Channel access protocol for video packets in IEEE 802.11 networks

The 802.11 DCF is contention-based channel access protocol, and medium access delay is highly increased with the number of stations in a service area. This severely affects on delay-sensitive video applications. In this paper, we focus on the MAC-layer solution for realizing high quality video transmissions in the 802.11 DCF networks. A new channel access protocol is proposed for real-time video, based on the timestamp (TS) of video packets. The TS information is carried by RTP header from the video application to the 802.11 MAC. For video packets with the same TS, they are simultaneously sent in a single channel access. Thus, additional contention and back-off processes can be avoided. The proposed TS-based access protocol can be easily implemented by the DCF with packet bursting. In addition, it is backward compatible to the legacy DCF. Simulation results show that the TS-based channel access achieves lower cumulative distributions of application-level video frame delay when compared to the DCF protocol.