KR20040035287A - OFDM transmission system capable of reducing synchronous obtaining timing and a method thereof - Google Patents

OFDM transmission system capable of reducing synchronous obtaining timing and a method thereof Download PDF

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KR20040035287A
KR20040035287A KR1020020064075A KR20020064075A KR20040035287A KR 20040035287 A KR20040035287 A KR 20040035287A KR 1020020064075 A KR1020020064075 A KR 1020020064075A KR 20020064075 A KR20020064075 A KR 20020064075A KR 20040035287 A KR20040035287 A KR 20040035287A
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noise
ofdm
ofdm signal
information
sequence information
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KR1020020064075A
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KR100852277B1 (en
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권용식
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삼성전자주식회사
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Priority to CNB031103715A priority patent/CN100518027C/en
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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
    • H04L27/264—Pulse-shaped multi-carrier, i.e. not using rectangular window
    • H04L27/26412—Filtering over the entire frequency band, e.g. filtered orthogonal frequency-division multiplexing [OFDM]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J13/00—Code division multiplex systems
    • H04J13/0007—Code type
    • H04J13/0022—PN, e.g. Kronecker
    • 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
    • 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
    • H04L27/2602—Signal structure
    • H04L27/2605—Symbol extensions, e.g. Zero Tail, Unique Word [UW]
    • H04L27/2607—Cyclic extensions

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)

Abstract

PURPOSE: An OFDM transmission system for shortening a synchronization period of an OFDM reception system and a transmitting method thereof are provided to shorten a synchronous period by inserting pseudo noise sequences into all parts of OFDM signals. CONSTITUTION: An OFDM transmission system for shortening a synchronization period of an OFDM reception system includes a GI insertion unit(120), a first PN insertion unit(135), a second PN insertion unit(145), and a shaping/filtering unit(150). The GI(Guard Interval) insertion unit(120) inserts a guard interval into an OFDM signal to restrict interference between symbols of OFDM signals. The first PN(Pseudo Noise) insertion unit(135) inserts the first pseudo noise sequence between the guard intervals. The second PN insertion unit(145) inserts the second pseudo noise sequence. The shaping/filtering unit(150) shapes and filters the OFDM signals including the first and the second pseudo noise sequences.

Description

ＯＦＤＭ 수신시스템의 동기획득시간을 단축시킬 수 있는 ＯＦＤＭ 전송시스템 및 그 방법{ＯＦＤＭ transmission system capable of reducing synchronous obtaining timing and a method thereof}ODP transmission system capable of shortening the synchronous acquisition time of the OFM reception system and method thereof

본 발명은 OFDM 전송시스템 및 그 방법에 관한 것으로서, 보다 상세하게는, OFDM 수신시스템의 동기 획득시간을 줄일 수 있는 OFDM 전송시스템 및 그 방법에 관한 것이다.The present invention relates to an OFDM transmission system and a method thereof, and more particularly, to an OFDM transmission system and method that can reduce the synchronization acquisition time of the OFDM reception system.

OFDM(Orthogonal Frequency Division Multiplexing : 직교 주파수 분할 다중)이란 대역폭당 전송속도의 향상과 멀티패스(multi-path) 간섭을 방지하는 디지털 변조방식을 말한다. OFDM의 특징은 가지는 수백개의 반송파(서브캐리어)를 사용하는 다중반송파 변조방식이라는 점이다. 즉, OFDM은 전체 전송대역을 다수의 협대역 직교 부채널로 분할하고, 각 부채널 별로 QAM(Quadrature Amplitude Modulation) 변조하여 데이터를 동시에 전송한다. 그 때문에 각각의 부채널 별로 전송되는 각 반송파의 주파수 성분이 서로 겹쳐 있어도 좋다.Orthogonal Frequency Division Multiplexing (OFDM) refers to a digital modulation scheme that improves transmission rate per bandwidth and prevents multipath interference. The characteristic of OFDM is that it is a multicarrier modulation scheme using several hundred carriers (subcarriers). That is, OFDM divides an entire transmission band into a plurality of narrowband orthogonal subchannels, modulates quadrature amplitude modulation (QAM) for each subchannel, and simultaneously transmits data. Therefore, the frequency components of the respective carriers transmitted for each subchannel may overlap each other.

