CUMAC-CAM: Addressing Triple Hidden Terminal Problems for Multi-channel Transmission in Underwater Sensor Networks

As multi-channel communication is becoming more and more common in Radio Frequency (RF) arena, acoustic communication protocols have also started to adopt the same concept to utilize multiple channels in Underwater Sensor Networks (UWSN). Although the deployment of multi-channel increases throughput significantly, it also opens up the possibility of collision occurrence due to the hidden terminal problem. In particular, the "Triple Hidden Terminal (THT)" problems, a phenomenon characterized by collision occurrence due to multi-hop, multi-channel communication with long propagation delay, persists more dominantly in UWSN. Existing MAC protocols try to mitigate the adverse effect of THT without utilizing the information of propagation delay that may be exploited to improve the performance of UWSN significantly. The current work proposes a Cooperative Underwater Multi-Channel MAC protocol with Channel Allocation Matrix (CUMAC-CAM). A new Channel Allocation Matrix (CAM) has been introduced for estimating propagation delay to ensure enhanced channel utilization. In this scheme, each node maintains a delay mapping database, based on which senders and receivers perform a scheduling algorithm before initiating any transmission. This mapping helps a node to predict whether it's upcoming packet transmission will collide with other nodes' transmission or not. In brief, the objective is to ensure successful transmission by mitigating triple hidden terminal problems in multi-channel underwater sensor networks as well as to enhance the channel utilization with the benefit of delay mapping and channel allocation assessment. Simulation results, carried out for performance analysis, show that the proposed MAC protocol is more efficient in terms of network throughput, energy consumption, end to end delay and packet delivery ratio compared to the contemporary CUMAC protocol.