Cross-Layer Optimization for Downlink Wavelet Video Transmission

Cross-layer optimization for efficient multimedia communications is an important emerging issue towards providing better quality-of-service (QoS) over capacity-limited wireless channels. This paper presents a cross-layer optimization approach that operates between the application and physical layers to achieve high fidelity downlink video transmission by optimizing with respect to a quality criterion termed “visual entropy” using Lagrangian relaxation. By utilizing the natural layered structure of wavelet coding, an optimal level of power allocation is determined, which permits the throughput of visual entropy to be maximized over a multi-cell environment. A theoretical approach to optimization using the Shannon capacity and the Karush-Kuhn-Tucker (KKT) conditions is explored when coupling the application with the physical layers. Simulations show that the throughput gain for cross-layer optimization by visual entropy is increased by nearly 80% at the cell boundary as compared with peak signal-to-noise ratio (PSNR).