CU-MAC: A duty-cycle MAC protocol for internet of things in wireless sensor networks

Abstract

Nowadays "Internet of Things" or IoT becomes the most popular technology in the Internet system. Types of devices and sensors have been connected as a network of devices and sensors. While a wireless sensor network is a traditional network of sensors that can be considered as a beginning point of IoT systems. Currently, these sensor data are not only exchanged within a local network but also are delivered to other devices in the Internet. Consequently, well-known organizations such as IEEE, IETF, ITU-T and ISO/IET are trying to set standards for wireless sensor devices in IoT systems. The recommended standard utilizes many of internet stack standards such as CoAP, UDP and IP. However, the traditional design of WSNs is to avoid using internet protocol in the system to reduce transmission overhead and power consumption due to resource limitation. Fortunately, the current technology in both hardware and software allow the internet standard to sufficiently operate in a small sensor. In this paper, we propose a MAC protocol named CU-MAC to efficiently support IoT standard that need request-respond communication or bi-direction communication. CU-MAC uses multi-channel communication to perform continuous and bidirectional data transfer at low duty-cycle. It also has a mechanism to overcome the hidden terminal problem. We evaluated the performance of CU-MAC on both simulation and real testbed based on Contiki OS. The result shows that CU-MAC outperforms other existing MAC protocols in term of packet delivery ratio at 98.7% and requires lower duty-cycle than others to operate in the high traffic environment.