KR101050620B1 - Preprocessing method for symbol transmission using orthogonal frequency division multiplexing in wireless packet mobile communication system and base station transmitting device using same - Google Patents

Abstract

The present invention provides an orthogonal frequency division multiplexing (OFDM) scheme for symbol transmission in order to efficiently support a broadcast service while maintaining compatibility with an existing wireless packet mobile communication system in a forward link. And an apparatus thereof, which is an inverse fast Fourier in an Orthogonal Frequency Division Multiplexing (OFDM) wireless packet mobile communication system that transmits a forward packet through a time slot having the same pilot and MAC signal intervals as a conventional wireless packet mobile communication system. And preprocessing the OFDM symbol transmission by dividing the OFDM data included in the converted OFDM symbol into at least two sections and inserting a null section into a region between the divided OFDM data. do.

OFDM, packet, broadcast service, slot, forward, preprocessing, symbol, HRPD, compatible

Description

Preprocessing method for symbol transmission in orthogonal frequency division multiplexing in wireless packet mobile communication system and base station transmission apparatus using same }             

1 is a diagram illustrating a slot structure of a forward link of a conventional wireless packet mobile communication system.

2 is a block diagram illustrating a structure of a base station transmitter in a conventional wireless packet mobile communication system.

3 illustrates a slot structure of a wireless packet mobile communication system to which a general OFDM scheme is applied.

4 illustrates a structure of a general OFDM symbol

5 is a block diagram showing the configuration of a base station transmitter in a wireless packet mobile communication system to which a general OFDM scheme is applied.

6 illustrates a slot structure to which an OFDM preprocessing scheme is applied according to an embodiment of the present invention.                 

7 illustrates a slot structure to which an OFDM preprocessing scheme is applied according to another embodiment of the present invention.

8 is a block diagram illustrating a configuration of a base station transmitter of a wireless packet mobile communication system to which an OFDM preprocessing scheme according to the present invention is applied.

9 is a diagram illustrating a method of preprocessing an OFDM symbol according to an embodiment of the present invention.

10 is a diagram for describing a preprocessing method of an OFDM symbol according to another embodiment of the present invention.

11 is a block diagram illustrating a configuration of a base station transmitter to which a linear combined preprocessing scheme is applied to OFDM symbol preprocessing according to the present invention.

12 is a view for explaining a process of inducing linear coupling pretreatment of FIG.

The present invention relates to a method and apparatus for transmitting data in a wireless packet mobile communication system, and in particular, orthogonal frequency division multiplexing for efficiently supporting a broadcast service while maintaining compatibility with an existing wireless packet mobile communication system in a forward link. Division Multiplexing: Hereinafter, the present invention relates to a preprocessing method for symbol transmission in the " OFDM " method and a base station transmission apparatus using the same.                         

In general, a service supported by a wireless packet mobile communication system is a communication service that exchanges information between a specific sender and a receiver. In a communication service, different receivers receive information through different channels. However, in the wireless mobile communication system, since the isolation between channels is low, performance is limited by interference. Existing mobile communication systems use multiple access schemes and cellular concepts such as code division multiple access (CDMA), time division multiple access (TDMA), and frequency division multiple access (FDMA) to increase the isolation between channels. .

On the other hand, the wireless transmission method for a conventional broadcast service or a multicast service (hereinafter, referred to as a "broadcast service") has been developed for the purpose of fixed reception and low-speed mobile reception. There is an active development of technology for receiving. For example, broadcast technologies such as DMB (Digital Multimedia Broadcast) and DVB-H (Digital Video Broadcast-Handheld) are technologies developed for receiving video-level broadcasts in a small sized portable terminal. On the other hand, researches to develop the existing one-way broadcasting service in both directions are being conducted in parallel, and for this purpose, a method of using the existing wired / wireless communication network as a return channel is being sought.

However, this approach has a limitation in the implementation of the fundamental two-way broadcasting because broadcasting and communication use different transmission methods. In addition, in the case of a multi-transmission scheme or a cellular scheme supported by the existing wireless packet mobile communication system, interference does not fundamentally suppress interference, so interference still limits performance. As an example of the conventional wireless packet mobile communication system, a forward link of a high rate packet data communication system (HRPD) uses a TDMA technique as a multiple access technique and a TDM / CDM technique as a multiplexing technique.

