TCP streaming for low-delay wireless video

With the penetration and popularity of mobile devices such as pocket PCs and smart-phones, there is an increasing need of low-delay video streaming over wireless channel. Traditionally, UDP (user datagram protocol) is used for video streaming. However, due to unreliable transmission and fluctuating bandwidth of wireless channel, this requires error concealment and recovery mechanisms which greatly increases the complexity and delay of the system. Furthermore, UDP streams are often more difficult to penetrate firewalls. We hence propose using TCP (transmission control protocol) for video streaming in this paper, due to its ease of use, reliability, and flexibility in selecting frames to transmit. After discussing the wireless system architecture under consideration, we present a multi-worker model as implemented at wireless proxy (or encoder) which handles client requests independently. Our model makes use of a technique (selective packet drop) which selectively drops those unimportant frames so as to maintain video quality and low delay in the presence of congestion and fluctuating bandwidth. We have implemented a cellular and WLAN-based surveillance system using the model, and conduct real network measurement on its performance. Our model is simple and effective for mobile clients of heterogeneous bandwidth and computing power. Our results show that using TCP for streaming leads to good video quality in wireless networks.