Multi-link Techniques for New Radio-Unlicensed URLLC in Hostile Environments

Unlicensed spectrum operation mandates the performance of channel access mechanisms to ensure the absence of transmissions by other unlicensed radio access technologies. Packets are prone to be impacted by these mechanisms as transmissions might be delayed. In this paper, we first analyse the impact of unexpected and sporadic IEEE 802.11ax interference on a New Radio-Unlicensed (NR-U) deployment in an industrial environment. Given the need for improvement in such scenarios, frequency diversity techniques are proposed to fulfil tight latency-reliability requirements and combat the impact of 802.11ax interference. A multi-channel NR-U system in which, at least, one of the channels is free of IEEE 802.11ax interference is studied. The paper shows that multi-channel techniques with a lack of flexibility in the channel selection exhibit modest benefits in scenarios with the presence of sporadic interference. A scheme with flexible channel selection is proposed and verified as the preferred option for stringent latency and reliability applications.