A distortion-minimizing rate controller for wireless multimedia sensor networks

The availability of inexpensive CMOS cameras and microphones that can ubiquitously capture multimedia content from the environment is fostering the development of wireless multimedia sensor networks (WMSNs), i.e., distributed systems of wirelessly networked devices that can retrieve video and audio streams, still images, and scalar sensor data.A new cross-layer rate control scheme for WMSNs is introduced in this paper with a twofold objective: (i) maximize the video quality of each individual video stream; (ii) maintain fairness in the domain of video quality between different video streams. The rate control scheme is based on analytical and empirical models of video distortion and consists of a new cross-layer control algorithm that jointly regulates the end-to-end data rate, the video quality, and the strength of the channel coding at the physical layer. The end-to-end data rate is regulated to avoid congestion while maintaining fairness in the domain of video quality rather than data rate. Once the end-to-end data rate has been determined, the sender adjusts the video encoder rate and the channel encoder rate based on the overall rate and the current channel quality, with the objective of minimizing the distortion of the received video. Simulations show that the proposed algorithm considerably improves the received video quality with respect to state-of-the art rate control algorithms, without sacrificing on fairness.