Research Of A Bandwidth Allocation Algorithm Based On Token Ring In TDMA MANETs

Mobile Ad Hoc Networks(MANETs)have the characteristics of rapid networking,multihop communication,distributed control and high mobility,so they are widely applied in such the scenarios as inter-vehicle communications,sensor networks,emergency rescues and battlefields.In a multi-hop ad hoc network,those existing protocols based on TDMA are not flexible enough to dynamically adjust the transmission slots according to network load.Consequently,the network throughput cannot be guaranteed,although wireless channels have enough bandwidth.On the other hand,as the increase of the number of network nodes,the allocation of time slots cannot be adaptively adjusted,resulting in a higher end-to-end delay in the multi-hop scenarios.Token Ring Protocol has the characteristics of the flexibility of bandwidth allocation and the guarantee of low end-to-end delay.Therefore,this paper proposes a token ring-based MAC protocol in TDMA Ad Hoc network,TWTR(TDMA With Token Ring)protocol.In the TWTR protocol,the nodes are divided into different one-hop networks to form different token rings at first.Then,a TDMA-based superframe structure allocates time durations to different token rings.Finally,To achieve minimal average end-to-end dealy,TWTR protocol uses the number of slots optimization algorithm to dynamically adjust the number of time slots of each token ring.And the token delivery algorithm can pass the token to the node which has higher load traffic and higher-priority traffic.So TWTR protocol effectively combines the TDMA protocol with the Token Ring protocol to achieve minimal end-to-end delay and high throughput for multi-hop ad hoc networks.Based on the three-hop network,this paper first analyzes the average service time and endto-end delay of the TWTR protocol.Afterwards,the validity of the time slot number optimization algorithm is verified theoretically,and the TWTR protocol proposed in this paper is modeled and simulated on the OPNET platform.Finally,the end-to-end delay and network throughput are compared with the traditional USAP(Unifying Slot Assignment Protocol)protocol and the WTRP(Wireless Token Ring Protocol)protocol.The simulation results show that the TWTR protocol has lower end-to-end delay and higher throughput,and has a certain performance improvement compared with the traditional MAC protocol.