KR20040035294A - Multi-carrier transmission system capable of improving receiving efficiency of multi-carrier receiving system and a method thereof - Google Patents
Multi-carrier transmission system capable of improving receiving efficiency of multi-carrier receiving system and a method thereof Download PDFInfo
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- KR20040035294A KR20040035294A KR1020020064082A KR20020064082A KR20040035294A KR 20040035294 A KR20040035294 A KR 20040035294A KR 1020020064082 A KR1020020064082 A KR 1020020064082A KR 20020064082 A KR20020064082 A KR 20020064082A KR 20040035294 A KR20040035294 A KR 20040035294A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2626—Arrangements specific to the transmitter only
- H04L27/2627—Modulators
- H04L27/2634—Inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators in combination with other circuits for modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
- H04L1/0041—Arrangements at the transmitter end
- H04L1/0042—Encoding specially adapted to other signal generation operation, e.g. in order to reduce transmit distortions, jitter, or to improve signal shape
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
- H04L25/03019—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
- H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
- H04N21/238—Interfacing the downstream path of the transmission network, e.g. adapting the transmission rate of a video stream to network bandwidth; Processing of multiplex streams
- H04N21/2383—Channel coding or modulation of digital bit-stream, e.g. QPSK modulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
- H04N21/438—Interfacing the downstream path of the transmission network originating from a server, e.g. retrieving encoded video stream packets from an IP network
- H04N21/4382—Demodulation or channel decoding, e.g. QPSK demodulation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/38—Transmitter circuitry for the transmission of television signals according to analogue transmission standards
- H04N5/40—Modulation circuits
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Abstract
Description
본 발명은 다중반송파 전송시스템 및 그 전송방법에 관한 것으로서, 보다 상세하게는, 다중반송파 수신시스템의 신호처리속도를 향상시킬 수 있는 다중반송파 전송시스템 및 그 전송방법에 관한 것이다.The present invention relates to a multi-carrier transmission system and a transmission method thereof, and more particularly, to a multi-carrier transmission system and a transmission method that can improve the signal processing speed of the multi-carrier reception system.
다중 반송파 변조 방식의 일종인 OFDM(Orthogonal Frequency Division Multiplexing) 방식은, 멀티패스(multi-path) 및 이동수신 환경에서 우수한 성능을 갖는다.Orthogonal Frequency Division Multiplexing (OFDM), which is a type of multicarrier modulation, has excellent performance in multipath and mobile reception environments.
OFDM 방식은 상호 직교성을 갖는 복수의 반송파를 사용하여 주파수 이용효율을 높이는 방식으로, 유무선 채널에서 다중 반송파(Multi-Carrier)를 사용하여, 고속 데이터 전송에 적합한 방식이다. 다중경로 페이딩을 갖는 무선통신채널에서 심벌주기가 짧은 고속 데이터 전송시 단일반송파(Single Carrier) 방식을 사용하게 되면 심벌간 간섭이 더욱 심해지기 때문에 수신단의 복잡도가 크게 증가하는 반면, 다중반송파 방식의 경우에는 데이터 전송속도를 그대로 유지하면서 각 부반송파에서의 심벌주기를 부반송파의 수만큼 확장시킬 수 있기 때문에 하나의 탭을 갖는 간단한 등화기로 다중경로에 의한 심각한 주파수 선택적 페이딩 채널을 잘 대처할 수 있다.The OFDM method improves frequency utilization efficiency by using a plurality of carriers having mutual orthogonality, and is a method suitable for high-speed data transmission using a multi-carrier in a wired or wireless channel. In the case of a high-speed data transmission with a short symbol period in a wireless communication channel having multipath fading, when the single carrier method is used, the inter-symbol interference becomes more severe, whereas the complexity of the receiver is greatly increased. Since the symbol period in each subcarrier can be extended by the number of subcarriers while maintaining the data rate, a simple equalizer with one tap can cope with severe frequency selective fading channels by multipath.
