Analysis and design of wireless two-way relay networks with energy harvesting

Abstract

Modern wireless communication networks are powered by conventional energy sources such as power grids, generators, and rechargeable batteries, as they supply steady energy. However, such energy sources demand regular maintenance or replacement which incurs more operational cost and sometimes may become impractical in hazardous environments. On the other hand, energy harvesting (EH) techniques have been gaining signi cant attention for complementing the current grid-powered wireless communication networks by prolonging their lifespan and making them more environment friendly. As such, the energy can be harvested opportunistically from the ambient radio-frequency (RF) signals. The basis for such EH lies in a fact that both information and the energy can be transmitted simultaneously through the RF signals. In this thesis, we adopt various EH approaches for the performance analysis of two-way relay (TWR) networks. Firstly, we analyze the outage performance of TWR networks wherein two communicating nodes exchange their information via a half-duplex battery-enabled relay node. A hybrid decode-amplify-forward based relaying scheme is proposed to make communication links more reliable. In this system setup, the relay node harvests energy from the received RF signals using the time switching based EH approach. Further, it is considered that destination nodes can exploit both direct and relaying links for communication purpose. After the successful EH process, the relay utilizes the harvested energy for processing and broadcasting the received information signals to the destination nodes. At the destination nodes, selection combining (SC) technique has been employed to retrieve the information via direct and relaying links. Furthermore, we also consider the power splitting approach of EH at the relay node in which the power of received signals is split into the information and the EH seg-ments. Hereby, relay node harvests energy from the received RF signals in the rst two phases and utilizes the harvested energy for information processing and broadcasting in the third phase. Relay node relies on amplify-and-forward operation to broadcast the signals and destination nodes employ the maximum-ratio combining (MRC) technique to combine the signals via direct link as well as relaying link. For this setup, we obtain the expressions for user outage probability, energy e ciency, and achievable system throughput for both MRC and SC schemes under Nakagami-m fading channels. Moreover, we show analytically the importance of considering direct link in the simultaneous wireless information and power transfer in TWR networks.