JOINT POWER ALLOCATION AND BIT LOADING FOR ENHANCED SVC VIDEO DOWNLINK TRANSMISSIONS OVER SDMA/OFDMA NETWORKS

We address in this paper the utility maximization of scalable video transmission under limited radio resource in a multi-user, multi-antenna downlink. The proposed utility maximization frame work comprises two parts: a utility analysis of scalable video based on approximated rate-distortion function and a resource allocation scheme by joint power allocation and bit loading. Scalable video packets are entitled with differentiated priority due to the inherent dependency relations hip in a layer-based encoding scheme. First, we analyze the rate-utility of scalable video by packet prioritization, which plays a key role in video utility maximization under a fixed rate constraint. Then to cater for diverse rate-utility character and time-varying network condition for multiple scalable video downlink over SDMA/OFDMA system, a joint power allocation and bit loading scheme is proposed to increase the overall video utility under limited radio resource. The resource allocation is accomplished by three important procedures, user grouping, bit loading and power adaptation. The performance of the proposed scheme is validated by comparing with conventional radio resource allocation schemes.