An Advanced AIS Receiver using a Priori Information

Abstract

Automtic Identifcation System (AIS) reception at flying platforms (satellites or airliners) has attracted an increasing level of attention over the last years. AIS allows vessels to communicate with each other and was originally designed as a vessel collision avoidance mechanism. Although AIS was not designed taking into account a satellite component, it is possible to receive AIS packets using satellites. However, satellite-aided AIS reception is challenging. Satellites receive AIS messages of all ships within a vast geographical area that usually tend to collide with each other. Consequently, the satellite receiver operates at lower SINR values compared to a conventional AIS receiver in a vessel or base station. In this paper we present an advanced receiver for AIS. This receiver exploits the a priori knowledge that the receiver has on some of the fields of the AIS position reports messages. In some cases this allows the receiver to double the number of training symbols that can be used for channel estimation. This receiver design is particularly suitable for receivers placed on flying platforms but it can also be used in other platforms such as vessels.