多用户MIMO系统高可靠低时延通信的能效优化研究

Ultra-reliable and low latency communications (URLLCs) are very important scenarios in the fifth generation (5G), which require guaranteeing the reliability of 99.999% in one millisecond or less. The existing theories and methods on the quality of service (QoS) guarantees have to pay the price of low spectral efficiency and high energy consumption for achieving URLLCs. Thus, how to achieve URLLC in an energy-efficient way is a hot but difficult problem..Focusing on the above issue, jointly considering the grant-free access scheme recommended by 3GPP recently, this project dedicates to solving the problem by leveraging the combined advantage of diversity and multiplexing of MIMO techniques. The features and innovation points of this project include: (1) Focusing on the features of short packets of URLLC traffic, we construct the MAC-PHY cross-layer service model for multi-users MIMO systems; (2) Based on the martingales theory, we propose to transform the sporadic arrival of URLLC traffic and the service characterising the cross-layer access into exponential super-martingales. Most importantly, we explore the new theories and methods to analyse and guarantee the reliability-delay performance for multi-users MIMO systems. (3) Relying on our theoretic results, we investigate the cross-layer grant-free access schemes and algorithms in multi-users MIMO systems to achieve the optimum joint configuration of multiple parameters (i.e., the access parameters, the power controlling, the trade-off between the diversity and multiplexing, and the duration of a slot) for maximizing the energy efficiency of system on the premise of carrying URLLC traffic..The research findings can provide not only theoretic support but also technical references for boosting URLLC as a trump application scenario.

高可靠低时延通信(URLLC)是5G重要场景，需在1毫秒内至少满足99.999%的可靠性。现有的服务质量(QoS)保障理论只能以带宽及能耗为代价支持URLLC。如何高能效地支持URLLC是当前研究的热点和难点。.鉴于此，结合3GPP新近推荐的免授权机制，本项目利用MIMO技术分集和复用的联合优势致力于解决上述问题。项目特色与创新在于：(1)针对URLLC业务的短包特性，构建多用户MIMO系统中MAC-PHY跨层服务模型；(2)基于鞅论，提出将URLLC偶发到达、及表征跨层接入的服务分别转换为指数上鞅，探索多用户MIMO系统可靠性-时延性能分析与保障的新理论新方法；(3)在此基础上，研究多用户MIMO的跨层免授权接入机制与算法，实现接入参数、功率控制、分集-复用和时隙时长的最优联合设置，以支持URLLC、使系统能效最大。.项目成果将为URLLC成长为5G杀手级应用场景提供理论支撑和技术参考。

高可靠低时延通信(URLLC)类业务的数据包短、偶发性强，要求在1毫秒内至少满足99.999%的可靠性。现有的QoS分析和保障方法主要是稳态分析方法，高估了URLLC对带宽和功耗的需求。因此，基于这些方法只能以带宽和功耗为代价来支持URLLC，尤其是上行URLLC。如何高能效地实现上行URLLC是一个具有挑战性的问题。鉴于此，本项目主要关注上行多用户MIMO系统，研究多用户MIMO系统可靠性、时延QoS的瞬态理论分析方法，以及满足URLLC高可靠、低时延要求的多用户MIMO系统的高能效传输方案。主要研究内容包括：(1)综合考虑无线信道的不确定性、URLLC业务偶发特性以及5G/B5G新空口传输特性，研究了多用户MIMO上行传输的服务速率的统计模型。(2)分别以鞅论和吸收马尔可夫理论为基础，研究了时延-可靠性QoS的瞬态分析新方法，揭示出时延和可靠性QoS要求、随机到达特性以及物理资源需求量之间的关系。(3)基于理论分析结果，设计了多用户MIMO系统能效最大的参数配置最优配置方案、提出了自适应的免授权传输机制。研究结果表明，数据包差错概率与时延界、接收天线数目等近似呈现负指数依赖关系。更为重要的是，在上行MIMO系统中实现了高能效、高可靠和低时延的跨层传输，为工业互联网和触觉互联网等新型应用落地提供理论指导和技术支撑。.项目资助发表12篇论文和1项授权专利。其中，8篇论文发表在IEEE TWC、IEEE TVT等IEEE主流期刊上，2篇发表在IEEE ICC 2020和2021会议上。