We present an overview of ongoing research endeavors focused on in-band full-duplex (IBFD) massive multiple-input multiple-output (MIMO) systems and their applications. In response to the unprecedented demands for mobile traffic in concurrent and upcoming wireless networks, a paradigm shift from conventional cellular networks to distributed communication systems becomes imperative. Cell-free massive MIMO (CF-mMIMO) emerges as a practical and scalable implementation of distributed/network MIMO systems, serving as a crucial physical layer technology for the advancement of next-generation wireless networks. This architecture inherits benefits from co-located massive MIMO and distributed systems and provides the flexibility for integration with the IBFD technology. We delineate the evolutionary trajectory of cellular networks, transitioning from conventional half-duplex multi-user MIMO networks to IBFD CF-mMIMO. The discussion extends further to the emerging paradigm of network-assisted IBFD CF-mMIMO (NAFD CF-mMIMO), serving as an energy-efficient prototype for asymmetric uplink and downlink communication services. This novel approach finds applications in dual-functionality scenarios, including simultaneous wireless power and information transmission, wireless surveillance, and integrated sensing and communications. We highlight various current use case applications, discuss open challenges, and outline future research directions aimed at fully realizing the potential of NAFD CF-mMIMO systems to meet the evolving demands of future wireless networks.

翻译：本文系统综述了当前针对带内全双工大规模多输入多输出系统及其应用的研究进展。为应对当前及未来无线网络对移动流量的空前需求，从传统蜂窝网络向分布式通信系统的范式转变势在必行。无蜂窝大规模MIMO作为分布式/网络化MIMO系统的实用化可扩展实施方案，已成为推动下一代无线网络发展的关键物理层技术。该架构继承了集中式大规模MIMO与分布式系统的双重优势，并为融合带内全双工技术提供了灵活性。本文阐述了蜂窝网络从传统半双工多用户MIMO向带内全双工无蜂窝大规模MIMO的演进路径，进一步探讨了新兴的网络辅助型带内全双工无蜂窝大规模MIMO范式——该范式作为非对称上下行通信服务的能效优化原型，在无线能量与信息同传、无线监控、感知通信一体化等双功能场景中具有重要应用价值。文中重点分析了当前典型应用案例，讨论了现存技术挑战，并展望了未来研究方向，以充分释放网络辅助型带内全双工无蜂窝大规模MIMO系统的潜力，满足未来无线网络持续演进的需求。