In downlink non-orthogonal multiple access (NOMA) with multiuser clustering, a single beamforming (BF) vector precodes the superimposed signal of strong and weak users. This precoding results in an imperfect inter-cluster interference (ICI) cancellation at weak users since the BF vectors are designed based on strong users’ channels. Also, the ICI is highly increased with the number of transmit antennas, causing severe degradation in the performance of weak users and total system. In this paper, first , a new cooperative NOMA is introduced, in which weak user beam-matching (WBM) equalizer is proposed to remove the ICI at weak users by matching weak users’ channels with the designed BF vectors. The process of WBM is accomplished with the aid of device-to-device (D2D) channel state information (CSI) sharing between the nearby strong and weak users. Second , based on WBM principle, strong user beam-matching (SBM) equalizer is proposed to eliminate the generated ICI at strong users in the case of limited feedback. Third , a new power allocation strategy is proposed to improve weak users’ performance by considering the gained throughput from interference cancellation. Finally , besides the sum-rate, which is adopted as the performance metric by most of the existing NOMA works, the bit error rate (BER) of NOMA users in cooperative NOMA is calculated and compared with those in other schemes. Simulation results show that our cooperative NOMA with the proposed equalizers achieves significant sum-rate and BER improvements over other non-cooperative schemes with both perfect and limited feedback scenarios.

中文翻译：

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反馈有限的 MU-MISO-NOMA 系统通过 D2D CSI 共享消除干扰

在具有多用户聚类的下行链路非正交多址 (NOMA) 中，单个波束成形 (BF) 矢量对强弱用户的叠加信号进行预编码。由于 BF 向量是基于强用户的信道设计的，因此这种预编码会导致弱用户的簇间干扰 (ICI) 消除不完美。此外，ICI随着发射天线数量的增加而大幅增加，导致弱用户和整个系统的性能严重下降。在本文中，第一的 ，引入了一种新的协作 NOMA，其中提出了弱用户波束匹配 (WBM) 均衡器，通过将弱用户的信道与设计的 BF 向量进行匹配来消除弱用户处的 ICI。WBM 的过程是在附近强用户和弱用户之间共享设备到设备 (D2D) 信道状态信息 (CSI) 的帮助下完成的。第二 , 基于 WBM 原理，提出了强用户波束匹配 (SBM) 均衡器，以在反馈有限的情况下消除强用户处产生的 ICI。 第三 ，提出了一种新的功率分配策略，通过考虑从干扰消除中获得的吞吐量来提高弱用户的性能。 最后 , 除了现有的大多数 NOMA 工作采用 sum-rate 作为性能指标外，还计算了合作 NOMA 中 NOMA 用户的误码率 (BER) 并与其他方案中的进行比较。仿真结果表明，与具有完美和有限反馈场景​​的其他非合作方案相比，我们与所提出的均衡器的合作 NOMA 实现了显着的总速率和 BER 改进。