Multi-Hop MIMO Relaying Based on Simultaneous Wireless Information and Power Transfer

This paper studies a multiple-input and multiple-output (MIMO) multi-hop decode-and-forward (DF) relaying wireless network. Communication between a source node and a destination node is aided via multi-hop relays with simultaneous wireless information and power transfer (SWIPT). We investigate the separate application of both power splitting (PS) and time splitting (TS) based SWIPT relaying protocols in our system model. The performances of the two are then compared and analyzed. The SWIPT protocol enables the current relay to harvest energy from the immediately preceding relay node, to reliably forward the information signals between the source and the destination. We aim to minimize the transmit power at the source under the end-to-end system throughput constraint by optimizing either PS or TS ratios at each relay node. For that, the global solutions for the ratios of either PS or TS are attained via convex optimization techniques. A closed-form solution was reached for the SWIPT PS approach. However, the SWIPT TS approach is achieved via an iterative algorithm. Also, we propose a simple routing algorithm based on Dijkstra’s algorithm for our proposed DF-SWIPT multi-hop system. Finally, we compare the proposed PS and TS ratio schemes to their corresponding fixed PS and TS ratio schemes, in terms of source power resource consumption, computational complexity, and overhead analysis. It is found that the PS outperforms the TS, owing to the higher computationally demands of the TS.