Link Adaptation for Grant-Free Uplink URLLC Transmissions
01 September 2018
Ultra-reliable and low-latency communication (URLLC) represents the most challenging set of services for 5G new radio. Uplink Grant-free transmissions is recognized as a promising solution to meet the ambitious URLLC target (1 ms latency at a 99.999% reliability). However, achieving such a high reliability comes at the expense of poor spectral efficiency, which ultimately affects the supported URLLC load. This paper proposes a resource configuration scheme including multiple modulation and coding schemes (MCSs) and power control settings to enable link adaptation for grantfree uplink transmissions. A semi-static link adaptation strategy is presented based on the cell coupling gain. The presented link adaptation scheme is shown to be capable of increasing the system outage capacity by 90%, compared to prior art using a conservative single-MCS configuration