Research On Energy And Spectrum Efficiency Equalization Algorithm For Decode-and-forward Multi-relay Networks

Wireless relay is widely used in various wireless communication networks because of its high received signal-to-noise ratio,wide coverage,high throughput,and low transmitting power consumption.However,the rapid growth of wireless infrastructure and user terminals has caused a surge in energy consumption,which has further brought huge electricity and maintenance costs to network operators and brought many environmental problems.In order to alleviate these problems,green wireless communication has attracted the attention of academia and industry.In addition,when the spectrum efficiency（SE）of the wireless communication network increases,more data needs to be transmitted and more energy is consumed,causing a decrease in energy efficiency（EE）.Therefore,the trade-off between EE and SE is of vital importance to future wireless communications.Based on this,this thesis studies the balance optimization of EE and SE for wireless multi-relay networks.The EE and SE balance optimization schemes for decode-and-forward（DF）half-duplex（HD）multi-relay networks,DF full-duplex（FD）multi-relay networks,and DF FD multi-relay networks under imperfect channel state information are respectively proposed.These solutions are proposed to further realize green wireless communication.The main research contents and contributions of this paper are as follows:1.An optimization method for energy efficiency and spectrum efficiency balance applied to DF half-duplex multi-relay networks is proposed.First,consider the case of multiple relays,in order to improve EE,the relay node with the highest EE is regarded as the best relay node.Then,the optimal node transmitting power is allocated to each node based on the optimal SE.Finally,find the optimal total power of the node in the EE analysis expression to obtain the corresponding EE optimal solution,and analyze the influence of EE and SE on the relative position of the relay node.The simulation results show that compared with methods such as optimal power allocation,the proposed optimization method has higher energy efficiency and spectrum efficiency.In addition,when the relay node approaches the two ends from the middle of the base station node and the user node,the energy efficiency and spectrum efficiency first increase and then decrease.2.An iterative optimization method for the balance of EE and SE applied to DF FD multi-relay networks is proposed.The method combines the transmitting power adjustment of each node with the selection of relay nodes participating in data transmission.Compare the scenarios of using different relay nodes,select the relay node that can achieve the best energy efficiency in the DF fullduplex multi-relay network as the best relay node,and then deduce the analytical expressions of energy efficiency and spectrum efficiency under the best relay node.The EE was optimized under the constraints of the minimum SE and the maximum transmitting power of each node.The effects of residual self-interference on EE and SE of the DF FD multi-relay network were analyzed.Simulation results show that compared with the existing optimal transmitting power method,the EE and SE of DF full-duplex multi-relay network under the iterative optimization method are higher.3.For the DF full-duplex multi-relay network under imperfect channel state information,in order to optimize energy efficiency and spectrum efficiency,the iterative optimization of node transmitting power and relay selection is realized by the KKT（Karush-Kuhn-Tucker）conditions.Considering the imperfect channel state information,comparing the scenarios using different relay nodes,selecting the relay node that can achieve the best energy efficiency in the DF full-duplex multi-relay network as the best relay node,and deriving the analytical expressions of EE and SE under the best relay node.The KKT conditions are used to solve the node transmitting power to find the optimal value of EE and SE,and to analyze the influence of residual self-interference and channel estimation error on EE and SE of the DF FD multi-relay network.