OFDM 방식에서는 상호 직교성을 갖는 복수의 반송파를 사용함으로 주파수 이용효율이 높아지고 송수신단에서 이러한 복수의 반송파를 변복조하는 과정은 각각 IDFT와 DFT를 수행한 것과 같은 결과의 IFFT와 FFT를 사용하여 고속으로 구현할 수 있다. OFDM 방식은 지상파 디지털 오디오 방송 또는 지상파 디지털 비디오 방송의 표준 방식으로 채택되고 있다.In the OFDM method, the frequency utilization efficiency is increased by using a plurality of carriers having mutual orthogonality, and the process of modulating and demodulating the plurality of carriers at the transmitting and receiving end can be implemented at high speed by using the resultant IFFT and FFT. Can be. The OFDM method is adopted as a standard method of terrestrial digital audio broadcasting or terrestrial digital video broadcasting.
디지털 지상파 DTV(Digital Television) 방송에 대한 표준 중의 하나인 DMB-T(Terrestrial Digital Multimedia Television Broadcasting)는 TDS-OFDM(Time Domain Synchronous-Orthogonal Frequence Division Multiplexing) 전송방식을 사용한다. TDS-OFDM 전송방식은 시간영역에 송신기와 수신기 간에 동기를 얻기 위한 동기정보인 PN(Pseudo Noise)시퀀스를 삽입하는 것을 특징으로 한다.Terrestrial Digital Multimedia Television Broadcasting (DMB-T), one of the standards for digital terrestrial digital television (DTV) broadcasting, uses TDS-OFDM (Time Domain Synchronous-Orthogonal Frequency Division Multiplexing) transmission method. The TDS-OFDM transmission method is characterized by inserting a PN (Pseudo Noise) sequence, which is synchronization information for obtaining synchronization between a transmitter and a receiver in a time domain.
도 1은 DMB-T 표준에 따른 다중반송파 전송시스템의 개략적인 블록도이다. 도면을 참조하면, 다중반송파 전송시스템은 시스템정보삽입부(5), IDFT(Inveres discrete fourier transform)부(10), GI(Guard Interval : 보호구간)삽입부(20), PN(Pseudo Noise : 의사잡음열)정보삽입부(30), 및 성형필터링부(40)를 구비한다.1 is a schematic block diagram of a multicarrier transmission system according to the DMB-T standard. Referring to the drawings, a multi-carrier transmission system includes a system information insertion unit 5, an IDFT (Inveres discrete fourier transform) unit 10, a GI (Guard Interval) insertion unit 20, PN (Pseudo Noise) pseudo Noise string) information insertion unit 30, and shaping filtering unit 40.
다중반송파 전송시스템은 다중반송파 전송시스템에 전송하기 위하여, 주파수 영역의 전송신호에 대한 에러를 보정하기 위한 인코딩을 수행하며, 코딩된 데이터를 QPSK, 16QAM, 64QAM 방식 등으로 맵핑한다.In order to transmit the multicarrier transmission system, the multicarrier transmission system performs encoding to correct an error of a transmission signal in a frequency domain, and maps the coded data in a QPSK, 16QAM, 64QAM scheme, and the like.
시스템정보삽입부(5)는 맵핑된 전송신호에 시스템정보를 삽입한다. 시스템정보가 삽입된 전송신호는 IDFT부(10)로 전송되며, IDFT부(10)는 수신된 전송신호를 시간영역으로 변조하여 시간영역의 OFDM신호를 형성한다.The system information insertion unit 5 inserts system information into the mapped transmission signal. The transmission signal in which the system information is inserted is transmitted to the IDFT unit 10, and the IDFT unit 10 modulates the received transmission signal into the time domain to form an OFDM signal in the time domain.
GI삽입부(20)는 멀티패스 환경에서의 ISI(Inter syambol Interference : 심볼간의 간섭)를 방지하기 위해 시간영역으로 형성된 OFDM신호에 보호구간을 삽입한다. 이때, 보호구간(Guard Interval : GI)은 OFDM신호의 뒤쪽 일부분을 복사한 것이며, GI삽입부(20)는 복사된 보호구간을 OFDM신호의 앞에 삽입한다.The GI insertion unit 20 inserts a guard interval into an OFDM signal formed in the time domain to prevent ISI (Inter-Symbol Interference) in a multipath environment. At this time, the guard interval (GI) is a copy of the rear part of the OFDM signal, the GI insertion unit 20 inserts the copied guard interval in front of the OFDM signal.
