Performance of a Cooperative Communication Network With Green Self-Sustaining Nodes

The desire to reduce carbon foot-print and avoid frequent battery replacement has increased interest in green self-sustaining wireless nodes based on energy harvesting. In this article, we analyze the performance of a two-hop cooperative network with green self-sustaining nodes. The source and relay nodes are equipped with energy buffers, and store the energy harvested from the ambience. Signal transmission is powered at both source and relay solely by the stored energy. Both fixed and adaptive-rate transmission schemes are considered, and analytical expressions are presented for throughput and ergodic rate. Unlike all previous works that use discrete-state Markov chains to model the buffer dynamics, we use the more appropriate discrete-time continuous-state space Markov chain. We consider two different energy management policies at the source and relay: best-effort policy (BEP) and on-off policy (OOP). It is observed that for fixed-rate transmission, the better choice of buffer management policy (throughput-wise) at the source and the relay buffers depends on the relay location and target rate. On the other hand, for adaptive rate transmission, using BEP policy at both the energy buffers ensures best performance. The derived analytical expressions are validated by Monte Carlo simulations.