Journal of the Institute of Electronics Engineers of Korea TC (대한전자공학회논문지TC)

The Institute of Electronics and Information Engineers (대한전자공학회)
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QoS Enhancement Scheme through Service Differentiation in IEEE 802.11e Wireless Networks

IEEE 802.11e 무선랜에서 서비스 차별화를 통한 QoS 향상 방법

  • 김선명 (플로리다 대학교 전기및컴퓨터공학과) ;
  • 조영종 (아주대학교 정보및컴퓨터공학부)
  • Published : 2007.04.25
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Abstract

The enhanced distributed channel access (EDCA) of IEEE 802.11e has been standardized for supporting Quality of Service (QoS) in wireless LANs. In the EDCA, support of QoS can be achieved statistically by reducing the probability of medium access for lower priority traffics. In other words, it provides statistical channel access rather than deterministically prioritized access to high priority traffic. Therefore, lower priority traffics affect the performance of higher priority traffics. Consequently, at the high loads, the EDCA does not guarantee the QoS of multimedia applications such as voice and video even though it provides higher priority. In this paper, we propose a simple and effective scheme, called deterministic priority channel access (DPCA), for improving the QoS performance of the EDCA mechanism. In order to provide guaranteed priority channel access to multimedia applications, the proposed scheme uses a busy tone for limiting the transmissions of lower priority traffics when higher priority traffic has data packets to send. Performance of the proposed scheme is investigated by numerical analysis and simulation. Our results show that the proposed scheme outperforms the EDCA in terms of throughput, delay, jitter, and drop under a wide range of contention levels.

IEEE 802.11e의 EDCA (Enhanced Distributed Channel Access)는 무선 랜에서의 QoS(Quality of Service)를 지원하기 위해 표준화되었다. EDCA는 낮은 우선순위 트래픽의 채널 접근 확률을 낮춤으로써 높은 우선순위 트래픽에 QoS를 제공한다. 이는 높은 우선순위 트래픽에 대한 확정된(Deterministic) 우선순위를 제공하는 것이 아니라 통계적인(Statistical) 우선순위를 제공한다. 그러므로 낮은 우선 순위트래픽은 높은 우선순위 트래픽의 성능에 계속 영향을 미친다. 결과적으로 높은 채널 트래픽 환경에서 EDCA는 음성이나 비디오와 같은 멀티미디어 응용에 QoS를 보장하지 못한다. 본 논문에서는 EDCA 메커니즘의 QoS 성능을 향상시키기 위해 DPCA(Deterministic Priority Channel Access) 방법을 제안한다. 멀티미디어 응용에 보장된 우선순위 채널 접근을 제공하기 위해 제안된 방법은 높은 우선순위 트래픽이 전송할 패킷을 가지고 있을 때 낮은 우선순위 트래픽의 전송을 제한하기 위해 비지톤(Busy Tone)을 사용한다. 제안된 방법의 성능을 수학적 분석과 시뮬레이션을 통해 EDCA와 비교 분석한다. 성능 비교 분석 결과, 제안된 방법이 다양한 경쟁 수준 환경에서 EDCA보다 더 좋은 효율과 지연, 폐기율 등을 가짐을 확인하였다.

Keywords

References

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