frequency-axis symbol sequences and generating code symbol sequences;

(d) dividing each of the code symbol sequences into two or more symbol blocks, and outputting the code symbol sequences respectively toward the transmitting antenna s selected according to a preset pattern in units of symbol; and

(e) performing an IFFT on the code symbol sequences output in units of symbol blocks and outputting the IFFTed code symbol sequences to the respective transmitting antennas.

49.

The method of claim 48, wherein the code symbol sequences are generated thro ugh any one of STBC or SFBC.

50.

The method of claim 49, wherein a pattern in which a transmitting antenna is sel ected is set for each of two or more cell groups into which adjacent cells transmitting th e common input data are divided.

51 .

The method of claim 48, further comprising (f) precoding an output of operation ( e) in order to form a virtual transmitting antenna.

52.

A computer-readable recording medium on which a program for executing the m ethod of any one of claims 26 through 51 is recorded.