또한, OFDM은 일반적인 주파수 분할 다중(FDM; Frequency Division Multiplexing)보다 훨씬 많은 반송파를 전송할 수 있기 때문에 주파수 이용률이 높아진다. OFDM은 이들 각각의 반송파에 직병렬 변환한 부호화 데이터를 할당하고, 할당된 데이터를 디지털 변조한다.In addition, since OFDM can transmit much more carriers than conventional Frequency Division Multiplexing (FDM), frequency utilization is increased. OFDM allocates encoded data obtained by performing serial-to-parallel conversion to each of these carriers, and digitally modulates the allocated data.

OFDM 송신기는 각각의 직교 부채널들로 전송되는 각 반송파의 주파수 영역을 IFFT(Inverse Fast Fourier Transform)에 의해 시간 영역으로 디지털 변조한다. 또한, OFDM 송신기는 전송되는 심볼 상호간의 간섭(Inter-Symbol Interference : ISI)을 줄이기 위해 보호구간(Guard Interval)을 추가하여 전송한다. OFDM 수신기는 수신된 전송신호에서 보호구간을 제거한 후, FFT(Fast Fourier Transform)에 의해 전송신호를 복조한다. 이러한 OFDM 변조방식은 지상파 디지털 오디오 방송 또는 지상파 디지털 비디오 방송의 표준 전송방식으로 채택되고 있다.The OFDM transmitter digitally modulates the frequency domain of each carrier transmitted on each orthogonal subchannel into the time domain by an inverse fast fourier transform (IFFT). In addition, the OFDM transmitter transmits by adding a guard interval in order to reduce inter-symbol interference (ISI). After removing the guard interval from the received transmission signal, the OFDM receiver demodulates the transmission signal by fast fourier transform (FFT). The OFDM modulation method is adopted as a standard transmission method of terrestrial digital audio broadcasting or terrestrial digital video broadcasting.

TDS-OFDM(Time Domain Synchronous-OFDM : 시간영역동기 OFDM)은 VOFDM(Vector Orthogonal Frequency Division Multiplexing), COFDM(Coded Orthogonal Frequency Division Multiplexing) 등과 함께 OFDM 방식중의 하나를 이룬다.Time Domain Synchronous-OFDM (TDS-OFDM) forms one of OFDM schemes together with Vector Orthogonal Frequency Division Multiplexing (VOFDM) and Coded Orthogonal Frequency Division Multiplexing (COFDM).

TDS-OFDM 전송시스템은, 시간영역동기를 이용하여 OFDM신호를 전송하며, 기 설정된 주파수 대역에 대해 할당된 OFDM 전송신호를 시간축을 따라 재 배열한다. 또한, TDS-OFDM 전송시스템은 시간축에 따라 형성된 OFDM 전송신호의 앞에 신호간의 간섭을 억제하기 위한 보호구간(Guard Interval : GI)을 삽입하고, 보호구간의 앞에 동기정보를 삽입하여 전송한다.The TDS-OFDM transmission system transmits an OFDM signal using time domain synchronization, and rearranges the OFDM transmission signal allocated for a predetermined frequency band along the time axis. In addition, the TDS-OFDM transmission system inserts a guard interval (GI) to suppress interference between signals in front of the OFDM transmission signal formed along the time axis, and transmits synchronization information before the guard interval.

도 1은 일반적인 TDS-OFDM 전송시스템을 개략적으로 도시한 블록도이다. 도면을 참조하면, TDS-OFDM 전송시스템은, IDFT(Inverse Discrete Fourier Transform)부(10), GI(Guard Interval)삽입부(20), PN(Pseudo Noise Sequence)삽입부(30), 및 성형필터링부(40)를 구비한다.1 is a block diagram schematically illustrating a general TDS-OFDM transmission system. Referring to the drawings, the TDS-OFDM transmission system includes an inverse discrete fourier transform (IDFT) unit 10, a guard interval (GI) insertion unit 20, a pseudo noise sequence (PN) insertion unit 30, and shaping filtering. The part 40 is provided.

