Research On Ergodic Capcity Analysis And Optimization Algo Rithm Of Full-Duplex Integrated Access And Backhaul System

3GPP proposes Integrated Access and Backhaul(IAB)system as a 5G high-speed wireless backhaul solution,and supports multi-hop relay to achieve greater coverage and more flexible topology.3GPP has clearly proposed a capacity increase requirement for IAB system,and research related to its capacity has become a hotspot.As one of the key technologies of 5G,full-duplex allows signal to be sent and received at the same node,in the same frequency and during the same time.Ideally,the system capacity can be doubled.Combining full-duplex with IAB system can effectively increase its system capacity,but at the same time it also brings the problem of self-interference that cannot be ignored,making the interference environment in IAB system more complicated.Therefore,in the case of considering interference,capacity analysis for full-duplex IAB system is very important,and on this basis,capacity optimization is the key to increase system capacity.This project originated from the National Natural Science Foundation of China's "Research on Full-duplex Polarization Self-interference Elimination Based on Phase Noise Additive Gaussization(61501050)".Because IAB system supports the multi-hop relay form,this thesis uses ergodic capacity as the performance index of capacity in this research,which is the most common index in the capacity research of multi-hop relay.In the case of residual self-interference and backward interference,the general expression of ergodic capacity is derived,which characterizes the actual capacity performance of the system.Based on this,an optimization algorithm based on Genetic Algorithm is proposed,which reduces the impact of interference and effectively improves the system ergodic capacity.The main research and achievements are as follows:(1)This thesis summarized the current research on IAB system,full duplex and full-duplex IAB system ergodic capacity.Firstly,the research status and challenges of IAB system are introduced,and the necessity and importance of capacity research on IAB system are pointed out.Secondly,it introduces the characteristics and research status of full-duplex,and explains the feasibility of introducing it into the IAB system,as well as the advantages and problems it brings.Finally,the research status of full-duplex IAB system ergodic capacity is introduced,and it is carried out from two aspects of analysis and optimization,which explains the problems that needs to be solved in this thesis.(2)The interference signals cause the SNR at each IAB node not to obey the same distribution or even the standard distribution,and there are differences in the number of interference signals in systems with different hops,so it is difficult to form a general ergodic capacity calculation method.In order to solve this problem,an ergodic capacity analysis method for multi-hop full-duplex IAB system is proposed.The ergodic capacity expressions of the three-hop full-duplex IAB system are firstly derived in detail,and mathematical methods such as probability theory and inequality variants are used to deal with non-standard distribution terms.Then the expression is extended to the system with arbitrary hops.Simulation results show that the obtained expression can achieve a relatively accurate approximation,which can accurately reflect the actual performance of the system.(3)The powers of the interference signals in the system are not only related to the transmit power of the nodes,but also to the distance between adjacent nodes.Aiming at this problem,an ergodic capacity optimization algorithm based on Genetic Algorithm is proposed.Firstly,an optimization problem including two groups of variables is constructed,then the genetic algorithm is used to solve the optimization problem,and the variable coding and decoding rules and fitness functions are designed.At the same time,an elite retention strategy is introduced to ensure the performance of the algorithm.Simulation results show that the proposed optimization algorithm can reduce the influence of interference signals and effectively increase the ergodic capacity of the system.