关键词: 全双工, 认知中继, 能量收集, 能效谱效, 权衡因子

Abstract: In a full-duplex multi-cognitive relay network supported by simultaneous wireless information and power transfer, in order to maximize energy-spectrum efficiency, the relay with the largest energy harvesting was selected for decoding and forwarding, thus forming an energy-spectrum efficiency trade-off optimization problem. The problem was transformed into a convex optimization problem by variable transformation and concave-convex process optimization method. When the trade-off factor was 0, the optimization problem was equivalent to the optimization problem of maximizing the spectrum efficiency. When the trade-off factor was 1, the optimization problem was equivalent to the problem of minimizing the energy consumed by the system. In order to solve this optimization problem, an improved algorithm that could directly obtain the trade-off factor that maximizes energy efficiency was proposed, which was optimized by combining the source node transmit power and the power split factor. The proposed algorithm was divided into two steps. First, the power split factor was fixed, and the source node transmit power and trade-off factor that made the energy efficiency optimal were obtained. Then, the optimal source node transmit power was fixed, and the optimal power split factor was obtained by using the relationship between energy-spectrum efficiency and power split factor. Through simulation experiments, it is found that the relay network with the largest energy harvesting is better in energy efficiency-spectrum efficiency than the network composed of other relays. In terms of energy-spectrum efficiency, the proposed optimization algorithm is better than other methods. Compared with the scheme that only optimizes the transmit power, the energy efficiency has increased by more than 63%, and the spectrum efficiency has increased by more than 30%, which is almost the same as the exhaustive method, which greatly improves the energy-spectrum efficiency, and the algorithm converges is faster. 

Key words: full-duplex, cognitive relay, energy harvesting, energy-spectrum efficiency, trade-off factor