We investigate the non-orthogonal coexistence between the ultra-reliable low-latency communication (URLLC) and the enhanced mobile broadband (eMBB) in the downlink of a cell-free massive multiple-input multiple-output (MIMO) system. We provide a unified information-theoretic framework that combines a finite-blocklength analysis of the URLLC error probability based on the use of mismatched decoding with an infinite-blocklength analysis of the eMBB spectral efficiency. Superposition coding and three levels of puncturing are considered as alternative downlink coexistence strategies to cope with the inter-service interference and the URLLC random activation pattern, under the assumption of imperfect pilot-based channel state information acquisition at the access points and statistical channel knowledge at the users. Numerical results shed light into the trade-off between eMBB and URLLC performances considering different precoding and power control strategies.

翻译：本文研究无蜂窝大规模多输入多输出（MIMO）系统下行链路中超可靠低延迟通信（URLLC）与增强移动宽带（eMBB）的非正交共存问题。我们提出统一的信息论框架，将基于误匹配解码的URLLC有限块长错误概率分析与eMBB无限块长频谱效率分析相结合。考虑接入点处基于非完美导频的信道状态信息获取与用户端统计信道知识，采用叠加编码与三种等级的穿孔作为下行共存策略，以应对服务间干扰及URLLC随机激活模式。数值结果揭示了不同预编码与功率控制策略下eMBB与URLLC性能之间的权衡关系。