Relay Placement of Two-Way Multi-Hop Relay Network with Power Adaptation in a Realistic Shadowing Environment

Deployment of relay nodes can enhance the coverage of wireless network in shadowing environments. Recently, MIMO Two-way Multi-hop Network (MTMN) has been introduced as a communication scheme to improve channel capacity of relay networks. Moreover, the strategy of Power Adaptation (PA) has been proposed for MTMN to adjust the Signal-to-Interference plus Noise Ratio (SINR) to achieve the highest performance. However, the studies of MTMN has been based on Rayleigh fading channel model which may be far from the reality since all links in the network are not in the same condition, especially when shadowing is dominant. Moreover, the realization of optimum placements in MTMN for relays in the real shadowing environment is still a left-behind issue. Therefore, this paper aims to investigate the optimum relay placements of MTMN by conducting 3D ray-tracing simulation of propagation channel in a real shadowing environment. Based on the results, the optimum relay placements of MTMN without PA are where relay links do not suffer from shadowing effect. On the contrary, the results show that the optimum placements for MTMN with PA case is different since PA can more efficiently reduce the interference at these locations. In addition, this paper proposed a methodology to estimate the optimum locations for MTMN with PA by using the knowledge of node-to-node signal strength which can be simply obtained in the real environment.