Reduction of HARQ Latency for URLLC 5G Services Based on Network Slicing and Massive MIMO Hybrid Beamforming

Ultra-Reliable and Low-Latency Communications (URLLC) is one of the three generic 5G services and probably the most challenging one, with strict quality of service requirements of 99.999% or more reliability and less than 1 milliseconds (ms) radio latency. To achieve latency targets, contributors to latency need to be addressed. Hybrid automatic repeat request (HARQ) retransmissions are major contributor to latency and need to be limited. The objective of this paper is to study the benefit of using Massive MIMO (M-MIMIO) along with radio network slicing to reduce number of HARQ retransmissions. A practical type of M-MIMO beamforming named hybrid beamforming is used. The performance of the proposed system is evaluated with slicing, without slicing and by alternating number of data streams per user. This work highlights the importance of technology enablers, such as M-MIMO and network slicing, in addressing quality-of-service (QoS) latency requirements for URLLC applications.