An Opportunistic Medium Access Control Protocol for Visible Light Ad Hoc Networks

Visible Light Ad Hoc Networks (LANETs) have the potential to offer capabilities to satisfy growing industrial and military requirements, including low-latency, high bandwidth communication under high network density and jamming conditions. The challenges imposed by hidden nodes, deafness and blockage are unique to LANET and influence the network differently from traditional Mobile Ad Hoc Networks (MANETs) due to directionality and Line of Sight (LOS) requirements. Therefore, networking protocols have to be redesigned with careful consideration of these challenges. As an initial step in this direction, this paper proposes a utility based opportunistic three-way handshake mechanism to negotiate medium access. First, a node chooses the optimal transmission sector, i.e., the "direction" that maximizes the probability of establishing a link even when some of the neighbors are affected by blockage or deafness. The utility function is designed to favor the establishment of full-duplex communication links. The full-duplex transmission or busy tone along with power control employed by the proposed Medium Access Control (MAC) protocol is aimed at mitigating the hidden node problem. All these factors contribute towards maximizing the throughput of LANET. Performance evaluation studies through extensive simulations show up to 61% increase in throughput and significant improvement in the number of full-duplex links established with respect to Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA).