Seamless Video Transmission over Wireless LANs based on an Effective QoS Model and Channel State Estimation

This paper presents a scheme for video transmission over wireless LANs based on an effective QoS model and channel state estimation (CSE). The proposed QoS model is able to effectively characterize the performance of video transmission over error prone wireless channels. Unlike existing schemes that use complicated metrics based on the actual distortion computed from decoded video frames, the proposed model employs H.264 group of pictures (GOP) level estimator of decodable slice rate (GEDSR). This new GEDSR model can be obtained from simplified calculation of decodable I, P, and B slices without computing the actual distortions. With this model, it is possible for the estimation to include the dependence of error control such as forward error correction and redundant slices. In this research, we also develop an adaptive cross-layer feedback mechanism based on channel status, maximum retry limit value, and RTS/CTS function. Extensive simulations have been carried out to confirm the effectiveness of the proposed GEDSR model for the distortion analysis. The experimental results of the GEDSR model analysis have been applied to selecting forward error correction (FEC) coding parameters for video streams to respond to dynamic channel changes. Simulations on video transmission over wireless LAN show that the proposed scheme is able to achieve significant performance gains (7dB) over schemes without channel feedback.