Network-adaptive video transmission and differentiation mechanisms over IEEE 802.11 wireless LAN

Abstract

Video over IEEE 802.11-based wireless LAN is facing lots of challenges due to the dynamically varying wireless channel and due to lack of appropriate QoS differentiation capability in the IEEE 802.11 MAC (medium access control). In this paper, differentiation mechanism coordinated by both video application and wireless MAC is adopted to realize a network-adaptive video transmission over the wireless LAN. To support the required QoS differentiation for loss/delay sensitive video stream, modified version of EDCF (enhanced distributed coordination function) MAC is utilized, which provides loss/delay differentiation by controlling contention window size and distributed inter-frame space interval. The differentiation is then matched by the prioritization of video application, represented in the relative priority index (RPI). The network simulation with NS2 (network simulator) verifies that the proposed prioritization and modified EDCF improves the performance of video transmission over IEEE 802.11 wireless LAN.Keywords: End-to-end wireless video, IEEE 802.11 wireless LAN, MAC differentiation mechanism, joint sourcechannel error control, network adaptive media transmission, and packet prioritization.