The Journal of Korean Institute of Communications and Information Sciences (한국통신학회논문지)

The Korean Institute of Commucations and Information Sciences (한국통신학회)
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Delay Determination of Cyclic Delay Diversity for Multi-user Scheduling in OFDMA Systems

OFDMA 시스템의 다중 사용자 스케줄링을 위한 순환지연 다이버시티의 지연값 결정

  • Published : 2008.03.31
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Abstract

In an OFDMA system the performance of multi-user scheduling in the frequency domain is affected by the frequency selectivity of the channel. If the channel is too flat in the frequency domain, the multi-user scheduling gain might be degraded. On the contrary, if the frequency selectivity is too high and the magnitude of the frequency response severely fluctuates on the allocation bandwidth, it is also hard to get sufficient scheduling gain. For maximizing the multi-user scheduling gain, a cyclic delay diversity technique can be used to adjust the frequency selectivity of the channel. This paper proposes a method to determine the optimal delay value of cyclic delay diversity according to the allocation bandwidth and the channel characteristics.

OFDMA 시스템에서 주파수축에서의 다중사용자 스케줄링의 성능은 채널의 주파수 선택적 특성과 상관이 있다. 채널이 주파수축에서 평탄하면 다중사용자 스케줄링의 이득이 줄어들 수 있으며 반대로 주파수 선택적 특성이 너무 커서 할당 대역폭 내에서 채널의 변화가 심하게 일어난다면 충분한 스케줄링 이득을 얻기 어려워진다. 다중 사용자 스케줄링 이득을 최대화하기 위해서는 순환지연 다이버시티를 적용하여 채널의 주파수 선택적 특성을 조절할 수 있다. 이 논문에서는 할당 대역폭과 채널 특성을 고려하여 순환지연 다이버시티를 적용할 때의 최적의 지연값을 결정하는 방법을 제안한다.

Keywords

References

  1. H. Liu, G. Li, OFDM-Based Broadband Wireless Networks, John Wiley & Sons Inc. 2005
  2. IEEE P802.16e/D12: Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems: Amendment for Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands, October 2005
  3. IEEE802.20: QFDD and QTDD: Proposed Draft Air Interface Specification, Qualcomm, October 2005
  4. 3GPP TR 25.814: Technical Specification Group Radio Access Network; Physical Layer Aspects for Evolved UTRA, February 2006
  5. G. Bauch, J.S. Malik, "Orthogonal Frequency Division Multiple Access with Cyclic Delay Diversity," Smart Antennas, 2004. ITG Workshop, pp.17-24, March 2004
  6. G. Bauch, and J. S. Malik, "Cyclic delay diversity with bit-interleaved coded modulation in orthogonal frequency division multiple access," IEEE Trans. Wireless Communications, vol.5, no.8, pp.2092-2100, Aug. 2006 https://doi.org/10.1109/TWC.2006.1687724
  7. A. Huebner, F. Schuehlein, M. Bossert, E. Costa, H. Haas, "A Simple Space-Frequency Coding Scheme with Cyclic Delay Diversity for OFDM," Personal Mobile Communications Conference, 2003. 5th European, pp.106-110, April 2003
  8. R1-051046, Samsung, Further Details on Adaptive Cyclic Delay Diversity Scheme, San Diego, USA, October 2005
  9. R1-050888, Samsung, Enhanced Frequency Diversity and Scheduling Performance in Evolved UTRA, London, UK, August-September 2005
  10. R1-061192, NTT DoCoMo, Channel Dependent Scheduling with Cyclic Delay Diversity, Shanghai, China, May 2006
  11. Theodore S. Rappaport, Wireless Communications Principles and Practice, p.197-203, Prentice Hall, 2002