标题： 通过分集合并方案为低成本物联网设备启用URLLC 显示英文标题

标题： Enabling URLLC for Low-Cost IoT Devices via Diversity Combining Schemes

摘要： 在物联网（IoT）时代，由于对时延和可靠性的严格限制以及物联网节点的简单电路，支持超可靠低时延通信（URLLC）具有挑战性。 通常需要分集来维持URLLC的可靠性水平，但需要考虑与辅助程序相关的额外延迟，特别是在通信包括低成本物联网设备时。 在此，我们分析选择合并（SC）和切换并保持合并（SSC）分集方案作为实现低成本物联网设备超可靠低时延下行通信的可行解决方案。 我们证明了在传统上未被考虑的情况下，需要考虑辅助程序所花费的时间，同时我们展示了它对可靠性性能的影响。 我们表明存在一个最优的接收天线数量，这表明在某些条件下可能需要关闭其中一些天线，特别是在SC操作下。 我们强调了SSC相对于SC的优势，只要相关信噪比阈值被正确选择。 我们建议仅依赖长期信道衰落统计使用固定阈值，这可以得到接近最优的结果。 显示英文摘要

摘要： Supporting Ultra-Reliable Low-Latency Communication (URLLC) in the Internet of Things (IoT) era is challenging due to stringent constraints on latency and reliability combined with the simple circuitry of IoT nodes. Diversity is usually required for sustaining the reliability levels of URLLC, but there is an additional delay associated to auxiliary procedures to be considered, specially when communication includes low-cost IoT devices. Herein, we analyze Selection Combining (SC) and Switch and Stay Combining (SSC) diversity schemes as plausible solutions for enabling ultra-reliable low-latency downlink communications to low-cost IoT devices. We demonstrate the necessity of considering the time spent in auxiliary procedures, which has not been traditionally taken into account, while we show its impact on the reliability performance. We show there is an optimum number of receive antennas, which suggests that under certain conditions it might be required to turn off some of them, specially under the SC operation. We highlight the superiority of SSC with respect to SC as long the associated Signal-to-Noise Ratio threshold is properly selected. We propose using a fixed threshold relying only on long-term channel fading statistics, which leads to near-optimum results.