IDFT부(10)는 주파수대역에 형성된 OFDM 전송신호를 시간축으로 재배열하는 역 이산 퓨리에변환(Inverse Discrete Fourier Transform)을 수행한다. GI삽입부(20)는 IDFT부(10)에 의해 역 이산 퓨리에변환된 OFDM 전송신호에 대해 이웃하는 OFDM 심볼들 간의 간섭을 억제하기 위한 보호구간(Guard Interval)을 삽입한다. PN삽입부(30)는 보호구간이 삽입된 OFDM 전송신호에 의사잡음열(PseudoNoise sequence : PN)정보를 삽입한다. 의사잡음열정보란, 전송된 OFDM 전송신호를 수신하는 OFDM 수신시스템에서 수신된 OFDM 전송신호의 동기 및 채널을 예측할 수 있도록 하는 동기정보를 말한다.The IDFT unit 10 performs an Inverse Discrete Fourier Transform for rearranging the OFDM transmission signals formed in the frequency band on the time axis. The GI inserting unit 20 inserts a guard interval for suppressing interference between neighboring OFDM symbols for the OFDM discrete signal inverse discrete Fourier transformed by the IDFT unit 10. The PN insertion unit 30 inserts pseudonoise sequence (PN) information into the OFDM transmission signal with the guard interval inserted. The pseudo noise string information refers to synchronization information for predicting synchronization and channel of an OFDM transmission signal received in an OFDM reception system that receives the transmitted OFDM transmission signal.

성형필터링부(40)는 PN삽입부(30)에 의해 의사잡음열정보가 삽입된 OFDM 전송신호를 성형 필터링한다. 성형 필터링된 OFDM 전송신호는 고주파 증폭되어 안테나(50)를 통해 송출된다.The shaping filtering unit 40 shaping filters the OFDM transmission signal into which the pseudo noise string information is inserted by the PN inserting unit 30. The shaping filtered OFDM transmission signal is a high frequency amplified signal transmitted through the antenna (50).

도 2는 도 1에 의한 OFDM 전송신호의 프레임 구조를 개략적으로 도시한 도면이다. 도면을 참조하면, TDS-OFDM 전송시스템에 따른 전송신호의 프레임 구조는 OFDM 신호, OFDM 신호의 앞 부분에 삽입된 보호구간(GI), 보호구간(GI)의 앞 부분에 삽입된 의사잡음열(PN)정보로 이루어진다. TDS-OFDM 수신시스템은 보호구간(GI) 앞 부분에 삽입된 의사잡음열(PN)정보를 이용하여 주파수동기, 심볼동기, 및 채널등화 등을 수행한다.FIG. 2 is a diagram schematically illustrating a frame structure of an OFDM transmission signal according to FIG. 1. Referring to the drawings, a frame structure of a transmission signal according to a TDS-OFDM transmission system includes an OFDM signal, a guard interval GI inserted at the front of the OFDM signal, and a pseudo noise string inserted at the front of the guard interval GI. PN) information. The TDS-OFDM receiving system performs frequency synchronization, symbol synchronization, and channel equalization using PN information inserted in front of the guard interval (GI).

그런데, TDS-OFDM 전송시스템에 따른 전송신호의 프레임 구조는 동기 획득을 위한 의사잡음열정보가 프레임의 일부분에만 삽입되어 있고 OFDM 신호의 부분에는 의사잡음열정보가 불연속된 구조를 이룬다. 따라서, TDS-OFDM 수신시스템은 주파수 동기와 심볼 타이밍 동기 등을 수신된 프레임의 일부 구간에서만 수행하므로, 프레임 전체에 대한 동기 획득을 수행하는데 시간이 많이 걸리는 문제점이 있다.However, in the frame structure of the transmission signal according to the TDS-OFDM transmission system, pseudo noise string information for synchronization acquisition is inserted only in a part of the frame, and pseudo noise string information is discontinuous in the portion of the OFDM signal. Therefore, since the TDS-OFDM receiving system performs frequency synchronization, symbol timing synchronization, and the like only in a partial period of the received frame, it takes a long time to perform synchronization acquisition for the entire frame.

본 발명은 상기와 같은 문제점을 해결하기 위하여 창안된 것으로서, OFDM 수신시스템에서의 동기획득 시간을 줄일 수 있는 OFDM 전송시스템 및 그 전송방법을제공하는데 그 목적이 있다.The present invention has been made to solve the above problems, and an object thereof is to provide an OFDM transmission system and a method for transmitting the same, which can reduce synchronization acquisition time in an OFDM reception system.

