MIMO video broadcast via transmit-precoding and SNR-scalable video coding

  • Authors:

  • Jun Xu;Raju Hormis;Xiaodong Wang

  • Affiliations:

  • Department of Electrical Engineering, Shanghai Jiao Tong University, Shanghai, China;Analog Devices, High-Speed Signal Processing Group, New Jersey, NJ;Department of Electrical Engineering, Columbia University, New Jersey, NJ

  • Venue:
  • IEEE Journal on Selected Areas in Communications
  • Year:
  • 2010

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Abstract

Video transmission on multiuser wireless channels faces manifold challenges in both source- and channel-coding. We propose a framework to analyze three facets of this idea: video distortion, transmit power, and delay. In the scenario considered here, both the transmitter and end-users are equipped with multi-antenna transceivers. The goal is to broadcast video to all users; however, the video is differentiated in quality to match the spatial and temporal variation of the channel. An emerging coding standard that is well-suited to this scenario is the Scalable Video Coding (SVC) extension of H.264. We employ the medium-grain scalability (MGS) feature of SVC, which allows us to generate quality-scalable layers from a single video sequence. For transport, the transmitter employs the block-diagonal zeroforcing (ZF) precoding technique, a well-known technique which yields good performance. With these assumptions, the idea here is to compute a precoder at fixed intervals. Crucially, the crosslayer framework allocates layers of video to the end-users jointly with precoder computation. The framework also ensures that delay and buffer constraints are met, which is necessary for real-time video. In terms of solution approach, the problem turns out to be a difficult mixed-integer nonlinear optimization problem. However, we show that it is tractable via a primaldual method. We analyze performance in various configurations, gaining insight into the relationship between the main system parameters.