Detection probabilities for satellite VHF data exchange system with decollision algorithm and spot beam

The Internet-of-Things (IoT) is gaining popularity recently. The IoT networks comprise of the wired, the wireless terrestrial and the satellite networks. The Satellite IoT networks can cover areas that are not reachable by the wired IoT networks and the wireless terrestrial networks. A Slot Carrier-sense Time Division Multiple Access (SCTDMA medium access control (MAC) protocol is used for the Satellite VHF Data Exchange System (S-VDES). This paper analyzes and derives the detection probabilities of the ship vessels from a VDES satellite for the S-VDES MAC protocol with a Decollision Algorithm (S-VDES-DA) as well as with Spot Beam (S-VDES-SB) or both (S-VDES-DA-SB). A simple probabilistic model is used to capture the packet error ratios in these schemes. Single-slot and multi-slot messages are also considered. It is shown that the performance gains in the number of ship vessels that can be detected can be up to 92% for the S-VDES-DA MAC protocol with a DA capability of up to 3 packets over a basic S-VDES MAC protocol and up to 88% for the S-VDES-DA-SB MAC protocol with a DA capability of up to 3 packets and with 7 spot beams over the S-VDES-SB MAC protocol, respectively, for a detection probability threshold of 90% On the other hand, the percentage drops in the detection probabilities of the S-VDES-DA MAC protocol and the S-VDES-DA-SB MAC protocol for detecting up to 3 packets with and without packet error ratios are 4.6% and 4.0%, respectively.