도 1은 일반적인 TDS-OFDM 전송시스템을 개략적으로 도시한 블록도,1 is a block diagram schematically showing a typical TDS-OFDM transmission system;

도 2는 도 1에 의한 OFDM 전송신호의 프레임 구조를 개략적으로 도시한 도면,2 is a view schematically showing a frame structure of an OFDM transmission signal according to FIG. 1;

도 3은 본 발명에 따른 OFDM 전송시스템을 개략적으로 도시한 도면,3 is a diagram schematically illustrating an OFDM transmission system according to the present invention;

도 4는 도 3에 의한 OFDM신호의 전송방법을 나타낸 흐름도, 그리고4 is a flowchart illustrating a method for transmitting an OFDM signal according to FIG. 3; and

도 5는 도 3에 의한 OFDM 전송신호의 프레임 구조를 개략적으로 도시한 도면이다.5 is a diagram schematically illustrating a frame structure of an OFDM transmission signal according to FIG. 3.

* 도면의 주요부분에 대한 부호의 설명 *Explanation of symbols on the main parts of the drawings

10, 110 : IDFT부 20, 120 : GI삽입부10, 110: IDFT unit 20, 120: GI insertion unit

30 : PN삽입부 130 : 제1 PN발생부30: PN insertion unit 130: first PN generating unit

135 : 제1 PN삽입부 140 : 제2 PN발생부135: first PN insertion unit 140: second PN generating unit

145 : 제2 PN삽입부 40, 150 : 성형 필터링부145: second PN insertion portion 40, 150: shaping filtering portion

상기의 목적을 달성하기 위한 본 발명에 다른 OFDM 전송시스템은, 송신측과 수신측의 동기를 위한 동기정보인 의사잡음열정보를 전송되는 OFDM신호에 삽입하여 전송하는 OFDM 전송시스템에 있어서, 상기 OFDM신호의 심볼 간의 간섭을 억제하기 위해 상기 OFDM신호에 보호구간을 삽입하는 GI삽입부, 상기 보호구간이 삽입된 상기 OFDM신호 및 상기 보호구간에 걸쳐 연속적인 제1의사잡음열정보를 삽입하는 제1PN삽입부, 상기 제1PN삽입부에 의해 상기 제1의사잡음열정보가 삽입된 상기 보호구간 앞 및 상기 제1의사잡음열정보의 앞에 걸쳐 제2의사잡음열정보를 삽입하는 제2PN삽입부, 및 상기 보호구간, 상기 제1의사잡음열정보, 및 상기 제2의사잡음열정보가 삽입된 상기 OFDM신호를 성형필터링하는 성형필터링부를 포함하는 것을 특징으로 한다.In the OFDM transmission system according to the present invention for achieving the above object, in the OFDM transmission system for inserting and transmitting the pseudo-noise sequence information, which is synchronization information for synchronization between the transmitting side and the receiving side into the transmitted OFDM signal, the OFDM A GI insertion unit inserting a guard interval into the OFDM signal to suppress interference between symbols of the signal, a first PN inserting continuous first noise sequence information over the guard interval into the OFDM signal and the guard interval; An insertion unit, a second PN insertion unit for inserting second noise noise information in front of the protection section into which the first noise noise information is inserted by the first PN insertion unit, and in front of the first noise noise information; And a shaping filtering unit for shaping and filtering the OFDM signal into which the protection period, the first noise noise sequence information, and the second noise noise sequence information are inserted.

여기서, 상기 OFDM 전송시스템은 상기 제1의사잡음열정보를 발생하는 제1PN발생부, 및 상기 제2의사잡음열정보를 발생하는 제2PN발생부를 더 포함한다. 또한, 상기 OFDM 전송시스템은 TDS-OFDM 방식에 따라 상기 OFDM 전송신호를 전송한다. 상기 제1PN발생부에 의해 발생되는 상기 제1의사잡음열정보의 레벨은 상기 OFDM신호에 비해 -16dB 이하로 구현되며, 상기 제2PN발생부에 의해 발생되는 상기 제2의사잡음열정보의 레벨은 상기 OFDM신호에 비해 0dB 이상으로 구현되는 것이 바람직하다.Here, the OFDM transmission system further includes a first PN generator for generating the first noise noise information and a second PN generator for generating the second noise noise information. In addition, the OFDM transmission system transmits the OFDM transmission signal according to the TDS-OFDM scheme. The level of the first noise sequence information generated by the first PN generator is implemented to be -16 dB or less than the OFDM signal, and the level of the second noise sequence information generated by the second PN generator is It is preferable to implement 0dB or more than the OFDM signal.

한편, 상기 OFDM 전송시스템은, 송신측과 수신측의 동기를 위한 동기정보인의사잡음열정보를 전송되는 OFDM신호에 삽입하여 전송하는 OFDM 전송방법에 있어서, 상기 OFDM신호의 심볼 간의 간섭을 억제하기 위해 상기 OFDM신호에 보호구간을 삽입하는 단계, 상기 보호구간이 삽입된 상기 OFDM신호 및 상기 보호구간에 걸쳐 연속적인 제1의사잡음열정보를 삽입하는 단계, 상기 제1의사잡음열정보가 삽입된 상기 보호구간의 앞 및 상기 제1의사잡음열정보의 앞에 걸쳐 제2의사잡음열정보를 삽입하는 제2PN삽입부, 및 상기 보호구간, 상기 제1의사잡음열정보, 및 상기 제2의사잡음열정보가 삽입된 상기 OFDM신호를 성형필터링하는 성형필터링단계;를 포함하는 OFDM 전송방법을 제공한다.In the OFDM transmission method, the OFDM transmission method inserts pseudo-noise information, which is synchronization information for synchronization between a transmitting side and a receiving side, into an transmitted OFDM signal and transmits the interference, to suppress interference between symbols of the OFDM signal. Inserting a guard interval into the OFDM signal, inserting the OFDM signal into which the guard interval is inserted and first continuous noise sequence information over the guard interval, and inserting the first noise sequence information A second PN inserting portion for inserting second noise noise information in front of the protection interval and in front of the first noise noise information, and the protection section, the first noise noise information, and the second noise noise sequence; And a shaping filtering step of shaping and filtering the OFDM signal into which the information is inserted.

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 OFDM 전송시스템을 개략적으로 도시한 도면이다. 도면을 참조하면, OFDM 전송시스템은, IDFT부(110), GI삽입부(120), 제1PN발생부(130), 제1PN삽입부(135), 제2PN발생부(140), 제2PN삽입부(145), 및 성형 필터링부(150)를 구비한다. 여기서, OFDM 전송시스템은 TDS-OFDM 전송방식에 따라 OFDM신호를 전송한다.3 is a diagram schematically illustrating an OFDM transmission system according to the present invention. Referring to the drawings, the OFDM transmission system, IDFT unit 110, GI insertion unit 120, the first PN generation unit 130, the first PN insertion unit 135, the second PN generation unit 140, the second PN insertion The unit 145 and the shaping filtering unit 150 are provided. Here, the OFDM transmission system transmits an OFDM signal according to the TDS-OFDM transmission scheme.

TDS-OFDM 전송방식은 시간영역동기를 이용하여 OFDM신호를 전송하는 방식이며, 기 설정된 주파수 대역에 대해 할당된 OFDM신호를 시간축을 따라 재 배열한다. 또한, TDS-OFDM 전송방식은 시간축에 따라 형성된 OFDM신호의 앞에 신호간의 간섭을 억제하기 위한 보호구간(GI)을 삽입하고, 보호구간의 앞에 동기정보를 삽입하여 전송하는 방식이다.In the TDS-OFDM transmission scheme, an OFDM signal is transmitted using time domain synchronization. The TDS-OFDM transmission scheme reorders OFDM signals allocated to a predetermined frequency band along a time axis. In addition, the TDS-OFDM transmission method is a method of inserting a guard interval (GI) for suppressing interference between signals in front of the OFDM signal formed along the time axis, and inserting synchronization information before the guard interval.

도 4는 도 3에 의한 OFDM신호의 전송방법을 나타낸 흐름도이다. 도면을 참조하여, 본 발명에 따른 OFDM 전송시스템의 작용을 보다 상세하게 설명한다.4 is a flowchart illustrating a method of transmitting an OFDM signal according to FIG. 3. Referring to the drawings, the operation of the OFDM transmission system according to the present invention will be described in more detail.

IDFT부(110)는 주파수대역에 형성된 OFDM신호를 시간축으로 재배열하는 역 이산 퓨리에변환을 수행한다. 여기서, OFDM신호는 각각의 직교 부채널들로 전송되는 각각의 반송파를 말한다. IDFT부(110)에 의해 OFDM신호는 2비트의 크기를 갖는 심볼이 연속적으로 나열된 심볼트레인(symbol train)으로 구현된다. 그러나, 심볼의 크기는 2비트에 한정된 것이 아니며, 4비트 또는 8비트의 크기를 갖도록 구현될 수도 있다.The IDFT unit 110 performs an inverse discrete Fourier transform that rearranges the OFDM signals formed in the frequency band on a time axis. Here, the OFDM signal refers to each carrier transmitted on each orthogonal subchannel. The IDFT unit 110 implements an OFDM signal as a symbol train in which symbols having a size of 2 bits are sequentially arranged. However, the size of the symbol is not limited to 2 bits, and may be implemented to have a size of 4 bits or 8 bits.

GI삽입부(120)는 IDFT부(110)에 의해 역 이산 퓨리에변환된 OFDM신호에 대해 이웃하는 OFDM 심볼들과의 간섭을 억제하기 위해 보호구간(GI)을 삽입한다(S401).The GI insertion unit 120 inserts a guard interval (GI) to suppress interference with neighboring OFDM symbols for the inverse discrete Fourier transformed OFDM signal by the IDFT unit 110 (S401).

제1PN발생부(130)는 레벨(파워)(power)이 OFDM신호에 비해 -16dB 이하인 저 레벨의 제1의사잡음열정보를 발생시킨다(S403).The first PN generation unit 130 generates first noise noise information having a low level whose power (power) is -16 dB or less compared to the OFDM signal (S403).

OFDM신호에 보호구간(GI)이 삽입된 후, 제1PN발생부(130)에 의해 저 레벨의 의사잡음열정보가 발생되면, 제1PN삽입부(135)는 제1PN발생부(130)에 의해 발생된 저 레벨의 의사잡음열정보를 보호구간(GI)의 선단으로부터 후속되는 보호구간(GI)이 삽입되기 전까지의 OFDM신호에 걸쳐 연속적으로 삽입한다(S405). 제1의사잡음열정보의 레벨은 OFDM신호에 비해 상당히 작기 때문에 OFDM신호에는 거의 영향을 미치지 않는다.After the guard interval GI is inserted into the OFDM signal, when low-level pseudo noise string information is generated by the first PN generator 130, the first PN inserter 135 is configured by the first PN generator 130. The generated low noise pseudo-noise string information is inserted continuously over the OFDM signal until the subsequent guard interval GI is inserted from the front end of the guard interval GI (S405). Since the level of the first pseudo-noise sequence information is considerably smaller than that of the OFDM signal, it has little effect on the OFDM signal.

한편, 제2PN발생부(140)는 레벨(파워)이 OFDM신호에 비해 0dB 이상인 고 레벨의 제2의사잡음열정보를 발생시킨다(S407).On the other hand, the second PN generation unit 140 generates second level noise information having a high level (power) of 0 dB or more compared to the OFDM signal (S407).

제2PN발생부(140)에 의해 제2의사잡음열정보가 발생되면, 제2PN삽입부(145)는 보호구간 및 제1의사잡음열정보가 삽입된 OFDM신호에 대하여 보호구간 앞 및 제1의사잡음열정보의 앞에 걸쳐 제2의사잡음열정보를 삽입한다(S409).When the second pseudo noise sequence information is generated by the second PN generation unit 140, the second PN inserting unit 145 performs the first and the first pseudo intervals for the OFDM signal in which the guard interval and the first pseudo noise sequence information are inserted. The second pseudo-noise string information is inserted in front of the noise string information (S409).

상기와 같은 방법에 의해 보호구간(GI), 제1의사잡음열정보, 및 제2의사잡음열정보가 삽입된 OFDM 전송신호의 프레임의 구조를 도 5에 도시하였다.FIG. 5 shows a structure of a frame of an OFDM transmission signal in which a guard period, first noise sequence information, and second noise sequence information are inserted by the above method.

