Video Packetization and Adaptive ARQ for Video Transmission over Wireless LANAbstract
With the technology advances in digital compression and wireless networks, real-time streaming of video content over IEEE 802.11 wireless networks is a multimedia application full of potentials. However, unlike wired packet switched networks, IEEE 802.11 wireless networks are relatively unreliable due to an error prone physical channel and the lack of QoS guarantee. Therefore, the video quality transmitting over wireless networks will possibly be degraded.
In the thesis, we propose a priority video packetization mechanism and an adaptive ARQ scheme according to video packet priorities to reduce the degradation in wireless networks. At the video encoder, the priority video packetization mechanism sets the video packet size base on the video types. Namely, the packet size is reduced for important video frames to reduce packet losses when transmitting over severely interfered wireless channels. The adaptive ARQ in the IEEE 802.11 point coordinator adapts the repeat limits depend on the wireless channel condition and video packet priorities to achieve both high channel utilization and good video quality. Simulation results show that with five error patterns and four video sequences, the proposed mechanism indeed achieves reduction of lost video packets and protection of important video packets within the delay constraint. As errors occur, the proposed mechanism can improve PSNR of the received video quality up to 3dB on average. |