Energy optimal scheduler for diversity fading channels with maximum delay constraints

We present a minimal energy packet scheduling and rate control scheme with a strict maximum delay constraint. This problem occures natually in real-time wireless multimedia transmission where a hard delay limit is imposed on each packet. In general, the communication link is assumed to be a diversity channel with multiple parallel sub-channels(e.g. OFDM, or MIMO eigenchannels.) We present both the theoretical optimal solution, which assumes prescient traffic and channel knowlodge, and a causal scheduler where the future is only known statistically. We show that the causal scheduler performs well, to within 3 dB of the prescient optimal in a single channel, and is even better with diversity channels.