Cyber-Physical Systems

The Internet of Interlaced Cyber-Physical Things 353

of X-MAC. It performed satisfactory in a 3D grid composed of 240 nodes. In this work, the authors

point out the weaknesses and suggest improvements.

There is also work that focuses on smaller-scale networks [31,32] and rather attempts to improve

the existing protocols. In Tang et al. [31], two opportunistic random access mechanisms are proposed:

overlapped contention and segmented contention, to favor the node of the best channel condition.

These algorithms are based on Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)

and polished to provide temporal fairness and avoid starving the nodes with poor channel condi-

tions. In Liu et al. [32], a hybrid between CSMA and TDMA is proposed. ...