Delay-power tradeoff of max queue-weighted (MWQ) power control for wireless systems with limited renewable energy storage

In this paper, we analyze the fundamental power-delay tradeoff in point-to-point wireless communication systems with renewable energy source. We consider the max queue-weighted (MWQ) algorithm, where the transmitter determines the rate and power control actions based on the instantaneous channel state information (CSI), the data queue state information (DQSI) and renewable energy storage information (RESI). We exploit a general fluid dynamics of the data queue and renewable energy storage buffer using continuous time dynamic equations. Using the sample-path approach and renewal theory, we decompose the average delay in terms of multiple unfinished works along a sample path, and obtain bounds for the average delay and AC power consumption under the MWQ algorithm, which are asymptotically tight at small delay regime. We show that despite the randomness of the renewable energy arrival and energy buffer size, the average AC power (P) of the MWQ policy is given by P = O(D exp(1/D)) at small delay D regime. We also quantify the impacts of the renewable energy storage size in the scaling coefficient.