1 is a view illustrating a slot structure of a forward link of a conventional wireless packet mobile communication system (HRPD), and the descriptions at the bottom of each section in the slot of FIG. it means.

In FIG. 1, one slot has a form in which a half slot structure is repeated. In the center of the half slot, pilots 103 and 108 of N _pilot chip length are inserted, which are used for channel estimation of the forward link at the receiving terminal. On both sides of the pilots 103 and 108, medium access control (MAC) information 102, 104, 107, and 109 of N _MAC chip length including reverse power control information, resource allocation information, and the like are transmitted. On both sides of the MAC information, actual transmission data (101, 105, 106, 110) of length N _DATA chip is transmitted. As described above, the slot structure of FIG. 1 is multiplexed by a TDM scheme in which Pilot, MAC, data, etc. are transmitted at different times.

On the other hand, MAC and data information are used by the CDM method using Walsh code. 2 illustrates a structure of a forward link transmitter of a conventional wireless packet mobile communication system (HRPD).

In other words, when data to be transmitted from the data generator 201 is transferred, the data is channel-coded through the encoder 202 and input to the modulator 203 to modulate the encoded signal into QPSK, QAM, or the like. The modulated signal becomes a multicode transmission signal through demultiplexer 204 and CDM multiplexer 205. The generated data signal is multiplexed through the TDM multiplexer 208 together with the MAC signal and the pilot signal generated by the MAC signal generator 206 and the pilot signal generator 207, respectively, to complete the slot structure of FIG. 1.

Although the slot structure and transmitter structure of the HRPD forward link described with reference to FIGS. 1 and 2 are designed for wireless packet mobile communication, the same slot structure and transmitter structure may be used even in a BCMCS (Broadcast Multicast Service) operation designed for a broadcast service. Is used.

Meanwhile, a new transmission scheme that efficiently supports BCMCS must maintain compatibility with the slot structure of FIG. 1. To this end, the sections in which the pilots 103 and 108 and the MAC information 102, 104, 107 and 109 are transmitted should transmit signals generated in the same manner as before. However, since the data (101, 105, 106, 110) section is to transmit the broadcast or multicast information, the transmission method may be changed if already agreed with the receiver.

In this regard, unlike a general communication service, a broadcast service or the like does not cause interference among users who receive the same information in a manner in which a sender unilaterally transmits information to a plurality of receivers because they share the same channel. However, in the case of mobile broadcast service, the multipath fading phenomenon occurring in a high speed mobile environment is the main cause of deterioration of performance. Meanwhile, broadcast systems, such as Digital Video Broadcast-Terrestrial (DVB-T), DVB-H, and Digital Audio Broadcast (DAB), which are designed to enable mobile reception to overcome multipath fading in broadcast services, use OFDM transmission schemes. I use it.

The OFDM method is a method of performing parallel orthogonal modulation of multiple serial carriers after modulating a plurality of subcarriers having a mutual orthogonality after parallel conversion of serially inputted symbol strings. There was a limit to the system application. However, in 1971, Weinstein et al. Announced that OFDM modulation can be efficiently processed using the Discrete Fourier Transform (DFT), and as the use and insertion of Guard Interval is known, the system of multipath fading phenomenon is known. Negative effects are further reduced and driven by advances in digital signal processing technologies, including the Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT), which address hardware complexity. The feasibility is getting higher.

Advantages of the OFDM transmission scheme in a broadcast system are as follows. In the case of using the OFDM transmission scheme, first, it is possible to prevent a phenomenon in which multipath fading causes magnetic interference. In particular, in a broadcast service, since different base stations transmit the same broadcast signal through a single frequency netwrok (SFN), a mobile terminal can receive signals transmitted from different base stations through OFDM without interfering with each other. Have Therefore, when the OFDM transmission scheme is applied to a broadcast system, an interference free environment can be realized, thereby maximizing transmission efficiency.                         

