I. Introduction
The Internet of Things (IoT) refers to a network of billions of objects that can send and receive data. M2M communication is considered as the core of IoT, whereby it is seen as is the key to making it a reality, i.e. enhancing the communication of real things in the world, transmitting information and executing smart tasks. Many solutions in the M2M domain have been provided, and it is anticipated that billions of devices will be connected using M2M in the future [1], [2]. Machine-to-machine (M2M) networks enabling networked nodes (sensors or actuators) to exchange information have been intensively studied lately, particularly for sensing and surveillance purposes where hundreds or thousands of nodes (devices) densely located over the small or medium area. Some of the key features of M2M include low mobility, Packet switching, time controlled data transmission, monitoring events of interest, low power consumption, and location specific triggering of M2M devices in a particular area. Moreover, sensors and communication devices are the essential endpoints for any M2M application. However, the endpoints cannot connect directly to the network operator or interconnect, unless supported by WPAN technology standards such as 6LoWPAN, ZigBee, and Bluetooth. Recent technological developments, including M2M, smart grids and smart environment applications, are having a marked impact on the development of Wireless Sensor Networks (WSNs). Moreover, most appliances are equipped with the capabilities for sensing people’s daily needs. However, the efficient use of the limited energy resources of WSN nodes is crucial to these technological advances, regarding which topology control methods are being employed to extend battery lifetime [3], [4]. We envision a future where millions of small sensors, actuators, and other devices can form self-organising wireless networks. This is dependent on the IoT concept, whereby billions of machines will be able to interact and control one another with no human involvement. These devices will connect continuously and bring significant benefits to people in their everyday lives to enhance their wellbeing. Areas that will be significantly improved are: