Research On Radio Resource Management On Heterogeneous Network And Non-orthogonal Multiple Access Based Cellular Networks

The rapid development of mobile Internet and Internet of Things(IoT)drives the mobile communication system to develop toward greater connection density,better communication transmission performance and higher system capacity.To cope with the challenges within the mobile communication system,heterogeneous cellular networks(HetNet),non-orthogonal multiple access(NOMA)and cooperative communication techniques are becoming the focuses of discussion and attention in academia and industry at present.The inclusion of NOMA and HetNet will call for more rigorous and intelligent radio resource management.As a result,this dissertation focuses on the radio resource management in mobile communication system under the applications of heterogeneous cellular network,NOMA cellular network and NOMA-based heterogeneous network and cooperative relay systems,and carries out in-depth research and analysis,ultimately achieving the improvement in the system performance of the mobile communication network.Firstly,a low-complexity distributed power allocation and user scheduling algorithm is proposed,which can maximize the total capacity of heterogeneous cellular network under the constraints of the transmit power of base station and quality of service requirement of users.In order to reduce the computational complexity,the power allocation and user scheduling are executed independently in each cell.Besides,the influence on surrounding macrocell users are taken into account for the radio resource management in each femtocell.The simulation results show that the distributed power allocation and user scheduling algorithm can improve the system capacity meanwhile effectively guaranteeing the outage performance of users in heterogeneous cellular network.Secondly,aiming at the balance among energy efficiency,spectral efficiency and user fair-ness,the user clustering and power allocation problem in multi-carrier NOMA-based cellular network is investigated.Since the radio resource allocation problem is NP-hard,exploiting the Lagrange duality theory and K-means clustering algorithm,we propose a suboptimal joint power allocation and user clustering scheme.Compared with the traditional orthogonal cellular networks,NOMA-based cellular network employing the joint user clustering and power allo-cation scheme can effectively enhance the energy efficiency and spectrum efficiency with the identical user fairness level.Thirdly,focusing on minimizing the overall transmit power of multi-cell and multi-carrier NOMA-based cellular network,this dissertation studies the radio resource management under the user quality of service constraint.Owing to the fact that the decoding order in succes-sive interference cancellation is associated with the inter-cell interference,the user clustering and power allocation are interwoven tightly,which will dramatically increase the difficulty of solving the optimization problem.To tackle this optimization problem,a centralized mini-mum power control algorithm with the fixed user assignment is developed firstly,upon which a greedy user clustering and power allocation scheme is proposed.The simulation results demon-strate that the proposed resource allocation algorithm can dramatically reduce the total power consumption meanwhile improving the user outage performance compared with existing liter-atures.Fourthly,to further improve the performance of mobile communication systems,in this dissertation,NOMA technology is applied to each cell in heterogeneous network.To sup-press the complicated interference environment effectively meanwhile maximize the sum rate of NOMA-based HetNet under the base station transmit power,user QoS requirement and the SIC decoding effectiveness constraints,an iterative power allocation and user scheduling algo-rithm is developed.The simulation results demonstrate that compared with the conventional or-thogonal multiple access(OMA)based HetNet and single-tier NOMA network,NOMA-based HetNet with the proposed algorithm can greatly improve the system performance in terms of the spectral efficiency and outage performance.Further,to optimize the system performance of cooperative non-orthogonal relaying sys-tem(CNRS),the optimum power allocation and relay placement problem is studied in cooper-ative non-orthogonal relaying system here.The dynamic power allocation scheme is developed firstly oriented by the total capacity maximum problem,and then the analytical close-form ex-pression of the outage probability of CNRS under Rayleigh channel is derived which can be utilized to capture the optimal relay location.The simulation results validate the accuracy of the obtained optimal relay location,and point out the fundamental difference at the optimum relay location between CNRS and the other conventional relaying systems,meanwhile indi-cating that CNRS dramatically outperforms the conventional OMA relaying scenarios in high SNR region.Finally,this dissertation studies the optimum power allocation and unmanned aerial vehi-cle(UAV)location problem by minimizing total transmit power in UAV assisted non-orthogonal(UAV-NOMA)cooperative relaying system.The dynamic power allocation is developed firstly,upon which the closed-form expression of the average minimum transmit power is derived over the Nakagami-m channel fading model in UAV-NOMA cooperative relaying system.Con-sequently,the optimal UAV hovering location can be captured according to the closed-form expression of the average minimum transmit power.The simulation results verify the validity of the closed-form expression of the average minimum overall transmit power,and demonstrate the optimal UAV location adjustment scheme when the system parameters change.