**2.2 M2M systems categories**

The authors in [6] categorize M2M systems into two types, namely dynamic M2M systems and static M2M systems. The main difference between the two is its topology, where in dynamic systems, some nodes (for example, M2M devices and M2M gateways) are moving, that is, the topology is changing over time, resulting in a change in the quality of communication, and dynamic resource allocation. Examples of dynamic M2M systems include: vehicle M2M system, the medical M2M system and the robotic M2M system. In contrast, the topology for static M2M systems remains unchanged for a relatively long time, as an example the M2M power system, domestic M2M system and the industrial M2M system.
