OFDM 신호의 PAPR 감소를 위한 소실 복호 기반의 SLM 기법

Selected Mapping Technique Based on Erasure Decoding for PAPR Reduction of OFDM Signals

  • 공민한 (원광대학교 제어계측공학과) ;
  • 송문규 (원광대학교 전기전자및정보공학부)
  • Kong, Min-Han (Dept. of Control and Instrumentation Engineering, Wonkwang University) ;
  • Song, Moon-Kyou (Dept. of Electrical, Electronic and Information Engineering, Wonkwang University)
  • 발행 : 2007.02.25

초록

높은 PAPR (peak-to-average power ratio)은 OFDM (orthogonal frequency division multiplexing) 신호의 주된 문제점이다. 본 논문에서는 RS (Reed-Solomon) 부호의 소실 복호 기능을 이용한 수정된 SLM (selective mapping) 기법을 제안한다. 송신기에서 RS 부호화된 OFDM 데이터 블록에 일련의 위상 시퀀스를 곱하여 일부의 체크 심볼의 위상을 천이시킨다. 수신기에서 위상 천이된 체크 심볼들을 소실로 간주하여 RS 복호를 수행한다. 그러므로 가장 낮은 PAPR을 갖도록 선택된 위상 시퀀스에 대한 부가 정보를 전송할 필요가 없다. 또한 선택된 위상 시퀀스에 대한 추정 과정이 더 이상 수신기에 필요하지 않게 되어 복잡도와 성능이 향상된다. 제안한 수정된 SLM 기법의 성능을 평가하기 위해 PAPR의 CCDF(complementary cumulative distribution function), BER(bit error rate) 그리고 복호 실패 확률을 기존의 SLM 기법과 비교한다.

High PAPR (peak-to-average power ratio) is a major drawback of OFDM (orthogonal frequency division multiplexing) signals. In this paper, a modified SLM (selective mapping) technique that uses erasure decoding of RS (Reed-Solomon) codes is presented. At the transmitter a set of phase sequences are multiplied such that some portions of check symbols in RS-coded OFDM data blocks are phase-rotated. At the receiver, RS decoding is performed with the phase-rotated check symbols being treated as erasures. Hence, there is no need to send side information about the phase sequence selected to transmit for the lowest PAPR. In addition, the estimation process for the selected phase sequence is no longer needed at the receiver, leading to improvement in terms of complexity and performance. To evaluate the performance of this technique, the CCDF (complementary cumulative distribution function) of PAPR, the BER (bit error rate) and the decoding failure probability are compared with those of the previous SLM techniques.

키워드

참고문헌

  1. L. J. Cimini Jr, 'Analysis and Simulation of a Digital Mobile Channel Using Orthgonal Frequency Division Multiplexing,' IEEE Trans. Commun., vol. 33, pp. 665-675, July 1985
  2. R. van Nee and R. Prasad, OFDM for Wireless Multimedia Communications, Boston, MA: Artech House, 2000
  3. J. Heiskala and J. Terry, OFDM Wireless LANs: A Theoretical and Practical Guide, Sam, 2002
  4. R. W. Bauml, R. F. H. Fisher and J. B. Huber, 'Reducing the Peak-to-Average Power Ratio of Multicarrier Modulation by Selected Mapping,' Elect. Lett., vol. 32, no. 22, pp. 2056-57, Oct. 1996 https://doi.org/10.1049/el:19961384
  5. H. Breiling and S. H. Muller-Weinfurtner, and J. B. Huber, 'SLM Peak-Power Reduction without Explicit Side Information,' IEEE Commun. Lett., vol. 5, no. 6, pp. 239-41, Jun. 2001 https://doi.org/10.1109/4234.929598
  6. Kyeongcheol Yang and Seok-Il Chang, 'Peak-to-Average Power Control in OFDM Using Standard Arrays of Linear Block Codes,' IEEE Commun. Lett., vol. 7, no. 4, pp. 174-176, Apr. 2003 https://doi.org/10.1109/LCOMM.2003.811204
  7. Yan Xin and Ivan J. Fair, 'Peak-to-Average Power Ratio Reduction of an OFDM Signal Using Guided Scrambling Coding,' IEEE GLOBECOM2003, vol. 4, pp. 2390-2394, Dec. 2003 https://doi.org/10.1109/GLOCOM.2003.1258663
  8. Seung Hee Han and Jae Hong Lee, 'Modified Selected Mapping Technique for PAPR Reduction of Coded OFDM Signal,' IEEE Transaction on Broadcasting, vol. 50, no. 3, pp. 335-341, Sep. 2004 https://doi.org/10.1109/TBC.2004.834200
  9. C. Tellambura, 'Computation of the Continuous-Time PAR of an OFDM Signal with BPSK Subcarriers,' IEEE Commun. Lett., vol. 5, no. 5, pp. 185-187, May 2001 https://doi.org/10.1109/4234.922754
  10. Howard M. Shao and Irving S. Reed, 'On the VLSI Design of a Pipeline Reed-Solomon Decoder Using Systolic Arrays,' IEEE Trans. on Computers, vol. 37, no. 10, Oct. 1988 https://doi.org/10.1109/12.5988
  11. M.K. Song, E.B. Kim, H.S. Won and M.H. Kong, 'Architecture for Decoding Adaptive Reed-Solomon Codes with Varying Block Length,' IEEE Transactions on Consumer Electronics, vol. 48, no. 3, pp. 631-637, Aug. 2002 https://doi.org/10.1109/TCE.2002.1037052
  12. M.K. Song and M.H. Kong, 'An Adaptive Reed-Solomon Decoder Using Separate Clocks in the Pipelined Steps,' IEICE Transactions on Communications, vol. E88-B, no. 2, pp. 615-621, Feb. 2005 https://doi.org/10.1093/ietcom/E88-B.2.615