Title: Fundamental Tradeoffs in Uplink Grant-Free Multiple Access with Protected CSI Show Chinese title

Title: 上行链路无许可多址接入中的基本权衡与受保护的信道状态信息

Abstract: In the envisioned 5G, uplink grant-free multiple access will become the enabler of ultra-reliable low-latency communications (URLLC) services. By removing the forward scheduling request (SR) and backward scheduling grant (SG), pilot-based channel estimation and data transmission are launched in one-shot communications with the aim of maintaining the reliability of $99.999\% $ or more and latency of 1ms or less under 5G new radio (NR) numerologies. The problem is that channel estimation can easily suffer from pilot aware attack which significantly reduces the system reliability. To solve this, we proposed to apply the hierarchical 2-D feature coding (H2DF) coding on time-frequency-code domain to safeguard channel state information (CSI), which informs a fundamental rethinking of reliability, latency and accessibility. Considering uplink large-scale single-input multiple-output (SIMO) reception of short packets, we characterize the analytical closed-form expression of reliability and define the accessibility of system. We find two fundamental tradeoffs: reliability-latency and reliability-accessibility. With the the help of the two fundamental trade-offs, we demonstrate how CSI protection could be integrated into uplink grant-free multiple access to strengthen URLLC services comprehensively. Show Chinese abstract

Abstract: 在设想的5G中，上行链路无授权多址接入将成为超可靠低时延通信（URLLC）服务的使能技术。 通过去除前向调度请求（SR）和反向调度授权（SG），基于导频的信道估计和数据传输在一个步骤中启动，目的是在5G新空口（NR）数值方案下保持$99.999\% $或更高的可靠性以及1ms或更小的时延。 问题在于信道估计很容易受到导频感知攻击，这会显著降低系统可靠性。 为了解决这个问题，我们提出将分层二维特征编码（H2DF）编码应用于时频码域以保护信道状态信息（CSI），这促使对可靠性、时延和可访问性进行了根本性的重新思考。 考虑到上行链路大规模单输入多输出（SIMO）对短包的接收，我们表征了可靠性的解析闭式表达式并定义了系统的可访问性。 我们发现了两个基本的权衡：可靠性-时延和可靠性-可访问性。 借助这两个基本权衡，我们展示了如何将CSI保护集成到上行链路无授权多址接入中，以全面增强URLLC服务。