In the broadcast service, since all base stations transmit the same information, a terminal receiver receives a broadcast signal as if a signal transmitted from different base stations experienced a multipath fading channel in one base station. Therefore, inter-cell interference can be prevented through OFDM technique. When the inter-cell interference does not occur, the performance of the terminal receiver located at the boundary of the cell does not decrease due to the interference. Therefore, if the OFDM scheme is applied to a broadcast service, it is possible to guarantee a uniform quality throughout the service area, so research on this is desired.

Disclosure of Invention An object of the present invention is to provide a preprocessing method for OFDM symbol transmission that efficiently supports a broadcast service while maintaining compatibility with an existing wireless packet mobile communication system in a forward link, and an apparatus for transmitting a base station using the same.

Another object of the present invention is to provide a pre-processing method for symbol transmission in an OFDM scheme for facilitating the implementation of two-way communication and to improve a broadcast efficiency and a base station transmission apparatus using the same.

In a wireless packet mobile communication system for achieving the above object, a preprocessing method for symbol transmission in an orthogonal frequency division multiplexing scheme is an OFDM for transmitting a forward packet through a time slot having the same pilot and MAC signal intervals as a general wireless packet mobile communication system. A preprocessing method for OFDM symbol transmission in an Orthogonal Frequency Division Multiplexing wireless packet mobile communication system, the method comprising: dividing OFDM data included in an inverse fast Fourier transformed OFDM symbol into at least two sections; And inserting a null section into a region between the OFDM data.

In the wireless packet mobile communication system for achieving the above object, a base station transmitting apparatus for symbol transmission in an orthogonal frequency division multiplexing scheme transmits forward packets through time slots having the same pilot and MAC signal intervals as those of a general wireless packet mobile communication system. A base station transmitter comprising a demultiplexer for demultiplexing modulated data into a plurality of data streams in an orthogonal frequency division multiplexing (OFDM) wireless packet mobile communication system, and a MAC signal generator and a pilot signal generator. A plurality of inverse fast Fourier transformers each converting a data stream into OFDM data, a plurality of preprocessors that divide the OFDM data into at least two sections, and insert a null section between the divided OFDM data; OFD with leading part in front of OFDM data And a multiplexer for outputting M symbols, and a multiplexer for time-division multiplexing the plurality of OFDM symbols, the MAC signal, and the pilot signal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention. In addition, the contents described at the bottom of each section for describing the slot structure will be referred to the chip length unless otherwise described.

First, the basic concept of the present invention will be briefly described before the present invention.

When the OFDM scheme is used as the multiplexing scheme, magnetic interference may be prevented from occurring in the multipath fading channel. In the broadcast service, since all base stations transmit the same information, from a mobile terminal that is a receiving side in the forward link, signals transmitted from different base stations may receive broadcast signals as if they were transmitted through multipath fading from one base station. Will be received. Therefore, intercell interference can be prevented by using an OFDM transmission scheme. If the inter-cell interference does not occur, even the mobile terminal located at the boundary of the cell does not degrade performance due to the interference, it is possible to ensure a uniform quality throughout the service area.

In order to implement a transmission operation in which no interference occurs using the OFDM scheme as described above, the size of a cyclic prefix fixed periodically to the front end of the OFDM symbol should be large enough. In this regard, the smaller the size of the OFDM symbol, the greater the portion occupied by the cyclic prefix, and thus the transmission efficiency is reduced. Accordingly, the present invention proposes a new OFDM symbol preprocessing scheme that allows the size of an OFDM symbol to exceed the size of the data field allowed in the HRPD slot structure while maintaining compatibility with the existing HRPD slot structure.

In addition, although the present invention was developed to be applied to an HRPD system used for broadcasting or multicast, it should be noted that the same method can be applied to a unicast service and other wireless packet mobile communication systems. .

Hereinafter, a slot structure and a configuration of a base station transmitting apparatus of a wireless packet mobile communication system to which a general OFDM scheme is applied will be described with reference to FIGS. 3 to 5 to help understand the present invention.

That is, FIG. 3 illustrates a slot structure of a wireless packet mobile communication system to which a general OFDM scheme is applied, which shows an example of a slot structure for transmitting an OFDM symbol in a data interval while maintaining compatibility with the HRPD slot structure of FIG. 1.

