Novel MAC Layer Proposal for URLLC in Industrial Wireless Sensor Networks

[Abstract] Ultra⁃reliable and low⁃latency communications (URLLC) has become a fundamental focus of future industrial wireless sensor networks (IWSNs). With the evolution of automation and process control in industrial environments, the need for increased reliability and reduced latencies in wireless communications is even pronounced. Furthermore, the 5G systems specifically target the URLLC in selected areas and industrial automation might turn into a suitable venue for future IWSNs, running 5G as a high speed inter⁃process linking technology. In this paper, a hybrid multi⁃channel scheme for performance and throughput enhancement of IWSNs is proposed. The scheme utilizes the multiple frequency channels to increase the overall throughput of the system along with the increase in reliability. A special purpose frequency channel is defined, which facilitates the failed communications by retransmissions where the retransmission slots are allocated according to the priority level of failed communications of different nodes. A scheduler is used to formulate priority based scheduling for retransmission in TDMA based communication slots of this channel. Furthermore, in carrier⁃sense multiple access with collision avoidance (CSMA/CA) based slots, a frequency polling is introduced to limit the collisions. Mathematical modelling for performance metrics is also presented. The performance of the proposed scheme is compared with that of IEEE802.15.4e, where the performance is evaluated on the basis of throughput, reliability and the number of nodes accommodated in a cluster. The proposed scheme offers a notable increase in the reliability and throughput over the existing IEEE802.15.4e Low Latency Deterministic Networks (LLDN) standard.

[Keywords] industrial wireless sensor network (IWSN); IEEE802.15.4e; Low Latency Deterministic Network (LLDN); low latency communications (LLC); ultra⁃reliable low latency communication (URLLC)