【作者】 吴静芳；

【导师】 李莉；

【作者基本信息】 上海师范大学 ， 电子与通信工程（专业学位）， 2021， 硕士

【摘要】 移动互联网不断增长的需求对第五代移动通信网络提出了诸如更高的频谱效率和大规模的用户连接密度等新的挑战。认知无线电和非正交多址接入(NonOrthogonal Multiple Access,NOMA)技术被认为是第五代移动通信网络的重要解决方案。传统的认知无线电网络中采用的是正交多址接入方式,但是正交多址接入方式中子信道内只允许接入一个次用户,造成信道利用率低,所以将NOMA技术应用到认知无线电网络下行链路场景中有望提高信道利用率。针对认知NOMA网络中在对次用户进行功率分配时存在可用功率没有得到使用的不足提出了两步功率分配算法。首先,在保证次用户对主用户造成的干扰小于主用户的最大干扰功率阈值,且满足次用户最小信息传输速率的约束条件下,采用两层功率分配算法使得系统可接入的次用户数最多。其次,在max-min准则下对上一步中未得到充分利用的可用功率在接入系统的次用户间进行功率分配,最大化次用户的最小信息传输速率。仿真结果显示:在给定的仿真参数下,当认知NOMA系统中请求次用户数为10时,与两层功率分配算法对比,所提的功率分配算法的频谱效率提升了约18%。由于认知NOMA网络中只考虑让更多的次用户接入同一子信道,这样会导致SIC算法实现复杂度高、信号检测过程中存在错误传播等问题。针对此问题,在认知混合NOMA网络下行链路中提出了一种公平性可调的信道分配方法,减少接入同一子信道内的次用户数。基于用户和信道匹配结果,在满足主用户的干扰功率阈值和次用户最小信息传输速率约束条件下,采用Charnes-Cooper变换的方法求解功率分配问题,最大化系统能效。仿真结果表明,给定基站发射功率为25d Bm时,所提信道分配算法的用户公平性指数约提升了55%。更多还原

【Abstract】 The ever-increasing demand of the mobile Internet poses new challenges to the fifth-generation mobile communication network,such as higher spectrum efficiency and large-scale user connection density.Cognitive radio and non-orthogonal multiple access(NOMA)technology are considered to be important solutions for the fifthgeneration mobile communication network.The traditional cognitive radio network adopts the orthogonal multiple access method,but in the orthogonal multiple access method,only one secondary user is allowed in the sub-channel,resulting in low channel utilization.Therefore,the NOMA technology is applied to It is expected to improve the channel utilization in the downlink scenario of cognitive radio networks.Aiming at the problem that the available power is not used in the cognitive NOMA network when the power is allocated to the secondary users,a two-step power allocation algorithm is proposed.First,to ensure that the interference caused by the secondary user to the primary user is less than the maximum interference power threshold of the primary user and meet the constraints of the minimum information transmission rate of the secondary user,a two-layer power allocation algorithm is used to maximize the number of secondary users that the system can access.Secondly,under the max-min criterion,the underutilized available power in the previous step is allocated among the secondary users accessing the system to maximize the minimum information transmission rate of the secondary users.The simulation results show that under given simulation parameters,when the number of requested users in the cognitive NOMA system is 10,compared with the two-layer power allocation algorithm,the spectrum efficiency of the proposed power allocation algorithm is increased by about 18%.Since the cognitive NOMA network only considers allowing more secondary users to access the same sub-channel,this will lead to problems such as high implementation complexity of the SIC algorithm and error propagation in the signal detection process.In response to this problem,a channel allocation method with adjustable fairness is proposed in the downlink of the cognitive hybrid NOMA network to reduce the number of secondary users accessing the same sub-channel.Based on the user and channel matching results,Charnes-Cooper transform is used to solve the power allocation problem and maximize the system energy efficiency under the conditions of meeting the interference power threshold of the primary user and the minimum information transmission rate of the secondary user.The simulation results show that when the transmit power of a given base station is 25 d Bm,the user fairness index of the proposed channel allocation algorithm is increased by 55%.更多还原