In order to maintain the HRPD forward compatibility of the slot structure of FIG. 3, the position and size of the pilot and MAC signals are set to match the HRPD slot structure of FIG. 1. That is, in FIG. 3, pilots 304 and 311 having a N _pilot chip length are positioned at the center of the half slot, and MAC signals 303, 305, 310, and 312 having N _MAC chip length are located at both sides of the pilot signal. Accordingly, the existing HRPD terminal not supporting the OFDM-based broadcast service may estimate the channel through the pilots 304 and 311 in the slot structure of FIG. 3 and receive the MAC signals 303, 305, 310, and 312. Pilot and MAC signals are allocated in the slot structure of FIG. 3, and OFDM symbols 301, 302, 306, 307, 308, 309, 313, and 314 are inserted in the remaining areas.

The slot structure of FIG. 3 is an example of inserting two N _OS chip length OFDM symbols 301, 302, 306, 307, 308, 309, 313, and 314 into an interval of N _DATA chip length for transmitting data in an HRPD slot. 2 The relationship of N _OS = N _DATA must be satisfied. Here, the general structure of the OFDM symbol is configured as shown in FIG.

In FIG. 4, 402 denotes OFDM data obtained by inverse fast fourier transform (IFFT) of a data symbol to be transmitted. In the latter part of the OFDM data 402 (shaded in FIG. 4), the N _CP chip size information 403 is copied to the front of the OFDM data, which is the cyclic prefix 401 of the OFDM symbol. . The head 401 is for preventing the time delay signal component due to multipath fading from acting as magnetic interference. For this purpose, the size of the head 401 ( N _CP chip) is larger than the maximum time delay occurring in the channel. It should be set at least long enough not to be small.

FIG. 5 is a block diagram illustrating a configuration of a base station transmitter in a wireless packet mobile communication system to which a general OFDM scheme is applied. The base station transmitter of FIG. 5 is configured to be compatible with the base station transmitter of the HRPD system described with reference to FIG. 3.

When data to be transmitted from the data generator 501 is transmitted in FIG. 5, it is channel coded through the encoder 502, and the coded signal is input to the modulator 503 to modulate with QPSK, QAM, or the like. The modulated signal is then demultiplexed into a plurality of data streams through the demultiplexer 504 to be converted into a plurality of OFDM symbols. Here, each demultiplexed data stream is converted into OFDM data through IFFTs 505 and 506, and CP appenders 507 and 508 attach the aforementioned head 401 to each OFDM data to generate OFDM symbols. do. The plurality of OFDM symbols generated in this manner are multiplexed (TDM) through the time division multiplexer 511 together with the MAC signal and the pilot signal generated by the MAC signal generator 509 and the pilot signal generator 510, respectively, as shown in FIG. Complete the slot structure.

The slot structure of the wireless packet mobile communication system to which the general OFDM scheme is applied is an example of inserting at least one OFDM symbol into a data field in an existing HRPD slot structure. The size of the OFDM symbol should not be larger than the size N _DATA of the data field. It is a technique of maintaining compatibility with the conventional slot structure of FIG. Since the size of the OFDM symbol is determined by the application environment of the communication system, if the size of the OFDM symbol is small, it is suitable for fast-changing multipath fading, but since the head portion 401 occupies a large portion in the OFDM symbol, transmission efficiency is increased. Has the disadvantage of falling.

That is, when providing a broadcast service, the mobile terminal should set the size of the top part sufficiently in consideration of the reception delay time of another base station signal so that the signal received from the other base station can also be regarded as the signal transmitted to the mobile station. For example, when the size of the head portion is set to 64 chips so that all of the delay signals up to 64 chips are magnetic signals, the case of the OFDM symbol is 256 chips compared to the case of 1024 chips, and the former case (256 In the latter case, the specific gravity occupies 1/4 of the symbol size, and in the latter case (1024 chip), it is 1/16 of the symbol size. However, since the head is not a section for transmitting actual information, the transmission efficiency of actual information transmission is 3/4, the latter is 15/16. In the latter case, that is, the larger the OFDM symbol, the higher the transmission efficiency. It can be seen.                     

