OFDMA 기반 Relay 시스템에서 Relay의 Capability에 따른 VoIP 성능 분석

Effect of Relay Capability on VoIP Performance in OFDMA based Relay Systems

  • 안성보 (서강대학교 통신시스템 연구실) ;
  • 최호영 (서강대학교 통신시스템 연구실) ;
  • 홍대형 (서강대학교 통신시스템 연구실) ;
  • 임재찬 (서강대학교 통신시스템 연구실)
  • 발행 : 2009.03.31

초록

본 논문에서는 OFDMA 기반 relay 시스템에서 사용자에게 VoIP 서비스를 제공할 경우, relay station (RS)의 capability에 따른 시스템의 성능 차이를 분석하였다. Relay 시스템은, relay의 스케줄링 수행 여부에 따라 mid-capability (MC)와 high-capability (HC) relay를 적용한 시스템으로 구분할 수 있다. HC relay를 적용한 시스템의 경우, base station (BS) 뿐만 아니라 RS도 직접 스케줄링을 수행한다. 반면에 MC relay를 적용한 시스템의 경우, 각 RS로부터 mobile station (MS) 들의 수신 SINR, 발생 traffic양 등의 정보를 BS에서 수집하여, BS가 단독으로 스케줄링을 수행한다. 이 경우 MS의 정보 수집 및 RS로의 스케줄링 정보 전달을 위해 control 오버헤드는 커지지만, BS가 모든 MS에 대한 정보를 알고 있으므로 효율적인 자원 할당 및 스케줄링이 가능하다. 따라서 RS의 capability에 따라 전체 시스템의 성능이 달라질 수 있고, 이에 대한 분석이 필요하다. 본 논문에서는 모의 실험을 통해 VoIP traffic 환경에서 RS의 capability에 따른 평균 packet delay, good packet ratio, cell goodput 등을 도출하였다. 선정한 VoIP 성능 지표에 의하면, MC relay를 적용한 시스템이 HC relay를 적용한 시스템에 비해 성능이 우수함을 확인하였다.

In this paper, we evaluate the performance of VoIP in OFDMA-based relay systems with various capabilities of relays. We classify relays according to capability as "mid-capability (MC)" and "high-capability (HC)" relay. In system with HC relays, not only base station (BS) but also relay station (RS) performs scheduling at its ova whereas only BS performs scheduling in system with MC relays using the information reported by MS (i.e. the received signal-to-interference-plus-noise ratio (SINR) of mobile station (HS), the amount of MS traffic, etc). In system with MC relays, the controling overhead of BS is larger than that of system with HC relays. However, since BS has all MS information, efficient resource allocation and scheduling is possible. We derived the "average packet delay," "good packet ratio," and "cell goodput" in a VoIP environment. The simulation results demonstrate that the system with MC relays has better VoIP performance over that with HC relays.

키워드

참고문헌

  1. V. Genc, S. Murphy, Y. Yu and J. Murphy, 'IEEE 802.16j relay-based wireless access networks: an overview,' IEEE Wireless Communications, Vol. 15, Issue 5, pp 56-63, Oct. 2008 https://doi.org/10.1109/MWC.2008.4653133
  2. IEEE Draft Standard P802.16j/D7, 'Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems- Multihop Relay Specification,' Oct. 2008
  3. H. Kang, J. Cho, S. Lee et al, 'Proposed Functional Requirements for IEEE 802.16 TGj : IEEE C802.16j-06/022r1,' IEEE 802.16j meeting #43, Tel Aviv, Israel, May 2006
  4. A. Zhang, Shangzheng et al, 'Recommendations on 802.16j technical requirements : IEEE C802.16j-06/053,' IEEE 802. 16j meeting #44, San Diego, USA, July 2006
  5. K. Park and C. Kang, 'Relay-enhanced Cellular Performance of OFDMA-TDD System for Mobile Wireless Broadband Services,' in Proc. of IEEE ICCCN 2007, pp.430-435, Aug. 2007
  6. Y. Liu, F. Liu et al, 'Relay Enhanced Architecture for Broadband Wireless Access Network,' in Proc. of IEEE IWCLD 2007, pp.91-95, Sep. 2007
  7. M. Nohara, K. Saito et al, 'Mobile Multi-hop Relay Networking in IEEE 802.16 : IEEE C802.16-05/013,' IEEE 802. 16 meeting #38, San Francisco, USA, Nov. 2005
  8. IEEE Std. 802.16eTM-2005 and IEEE Std. 802.16TM-2004/cor1-2005, Part16: Air interface for Fixed and Mobile Broadband Wireless Access Systems, Feb. 2006
  9. C. Zhu, D. Viorel et al, 'Frame Structure to Support Relay Node Operation : IEEE C802.16j-06/233r8,' IEEE 802.16j meeting #46, Dallas, USA, Nov. 2006
  10. ITU-T Rec. G.711,'Pulse Code Modulation of Voice Frequencies,' ITU Geneva, Nov. 1988
  11. G. Senarath, W. Tong et al, Multi-hop Relay System Evaluation Methodology [Channel Model and Performance Metric],' EMD of 802.16 Relay TG, Feb. 2007
  12. ITU-T G.1010, Series G: Transmission systems and media digital systems and networks-Quality of service and performance, Nov 2001
  13. Goode, B. 'Voice Over Internet Protocol (VoIP),' Proceedings of The IEEE, Vol. 90, No. 9, pp. 1495-1517, Sep. 2002 https://doi.org/10.1109/JPROC.2002.802005
  14. M. Mollah and M. Asa,'MAP construction and transmission for a relay station : IEEE C802.16j-06/157r1,' IEEE 802.16 Session #47, London, UK, Jan. 2007
  15. H. Zhang et al., 'Format of R-MAP within RS-Zone : IEEE C802.16j-07/090r7,' IEEE 802.16 Session #49, Portland, USA, May 2007