Study On Synchronous TDMA Channel Access Technology Based On Dynamic Reservation

Mobile Ad Hoc Networks is a temporary self-organized Multi-hop network, whichdoes not depend on any infrastructures and can be set up anywhere, anytime, withoutcenter organization. It is flexible, fast etc. In recent years, with the development ofportable device in mobility, wireless communication capacity etc, Ad Hoc Network iswidely used in many fields such as military tactical communication, shipbrone AISsystem, wireless access system and sensor networks.Mobile Ad Hoc Networks built up on moving object such as the airborne, vehicularor shipborne, which have known geographic location as they had been equipped withGPS, some of them can broadcast location for navigation. Accordingly locationinformation employed by MAC could meet the priority of the close and speed nodeswhich have a real-time traffic. The paper analyzes general channel access protocol for Adhoc networks and researches channel access technology for maritime mobile Ad Hocnetworks--take shipbrone as an example. On the basis of researching on Ad Hoc network,time division multiple access technology, the paper presents a channel access technologyprogram and protocol which is suitable for Shipborne Ad Hoc Networks (SANET). Thepaper researches the problems and solutions in channel access technology of Ad HocNetworks by analyzing current channel access technology. And the experimental resultsanalysis provides a basis for further theoretical studies.To begin with, the paper summarizes Ad hoc networks from the development of AdHoc networks, network structures, characteristics and applications etc. Second, the papergives a briefly introduction of the difficulties facing the channel access protocol, anddivides the protocol into contention-based protocols and contention-free protocolaccording to reliability, also analyzes several general channel access protocols and theirsuitable applications. According to previous channel access protocol and researchexperience, the paper presents a Dynamic Reservation MAC (DR-MAC) which issuitable for SANET. Two reservation methods are adopted by DR-MAC. That is controlchannel is based on Virtual SOTDMA and data channel reserved by control channel. In addition, the paper introduces the slot reuse and the emergency priority; also researchespriority scheme which considers two parameters: speed and distance to insure emergencymessages access channel in time in the situation of high speed or density. Based on thetheory of protocol algorithm, the paper designs the simulation experiment system andimplements effective simulation of the protocol mentioned above. The simulation resultsshow that it can decrease the average end-to-end delay and improve the reliability ofreal-time access channel.