Determination of a Finite Number of Ships With the Navigation Messages Mutual Exchange via Shipboard Equipment of the Automatic Identification System

Abstract

In accordance with SOLAS 74 Regulation 5.19 all seagoing ships with a gross tonnage of over 300 gt are required to be equipped with ship's equipment of the automatic identification system (AIS) that is to improve Maritime Safety. It provides mutual exchange with the navigation and safety messages between the ships. Mutual messaging is possible due to applying the schemes, proposed in the automatic identification system, of multi-station access and accurate synchronization of ships own time scales aligned with the signals of the Global Navigation Satellite System. The multi-station access performance is evaluated by the number of ships with ability of mutual exchange. However, any scheme has a finite capacity. The purpose of this paper is the calculation of the performance of the schemas used in the basic (stand-alone) operation of shipboard equipment for automatic identification system. The scheme performance depends on the ship's traffic mode. It has been shown that the technical parameters of the automatic identification system shipboard equipment and algorithms for multi-station access allow up to 100 vessels to be involved into exchange with navigation messages within the area of the vessel traffic management system. In the high seas when ships generally do not maneuver extensively when moving, the performance of multistation access decreases less than 50 ships. There is a possibility to increase the AIS effectiveness by using three and more carrier frequencies to transmit ship's data.