Research On Resource Allocation Algorithm In Non-orthogonal Multiple Access System

With the improvement of informationalization level,the development of wireless communication techniques makes a variety of application forms appear.Recently,spectrum resource is becoming increasingly scarce,so how to use the resource more effectively is a technical problem to be solved.In this case,the proposed non-orthogonal multiple access technology can improve the spectral efficiency to some extent,and it is likely to be adopted by the fifth generation mobile communication.In the non-orthogonal multiple access(NOMA)technology,power domain is regarded as the dimension to distinguish the signals of different users,and transmitter will use the same time/frequency resource to transmit signals to different users,so that the system can support more users.Meanwhile,among key technologies which increase spectral efficiency,relay is a technology which shouldn't be ignored,so we can consider to combine relay and non-orthogonal multiple access technology.In non-orthogonal multiple access system,power allocation and user grouping will influence the system performance.Therefore,this thesis studies the resource allocation in non-orthogonal multiple access system.Firstly,this thesis studies resource allocation scheme of a non-orthogonal multiple access system in a single cell.In chapter 3,the power allocation strategy in a single user group is studied,and the relevant theorem can be proven through mathematical derivation,then a dichotomy-based power allocation algorithm is proposed,and the feasibility of the scheme can be confirmed by Monte-Carlo simulation.In addition,this thesis studies resource allocation problem in an OFDM-non-orthogonal multiple access systems,and the original problem can be decomposed into power allocation in subcarriers,power allocation among subcarriers,and user grouping problem.Afterwards,game theory is used to transform the user grouping problem into a matching problem,which is solved by the improved Gale-Shapley algorithm.Finally,a joint optimization iteration algorithm is proposed,and the superiority of the scheme is verified by Monte-Carlo simulation.Secondly,this thesis studies the resource allocation in a relay-based non-orthogonal multiple access system.In this scenario,relay is under half-duplex mode,so that there is no self-interference.On this basis,this thesis proposes a power allocation problem on base station and relay.This optimization problem can be divided into a power allocation problem among users in a same subcarrier and a power allocation problem on eNB and relay.To solve the second problem,this problem is non-convex,but it can be transformed to a convex form through changing the form of variables and using successive approximation algorithm.The dual decomposition method is used and an iterative algorithm is proposed to solve it.Numerical simulations are given to verify that the resource allocation algorithm can improve system performance.