Prolonging User Battery Lifetime Using Green Communication in Spectrum Sharing Networks

In this letter, a zonal-based approach is proposed for a spectrum sharing (SS) network, with the primary transmitter (PT) forming device-to-device (D2D) communication links with multiple primary receivers (PRs), in contemplation of green communication. The transmission power of the PT is iteratively optimized within a zone, such that it is adequate to meet the target rates of the applications demanded by the PRs. This results in lower energy consumption at the PT, thus prolonging its battery lifetime. If the transmission power at the PT is insufficient to meet the target rates over the PT → PR D2D links, the PT relays information through a suitable secondary transmitter (ST) to guarantee the quality of service (QoS) in the network. The ST acts as an amplify-and-forward (AF) relay for forwarding the primary information and achieving the target rates. The ST selection is based on its remainder transmission power level and the PT → ST channel states. The performance of the proposed scheme, in terms of energy efficiency (EE) and battery lifetime, is demonstrated through simulations.