상기한 시스템정보는 IDFT부(10)에 의해 변조되는 전송신호의 길이모드정보,보호구간에 대한 길이모드정보, 전송신호의 맵핑모드에 대한 정보, 전송신호의 프레임 순서에 대한 정보, TPS정보 중 적어도 어느 하나를 포함하는 정보를 말한다. 여기서, TPS정보는 QAM 성상도 정보, 계층(hierarchy)정보, 및 이너코드율(inner code rate)에 대한 정보를 포함한다.The above system information includes length mode information of the transmission signal modulated by the IDFT unit 10, length mode information for the protection interval, information on the mapping mode of the transmission signal, information on the frame order of the transmission signal, and TPS information. Refers to information including at least one. Here, the TPS information includes QAM constellation information, hierarchy information, and information about an inner code rate.
PN정보삽입부(30)는 PN정보발생부(도시하지 않음)에 의해 발생된 의사잡음열(Psuedo Noise Sequence)정보를 OFDM신호에 삽입된 보호구간의 앞에 삽입한다. 여기서, 의사잡음열정보는 다중반송파 전송시스템에 대한 다중반송파 수신시스템의 동기를 위한 동기정보이며, 소정 갯수의 심볼이 연속적으로 나열된 심볼트레인(symbol train)으로 이루어진다. 이때, 하나의 심볼은 2비트에 해당되는 크기를 갖도록 구현된다. 그러나, 심볼의 크기는 이에 한정된 것은 아니며, 4비트 또는 8비트에 해당되는 크기를 갖도록 구현될 수도 있다. 의자잡음열정보는 랜덤(random)한 노이즈가 아니라 랜덤해 보이지만 규칙성을 갖는 1과 0의 연속적인 시퀀스이다. 또한, 의사잡음열정보는 2M-1개의 심볼로 이루어지며, 주기적으로 반복된다. 이때, M은 자연수로서, PN정보발생부의 레지스터의 수를 나타낸다.The PN information insertion unit 30 inserts pseudo noise sequence information generated by the PN information generation unit (not shown) in front of the guard interval inserted into the OFDM signal. Here, the pseudo noise string information is synchronization information for synchronization of the multicarrier reception system with respect to the multicarrier transmission system, and is composed of a symbol train in which a predetermined number of symbols are continuously arranged. At this time, one symbol is implemented to have a size corresponding to 2 bits. However, the size of the symbol is not limited thereto and may be implemented to have a size corresponding to 4 bits or 8 bits. The chair noise string information is not random noise but a continuous sequence of 1's and 0's that look random but have regularity. In addition, the pseudo noise string information is composed of 2 M -1 symbols, and is repeated periodically. At this time, M is a natural number and represents the number of registers of the PN information generator.
성형필터링부(40)는 OFDM신호에 삽입된 보호구간 및 의사잡음열정보의 펄스 성형을 위한 필터링을 수행한다. 성평필터링부(40)에 의해 보호구간 및 의사잡음열정보가 필터링된 OFDM신호는 안테나(50)를 통해 송출된다.The shaping filter 40 performs filtering for pulse shaping the guard interval and the pseudo noise string information inserted into the OFDM signal. The OFDM signal from which the guard period and the pseudo noise string information are filtered by the gender filtering unit 40 is transmitted through the antenna 50.
도 2는 도 1에 의한 전송신호의 프레임 구조를 도시한 도면이다. 도면을 참조하면, 다중반송파 수신시스템으로 전송되는 전송신호는 시간영역의 OFDM신호, 보호구간, 및 동기신호(frame sync)로 이루어진다. 여기서, OFDM신호는 주파수 영역에서 전송신호의 심볼들 사이에 삽입된 시스템정보 즉, FGN(Frame Group Number : 프레임 순서정보) 및 TPS(Transmission Parameter Signal)를 포함하는 것으로 도시하였다.FIG. 2 is a diagram illustrating a frame structure of a transmission signal according to FIG. 1. Referring to the drawings, a transmission signal transmitted to a multi-carrier reception system is composed of an OFDM signal, a guard interval, and a frame sync in the time domain. Here, the OFDM signal is shown to include system information inserted between symbols of the transmission signal in the frequency domain, that is, frame group number (FGN) and transmission parameter signal (TPS).
