多用户全双工协作PNOMA系统非正交率控制及功率分配优化算法

Non-Orthogonal Ratio Control and Power Allocation Optimization Algorithm for Multi-User Full-Duplex Cooperative PNOMA Systems

传统NOMA系统远近用户设备(User Equipment,UE)之间在时频资源上信号完全重叠,以期获得最高的频率利用率,但其中UE之间的干扰也成为核心问题之一.部分NOMA(Partial NOMA,PNOMA)系统由于仅在部分频段实现NOMA共存,因此可以优化协调UE之间的干扰.相较于传统NOMA系统,PNOMA系统能够极大地降低非理想连续干扰相消(imperfect Successive Interference Cancellation,ipSIC)对于系统和速率的消极影响.基于全双工协作NOMA(Full Duplex Cooperative NOMA,FD-CNOMA)系统和PNOMA系统,本文提出了一种全双工协作部分NOMA(FDCPNOMA)方案以优化UE之间干扰,提高系统可达速率.考虑由一个基站和若干个远近UE构成的FD-CPNOMA系统,针对实际中存在非理想连续干扰消除问题,本文给出了UE配对、非正交率控制及功率分配的优化算法,并推导了此模型下UE中断概率闭式解.仿真结果表明,本文提出的UE配对方案性能优于其他三种配对方案,所提出的PNOMA系统最大可达速率均优于相应的传统NOMA系统,提出的FD-CPNOMA系统在低信噪比下的最大可达速率比半双工协作部分NOMA(HD-CPNOMA)系统和PNOMA系统分别高出95.42%、44.06%,并且在高信噪比下可以较好地实现UE间公平性和平均可达速率的折衷.

In traditional NOMA systems,signals between the near and far user equipment(UE)in the time and frequency domain are fully overlapped to obtain the highest spectrum efficiency,but interference between the UEs has become a critical issue.Partial NOMA(PNOMA)systems can significantly reduce the interference between the UEs because the NOMA mechanism is only partially adopted in the whole frequency band.Compared to traditional NOMA systems,PNOMA systems can significantly reduce the negative impact of imperfect successive interference cancellation(ipSIC)on the system sum rate.Based on the full-duplex cooperative NOMA(FD-CNOMA)and PNOMA system,this paper proposes a full-duplex cooperative PNOMA(FD-CPNOMA)system to reduce the interference between the UEs and accordingly improve the achievable system rate.Considering the non-ideal interference cancellation in practice and a FD-CPNOMA system consisting of one base station and multiple UEs,this paper proposes an optimization algorithm for UE pairing,non-orthogonal ratio control and power allocation.In addition,closed-forms of UE outage probability and approximate closedforms of average achievable rates in this model are derived.Simulation results show that the performance of the proposed UE pairing scheme is better than the other three schemes,the maximum achievable rates of PNOMA systems are all better than the conventional NOMA systems,and the maximum achievable rate of FD-CPNOMA system is 95.42%and 44.06%higher than that of half-duplex cooperative NOMA(HD-CPNOMA)and PNOMA systems respectively with low signal-to-noise ratios(SNR).The proposed FD-CPNOMA system provides a better tradeoff between the fairness and average reachable rate among the UEs at high SNR.