Ultra-reliable low-latency communications (URLLC) entail the transmission of sporadic and small packets, with low latency and very high reliability. Among many potential areas of optimization for URLLC, the problems of large delays during HARQ retransmissions, and inaccurate link adaptation as a consequence of the rapidly-varying interference conditions are highlighted. The former is addressed by reducing the TTI length and HARQ round-trip time, as compared to what is used in LTE; whereas including time-filtered interference information in the CQI report also shows great potential. Extensive system-level simulations of the downlink performance show that the URLLC requirements, i.e. latencies below 1 ms and 99.999% reliability, are achievable at low load scenarios, whereas some performance degradation (1.4 - 2.4 ms latency) is experienced at higher loads due to the increased queuing delay and inter-cell interference.
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