Delay-constrained transmission of fine scalable coded content over P2P networks

Images or videos are generally coded before transmission, and they can be either non-scalable coded or scalable coded, which can be further classified into fine-scalable coded and coarse-scalable coded. In this paper, we focus on delivery of fine-scalable coded content. The objective of our work is to design algorithms to optimize the quality of finescalable coded images or videos on peer-to-peer networks when a requesting peer is delay-sensitive and has to display content within a certain delay bound. Fine-scalable coding has two properties: (1) it embeds lower bit-rate bitstreams into higher bit-rate bitstreams; and (2) its coding quality increases with every additional bit in the coded bitstream. These imply that for a given requesting peer, there may exist a dynamic set of supplying peers that have the same content coded in different bit-rates, have different outgoing bandwidth and may finish transmission at different times. In this paper, we first illustrate the importance of peer assignment problem using an example. Then we formally define and formulate the problem as two integer programming problems, from which we derive an optimal peer assignment solution. Finally, we carry out extensive experiments to verify the excellent performance of the proposed peer assignment algorithms by comparing with other heuristic schemes. r 2004 Elsevier B.V. All rights reserved.