Multiple Broadcast Channels with Energy Harvesting

In this chapter, we consider the energy-bandwidth allocation for a network with multiple broadcast channels, where the transmitters access the network orthogonally on the assigned frequency band and each transmitter communicates with multiple receivers orthogonally or non-orthogonally. We assume that the energy harvesting state and channel gain of each transmitter can be predicted for K slots a priori. To maximize the weighted throughput, we formulate an optimization problem with O(MK) constraints, where M is the number of the receivers, and decompose it into the energy and bandwidth allocation subproblems. An iterative algorithm is proposed that alternatively solves two sub-problems in each iteration for both the orthogonal and non-orthogonal broadcast channel. We also propose efficient algorithms to solve the two subproblems, so that the optimal energy-bandwidth allocation can be obtained with an overall complexity of O(MK2), even though the problem is non-convex when the broadcast channel is non-orthogonal. For the orthogonal broadcast channel, we further formulate a proportionally-fair (PF) throughput maximization problem and derive the equivalence conditions such that the optimal solution can be obtained by solving a weighted throughput maximization problem. Further, the algorithm to obtain the proper weights is proposed. Simulation results show that the proposed algorithm can make efficient use of the harvested energy and the available bandwidth, ∗E-mail address: [email protected] †E-mail address: [email protected] ‡E-mail address: [email protected] 2 Vaneet Aggarwal, Xiaodong Wang and Zhe Wang and achieve significantly better performance than some heuristic policies for energy and bandwidth allocation. Moreover, it is seen that with energy-harvesting transmitters, non-orthogonal broadcast offers limited gain over orthogonal broadcast.