STPAP: Source Transmit Power Adaptation Policy for Collaborative Wireless Systems

For the design of energy-efficient or green communication systems and networks, power adaptation has been studied extensively in the literature. A vital aspect of the same is to minimize the usage of resources wherever possible. This research implements a Source Transmit Power Adaptation Policy (STPAP) for a two hop collaborative wireless communication system. Our objective is to optimize end-to-end fading averaged-energy efficiency (FA-EE) when the source is subject to an average source power constraint. Specifically, we derive an analytical expression for FA-EE in terms of source power, which is adapted as a function of fading channels' state information (CSI). We compare optimal FA-EE results with CSI-independent, fixed source power FA-EE and verify through Monte-Carlo (MC) simulations and analytical results. We find that the proposed STPAP delivers superior performance in terms of FA-EE. We further extend our benchmarking to a scenario where a direct link between source and destination is absent. We also compare optimal FA-EE with fixed power FA-EE and quantify the proposed policy's performance gains.