On the stability of random access with energy harvesting and collision resolution

This paper studies the queues stability in a random access network in which the nodes have finite energy sources. The network consists of two nodes, each having a battery for energy storage. Each transmission consumes a fixed amount of energy, and the batteries are replenished through energy harvesting. Moreover, the nodes leverage the feedback information for collision resolution. In case of a collision, the destination stores the collided packets, and sends negative acknowledgement (NACK). Once the NACK is heard, one of the nodes retransmits its collided packet. The destination uses the retransmitted packet and the stored collided packets to recover the two packets involved in the collision. Therefore, the two nodes are served in two transmissions, but the retransmitting node has used more energy in the process. To characterize the stability region of this system, each node is modeled with two queues, the first for storing packets and the second models the energy in the battery. The random access nature of the network, as well as the interdependence between the battery and packet queues in each node, result in an interacting system of queues. To decouple this interaction, and characterize the stability region, we resort to a dominant system approach for the analysis. The stability region obtained is compared with the stability region of the system without energy constraints, and the losses due to finite energy are identified.