Low-latency and high-reliability performance analysis of relay systems

The latency and reliability of single-relay and multi-relay systems are investigated in this study. In a single-relay system with the amplify-and-forward protocol, a new approximation analytical method is proposed for the outage probability, which can also be extended to be used in the multi-relay system. The latency-reliability trade-off degree (LRTD) of single- and multi-relay systems, i.e. the slope of the latency-outage probability curve with logarithmic scales, is analysed and proved to be the same as the number of relay nodes. In the multi-relay system, the relationship between the system LRTD and the channel state information overhead is investigated. The optimum number of relay nodes can be derived according to the approximate expression of the outage probability. A simple iterative method is proposed to obtain the optimum number of relay nodes. The convergence of the iterative method is also proved