또한, 동기신호는 의사잡음열정보, 프리앰블(preamble), 및 포스트앰블(postamble)로 이루어진다. 여기서, 의사잡음열정보는 255개의 심볼로 이루어진 것으로 도시하였다. 프리앰블 및 포스트앰블은 다중반송파 수신시스템의 채널 추정 및 등화성능을 향상시키기 위해 부가되는 것으로서, 프리앰블은 PN발생부에 의해 발생된 의사잡음열정보의 심볼트레인 중, 뒤쪽의 일부분을 복사하여 의사잡음열정보의 앞에 부가한 것이며, 포스트앰블은 의사잡음열정보의 심볼트레인 중 앞쪽의 일부분을 복사하여 의사잡음열의 뒤에 부가한 것이다.In addition, the synchronization signal includes pseudo noise string information, a preamble, and a postamble. Here, the pseudo noise column information is illustrated as being composed of 255 symbols. The preamble and postamble are added to improve the channel estimation and equalization performance of the multicarrier reception system. The preamble is a pseudo noise sequence by copying a part of the rear part of the symbol train of the pseudo noise sequence information generated by the PN generator. It is added to the front of the information, and the postamble is a copy of the front part of the symbol train of the pseudo noise string information and added to the back of the pseudo noise string.
그런데, 종래의 기술에 따른 다중반송파 전송시스템에서 동기신호에 삽입하는 프리앰블 및 포스트앰블은, 일반적으로 고려중인 고스트 범위에 비해 짧기 때문에 다중반송파 수신시스템의 성능향상 정도가 크지 않다. 특히, 다중반송파 수신시스템은 일정 시간동안의 시간영역의 신호처리나 IDFT를 수행한 후에 주파수 영역에서 삽입된 시스템정보를 통해 부가정보를 얻어야 하므로, 전체적인 신호처리를 수행하는 속도가 저하되는 문제점이 있다.However, since the preamble and postamble inserted into the synchronization signal in the conventional multicarrier transmission system are shorter than the ghost range under consideration, the performance improvement of the multicarrier reception system is not large. In particular, the multi-carrier reception system needs to obtain additional information through system information inserted in the frequency domain after performing signal processing or IDFT in a time domain for a predetermined time, so that the overall signal processing speed is reduced. .
본 발명은 상기와 같은 문제점을 해결하기 위하여 창안된 것으로서, 다중반송파 수신시스템의 신호처리 속도를 향상시킬 수 있는 다중반송파 전송시스템 및그 전송방법을 제공하는데 그 목적이 있다.The present invention has been made to solve the above problems, and an object thereof is to provide a multi-carrier transmission system and a method for transmitting the same, which can improve the signal processing speed of a multi-carrier reception system.
도 1은 DMB-T 표준에 따른 다중반송파 전송시스템의 개략적인 블록도,1 is a schematic block diagram of a multicarrier transmission system according to the DMB-T standard;
도 2는 도 1에 의한 전송신호의 프레임 구조를 도시한 도면,2 is a view illustrating a frame structure of a transmission signal according to FIG. 1;
도 3은 본 발명에 따른 다중반송파 전송시스템의 개략적인 블록도,3 is a schematic block diagram of a multicarrier transmission system according to the present invention;
도 4는 도 3에 의한 다중반송파 전송방법을 나타낸 흐름도, 그리고4 is a flowchart illustrating a multicarrier transmission method according to FIG. 3; and
도 5는 도 3에 의한 전송신호의 프레임 구조를 도시한 도면이다.FIG. 5 is a diagram illustrating a frame structure of a transmission signal according to FIG. 3.
