Recent studies have demonstrated the superiority of non-orthogonal multiple access (NOMA) over orthogonal multiple access (OMA) in cooperative communication networks. In this paper, we propose a novel half-duplex cooperative asynchronous NOMA (C-ANOMA) framework with user relaying, where a timing mismatch is intentionally added in the broadcast signal. We derive the expressions for the throughputs of the strong user (acts as relay) which employs the block-wise successive interference cancellation (SIC) and the weak user which combines the symbol-asynchronous signal with the interference-free signal. We analytically prove that in the C-ANOMA systems with a sufficiently large block length, the strong user attains the same throughput to decode its own message while both users can achieve a higher throughput to decode the weak user’s message compared with those in the cooperative NOMA (C-NOMA) systems. Besides, we obtain the optimal timing mismatch when the block length goes to infinity. Furthermore, to exploit the trade-off between the power consumption of the base station and that of the relay user, we solve a weighted sum power minimization problem under quality of services (QoS) constraints. Numerical results show that the C-ANOMA system can consume less power compared with the C-NOMA system to satisfy the same QoS requirements.

中文翻译：

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QoS约束下功率最小的协作异步非正交多址接入

最近的研究表明，在协作通信网络中，非正交多址 (NOMA) 优于正交多址 (OMA)。在本文中，我们提出了一种具有用户中继的新型半双工协作异步 NOMA（C-ANOMA）框架，其中有意在广播信号中添加了定时失配。我们推导出采用逐块连续干扰消除 (SIC) 的强用户（充当中继）和将符号异步信号与无干扰信号相结合的弱用户的吞吐量表达式。我们分析证明，在具有足够大块长度的 C-ANOMA 系统中，强用户在解码自己的消息时获得相同的吞吐量，而与合作 NOMA (C-NOMA) 系统相比，两个用户都可以获得更高的吞吐量来解码弱用户的消息。此外，当块长度趋于无穷大时，我们获得了最佳时序失配。此外，为了利用基站功耗和中继用户功耗之间的权衡，我们解决了在服务质量 (QoS) 约束下的加权总和功率最小化问题。数值结果表明，与C-NOMA系统相比，C-ANOMA系统可以消耗更少的功率来满足相同的QoS要求。为了利用基站功耗和中继用户功耗之间的权衡，我们解决了在服务质量 (QoS) 约束下的加权总和功率最小化问题。数值结果表明，与C-NOMA系统相比，C-ANOMA系统可以消耗更少的功率来满足相同的QoS要求。为了利用基站功耗和中继用户功耗之间的权衡，我们解决了在服务质量 (QoS) 约束下的加权总和功率最小化问题。数值结果表明，与C-NOMA系统相比，C-ANOMA系统可以消耗更少的功率来满足相同的QoS要求。