성형필터링부(150)는 보호구간(GI), 제1의사잡음열정보, 및 제2의사잡음열정보를 OFDM신호에 적합하도록 성형 필터링한다. 성형 필터링된 OFDM 전송신호는 고주파 증폭되어 안테나(160)를 통해 송출된다. 이로써, 본 발명에 따른 OFDM 전송시스템에 의한 전송방법은 종료된다.The shaping filtering unit 150 shaping filters the protection interval GI, the first noise sequence information, and the second noise sequence information to fit the OFDM signal. The shaping filtered OFDM transmission signal is amplified by a high frequency and transmitted through the antenna 160. Thus, the transmission method by the OFDM transmission system according to the present invention is terminated.

본 발명에 따르면, 의사잡음열정보가 OFDM 전송신호의 모든 부분에 걸쳐 전송되므로, OFDM 수신시스템은 의사잡음열정보가 OFDM 전송신호의 일부 구간에만 삽입되는 종래의 수신신호에 비하여 훨씬 빠른 동기획득이 가능하게 된다.According to the present invention, since the pseudo-noise sequence information is transmitted over all parts of the OFDM transmission signal, the OFDM receiving system has much faster synchronization acquisition than the conventional received signal in which the pseudo-noise sequence information is inserted only in a portion of the OFDM transmission signal. It becomes possible.

또한, 본 발명에 따르는 OFDM 전송시스템은 의사잡음열정보의 길이를 OFDM 전송신호의 길이만큼 연장하여 삽입하기 때문에, OFDM 수신시스템의 정확한 다중 경로의 추정과 보상을 가능하도록 한다.In addition, the OFDM transmission system according to the present invention extends the length of the pseudo-noise string information by the length of the OFDM transmission signal, thereby enabling accurate multipath estimation and compensation of the OFDM reception system.

본 발명에 따르면, OFDM 전송시스템은 의사잡음열정보를 OFDM 전송신호의 모든 부분에 걸쳐 삽입함으로써, OFDM 수신시스템의 동기 획득시간을 단축시킬 수 있게 된다.According to the present invention, the OFDM transmission system can shorten the synchronization acquisition time of the OFDM reception system by inserting pseudo noise string information over all portions of the OFDM transmission signal.

이상에서는 본 발명의 바람직한 실시예에 대해서 도시하고 설명하였으나, 본 발명은 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.Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the present invention is not limited to the specific embodiments of the present invention without departing from the spirit of the present invention as 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.

Claims (10)