* 도면의 주요부분에 대한 부호의 설명 *Explanation of symbols on the main parts of the drawings
5, 100 : 시스템정보 삽입부 10, 110 : IDFT부5, 100: System information insertion section 10, 110: IDFT section
20, 120 : GI삽입부 30 : PN삽입부20, 120: GI insertion part 30: PN insertion part
130 : PN발생부 140 : 동기정보 형성부130: PN generating unit 140: synchronization information forming unit
141 : 부가정보 검색부 143 : 부가정보 복사부141: additional information search unit 143: additional information copy unit
150 : 동기정보 삽입부 40, 160 : 성형 필터링부150: synchronization information insertion unit 40, 160: molding filtering unit
상기의 목적을 달성하기 위한 본 발명에 따른 다중반송파 전송시스템은, 송신측과 수신측의 동기를 위한 의사잡음열정보를 OFDM신호에 삽입하여 전송하는 다중반송파 전송시스템에 있어서, 상기 OFDM신호의 심볼 간의 간섭을 억제하기 위해 상기 OFDM신호에 보호구간을 삽입하는 GI삽입부, 상기 의사잡음열정보를 발생하는 PN발생부, 상기 PN발생부에 의해 발생된 상기 의사잡음열정보에 시스템정보를 부가하여 동기정보를 형성하는 동기정보형성부, 및 상기 동기정보형성부에 의해 형성된 상기 동기정보를 상기 보호구간의 앞에 삽입하는 동기정보삽입부를 포함하는 것을 특징으로 한다.In the multi-carrier transmission system according to the present invention for achieving the above object, in the multi-carrier transmission system for inserting and transmitting pseudo-noise string information for synchronization of the transmitting side and the receiving side into the OFDM signal, the symbol of the OFDM signal In order to suppress the interference between the GI insertion unit for inserting the guard interval in the OFDM signal, the PN generator for generating the pseudo noise string information, the system information is added to the pseudo noise string information generated by the PN generator And a synchronization information insertion unit for forming synchronization information, and a synchronization information insertion unit for inserting the synchronization information formed by the synchronization information formation unit in front of the protection section.
바람직하게는, 상기 다중반송파 전송시스템은, 전송신호에 상기 시스템정보를 삽입하는 시스템정보삽입부, 및 상기 시스템정보삽입부에 의해 상기 시스템정보가 삽입된 상기 전송신호를 시간영역으로 변조하여 시간영역의 상기 OFDM신호를 형성하는 IDFT부를 더 포함한다.Preferably, the multicarrier transmission system includes a system information insertion unit for inserting the system information into a transmission signal, and a time domain by modulating the transmission signal into which the system information is inserted by the system information insertion unit into a time domain. And an IDFT unit for forming the OFDM signal.
여기서, 상기 시스템정보는 상기 IDFT부에 의해 변조되는 상기 전송신호에 대한 길이모드정보, 상기 보호구간에 대한 길이모드정보, 상기 전송신호의 맵핑모드에 대한 정보, 상기 전송신호의 프레임 순서에 대한 정보, 및 TPS정보 중 적어도 어느 하나를 포함한다.Here, the system information includes length mode information on the transmission signal modulated by the IDFT unit, length mode information on the protection interval, information on the mapping mode of the transmission signal, and information on the frame order of the transmission signal. And at least one of TPS information.
또한, 상기 동기정보형성부는, 상기 OFDM신호에서 상기 시스템정보를 검색하는 부가정보검색부, 및 검색된 상기 시스템정보를 복사하는 부가정보복사부를 포함하며, 상기 부가정보복사부에 의해 복사된 상기 시스템정보를 상기 의사잡음열정보에 부가하여 상기 동기정보를 형성한다. 이때, 상기 동기정보형성부는 복사된 상기 시스템정보를 상기 의사잡음열정보의 앞 및 상기 의사잡음열정보의 뒤 중, 적어도 어느 한 곳에 부가하여 상기 동기정보를 형성한다.The synchronization information forming unit may include an additional information searching unit for searching the system information in the OFDM signal, and an additional information copying unit for copying the retrieved system information. The system information copied by the additional information copying unit. Is added to the pseudo noise string information to form the synchronization information. In this case, the synchronization information forming unit adds the copied system information to at least one of the front of the pseudo noise string information and the back of the pseudo noise string information to form the synchronization information.
