Cross-Layer Optimization for Downlink Wavelet Image Transmission

Cross-layer optimization for efficient multimedia communications has been an emerging issue, in terms of providing better QoS (Quality of Service) over a capacity-limited wireless channel. This paper presents a cross-layer optimization approach between multimedia and wireless network layers for downlink image transmission by means of 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, to permit the throughput of visual entropy for downlink broadband wireless systems to be maximized over a multi-cell environment. In the simulation, the throughput gain of visual entropy is dramatically increased up at the cell boundary, with respect to the case of no considerations.