송신측과 수신측의 동기를 위한 동기정보인 의사잡음열정보를 전송되는 OFDM신호에 삽입하여 전송하는 OFDM 전송시스템에 있어서,In an OFDM transmission system for inserting and transmitting pseudo-noise string information, which is synchronization information for synchronization between a transmitter and a receiver, in a transmitted OFDM signal, 상기 OFDM신호의 심볼 간의 간섭을 억제하기 위해 상기 OFDM신호에 보호구간을 삽입하는 GI삽입부;A GI insertion unit for inserting a guard interval into the OFDM signal to suppress interference between symbols of the OFDM signal; 상기 보호구간의 선단으로부터 후속되는 후속보호구간이 삽입되기 전까지의 상기 OFDM신호에 걸쳐 연속적인 제1의사잡음열정보를 삽입하는 제1PN삽입부;A first PN inserter for inserting continuous first noise sequence information over the OFDM signal until a subsequent subsequent protection section is inserted from the leading edge of the protection section; 상기 보호구간 앞 및 상기 제1의사잡음열정보의 앞에 걸쳐 제2의사잡음열정보를 삽입하는 제2PN삽입부; 및A second PN inserter inserting second noise noise information in front of the protection section and in front of the first noise noise information; And 상기 보호구간, 상기 제1의사잡음열정보, 및 상기 제2의사잡음열정보가 삽입된 상기 OFDM신호를 성형필터링하는 성형필터링부;를 포함하는 것을 특징으로 하는 OFDM 전송시스템.And a shaping filter for shaping and filtering the OFDM signal into which the protection period, the first noise sequence information, and the second noise sequence information are inserted. 제 1항에 있어서,The method of claim 1, TDS-OFDM 방식에 따라 상기 OFDM신호를 전송하는 것을 특징으로 하는 OFDM 전송시스템.OFDM transmission system, characterized in that for transmitting the OFDM signal according to the TDS-OFDM scheme. 제 2항에 있어서,The method of claim 2, 상기 제1의사잡음열정보를 발생하는 제1PN발생부; 및A first PN generator configured to generate the first noise noise information; And 상기 제2의사잡음열정보를 발생하는 제2PN발생부;를 더 포함하는 것을 특징으로 하는 OFDM 전송시스템.And a second PN generator for generating the second pseudo-noise string information. 제 3항에 있어서,The method of claim 3, 상기 제1PN발생부에 의해 발생되는 상기 제1의사잡음열정보의 레벨은 상기 OFDM신호에 비해 -16dB 이하인 것을 특징으로 하는 OFDM 전송시스템.And the level of the first noise sequence information generated by the first PN generation unit is -16 dB or less compared to the OFDM signal. 제 4항에 있어서,The method of claim 4, wherein 상기 제2PN발생부에 의해 발생되는 상기 제2의사잡음열정보의 레벨은 상기 OFDM신호에 비해 0dB 이상인 것을 특징으로 하는 OFDM 전송시스템.And the level of the second noise sequence information generated by the second PN generator is 0 dB or more compared to the OFDM signal. 송신측과 수신측의 동기를 위한 동기정보인 의사잡음열정보를 전송되는 OFDM신호에 삽입하여 전송하는 OFDM 전송방법에 있어서,In the OFDM transmission method for inserting and transmitting the pseudo-noise sequence information, which is synchronization information for synchronization between the transmitting side and the receiving side into the transmitted OFDM signal, 상기 OFDM신호의 심볼 간의 간섭을 억제하기 위해 상기 OFDM신호에 보호구간을 삽입하는 단계;Inserting a guard interval into the OFDM signal to suppress interference between symbols of the OFDM signal; 상기 보호구간의 선단으로부터 후속되는 후속보호구간이 삽입되기 전까지의 상기 OFDM신호에 걸쳐 연속적인 제1의사잡음열정보를 삽입하는 단계;Inserting continuous first noise sequence information over the OFDM signal until a subsequent subsequent protection interval is inserted from the leading edge of the protection interval; 상기 보호구간의 앞 및 상기 제1의사잡음열정보의 앞에 걸쳐 제2의사잡음열정보를 삽입하는 제2PN삽입부; 및A second PN inserter inserting second noise noise information in front of the protection section and in front of the first noise noise information; And 상기 보호구간, 상기 제1의사잡음열정보, 및 상기 제2의사잡음열정보가 삽입된 상기 OFDM신호를 성형필터링하는 성형필터링단계;를 포함하는 것을 특징으로 하는 OFDM 전송방법.And a shaping filtering step of shaping and filtering the OFDM signal into which the protection period, the first noise sequence information, and the second noise sequence information are inserted. 제 6항에 있어서,The method of claim 6, 상기 제1의사잡음열정보를 발생하는 단계; 및Generating the first pseudo-noise sequence information; And 상기 제2의사잡음열정보를 발생하는 단계;를 더 포함하는 것을 특징으로 하는 OFDM 전송방법.And generating the second pseudo-noise sequence information. 제 7항에 있어서,The method of claim 7, wherein TDS-OFDM 방식에 따라 상기 OFDM신호를 전송하는 것을 특징으로 하는 OFDM 전송방법.OFDM transmission method for transmitting the OFDM signal according to the TDS-OFDM scheme. 제 8항에 있어서,The method of claim 8, 상기 제1의사잡음열정보 발생단계에 의해 발생되는 상기 제1의사잡음열정보의 레벨은 상기 OFDM신호에 비해 -16dB 이하인 것을 특징으로 하는 OFDM 전송방법.And the level of the first noise sequence information generated by the first noise sequence information generating step is -16 dB or less compared to the OFDM signal. 제 9항에 있어서,The method of claim 9, 상기 제2의사잡음열 발생단계에 의해 발생되는 상기 제2의사잡음열정보의 레벨은 상기 OFDM신호에 비해 0dB 이상인 것을 특징으로 하는 OFDM 전송방법.And a level of the second noise noise information generated by the second noise noise generation step is 0 dB or more compared to the OFDM signal.
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