Multimedia Distribution over Wireless Networks

Abhik Majumdar
(Professor Kannan Ramchandran)

We consider the problem of seamless distribution of multimedia data over high bandwidth wireless networks. Specifically, we focus on the popular IEEE 802.11b wireless LAN. In addition to the wireless channel related challenges, such as fluctuations in channel quality and high bit error rate, there is also the problem of heterogeneity among receivers, since each user will have different channel conditions, power limitations, processing capabilities, etc. We investigate novel algorithms for real-time multimedia transmission in such scenarios. This problem is complicated due to the close interaction of system parameters including source coding, channel coding, networking, transport layers, etc. Here, we address an integrated, end-to-end implementation of a multimedia dissemination system, rather than optimizing a component in isolation. To tackle this problem, we use progressive source coding together with the unequal error protection ideas presented in [1,2] to make the video bit stream insensitive to the position of packet loss. For the multicast case, we formulate the problem as an optimization of a maximum regret cost function across the multicast user space [3]. We have developed a modular server that works on a Linux platform and presents a transparent interface that enables it to support application layer error resilience with a wide range of video coders and transport protocols. We have successfully integrated the server with a real-time version of the packetization and transcoding ideas presented in [2]. We multicast the video stream to receivers with different channel characteristics and observe graceful quality degradation with the variation in packet loss rate and bandwidth. The end-to-end system operates in the 3 Mb/s regime and can be configured to run at higher rates. For details please refer to [3].

A. Albanese, J. Blomer, J. Edmonds, M. Luby, and M. Sudan, "Priority Encoded Transmission," IEEE Trans. Information Theory, November 1996.
K.-W. Lee, R. Puri, T.-E. Kim, K. Ramchandran, and V. Bhargavan, "An Integrated Source Coding and Congestion Control Framework for Video Streaming in the Internet," Proc. INFOCOM, March 2000.
A. Majumdar, D. G. Sachs, I. Kozintsev, K. Ramchandran, and M. Yeung, "Multicast and Unicast Real-Time Video Streaming over Wireless LANs," IEEE Trans. Circuits and Systems for Video Technology, Vol. 12, June 2002.

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