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We present in this paper a scheme of reliable transmission of H.264/AVC video over wireless mesh networks (WMNs) based on an opportunistic multi rate (OMR) IEEE 802.11 MAC strategy. This OMR strategy employs the channel reservation control packets at the MAC layer to exchange timely channel quality estimation (CQE) information for an adaptive adjustment of spectrally efficient transmission rate at the physical layer. Such rate adaptation scheme offers an optimized transmission to guarantee the minimum packets delay and drop rate needed for time bound applications, such as video. Since IEEE 802.11 standard does not adopt a multi-rate MAC to support time critical applications, we need to resolve the problem associated with IEEE 802.11 standard by designing a novel adaptive rate architecture with minor modification on IEEE 802.11 MAC protocol based on CQE. This integrated scheme allows the physical layer to achieve the optimal transmission via smart FEC scheme implemented in the application layer. We evaluate the proposed scheme based on network-level metrics, including bit rate, packets delay and drop rate, in comparison with the state-of-the-art opportunistic auto-rate (OAR) MAC scheme based on IEEE 802.11 WMNs. Extensive simulation results based on H.264/AVC video transmission for both proposed OMR scheme and OAR MAC have confirmed that the proposed OMR strategy outperforms the OAR MAC by a significant margin as CQE and smart FEC is able to adapt to the dynamic network conditions of IEEE 802.11 WMNs in a timely fashion.
Date of Conference: 24-27 May 2009