Cross-layer rate-adaptation and joint source-channel coding for delay-constrained video streaming over wireless ad-hoc networks

For video communications over wireless ad-hoc networks, there are fundamentally two different kinds of packet losses: packet losses due to channel over-pumping, where the operating transmission rate is higher than the prevailing channel capacity; packet losses due to transmission errors. To eliminate the first kind of packet loss, rate-adaptation is necessary in order to adapt to the time-varying channel capacity. For the second kind of packet loss, error-resilient coding techniques should be used. We propose a cross-layer rate-adaptation scheme based on an analytical study of how the effective video transmission rate is affected by the prevailing operating parameters. Furthermore, in order to provide error-resilient real-time video delivery over such wireless ad-hoc networks, a cross-layer delay-constrained joint source-channel coding (JSCC) approach, to be used in conjunction with rate-adaptation, is proposed and investigated. Simulation results demonstrate the effectiveness of this combination of cross-layer rate-adaptation and delay-constrained JSCC for supporting error-resilient video delivery over wireless ad-hoc networks operating under a delay constraint. We also demonstrate the influence of the imposed delay constraint on the overall system performance.