Research On Optimal Relay Selection Scheme Based On Power Allocation

In the actual communication system,due to the geographical environment,buildings,climate and other complex and changeable,the data transmission process there are fast,slow and multipath fading phenomenon,the use of relay forwarding can reduce the wireless transmission link interruption rate,System throughput,reduced power consumption.In the wireless relay communication system,the power distribution between the source node and the relay node is a matter of concern.In particular,power allocation is very important for relay communication systems.In a wireless network communication with relay,the traditional point-to-point communication mode is no longer present and is replaced by a more complex two-hop transmission link.The transmission power involves the distribution between the source node and the relay node.In such a system,the performance of the selected relay node will directly affect the overall performance of the link.In this paper,we first study the single-channel relay selection algorithm based on power allocation,consider a relay selection scheme with low interference and high communication quality,and allocate the power of the source node and the relay node with the Lagrangian extreme method.The purpose is to minimize the system's interrupt rate.The Lagrangian function is composed of the average signal-to-noise ratio of each link,the reciprocal of the transmitted power and the constraint condition,the extreme value of the Lagrangian function is obtained,and the power distribution value which maximizes the joint function is obtained,and the power and channel The parameters are substituted into the coefficients of the information to be sent,and the coefficients are selected and the relay nodes with the largest coefficients are selected,and the communication is completed in combination with the enlargement and forwarding strategy.This algorithm can choose a better communication link at the same time,but also save energy and reduce interference.Then,two-path relay selection scheme with self-interference control and power allocation is proposed for the minimum error rate,channel rate and computational complexity selected bytwo-path relay.Considering the optimal and suboptimal power allocation algorithm,the optimal algorithm uses the bisection method to find the optimal value of the nonconvex objective function.The suboptimal algorithm uses the high signal to noise ratio approximation to describe the optimal problem.Based on the power allocation algorithm The optimal criteria of two-path relay selection and the sub-optimal criterion of low self-interference are proposed.For two-path relay selection scheme with self-interference control and power allocation for communication in AF mode,four optimization variables are considered: the transmit power of the two source nodes of each link in successive slots,The transmission power of the node.The simulation results show that the bit error rate of the two-path relay selection is much smaller than that of the single-channel relay,and the bit error rate of the suboptimal selection criterion is almost equal to the optimal selection criterion.The computational complexity of the suboptimal scheme is much lower than the computational complexity of the optimal scheme.In practical application,the suboptimal option can be used to reduce the computational complexity and achieve the same performance as the optimal scheme.This research is very meaningful for limited wireless communication systems.