Study On Transmission Control In Wireless Streaming Media

With the rapid growth in wirless networks, the application of wireless streaming media becomes more and more popular. In wireless environment, the data delivery is easily affected by the time variety, high error rate,obvious jitter and delay. Providing quality of service(QoS) guarantees is an important objective in designing the next generation wireless networks.This thesis focuses on the QoS of wireless streaming media transmission and goes deep into the control mechanism based on the wireless channel characteristics.To support QoS guarantees, two general approaches have been proposed. The first approach is network-centric. The baisc idea is that the routers, switches, and base stations in the network are required to provide QoS support to satisfy data rate, bounded delay, and packet loss requirements imposed by user applications. The second approach is solely end-system-based and does not need any prerequisites on the network.This thesis adopts the second approach. We address the architecture of the streaming media network primarily from the transmission control perspective, including video coding/decoding, the multiple-layer design for the Server/Clients and the transmission mechanisms of the network. At last, an improved video-packet-based scheduling algorithm based on the wireless LAN platform is proposed.The main innovative points of this thesis are as follows:1. Multiple optimizations in system design. Many optimized algorithms are introduced to improve the quality of video streaming transmission.2. Dynamic round trip time(RTT) in multicast networks. The original packet scheduling algorithm supposes the RTT a constant value, while we adopt dynamic RTT, a mechnism that better simulates the real wireless network.3. Video packet based scheduling. The original algorithm is based on frames. We refine the scheduling to the level of video packets to offer the best video playback quality for the clients.