Abstract: Industrial Internet of Things (IIoT) is an emerging technology in recent years, which is widely utilized for control, manage the manufacturing environment, and monitor production lines in the smart factories. The IPv6 has enabled the use of many IIoT devices, so these devices consume large amounts of energy. Many research efforts were made in this area aimed to improve power consumption and performance. This paper proposed the Contention Access Period Reduction Medium Access Control protocol (CAP Reduction MAC protocol) for reducing the CAP duration size based on IEEE 802.15.4e. The proposed MAC protocol leads to reduce the CAP portion. Thus the number of time slots, which assigned to the sensors will decrease. Moreover, this paper intends to estimate the performance of IIoT devices in terms of energy consumption, throughput, and delay time through an analysis of their respective ways of operation running the Contiki Operating System (OS). To validate the proposed protocol, different experiments are conducted based on the Cooja simulator. The proposed protocol can be reduced the overall energy consumption with up to 64.14 %, decreases the delay by 33.7 %, and increases throughput by 63.0 %
