We introduce an energy-efficient downlink rate splitting multiple access (RSMA) scheme, employing a simple matched filter (MF) for precoding. We consider a transmitter equipped with multiple antennas, serving several single-antenna users at the same frequency-time resource, each with distinct message requests. Within the conventional 1-layer RSMA framework, requested messages undergo splitting into common and private streams, which are then precoded separately before transmission. In contrast, we propose a novel strategy where only an MF is employed to precode both the common and private streams in RSMA, promising significantly improved energy efficiency and reduced complexity. We demonstrate that this MF-precoded RSMA achieves the same delivery performance as conventional RSMA, where the common stream is beamformed using maximal ratio transmission (MRT) and the private streams are precoded by MF. Taking into account imperfect channel state information at the transmitter, we proceed to analyze the delivery performance of the MF-precoded RSMA. We derive the ergodic rates for decoding the common and private streams at a target user respectively in the massive MIMO regime. Finally, numerical simulations validate the accuracy of our analytical models, as well as demonstrate the advantages over conventional RSMA.

翻译：本文提出了一种能效高的下行链路速率分裂多址接入（RSMA）方案，采用简单的匹配滤波器（MF）进行预编码。我们考虑一台配备多天线的发射机，在相同的时频资源上服务多个单天线用户，每个用户均有不同的消息请求。在传统的单层RSMA框架中，请求消息被分裂为公共流和私有流，然后在传输前分别进行预编码。相比之下，我们提出了一种新策略，即仅使用MF对RSMA中的公共流和私有流进行预编码，从而显著提升能效并降低复杂度。我们证明，这种MF预编码的RSMA能够实现与传统RSMA相同的传输性能，其中传统方案中公共流采用最大比传输（MRT）波束赋形，私有流则采用MF预编码。考虑发射机处信道状态信息不完善的情况，我们进一步分析了MF预编码RSMA的传输性能。在大规模MIMO场景下，我们分别推导了目标用户解码公共流和私有流的遍历速率。最后，数值仿真验证了我们分析模型的准确性，并展示了其相对于传统RSMA的优势。