QoS cross layer architecture with adaptive enhanced distributed channel access for efficient video transmission

Introduction Increased bandwidth of wireless technologies motivated delivery of video over wireless networks. H.264 compressed video source, applied to video coding layer (VCL) for high compression representation of video content, has a number of error resilience tools. Data partitioning (DP) creates partitions on highest data structure called slices. By enabling DP technique, VCL divides original video stream into several streams to obtain slices as follows: i) Partition A – Macro Block (MB) types, quantization parameters and motion vector; ii) Partition B – Intra partition; and iii) Partition C – Inter partition. Slices are directed to Network Abstraction Layer (NAL). Associated header of each slice is made available to NAL as data structure, elements of which include slice type, picture ID, MB address and entropy coding. NAL facilitates delivery of H.264 VCL data to underlying transport layers. Each NAL unit is considered as a packet having a header and a payload. Incoming VCL layer’s slices are differentiated and encapsulated as per assigned priority. Partition A and Instantaneous Decoding Refresh (IDR) picture have more priority than Partition B and C. Larger values of mean packet loss, end to end delays, noise and interference affect video quality and result in inefficient bandwidth utilization. Existing cross layer architecture (Fig. 1) makes use of Enhanced Distributed Channel Access (EDCA) mechanism at its MAC layer. Because of high contention rate, its performance is poor during heavy load conditions. This paper proposes cross layer architecture for H.264 video transmission over IEEE 802.11e WLAN with Adaptive Enhanced Distributed Channel Access (AEDCA) scheme.