In this letter, we propose an intelligent rate-splitting multiple access (RSMA)-enabled coordinated direct and relay transmission (CDRT) scheme, in which transmissions from a pair of the far and near users to a base-station are coordinated by a decode-and-forward relay. In contrast to existing published concepts, near-user (NU) is switched on/off intelligently across the two time phases to exploit RSMA to enhance transmission reliability and improve throughput of far-user (FU), while ensuring the desired performance at NU. The optimal transmit power allocation factors that maximize the achievable rates of the dual-hop transmissions are derived, respectively. For the delay-limited transmission mode, closed-form expression is extracted for the end-to-end outage probability of FU and asymptotic outage performance is studied in the high signal-to-noise ratio region. For the delay-tolerant transmission mode, analytical expression is also derived for the end-to-end ergodic rate of FU, and the effective sum rate is characterized. Numerical results validate the theoretical analysis and highlight the superior performance of the proposed RSMA-enabled CDRT scheme over the existing benchmark schemes in terms of reliability and throughput.

中文翻译：

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支持智能速率分割多址的协调直接和中继传输


在这封信中，我们提出了一种支持智能速率分割多址（RSMA）的协调直接和中继传输（CDRT）方案，其中从一对远近用户到基站的传输通过解码器进行协调-并转发中继。与现有已发布的概念相反，近用户 (NU) 在两个时间阶段智能地打开/关闭，以利用 RSMA 来增强传输可靠性并提高远用户 (FU) 的吞吐量，同时确保 NU 的所需性能。分别导出了最大化双跳传输可实现速率的最佳发射功率分配因子。针对时延有限的传输模式，提取了FU端到端中断概率的闭式表达式，并研究了高信噪比区域的渐近中断性能。对于延迟容忍传输模式，还推导了FU的端到端遍历速率的解析表达式，并表征了有效和速率。数值结果验证了理论分析，并强调了所提出的支持 RSMA 的 CDRT 方案在可靠性和吞吐量方面优于现有基准方案的性能。