Exploiting multi-channel transmission for opportunistic access with renewable energy sources

We consider an uplink system where multiple users have independent private channels plus a randomly accessible common channel. Moreover, each user is powered by some renewable energy sources via an energy harvester. Due to the variation of channel gains and energy arrivals, each transmitter could opportunistically wait for a better channel state and a higher energy level by postponing transmissions. Clearly, there exists an interesting relationship between channel-energy probing and the achievable average transmission rate. To optimally explore such a relationship, we study a distributed opportunistic scheduling (DOS) scheme, which allows the transmitter to make a choice between continuing to probe the channel-energy state and stopping for data transmission. By applying the optimal stopping theory, we develop the optimal stopping rule that maximizes the average throughput for each user. Numerical results validate the analysis and show that DOS can achieve approximately 10~20% throughput gain over the method of best-effort delivery.