Two-hop networks with energy harvesting: The (non-)impact of buffer size

Abstract—In this paper, a two-hop channel is considered with energy harvesting transmitter nodes. In particular, the offline throughput max-imization problem is solved for a constant power relay, and a relay with one energy arrival, in both cases assuming a finite buffer is available at the relay for temporarily storing data received from the source. The focus is on assessing the impact of this data buffer at the relay on optimal transmission policies. The solution is found indirectly, by first assuming that the relay has an infinite size buffer, and then proving that an optimal policy exists that does not require any data buffer at the relay, thus solving the problem regardless of the data buffer size at the relay. Numerical results demonstrate that the proposed solution performs significantly better than naı̈ve policies, and a constant relay rate limits the average throughput as the peak energy harvest rate for the source increases. Index Terms—Energy harvesting nodes, two-hop channel, relay chan-nel, throughput maximization, finite buffer. I

Incentivizing Signal and Energy Cooperation in Wireless Networks

Abstract-We consider a two-hop wireless network where the source(s) in the network have the ability to wirelessly power the relay(s) who also have their own data to send to the destination. Considering the fact that each node in the network aims to maximize its own metric, we adopt a game theoretic approach that foresees offering relaying of the sources' data in exchange for energy provided to the relays, and simultaneously offering energy to the relays in exchange for their relaying services. We first study a Stackelberg competition with the single relay node as the leader, and investigate the impact of having multiple source nodes in the system. We next study the reciprocal Stackelberg game with the single source as the leader, and investigate the inter-relay competition with multiple relays. We find that in the Stackelberg games, the leader can improve its individual utility by influencing the follower's decision accordingly, even more so when there are multiple followers. We next formulate a noncooperative game between the source and the relay and show the existence of a unique Nash equilibrium by an appropriate pricing mechanism. The equilibrium maximizes the total utility of the network and allows the destination to choose how much data to receive from each node