However, even if trying to increase the size of the OFDM symbol to increase the transmission efficiency, in order to maintain compatibility with the HRPD slot structure as shown in Figure 1, the size of the OFDM symbol can not be set larger than the N _DATA , the size of the HRPD data field constraints of transmission efficiency In this case, the present invention proposes a new OFDM symbol preprocessing scheme that allows the size of an OFDM symbol to exceed the size of a data field allowed in the existing HRPD slot structure while maintaining compatibility with the existing HRPD slot structure.

Hereinafter, a preprocessing method of an OFDM symbol according to the present invention will be described with reference to FIGS. 6 to 12. The accompanying drawings will be briefly described with reference to FIGS. 6 and 7, after explaining the slot structure proposed by the present invention, a base station transmitter for transmitting an OFDM symbol in the slot structure according to the present invention will be described with reference to FIG. 8. 9 and 10 will be described in the OFDM symbol preprocessing method of the present invention. 11 and 12 will be described an embodiment in which a linear combined preprocessing scheme is introduced into OFDM symbol preprocessing according to the present invention.

6 illustrates a slot structure to which an OFDM preprocessing scheme according to an embodiment of the present invention is applied, which illustrates an example of inserting two OFDM symbols into one slot of an HRPD of FIG. 1.

The OFDM symbol proposed by the present invention has a form in which a NULL section in which pilot signals of the same size do not exist at positions of pilot and MAC signals 606 and 612 is maintained to maintain compatibility with HRPD as shown in 601 and 607 of FIG. 6. . In addition, the size of the OFDM symbol filled in the data region is set to be the same as the HRPD for compatibility with the HRPD. Referring to the example of FIG. 6, the OFDM data 601 and 607 preprocessed according to the present invention is NULL in which no signal exists during the ( N _Pilot +2 N _MAC ) chip length at the positions of the pilot and MAC signals 606 and 612. There is a section. For convenience, the front of the NULL section is named OFDM data A, and the back is called OFDM data B. And a detailed description of the pretreatment process will be described later.

The OFDM data 601 and 607 of FIG. 6 is generated through a preprocessing process to be described later after the data to be transmitted undergoes an IFFT process. Cyclic Prefixes 603 and 609 copy the portions 602 and 608 corresponding to the N _CP chip lengths from the rear part of the preprocessed OFDM data 601 and 607 and copy them to the front half of the slot. The preprocessed OFDM data 601, 607 is then placed after the heads 603, 609. Thus, the OFDM data A and B portions are placed at positions 604, 610, 605, and 611, respectively. Since NULL is positioned in the preprocessed OFDM data 601 and 607, a pilot structure and a MAC signal 606 and 612 can be inserted into this portion to generate a slot structure compatible with the existing HRPD.

FIG. 7 illustrates a slot structure to which an OFDM preprocessing scheme is applied according to another embodiment of the present invention, which illustrates an example of inserting one OFDM symbol into one slot of an HRPD of FIG. 1.

Referring to the example of FIG. 7, the preprocessed OFDM data 701 has two NULL intervals in which no signal exists during the ( N _Pilot +2 N _MAC ) chip length at the positions of the pilot and the MAC signals 707 and 708. For convenience of description, the first part of the first NULL is called OFDM data A, the part between NULL is called OFDM data B, and the second part of the second NULL is called OFDM data B. In FIG. 7, as in FIG. 6, preprocessed OFDM data is obtained through IFFT and preprocessing of data to be actually transmitted, and a preprocessing method used will be described later.

In the preprocessed OFDM data 701 of FIG. 7, a portion 702 corresponding to the N _CP chip length is copied from the rear portion and copied to the front half of the slot. The preprocessed OFDM data 701 is placed after the head part 703. Thus, in FIG. 7, OFDM data A, B, and C are placed at positions 704, 705, and 706, respectively. Since two NULLs are positioned in the middle of the pre-processed OFDM data 701, inserting Pilot and MAC signals 707 and 708 into this portion can generate a slot structure compatible with the existing HRPD.

