铁路物联网中无线携能中继网络性能分析

Performance analysis of simultaneous wireless information and power transfer relay network in railway Internet of things

面向铁路物联网场景研究了能量受限的两跳多中继网络的系统性能。源节点部署在列车上,向地面上能量受限的中继节点传输能量和信息,中继节点利用收集的能量向目的节点转发信息,中继节点采用半双工放大转发模式。在考虑中继电路具有能量激活门限的情况下,推导出在莱斯衰落信道下系统中断概率和吞吐量的闭合表达式。通过蒙特卡洛仿真验证了理论分析的正确性,对比分析了第一跳距离最短和两跳距离之和最短的两种中继选择策略下,莱斯因子、时间分割因子、源节点天线数量、源节点总发射功率、能量转化效率、各节点相对位置对系统端到端中断概率和吞吐量的影响。当列车先后经过各个中继时,系统的中断概率先减小后增大,吞吐量先增大后减小,并且选择两跳距离之和最短时的系统性能优于选择第一跳距离最短时的系统性能。

The system performance of energy constrained dual-hop multi relay network was studied in railway Internet of things. The source node was deployed on the train to transmit energy and information to the relay node with constrained energy on the ground. The harvested energy was used by the relay node to forward information to the destination node, and the relay node used half-duplex amplify-and-forward mode. Considering that the relay circuit has energy activation threshold, the closed-form expression of outage probability and throughput in Rician fading channel was derived. The correctness of the theoretical analysis was verified by Monte Carlo simulation, and the effects of Rician factor, time switching factor, the number of source node antennas, total transmission power of source node, energy conversion efficiency, relative position of each node on the end-to-end outage probability and throughput were compared and analyzed under the two relay selection strategies with the shortest first hop distance and the shortest sum of dual-hop distance. When the train passes through each relay successively, the outage probability of the system decreases first and then increases, and the throughput increases first and then decreases. The performance of the system with the shortest sum of dual-hop distances is better than that with the shortest first hop distance.