한편, 본 발명에 따른 다중반송파 전송시스템은, 송신측과 수신측의 동기를 위한 의사잡음열정보를 OFDM신호에 삽입하여 전송하는 다중반송파 전송방법에 있어서, 상기 OFDM신호의 심볼 간의 간섭을 억제하기 위해 상기 OFDM신호에 보호구간을 삽입하는 단계, 상기 의사잡음열정보를 발생하는 단계, 상기 의사잡음열발생단계에 의해 발생된 상기 의사잡음열정보에 시스템정보를 부가하여 동기정보를 형성하는 동기정보형성단계, 및 상기 동기정보 형성단계에 의해 형성된 상기 동기정보를 상기 보호구간의 앞에 삽입하는 동기정보삽입단계를 포함하는 다중반송파 전송방법을 제공한다.On the other hand, in the multi-carrier transmission system according to the present invention, in the multi-carrier transmission method for inserting and transmitting pseudo-noise sequence information for synchronization between the transmitting side and the receiving side into the OFDM signal, to suppress the interference between symbols of the OFDM signal Inserting a guard interval into the OFDM signal, generating the pseudo noise string information, and synchronizing information to form synchronization information by adding system information to the pseudo noise string information generated by the pseudo noise string generation step. And a synchronization information insertion step of inserting the synchronization information formed by the synchronization information formation step in front of the protection section.
이하, 첨부된 도면을 참조하여 본 발명을 보다 상세하게 설명한다.Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.
도 3은 본 발명에 따른 다중반송파 전송시스템의 개략적인 블록도이다. 도면을 참조하면, 다중반송파 전송시스템은 시스템정보삽입부(100), IDFT부(110), GI삽입부(120), PN발생부(130), 동기정보형성부(140), 동기정보삽입부(150), 및 성형필터링부(160)를 구비한다. 여기서, 동기정보형성부(140)는 부가정보검색부(141), 및 부가정보복사부(143)를 구비한다.3 is a schematic block diagram of a multicarrier transmission system according to the present invention. Referring to the drawings, a multicarrier transmission system includes a system information inserter 100, an IDFT unit 110, a GI inserter 120, a PN generator 130, a sync information forming unit 140, and a sync information inserter. 150, and a shaping filtering unit 160. Here, the synchronization information forming unit 140 includes an additional information searching unit 141 and an additional information copying unit 143.
도 4는 도 3에 의한 다중반송파 전송방법을 나타낸 흐름도이다. 도면을 참조하여 본 발명에 따른 다중반송파 전송시스템의 작용을 보다 상세하게 설명한다.4 is a flowchart illustrating a multicarrier transmission method according to FIG. 3. Referring to the drawings will be described in more detail the operation of the multi-carrier transmission system according to the present invention.
다중반송파 전송시스템은 다중반송파 전송시스템에 전송하기 위하여, 주파수 영역의 전송신호에 대한 에러를 보정하기 위한 인코딩을 수행하며, 코딩된 데이터를 QPSK, 16QAM, 64QAM 방식 등으로 맵핑한다.In order to transmit the multicarrier transmission system, the multicarrier transmission system performs encoding to correct an error of a transmission signal in a frequency domain, and maps the coded data in a QPSK, 16QAM, 64QAM scheme, and the like.
시스템정보삽입부(100)는 맵핑된 주파수 영역의 전송신호에 시스템정보를 삽입한다(S401). 시스템정보가 삽입된 전송신호는 IDFT부(110)로 전송되며, IDFT부(110)는 수신된 주파수 영역의 전송신호를 변조하여 시간영역의 OFDM신호를 형성한다(S403).The system information insertion unit 100 inserts system information into the mapped transmission signal of the frequency domain (S401). The transmission signal in which the system information is inserted is transmitted to the IDFT unit 110, and the IDFT unit 110 modulates the received transmission signal in the frequency domain to form an OFDM signal in the time domain (S403).
GI삽입부(120)는 멀티패스 환경에서의 ISI(Inter syambol Interference : 심볼간의 간섭)를 방지하기 위해 시간영역으로 형성된 OFDM신호에 보호구간을 삽입한다(S405). 이때, 보호구간(Guard Interval : GI)은 OFDM신호의 뒤쪽 일부분을 복사한 것이며, GI삽입부(20)는 복사된 보호구간을 OFDM신호의 앞에 삽입한다.The GI insertion unit 120 inserts a guard interval in the OFDM signal formed in the time domain to prevent ISI (Inter-Symbol Interference) in a multipath environment (S405). At this time, the guard interval (GI) is a copy of the rear part of the OFDM signal, the GI insertion unit 20 inserts the copied guard interval in front of the OFDM signal.
