Title: Downlink Transmission with Heterogeneous URLLC Services: Discrete Signaling With Single-User Decoding Show Chinese title

Title: 下行传输与异构URLLC服务：单用户解码的离散信令

Abstract: The problem of designing downlink transmission schemes for supporting heterogeneous ultra-reliable low-latency communications (URLLC) and/or with other types of services is investigated. We consider the broadcast channel, where the base station sends superimposed signals to multiple users. Under heterogeneous blocklength constraints, strong users who are URLLC users cannot wait to receive the entire transmission frame and perform successive interference cancellation (SIC) due to stringent latency requirements, in contrast to the conventional infinite blocklength cases. Even if SIC is feasible, SIC may be imperfect under finite blocklength constraints. To cope with the heterogeneity in latency and reliability requirements, we propose a practical downlink transmission scheme with discrete signaling and single-user decoding (SUD), i.e., without SIC. We carefully design the discrete input distributions to enable efficient SUD by exploiting the structural interference. Furthermore, we derive the second-order achievable rate under heterogenous blocklength and error probability constraints and use it to guide the design of channel coding and modulations. It is shown that in terms of achievable rate under short blocklength, the proposed scheme with regular quadrature amplitude modulations and SUD can operate extremely close to the benchmark schemes that assume perfect SIC with Gaussian signaling. Show Chinese abstract

Abstract: 设计用于支持异构超可靠低延迟通信（URLLC）和/或其他类型服务的下行链路传输方案的问题得到了研究。 我们考虑广播信道，其中基站向多个用户发送叠加信号。 在异构码长约束下，强用户（即URLLC用户）由于严格的时延要求，不能等待接收整个传输帧并执行连续干扰消除（SIC），这与传统的无限码长情况相反。 即使SIC是可行的，在有限码长约束下SIC可能不完美。 为了应对时延和可靠性要求的异构性，我们提出了一种具有离散信号和单用户解码（SUD）的实用下行链路传输方案，即没有SIC。 我们仔细设计了离散输入分布，以利用结构干扰实现高效的SUD。 此外，我们推导了在异构码长和误码概率约束下的二阶可实现速率，并用它来指导信道编码和调制的设计。 结果表明，在短码长条件下，采用常规正交幅度调制和SUD的所提方案可以非常接近假设完美SIC和高斯信号的基准方案。