Cross-Layer QoS Scheduling for Layered Multicast Streaming in OFDMA Wireless Networks |
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Authors: | Yuedong Xu Xiaoxin Wu John C S Lui |
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Affiliation: | (1) Laboratory for Communication Networks, KTH - Royal Institute of Technology, 10044 Stockholm, Sweden |
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Abstract: | The conventional multicast scheme of wireless networks, though establishing a bandwidth-saving means for point-to-multipoint
transmission, is very conservative by limiting the throughput of short-range communications. The multicast performance can
be significantly improved if some low-rate users are pruned. In this paper, we investigate the subchannel assignment mechanism
of multicast streaming services in the emerging WiMax/802.16e systems, where each multimedia stream is composed of a basic layer and an enhancement layer. The former affords a low-resolution video image to all the subscribers, while the latter only serves those with preferable
channel states. Optimization frameworks are formulated to characterize the QoS requirements of multicast flows: pruned proportional rate ratio (PPRR), pruned stream rate guarantee (PSRG) and pruned user proportional fairness (PUPF). Three cross-layer algorithms are presented to perform channel assignment for different QoS requirements. Analytical study
shows that the proposed algorithms have polynomial-time computational complexity. Numerical experiments validate that our
proposals significantly outperform the conventional peer schedulers in terms of system throughput. |
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