상기한 시스템정보는 IDFT부(110)에 의해 변조되는 전송신호의 길이모드정보, 보호구간에 대한 길이모드정보, 전송신호의 맵핑모드에 대한 정보, 전송신호의 프레임 순서에 대한 정보, TPS정보 중 적어도 어느 하나를 포함하는 정보를 말한다. 여기서, TPS정보는 QAM 성상도 정보, 계층(hierarchy)정보, 및 이너코드율(inner code rate)에 대한 정보를 포함한다.The system information includes length mode information of a transmission signal modulated by the IDFT unit 110, length mode information of a protection interval, information on a mapping mode of a transmission signal, information on a frame order of the transmission signal, and TPS information. Refers to information including at least one. Here, the TPS information includes QAM constellation information, hierarchy information, and information about an inner code rate.
한편, PN발생부(130)는 의사잡음열정보를 발생시킨다(S407). 의사잡음열정보는 다중반송파 전송시스템에 대한 다중반송파 수신시스템의 동기를 위한 동기정보이며, 소정 갯수의 심볼이 연속적으로 나열된 심볼트레인으로 이루어진다. 이때, 하나의 심볼은 2비트에 해당되는 크기를 갖도록 구현된다. 그러나, 심볼의 크기는이에 한정된 것은 아니며, 4비트 또는 8비트에 해당되는 크기를 갖도록 구현될 수도 있다. 의자잡음열정보는 랜덤(random)한 노이즈가 아니라 랜덤해 보이지만 규칙성을 갖는 1과 0의 연속적인 시퀀스이다. 또한, 의사잡음열정보는 2M-1개의 심볼로 이루어지며, 주기적으로 반복된다. 이때, M은 자연수로서, PN정보발생부의 레지스터의 수를 나타낸다.On the other hand, the PN generation unit 130 generates pseudo noise string information (S407). Pseudo-noise sequence information is synchronization information for synchronization of a multi-carrier reception system with respect to a multi-carrier transmission system, and consists of a symbol train in which a predetermined number of symbols are continuously arranged. At this time, one symbol is implemented to have a size corresponding to 2 bits. However, the size of the symbol is not limited thereto, and may be implemented to have a size corresponding to 4 bits or 8 bits. The chair noise string information is not random noise but a continuous sequence of 1's and 0's that look random but have regularity. In addition, the pseudo noise string information is composed of 2 M -1 symbols, and is repeated periodically. At this time, M is a natural number and represents the number of registers of the PN information generator.
동기정보형성부(140)에 구비된 부가정보검색부(141)는 OFDM신호에서 시스템정보를 검색한다(S409). 이때, 부가정보검색부(141)는 주파수 영역의 전송신호에 삽입된 시스템정보 중 의사잡음열정보에 부가하기 위한 시스템정보를 검색하며, 의사잡음열에 부가되는 부가정보는 주파수 영역의 전송신호에 삽입된 시스템정보 중 적어도 하나를 포함하는 시스템정보이다.The additional information search unit 141 included in the synchronization information forming unit 140 searches for system information in the OFDM signal (S409). At this time, the additional information search unit 141 searches for system information to be added to the pseudo noise string information among the system information inserted into the transmission signal in the frequency domain, and the additional information added to the pseudo noise string is inserted into the transmission signal in the frequency domain. System information including at least one of the system information.
부가정보복사부(143)는 부가정보검색부(141)에 의해 검색된 시스템정보를 복사한다(S411). 동기정보형성부(140)는 부가정보복사부(143)에 의해 복사된 시스템정보를 PN발생부(130)에 의해 발생된 의사잡음열정보에 부가하여 동기정보를 형성한다(S413). 이때, 동기정보형성부(140)는 부가정보복사부(143)에 의해 복사된 시스템정보를 의사잡음열정보의 앞에 부가하거나 뒤에 부가할 수 있으며, 의사잡음열정보의 앞과 뒤에 모두 부가할 수도 있다.The additional information copying unit 143 copies the system information searched by the additional information searching unit 141 (S411). The synchronization information forming unit 140 forms the synchronization information by adding the system information copied by the additional information copying unit 143 to the pseudo noise string information generated by the PN generation unit 130 (S413). In this case, the synchronization information forming unit 140 may add the system information copied by the additional information copying unit 143 before or after the pseudo noise string information, and may add both before and after the pseudo noise string information. have.
