Performance Analysis Of NOMA Based Heterogeneous Cellular Networks

Driven by the research and mature of the Internet of Things,the smart terminals need access to wireless networks have dramatically increased.Due to the exclusive share of one internet resource,the orthogonal multiple access cannot effectively fulfill the requirements of the access of large amounts of smart terminals in the future 5G mobile internet.Non-Orthogonal Multiple Access(NOMA),by exploiting power domain multiplexing,can provide access to several terminals sharing one frequency resource the same time.Compared to orthogonal multiple access,NOMA can achieve higher spectral efficiency while guaranteeing the quality of service in the meantime.Thus NOMA is considered a promising multiple access technology in the future 5G network.Heterogeneous network is one of the core technology in the future 5G mobile network,which provide adequate increase in network capacity by deploying multi-tier base stations having different transmit power and distribution density.In this paper,we investigate the performance of the heterogeneous network applied with NOMA.Firstly,we proposed a NOMA based uniform heterogeneous network model,where users associate to base stations according to the largest long-term average receive power principle.Moreover the random user pairing is utilized for simplification.We derive the signal to interference plus noise ration expression by using stochastic geometry to model the aggregate interference,and then the coverage probability and achievable rate are given.Then a NOMA based non-uniform deployed heterogeneous network,which is more coincident with the real world,is considered,we propose a novel user pairing strategy based on the user association situation,utilizing the fact that the users in one NOMA group difference in channel condition have better performance.Then the distribution of the order statistic for the distances between different NOMA users and the serving base station is presented.On this basis,we analytically demonstrate the impact of various network parameters,such as base station density,on the coverage probability and achievable rate.Finally extensive simulations and comparisons are conducted,which validate the advantages of non-orthogonal multiple access over orthogonal multiple access in the considered heterogeneous network.Furthermore,the comparison between our proposed user pairing and random user pairing strategy shows the significant improvement on system performance.All the results illustrate that non-orthogonal multiple access will benefit heterogeneous network in the future 5G network.