A power-aware scheduler for streaming multimedia clients
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Mobile computers consume signi .cant amounts of energy when receiving streamed multimedia data.The wireless network interface card (WNIC)consumes a large portion of this energy.One way to reduce the energy consumed is to transmit the packets to clients in a predictable fashion.Speci .cally,the packets can be sent in bursts to clients,who can then switch to a lower power sleep state between bursts. This technique is especially e .ective when the bandwidth of a multimedia stream is small. This paper investigates techniques for saving energy in a multiple-client scenario, where clients may be either (1)viewing streaming multimedia or (2)receiving back- ground (e.g.,web)data.Given the real-time requirements of multimedia tra .c,we di .erentiate network tra .c into two types:multimedia and background.We then generate di .erent global schedules for multimedia packets and background packets. Several di .culties arise with multiple clients,including delays,droughts and band- width limitations.Despite this,multimedia clients using our schedule save signi .cant energy with few missed packets,while general clients achieve reasonable end-to-end latency.For example,our schedule saves over 90%of the energy for ten multimedia clients viewing 56kbps video streams.With an additional 220kbps of web tra .c, end-to-end latency averages 32 ms,while multimedia clients save 86.9%.