As described above, in the slot structure proposed in FIGS. 6 and 7, an example in which two or one OFDM symbols are inserted into one slot of the HRPD of FIG. 1 has been described. However, at least one OFDM symbol is spread over a plurality of slots in a similar manner. It will be appreciated that it is possible to extend this to be inserted.

Also preferably, according to the present embodiment, at least one OFDM symbol may be inserted into a plurality of half slot sections by using the half slot section of the time slot as a minimum unit. Even in this case, the positions of the pilot and MAC signal sections are maintained in the existing HRPD slot structure, and it should be noted that a NULL section is inserted at a corresponding position of the pilot and MAC signal sections in the divided OFDM data.

In some cases, for example, one OFDM symbol may be divided and inserted into three N _DATA sections in the HRPD slot structure shown in FIG. 1. In this case, one OFDM symbol is carried in the 'half slot + N _{DATA period} ' rather than the half slot unit.

FIG. 8 is a block diagram illustrating a configuration of a base station transmitter of a wireless packet mobile communication system to which an OFDM preprocessing scheme is applied according to the present invention. This is illustrated in FIG. It is composed.

In FIG. 8, when data to be transmitted from the data generator 801 is transmitted, it is channel coded through the encoder 802, and the encoded signal is input to the modulator 803 to modulate with QPSK, QAM, or the like. The modulated signal is demultiplexed into a plurality of data streams using demultiplexer 804 to be converted into a plurality of OFDM symbols. Here, each demultiplexed data stream is converted into OFDM data through IFFTs 805 and 806, and the OFDM data is matched to the slot structure of FIG. 6 or 7 via preprocessors 807 and 808. The interval is inserted to output preprocessed OFDM data 601, 607, 701. The CP appenders 809 and 810 attach the heads 809 and 810 to the front end of the preprocessed OFDM data 601, 607 and 701 to generate preprocessed OFDM symbols.

Accordingly, the OFDM symbol generated according to the above process has a form in which no signal exists in the pilot and MAC signal parts. This NULL part is TDM multiplexed through the time division multiplexer 813 together with the MAC signal and the pilot signal generated by the MAC signal generator 811 and the pilot signal generator 812, respectively. Complete the structure. As described above, the present invention proposes a slot structure that maintains compatibility with the existing HRPD by generating OFDM symbols having a pilot and MAC signal parts having a NULL form. Hereinafter, a preprocessing process for making this type of OFDM symbol will be described.

FIG. 9 is a diagram illustrating a preprocessing method of an OFDM symbol according to an embodiment of the present invention, which illustrates a preprocessing process applied to the slot structure of FIG. 6.

In FIG. 9, OFDM data 901 having an IFFT length of 2 N _Data -N _CP chips is converted into preprocessed OFDM data 907 whose pilot and MAC signal portions are NULL. To this end, the front portion 902 of the N _Data - N _CP chip length is separated from the OFDM data 901 and copied to the OFDM data A portion 904, and the remaining portion 903 of the N _data chip length is copied to the OFDM data B portion ( 905). In addition, the interval between the OFDM data A 904 and the OFDM data B 905 is inserted into a NULL (906) section corresponding to the pilot and MAC signal size ( N _Pilot +2 N _MAC chip length) to be applied to the slot structure of FIG. 6. Generate preprocessed OFDM data 907.

FIG. 10 is a diagram illustrating a preprocessing method of an OFDM symbol according to another embodiment of the present invention, which shows a preprocessing process applied to the slot structure of FIG. 7.                     

In FIG. 10, the OFDM data 1001 having an IFFT of 4N _Data - N _CP chip length is converted into preprocessed OFDM data 1010 having a pilot and a MAC signal portion of NULL. To this end, the front portion 1002 of the length of the N _Data - N _CP chip is separated from the OFDM data 1001 and copied to the OFDM data A portion 1005, and the middle portion 1003 of the 2 N _Data chip length is copied to the OFDM data B portion. Copy to (1006). Then, the back portion 1004 of the length of the N _data chip is copied to the OFDM data C portion 1007. And between the OFDM data A 1005 and the B portion 1006 and between the OFDM data B 1006 and the C 1007, NULL (1008, N ) equal to pilot and MAC signal sizes ( N _Pilot +2 N _MAC chip length), respectively. 1009 is inserted to generate preprocessed OFDM data 1010 applied to the slot structure of FIG.

