Research And Development Of A Link Scheduling Algorithm In Multi-channel TDMA Manet

A mobile Ad Hoc network(MANET)is a distributed wireless network which does not require fixed infrastructures and can adapt to network topologies.The main characteristic of MANET,which is self-organizing,makes it widely used in military and disaster relief fields.Wireless channels are commonly used in a MANET.Therefore,the broadcast feature of wireless channels and the networking control in a distributed manner make it of great difficulty that an efficient MAC(Multiple Access Control)protocol is designed for a MANET.The TDMA(Time Division Multiple Access)protocol has a higher throughput,but nodes work in a half-duplex mode in the traditional single-channel MANET.The end-to-end delay still cannot be guaranteed in the case of multi-hop.Therefore,nodes can work in a frequency division full-duplex mode by using multiple independent channels.The end-to-end delay can be shortened significantly by transmitting and receiving data simultaneously on different channels in multi-hop situations.The throughput of the network will also be improved.This thesis studies in the link scheduling problem which has larger transmission opportunities.Firstly,the related problems of multi-channel link scheduling are analyzed.Then,the models of multi-channel link scheduling are established with reference to the knowledge of graph theory.These models are used to calculate the upper limit of multi-channel link scheduling,which provides a theoretical reference for the following distributed link scheduling algorithm.Finally,a reservation-based distributed multi-channel TDMA link scheduling algorithm,BR-DMC link scheduling algorithm,is proposed to solve the problems of the existing multi-channel link scheduling algorithms.Multiple independent channels are used to make nodes work in a frequency division full-duplex mode.The three-step handshake reservation is performed to ensure that there is no conflict in link scheduling.Fixed time slots are allocated to each node on the common channel,so that there is still a time slot to transmit data before each reservation is successful.Dynamic time slots are used for transmission once the reservation is successful.The algorithm can also continuously reserve and release dynamic time slots according to the traffic change on the link.Frequency division multiplexing is added on the basis of time division multiplexing and space division multiplexing,which increases the number of links that can be scheduled in the same time slot,increasing the network throughput,and shortening the access delay of nodes.In this thesis,the network simulation software OPNET is used to simulate the BR-DMC link scheduling algorithm.The effects of the load on the network throughput,time delay and the number of links that can be scheduled in the same slot are observed.Firstly,under different network topologies of the static scene,the effect of increasing the number of available channels on protocol performance is observed,then the performance difference between different protocols is observed by comparing with the USAP-MA protocol and the TFMAC protocol.Finally,in the mobile scene,the mobility analysis of each protocol and the comparison analysis between the protocols are performed.The results of the simulation show that the BR-DMC link scheduling algorithm can shorten the end-to-end delay,improving the network throughput,and increasing the number of links that can be scheduled in the same time slot effectively,which verifies the superiority of the algorithm.