In the 1990s, the International Maritime Organization (IMO), the International Telecommunications Union (ITU) and the International Electrotechnical Commission (IEC) adopteda new navigation aid known as the Automatic Identification System (AIS) to help improve safety-of-navigation, maritime traffic control and efficiency of maritime commerce.The primary purpose of the AIS is to facilitate the efficient exchange of navigation and voyage data between ships, and between ships and shore stations. The technical characteristics of the AIS using time division multiple access (TDMA) techniques in the VHF maritime mobile band are described in Recommendation ITU-R M.1371.