Asynchronous random access schemes for the VDES satellite uplink

The paper focuses on the satellite uplink for the new VHF data exchange system (VDES), which aims at providing a worldwide messaging service for vessels. In this context, we investigate the use of some recently proposed asynchronous schemes for the narrowband random access mode of the standard. Remarkable improvements over the basic VDES self-organised TDMA return link access are shown in terms of both spectral efficiency and system coverage when considering realistic ships distributions. The study offers relevant insights for the ongoing discussions on the MAC layer design for upcoming versions of the VDES standard.