Hereinafter, an embodiment in which a linear combined preprocessing scheme is introduced into OFDM symbol preprocessing according to the present invention will be described with reference to FIGS. 11 and 12.

11 is a block diagram illustrating a configuration of a base station transmitter using a linear combined preprocessing scheme for OFDM symbol preprocessing according to the present invention. The base station transmitter of FIG. 11 is different from the base station transmitter of FIG. 8 in which the preprocessor is applied after the IFFT. It is characterized in that the preprocessor was applied previously.

In FIG. 11, when data to be transmitted from the data generator 1101 is transmitted, it is channel-coded through the encoder 1102, and the coded signal is input to the modulator 1103 to modulate QPSK, QAM, or the like. The modulated signal is demultiplexed into a plurality of data streams through the demultiplexer 1104 to be converted into a plurality of OFDM symbols. Here, each demultiplexed data stream is preprocessed through the linear combination preprocessors 1105 and 1106 and then converted into OFDM data through the IFFTs 1107 and 1108.

In this case, the linear combination preprocessors 1105 and 1106 each have a form of OFDM data in which pilot and MAC signal parts such as 601, 607 of FIG. 6 and 701 of FIG. 7 are preprocessed to NULL after IFFT conversion. . That is, the linear combination preprocessors 1105 and 1106 perform a process to make the desired position NULL in the IFFT process. The CP appenders 1109 and 1110 attach the head to the preprocessed OFDM data to generate OFDM symbols.

Accordingly, the OFDM symbol generated according to the above process has a form in which no signal exists in the pilot and MAC signal parts. This NULL part is TDM multiplexed through the time division multiplexer 1113 together with the MAC signal and the pilot signal generated by the MAC signal generator 1111 and the pilot signal generator 1112, respectively. Complete the structure.

FIG. 12 illustrates the process of deriving the linear combination preprocessing of FIG. 11. For example, FIG. 12 illustrates the structure of OFDM data preprocessed through the preprocessing method of FIG. 6. In FIG. 12, OFDM data A 1202 and B 1204 are illustrated. ) Are denoted by M _A and M _B , and the size of the NULL portion 1203 therebetween is denoted by M _C. And the total size of the preprocessed OFDM data is denoted by M. In order for the OFDM data of FIG. 12 to have the same shape as that of FIG. 6, M _A , M _B , M _C , and M must be defined as shown in Equation 1 below.

Write the data stream to be transmitted as vector S, the linear combination preprocessing as G _PRE , and IFFT as F. Here, the size of S is MM _C , G _PRE is a matrix of size M × (MM _C ), and F is an M × M matrix satisfying Equation 2 below.

According to FIG. 11, preprocessed OFDM data is obtained by preprocessing S and IFFT. When the pre-processed OFDM data is expressed as a vector X of M size, the process of obtaining X is shown in Equation 3 below. X has a value of 0 during the M _C size in the middle as shown in FIG. 12. Accordingly, if the OFDM data A portion is denoted as a vector of M _A size and the OFDM data B portion is denoted as a vector X _B of M _B size, the remaining portion may be expressed as a zero vector 0 of M _C size. Equation 3 below represents X in this manner.

However, the part which produces zero vector 0 is obtained through the sub-matrix from M _{A + 1} th row to M ₁ + M _C th row of IFFT F. This operation is expressed again as in Equation 4 below.

Regardless of S, in order to satisfy Equation 4, F _SUB G _PRE = 0. Therefore, G _PRE must be an element of null space of F _SUB . Here, looking at how to configure the G _PRE , F _SUB Singular Value Decomposition is expressed as shown in Equation 5 below.

Where I _MAC is an identity matrix of size M _C × M _C ,

O _{MC ㅧ (M-MC)} is a matrix of size M _C × (MM _C ). When F _SUB is decomposed as shown in Equation 5, G _PRE can be obtained as shown in Equation 6.

