Video transmission over wireless networks has quality of service (QoS) requirements and the time-varying characteristics of wireless channels make it a challenging task. IEEE 802.11 Wireless LAN has been widely used for the last mile connection for multimedia transmission. In this paper, a cross-layer design is presented for video streaming over IEEE 802.11e HCF Controlled Channel Access (HCCA) WLAN. The goal of the cross-layer design is to improve the quality of the video received in a wireless network under the constraint of network bandwidth. The approach is composed of two algorithms. First, an allocation of optimal TXOP is calculated which aims at maintaining a short queuing delay at the wireless station at the cost of a small TXOP allocation. Second, the transmission of the packets is scheduled according to the importance of the packets in order to maximize the visual quality of video. The approach is compared with the standard HCCA on NS2 simulation tools using H.264 video codec. The proposed cross-layer design outperforms the standard approach in terms of the PSNRs of the received video. This approach reduces the packet loss to allow the graceful video degradation, especially under heavy network traffic.
