The advent of new use cases and new applications such as augmented/virtual reality, industrial automation, autonomous vehicles, etc. in 5G has made the Third Generation Partnership Project (3GPP) specify Ultra-reliable low-latency communications (URLLC) as one of the service categories. To support URLLC with the strict requirements of reliability and latency, 3GPP Release 15 and Release 16 have specified the URLLC features in licensed spectrum. The ongoing 3GPP Release 17 extends the URLLC features to unlicensed spectrum to target the new use cases in the industrial scenario.
In the first part of the thesis from Chapter 2 to Chapter 4, we focus on the URLLC in licensed spectrum. The first study deals with the problem of ensuring the configured number of uplink (UL) configured-grant (CG) repetitions of a transport block. Secondly, we study the collisions of an eMBB UL transmission of a user equipment (UE) and an URLLC UL transmission of another UE on the CG resources. Thirdly, the focus of this study is the downlink (DL) transmission where the feedback of the DL semi-persistent scheduling transmission is dropped due to the conflict of the DL/UL symbols.
In the second part from Chapter 5 to Chapter 8, we focus on URLLC operation in unlicensed spectrum. In unlicensed spectrum, a 5G device is required to access to a channel by using load based equipment (LBE) or frame based equipment (FBE). The uncertainty of obtaining channel access through LBE or FBE can impede the achievement of the URLLC latency requirements. Therefore, the study of the impact of LBE and FBE on URLLC transmission and the enhancements of LBE and FBE are needed.