The KIPS Transactions:PartC (정보처리학회논문지C)

Korea Information Processing Society (한국정보처리학회)
권호 표지
DOI QR코드

DOI QR Code

Application of LLR on Cooperative Communications for Wireless Relay Networks

무선 중계 네트워크의 협력 통신 방법에 대한 LLR 적용 연구

  • ;
  • 공형윤 (울산대학교 전기 전자정보시스템공학부) ;
  • 이동운 (울산대학교 전기 전자정보시스템공학과)
  • Published : 2006.10.30
Download PDF
⟨ Previous Next ⟩

Abstract

Decode-and-forward cooperative communications protocol (DFP) allows single-antenna users in wireless medium to obtain the powerful benefits of multi-antenna systems without physical antenna arrays. For this protocol, so far the relays have used SNR to evaluate the reliability of the received signal before deciding whether to forward the decoded data so as to prevent their unsuccessful detection. However, SNR only characterizes the long-term statistic of Gaussian noise and thus leading to inaccurate assesment. Therefore, we propose using log-likelihood ratio (LLR) which accounts for the instantaneous noise in the received signal as an alternative to SNR. A variety of simulation results reveal the significant superiority of the SNR-based DFP to the SNR-based DFP regardless of threshold level and relay position under the flat Rayleigh fading channel plus AWGN (Additive White Gaussian Noise).

복호 후 전달 협력 통신 프로토콜(DFP: Decode-and-Forward Cooperative Communication Protocol)은 하나의 안테나를 쓰는 사용자에게 물리적인 안테나의 증가 없이 다중 안테나 시스템의 강력한 장점을 얻을 수 있는 통신 방법이다. 지금까지는 신호 대 잡음 비율(SNR: Signal to Noise Ratio)이나 경로이득 크기의 루트를 취한 값들을 이용하여 중계 노드에서 복호한 데이터를 전달할지 안 할지를 결정하여 중계 노드에서 부정확한 검파가 되지 않도록 방지하였다. 본 논문에서는 기존의 DFP에서 사용되던 SNR을 대체할 수 있는 LLR(Log-Likelihood Ratio)를 이용하는 방법을 제안하였다. 여러 가지 많은 모의 실험을 통해 레일리 페이딩 환경과 AWGN환경에서 기준 값이나 중계 노드의 위치에 상관없이 LLR기반의 DFP가 SNR기반의 DFP보다 아주 우수한 성능을 보이는 것을 확인하였다.

Keywords

References

  1. John G. Proakis, 'Digital communications,' Fourth Edition, McGraw-Hill, 2001
  2. V. Tarokh, H. Jafarkhani, A.R. Calderbank, 'Space-time block coding for wireless communications: performance results,' IEEE Trans on Communications, Vol.17, pp.451 - 460, March, 1999 https://doi.org/10.1109/49.753730
  3. Aria Nosratinia, Todd E. Hunter, 'Cooperative Communication in Wireless Networks,' IEEE Communications Magazine, Vol.42, pp.74-80, Oct., 2004 https://doi.org/10.1109/MCOM.2004.1341264
  4. J.N. Laneman, D.N.C. Tse, G.W. Wornell, 'Cooperative diversity in wireless networks: Efficient protocols and outage behavior,' IEEE Trans. Inform. Theory, Vol. 50, Issue 12, pp.3062 - 3080, Dec., 2004 https://doi.org/10.1109/TIT.2004.838089
  5. P. Herhold, E.Zimmermann, G. Fettweis, 'A Simple Cooperative Extension to Wireless Relaying,' 2004 Int. Zurich Seminar on Communications, Zurich, Switzerland, Feb., 2004 https://doi.org/10.1109/IZS.2004.1287382
  6. E. Zimmermann, P. Herhold and G. Fettweis, 'On the Performance of Cooperative Relaying in Wireless Networks,' European Trans. on Telecommunications, Vol. 16, no.1, Jan.,-Feb., 2005 https://doi.org/10.1002/ett.1028
  7. A. Sendonaris, E. Erkip, B. Aazhang, 'User cooperation diversity. Part I-II,' IEEE Trans on Communications, Vol. 51, pp.1927-1948, Nov., 2003 https://doi.org/10.1109/TCOMM.2003.818096
  8. A. Sendonaris, E. Erkip, B. Aazhang, 'User cooperation diversity. Part I-II,' IEEE Trans on Communications, Vol. 51, pp.1927-1948, Nov., 2003 https://doi.org/10.1109/TCOMM.2003.819238
  9. P. Mitran, H. Ochiai, V. Tarokh, 'Space-time diversity enhancements using collaborative communications,' IEEE Trans. on Inform. Theory, Vol. 51, Issue 6, pp.2041-2057, June, 2005 https://doi.org/10.1109/TIT.2005.847731
  10. J.N. Laneman, G.W. Womell, 'Distributed space-time-coded protocols for exploiting cooperative diversity in wireless networks,' IEEE Trans. Inform. Theory, vol.49, pp.2415-2525, Oct., 2003 https://doi.org/10.1109/TIT.2003.817829
  11. E. Zimmermann, P. Herhold, G. Fettweis, 'The Impact of Cooperation on Diversity-Exploiting Protocols,' 59th VTC 2004, Genoa, Italy, May, 2004
  12. Sang Wu Kim, Eun Yong Kim, 'Optimum receive antenna selection minimizing error probability,' WCNC 2003, Vol. 1, pp.441 - 447, 16-20 March, 2003 https://doi.org/10.1109/WCNC.2003.1200389
  13. Young Gil Kim, Sang Wu Kim, 'Optimum selection combining for M-ary signals in frequency-nonselective fading channels,' IEEE Trans. on Commun., Vol.53, Issue 1, pp.84-93, Jan., 2005 https://doi.org/10.1109/TCOMM.2004.840622
  14. Athanasios Papoulis, S. Unnikrishna Pillai, 'Probability, Random Variables and Stochastic Process,' Fourth Edition, McGraw Hill, 2002
  15. I.S. Gradshteyn, I. M. Ryzhik, 'Table of Integrals, Series, and Products,' Academic Press, 2000
  16. Marvin K. Simon and Mohamed-Slim Alouini, 'Digital Communication over Fading Channels,' Second Edition, John Wiley & Sons, Inc, 2005
  17. R. Pabst, B. Walke, D. Schultz, P. Herhold, H. Yanikomeroglu, S. Mukherjee, H. Visvanathan, M. Lott , W. Zirwas, M. Dohler, H. Aghvami, D. Falconer, G. Fettweis, 'Relay-based Deployment Concepts for Wireless and Mobile Broadband Cellular Radio,' IEEE Communications Magazine, Sept., 2004 https://doi.org/10.1109/MCOM.2004.1336724