Massive interconnection has sparked people's envisioning for next-generation ultra-reliable and low-latency communications (xURLLC), prompting the design of customized next-generation advanced transceivers (NGAT). Rate-splitting multiple access (RSMA) has emerged as a pivotal technology for NGAT design, given its robustness to imperfect channel state information (CSI) and resilience to quality of service (QoS). Additionally, xURLLC urgently appeals to large-scale access techniques, thus massive multiple-input multiple-output (mMIMO) is anticipated to integrate with RSMA to enhance xURLLC. In this paper, we develop an innovative RSMA-assisted massive-MIMO xURLLC (RSMA-mMIMO-xURLLC) network architecture tailored to accommodate xURLLC's critical QoS constraints in finite blocklength (FBL) regimes. Leveraging uplink pilot training under imperfect CSI at the transmitter, we estimate channel gains and customize linear precoders for efficient downlink short-packet data transmission. Subsequently, we formulate a joint rate-splitting, beamforming, and transmit antenna selection optimization problem to maximize the total effective transmission rate (ETR). Addressing this multi-variable coupled non-convex problem, we decompose it into three corresponding subproblems and propose a low-complexity joint iterative algorithm for efficient optimization. Extensive simulations substantiate that compared with non-orthogonal multiple access (NOMA) and space division multiple access (SDMA), the developed architecture improves the total ETR by 15.3% and 41.91%, respectively, as well as accommodates larger-scale access.

翻译：大规模互连激发了人们对下一代超可靠低延迟通信（xURLLC）的构想，推动了定制化下一代先进收发机（NGAT）的设计。速率分割多址接入（RSMA）因其对非理想信道状态信息（CSI）的鲁棒性和服务质量（QoS）弹性，已成为NGAT设计的关键技术。此外，xURLLC迫切需要大规模接入技术，因此大规模多输入多输出（mMIMO）有望与RSMA集成以增强xURLLC。本文针对有限块长（FBL）场景下xURLLC的严格QoS约束，提出了一种创新的RSMA辅助大规模MIMO xURLLC（RSMA-mMIMO-xURLLC）网络架构。利用发射端非理想CSI下的上行导频训练，我们估计信道增益并定制线性预编码器，实现高效的短包下行数据传输。随后，我们建立联合速率分割、波束赋形和发射天线选择的优化问题，以最大化总有效传输速率（ETR）。针对该多变量耦合非凸问题，我们将其分解为三个对应子问题，并设计低复杂度联合迭代算法进行高效优化。大量仿真结果表明，与非正交多址接入（NOMA）和空分多址接入（SDMA）相比，所提架构分别将总ETR提升15.3%和41.91%，并支持更大规模接入。