802.11 wireless local area networks are now common in the home. The 802.11e amendment allows for quality of service (QoS) provisioning over these networks to help meet the QoS demands of the growing number of multimedia applications on these home networks. The H.264 video coding standard is suitable for most multimedia applications due to its high compression and error resilience. This paper investigates how the quality of H.264 video is affected as the number of concurrent video streams sent over an 802.11e network is increased. We compare two traffic mapping schemes with and without the use of the flexible macroblock ordering (FMO) tool of H.264. We show that the mapping scheme which prioritises video packets based on their frame type is more successful at maintaining the quality of video when congestion occurs. A more gradual degradation in quality can be achieved rather than the cliff-edge drop that otherwise occurs. We also identify that errors caused by congestion tend to occur towards the bottom of each frame and that FMO can reduce this effect.
['Richard MacKenzie', 'David S. Hands', "Timothy O'Farrell"]
Effectiveness of H.264 Error Resilience Techniques in 802.11e WLANs