A deadline-aware transmission framework for H.264/AVC video over IEEE 802.11e EDCA wireless networks

One of the most challenging issues in video transmission over wireless networks is to address the rigid time bounded constraint for video delivery. We propose in this paper a deadline-aware transmission framework (DATF) for video over IEEE 802.11e EDCA wireless networks. In this new framework, we estimate the deadline for time bounded video delivery for each packet in queues at MAC layer according to the sequence number of a frame a given video data packet belonging to as well as the current network delay. Then, the MAC layer determines whether a packet should be sent or should be dropped based on the estimated deadline information. To accomplish the scheme of DATF, we propose to modify the mapping scheme in IEEE 802.11e EDCA to facilitate unequal deadline requirement of video packets. Instead of mapping all video packets into class AC_VI, which is defined for video data in IEEE 802.11e EDCA, we differentiate video packets further based on the dependency characteristics of a given frame type. The proposed DATF scheme has been implemented with NS-2 simulation based on the scenario of wired-cum-wireless network architecture. We compare the proposed approach with several competing schemes and the simulation results show that the proposed scheme outperforms these competing schemes in terms of both wireless networking metrics and received video quality.