도 5는 도 3에 의한 전송신호의 프레임 구조를 도시한 도면이다. 도면을 참조하면, 다중반송파 수신시스템으로 전송되는 전송신호는 시간영역의 OFDM신호, 보호구간, 및 동기신호로 이루어진다. 여기서, OFDM신호는 주파수 영역에서 전송신호의 심볼들 사이에 삽입된 시스템정보 즉, FGN정보 및 TPS정보를 포함하는 것으로 도시하였으며, 부가정보는 의사잡음열정보의 앞과 뒤에 모두 부가된 것으로 도시하였다.FIG. 5 is a diagram illustrating a frame structure of a transmission signal according to FIG. 3. Referring to the drawings, a transmission signal transmitted to a multi-carrier reception system is composed of an OFDM signal, a guard interval, and a synchronization signal in a time domain. Here, the OFDM signal is shown as including the system information, that is, the FGN information and the TPS information inserted between the symbols of the transmission signal in the frequency domain, and the additional information is shown as added before and after the pseudo-noise sequence information. .
동기정보삽입부(150)는 동기정보형성부(140)에 의해 형성된 동기정보를 OFDM신호에 삽입된 보호구간의 앞에 삽입한다(S415).The synchronization information inserting unit 150 inserts the synchronization information formed by the synchronization information forming unit 140 before the protection period inserted into the OFDM signal (S415).
성형필터링부(160)는 OFDM신호에 삽입된 보호구간 및 동기정보의 펄스 성형을 위해 OFDM신호를 성형 필터링한다(S417). 성평필터링부(160)에 의해 성형 필터링된 OFDM신호는 안테나(170)를 통해 OFDM 수신시스템에 전송된다(S419). 이로써, 본 발명에 따른 다중반송파 전송시스템의 다중반송파 전송은 종료된다.The shaping filter 160 shaping and filtering the OFDM signal for pulse shaping the guard interval and the synchronization information inserted in the OFDM signal (S417). The OFDM signal shaping-filtered by the gender filtering unit 160 is transmitted to the OFDM receiving system through the antenna 170 (S419). As a result, the multicarrier transmission of the multicarrier transmission system according to the present invention is terminated.
본 발명에 따른 다중반송파 전송시스템은 시스템정보를 의사잡음열정보에 부가하여 다중반송파 수신시스템에 전송하기 때문에, 다중반송파 수신시스템은 DFT에 대한 길이모드, 보호구간에 대한 길이모드, 성상모드 등의 정보를 알기 위한 수신신호의 누적시간이나 추가적인 신호처리 과정을 줄일 수 있게 되며, 따라서 DFT를 수행하기 이전의 시간영역에서 동기획득을 할 수 있게 되어 빠른 신호처리를 수행할 수 있게 된다.Since the multi-carrier transmission system according to the present invention transmits system information to the multi-carrier reception system in addition to pseudo-noise string information, the multi-carrier reception system includes a length mode for a DFT, a length mode for a guard interval, and a constellation mode. It is possible to reduce the cumulative time or additional signal processing of the received signal to know the information. Therefore, the synchronization can be acquired in the time domain before performing the DFT, so that fast signal processing can be performed.
본 발명에 따른 다중반송파 전송시스템은 다중반송파 수신시스템이 DFT를 수행하기 이전의 시간영역에서 동기획득을 할 수 있게 함으로써, 다중반송파 수신시스템의 수신성능을 향상시킬 수 있도록 한다.The multi-carrier transmission system according to the present invention enables the multi-carrier reception system to acquire the synchronization in the time domain before performing the DFT, thereby improving the reception performance of the multi-carrier reception system.
이상에서는 본 발명의 바람직한 실시예에 대해서 도시하고 설명하였으나, 본발명은 상술한 특정의 실시예에 한정되지 아니하며, 청구범위에서 청구하는 본 발명의 요지를 벗어남이 없이 당해 발명이 속하는 기술분야에서 통상의 지식을 가진 자라면 누구든지 다양한 변형 실시가 가능한 것은 물론이고, 그와 같은 변경은 청구범위 기재의 범위 내에 있게 된다.While the above has been shown and described with respect to preferred embodiments of the present invention, the invention is not limited to the specific embodiments described above, it is usually in the art to which the invention belongs without departing from the spirit of the invention claimed in the claims. Anyone skilled in the art can make various modifications, as well as such modifications are within the scope of the claims.
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