A Prioritized Adaptive Scheme for Multimedia Services over IEEE 802.11 WLANs

摘要

IEEE 802.11e protocol enables QoS differentiation between different traffic types, but requires MAC layer support and assigns traffic with static priority. This paper proposes an intelligent Prioritized Adaptive Scheme (iPAS) to provide QoS differentiation for heterogeneous multimedia delivery over wireless networks. iPAS assigns dynamic priorities to various streams and determines their bandwidth share by employing a probabilistic approach-which makes use of stereotypes. Unlike existing QoS differentiation solutions, the priority level of individual streams in iPAS is variable and considers service types and network delivery QoS parameters (i.e. delay, jitter, and packet loss rate). A bandwidth estimation technique is adopted to provide network conditions and the IEEE 802.21 framework is used to enable control information exchange between network components without modifying existing MAC protocol. Simulations and real life tests demonstrate how better results are obtained when employing iPAS than when either IEEE 802.11 DCF or 802.11e EDCA mechanisms are used. The iPAS key performance benefits are as follows: 1) better fairness in bandwidth allocation; 2) higher throughput than 802.11 DCF and 802.11e EDCA with up to 38% and 20%, respectively; 3) enables definite throughput and delay differentiation between streams.