  We consider a two-hop communication network consisted of a source node, a
relay and a destination node in which the source and the relay node have
external traffic arrivals. The relay forwards a fraction of the source node's
traffic to the destination and the cooperation is performed at the network
level. In addition, both source and relay nodes have energy harvesting
capabilities and an unlimited battery to store the harvested energy. We study
the impact of the energy constraints on the stability region. Specifically, we
provide inner and outer bounds on the stability region of the two-hop network
with energy harvesting source and relay.
