Energy Harvesting Multiple Access Channel with Peak Temperature Constraints

We consider a two-user energy harvesting multiple access channel where the temperatures of the nodes are affected by the electromagnetic waves caused by the data transmission. To protect the nodes from excess heat, power allocation policies should take into consideration the temperature of all the nodes. In this paper, we study the optimal power allocations when the temperatures of the nodes are subject to peak temperature constraints. We first study the general case where each node has a different peak temperature requirement and the nodes have different temperature parameters. For this case, we show that the capacity region of the single energy arrival case is a single pentagon. We also show that the optimal policy for the multiple energy arrivals can be obtained by using generalized water-filling. We then study the temperature limited case where the transmitters have abundant energy and the only binding constraints are the temperature constraints. We study the optimal power allocation in this case and we derive sufficient conditions under which the rate region collapses to a single pentagon.