Robust Real-Time Multimedia Transmissions in Wireless Ad Hoc Networks

To support the quality of service in wireless multimedia communications, wireless systems should work well in typical wireless environments characterized by the path loss of the signals, multipath fading, interference to adjacent channels, and random errors. A variety of researches in the application-layer have been proposed to adapt the video encoder to the link quality by compressing the data with different rates. However, these approaches introduce additional overhead and are inefficient when the round-trip delays are long. This paper proposes an algorithm to prevent packet losses and skipped frames by using optimal fragmentation technique with rate adaptation. Using an adaptive SNR estimator, the sender estimates the SNR of the receiver, and shapes arbitrary sized packets into optimal length packets with rate adaptation. Through rigorous analysis and extensive experiments with an implemented test-bed, we show that the algorithm significantly enhances the visual quality of real-time multimedia streaming in noisy ad hoc networks. The experimental results reinforce the fact that the algorithm is a realistic approach that can be deployed without modifying existing standards.