Resource Allocation Algorithm For Non-orthogonal Multiple Access Technology In Heterogeneous Cellular Networks

Non-orthogonal multiple access(NOMA)technology is one of the key technologies of 5G mobile communication system.It can distinguish different users by power domain reuse,which can significantly improve the spectrum utilization of the system and alleviate the problem of resource shortage to some extent.However,because NOMA is multiple cellular users multiplexing data over the same channel,it can cause signal interference problems between cellular users on the same channel.Therefore,in order to coordinate the interference caused by multiplexing channels in NOMA system,it is necessary to optimize the allocation of wireless resources,which is one of the key problems in the application of NOMA technology.This thesis mainly studies the resource allocation problem based on NOMA technology in the cellular network system,analyzes the causes of interference in various scenarios using NOMA technology,and proposes the specific contents of interference management algorithm as follows:(1)For two stage NOMA-D2 D and cooperative relay(NOMA-DC)scenario,this thesis proposes a optimization algorithm of power allocation factor to maximize the system the capacity of the algorithm to two phase optimization problem is divided into two parts,and to solve the first stage of power allocation and decisive factor,first simplifies the objective function,and then the convex function to get the optimal power allocation factor,the first stage is analyzed based on the user outage probability performance changes.Simulation results show that the proposed algorithm can significantly improve the system capacity and reduce the interrupt probability of relay users.(2)A user matching and power allocation algorithm for NOMA-D2 D heterogeneous cellular system is proposed.Firstly constructs the system to maximize the total rate as the target of optimization problem,because the original the non-convex optimization problems for mixed integer optimization,it is divided into user pairing and power allocation in two sub-problems to solve user with sub-problems,respectively is proposed based on cellular subscribers and D2 D to matching algorithm;In power distribution sub-problems,respectively using auxiliary gradient binary search algorithm and successive convex approximation of logarithmic approximation sub-channel power was optimized and the D2 D sending power.Simulation results show that the proposed algorithm can effectively improve the system total rate,and the proposed optimization algorithm greatly reduces the complexity of algorithm performance.(3)Aiming at the problem of energy efficiency resource allocation in NOMA basedheterogeneous cellular network,this thesis proposes a channel allocation and power allocation algorithm.Pair and then matching problem of channel and power allocation sub-problem optimization respectively,matching problem many-to-many matching algorithm for channel using Lagrange dual method to optimize the user power allocation,the joint iterative solving the problem of system energy efficiency maximization simulation results show that this proposed algorithm can effectively improve system efficiency,phase time optimization algorithm performance approximate to the optimum algorithm and has lower complexity.