A Game Theoretic Approach for Backscatter-Aided Relay Communications in Hybrid Radio Networks

In this paper, we consider a multi-user device-to-device network capable of harvesting energy from radio frequency (RF) signals. We assume that each user has a dual-mode radio architecture and can operate in either conventional active RF communications or passive backscatter communications. In the latter, the data transmission relies on the reflection of ambient RF signals. We capitalize the fact that the two communications technologies can complement each other in a hybrid radio network, by proposing the passive relaying scheme for active RF communications. Specifically, each active RF radio is allocated a fixed time slot for its data transmission. It is also assisted by a set of passive radios via backscattering the RF signals of the active radio. Though passive relaying is energy efficient as it consumes minuscule amount of energy in backscatter communications, it indeed competes the channel time that can be used by the passive radios to harvest RF energy. We propose a game-theoretic approach to balance energy harvesting and relaying performance, by allowing each passive radio to iteratively optimize its reflection coefficients. The simulation results verify that the passive relaying scheme significantly enhances the sum throughput of a hybrid radio network.