The novel concept of non-orthogonal multiple access (NOMA) aided joint radar and multicast-unicast communication (Rad-MU-Com) is investigated. Employing the same spectrum resource, a multi-input-multi-output (MIMO) dual-functional radar-communication (DFRC) base station detects the radar-centric users (R-user), while transmitting mixed multicast-unicast messages both to the R-user and to the communication-centric user (C-user). In particular, the multicast information is intended for both the R- and C-users, whereas the unicast information is only intended for the C-user. More explicitly, NOMA is employed to facilitate this double spectrum sharing , where the multicast and unicast signals are superimposed in the power domain and the superimposed communication signals are also exploited as radar probing waveforms. First, a beamformer-based NOMA-aided joint Rad-MU-Com framework is proposed for the system having a single R-user and a single C-user. Based on this framework, the unicast rate maximization problem is formulated by optimizing the beamformers employed, while satisfying the rate requirement of multicast and the predefined accuracy of the radar beam pattern. The resultant non-convex optimization problem is solved by a penalty-based iterative algorithm to find a high-quality near-optimal solution. Next, the system is extended to the scenario of multiple pairs of R- and C-users, where a cluster-based NOMA-aided joint Rad-MU-Com framework is proposed. A joint beamformer design and power allocation optimization problem is formulated for the maximization of the sum of the unicast rate at each C-user, subject to the constraints on both the minimum multicast rate for each R&C pair and on accuracy of the radar beam pattern for detecting multiple R-users. The resultant joint optimization problem is efficiently solved by another penalty-based iterative algorithm developed. Finally, our numerical results reveal that significant performance gains can be achieved by the proposed schemes over the benchmark schemes employing conventional transmission strategies.

中文翻译：

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NOMA 辅助的联合雷达和组播单播通信系统

研究了非正交多址 (NOMA) 辅助联合雷达和多播-单播通信 (Rad-MU-Com) 的新概念。使用相同的频谱资源，多输入多输出 (MIMO) 双功能雷达通信 (DFRC) 基站检测以雷达为中心的用户 (R-user)，同时将混合组播-单播消息发送到R 用户和以通信为中心的用户（C 用户）。特别是，多播信息既适用于 R 用户，也适用于 C 用户，而单播信息仅适用于 C 用户。更明确地说，使用 NOMA 来促进这一点双频谱共享，其中多播和单播信号叠加在功率域中，叠加的通信信号也被用作雷达探测波形。首先，一个为具有单个 R 用户和单个 C 用户的系统提出了基于波束形成器的 NOMA 辅助联合 Rad-MU-Com 框架。在此框架的基础上，通过优化所采用的波束形成器，在满足组播速率要求和雷达波束方向图的预定精度的同时，制定了单播速率最大化问题。由此产生的非凸优化问题通过基于惩罚的迭代算法来解决，以找到高质量的接近最优解。接下来，将系统扩展到多对 R 和 C 用户的场景，其中一个提出了基于集群的 NOMA 辅助联合 Rad-MU-Com 框架。为了最大化每个 C 用户的单播速率之和，制定了一个联合波束形成器设计和功率分配优化问题，同时受到每个 R&C 对的最小组播速率和雷达波束方向图精度的约束检测多个 R 用户。通过开发的另一种基于惩罚的迭代算法有效地解决了由此产生的联合优化问题。最后，我们的数值结果表明，与采用传统传输策略的基准方案相比，所提出的方案可以实现显着的性能提升。