In Equation 6, the matrix V _SUB is a _sub- matrix from the M _C + 1th column to the last column (Mth column) of the matrix V obtained by the non-normal value decomposition in Equation 5, and A is An arbitrary matrix satisfying Trace (AA ^H ) = 1. The condition A, Trace (AA ^H ) = 1, is intended to prevent the effect of increasing the power of the signal through the application of G _PRE and, in practice, does not need to be considered when designed with an amplifier. According to Equation 5, the singular values corresponding to the matrix V _SUB are all zero. Therefore, G _PRE made as shown in Equation 6 belongs to the zero space of F _SUB .

Extending the method of making the linear combination preprocessor F _SUB described above, it is applicable not only to the form having one NULL section as shown in FIG. 6, but also to the form having two or more NULL sections as shown in FIG. 7. When defining the sub-matrix F _SUB , taking the rows corresponding to the zero portion of X from the matrix F can generate preprocessed OFDM data in the form of any position, size, and number of NULLs. have.

As described above, according to the present invention, there is provided a pre-processing method for OFDM symbol transmission that efficiently supports a broadcast service and a multicast service while maintaining compatibility with a wireless packet mobile communication system having a slot structure of an HPRD scheme. A base station transmission apparatus using the same can be provided.

In addition, the present invention provides a new OFDM symbol preprocessing scheme that allows the OFDM symbol size to exceed the size of the data field allowed in the existing HRPD slot structure while maintaining compatibility with the HRPD slot structure. It is easy to provide a broadcast service with high transmission efficiency.

Claims (11)

A preprocessing method for OFDM symbol transmission in an Orthogonal Frequency Division Multiplexing (OFDM) wireless packet mobile communication system for transmitting a forward packet through a time slot having the same pilot and MAC signal intervals as a general wireless packet mobile communication system, Dividing the OFDM data included in the inverse fast Fourier transformed OFDM symbol into at least two sections; Inserting a null interval into a region between the divided OFDM data; The pilot and MAC signals are copied to an area corresponding to the null period in the time slot. delete The method of claim 1, And at least one OFDM symbol is carried in a plurality of half-slot periods forming the time slot. The method of claim 1, And one OFDM symbol carried in one slot section of the time slot. The method of claim 1, And one OFDM symbol carried in a half slot section of the time slot. The method of claim 1, And copying data having a predetermined chip length to the beginning of the time slot at the rear of the OFDM data. The method of claim 5, And a head of a predetermined chip length copied from the rear of the OFDM data is attached to each head of the half slot section. In the Orthogonal Frequency Division Multiplexing (OFDM) wireless packet mobile communication system, which transmits a forward packet through a time slot having the same pilot and MAC signal intervals as in a conventional wireless packet mobile communication system, demultiplexing modulated data into multiple data streams A base station transmitter comprising a demultiplexer, a MAC signal generator, and a pilot signal generator, A plurality of inverse fast Fourier transformers for converting the plurality of data streams into OFDM data, respectively; A plurality of preprocessors for dividing the OFDM data into at least two sections and inserting a null section between the divided OFDM data; A plurality of head attachments for outputting OFDM symbols by attaching a head to the front of the OFDM data; A multiplexer for time-division multiplexing the plurality of OFDM symbols and the MAC signal and the pilot signal, and outputting the same; And the multiplexer multiplexes the pilot and MAC signals in a region corresponding to the null period in the time slot. delete In the Orthogonal Frequency Division Multiplexing (OFDM) wireless packet mobile communication system, which transmits a forward packet through a time slot having the same pilot and MAC signal intervals as in a conventional wireless packet mobile communication system, demultiplexing modulated data into multiple data streams A base station transmitter comprising a demultiplexer, a MAC signal generator, and a pilot signal generator, A plurality of linear combination preprocessors that designate positions at which null intervals are inserted after inverse fast Fourier transform at a predetermined position of the data stream; A plurality of inverse fast Fourier transformers for converting the data streams into OFDM data; A plurality of head attachments for outputting OFDM symbols by attaching a head to the front of the OFDM data; A multiplexer for time-division multiplexing the plurality of OFDM symbols and the MAC signal and the pilot signal, and outputting the same; And the multiplexer multiplexes the pilot and MAC signals in a region corresponding to the null period in the time slot. delete

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