Research And Simulation In MANET Based On HTDMA

In recent years, people have an urgent need to transmit a quality of service of multimedia data in the unstable radio channel because of the rapid development of wireless multimedia services. But mobile ad hoc networks topology changes dynamically, so a higher demand is proposed for the media access control protocol design and implementation. This paper analyzes the existing advantages and disadvantages of media access control protocol and for the characteristics of multimedia services, to achieve a hybrid time division multiple access protocol.Firstly, this paper describes requirements and classification of the media access control protocol for MANET. For the characteristics of MANET, the MAC protocol requirements is presented; based on different wireless media access strategy, mainstream MAC protocol is divided into three categories, competition agreement, assigned agreement, mixed competition and assigned agreement. IEEE 802.11 MAC protocol works will be introduced in detail.Secondly, this paper introduces hybrid time-division multiple access protocol how to work. A brief introduction of hybrid time-division multiple access protocol contains the basic idea; the details including the state defined time slot, frame structure, and logical process. HTDMA protocol is a dynamic, on-demand MAC protocol, which mixes competitive MAC protocol (carrier sense multiple access with collision avoidance CSMA/CA protocol and the virtual carrier sense RTS/CTS protocol) and allocation MAC protocol. HTDMA protocol can effectively avoid the "hidden terminal" and "exposed terminal" problem, rationally allocate resources for real-time traffic, and be easily achieved.After all, HTDMA protocol is achieved step by step through using OPNET simulation software, including the data structure of hash table storing node state slot, RTS/CTS/DATA packet format, and the process model of HTDMA protocol. Finally we compare HTDMA with IEEE802.11 through simulation. The simulation results show that HTDMA outperforms IEEE802.11 in terms of end-to-end delay and packet delivery radio.In summary, HTDMA protocol applies to multimedia services with large amount of data, high requirement of real-time.