An Advanced Networking Protocol for VHF Data Exchange System

An Advanced Networking Protocol for VHF Data Exchange System

Since the appearance, AIS has been widely applied in worldwide navigation fields by virtue of outstanding performance. It helps to achieve automatic identification between ships, guarantee ships navigation safety and increase efficiency of maritime traffic management. However, with increasingly higher demands for maritime communication, a lot of problems of AIS are exposed one after another. System upgrade is urgently required due to stress from frequency bands and higher demands for data exchange. As a novel maritime digital communication system, VDES (VHF Data Exchange System) is developed based on AIS and aims to solve the problem that AIS is unqualified for high-speed data transmission. VDES are still under researching, wherein networking protocols play a crucial role in VDES, and an efficient networking protocol is of great importance to the system. At present, networking protocol is also under researching [1], but CSTMDA is the main consideration because of the high performance in AIS. The paper mainly researches and improves the CSTDMA networking access protocols. In comparison with traditional CSTDMA protocols, the improved CSTDMA protocol has a lower slot collision rate and can satisfy requirements of VDES for data transmission performance.