Study On A Network Convergence Algorithm In Ad Hoc Networks With Pure Directional Antennas

With the development of mobile communication technology and antenna technology,mobile Ad Hocnetworks with purely directional antennas has been more and more widely used in the military field.The pure directional mobile Ad Hoc network consists of several wireless mobile nodes,which use only directional antennas for data transmission and reception.No fixed network infrastructure is required in mobile Ad Hoc network.So the topology of network is dynamically changing.The random motion characteristics of the nodes may cause the segmentation and collision of the network.Segmentation can cause an Ad Hocnetworks to split into two or more subnets.When two or more subnets collision,they need to be merged into an Ad Hocnetworks.Network convergence algorithm which based on purely directed TDMA protocol is used to make multiple subnets find each other and solve the problem when merging multiple subnets,for example,conflicts of time slot and synchronized clocks.The procedure of converging multiple subnets is divided into two parts in this paper,discovering network and merging network.Discovering network means network nodes belonging to different subnet in a certain distance finding each other.Merging network is used to solve the conflicts of time slot and synchronize the time clocks.When the network nodes belonging to different subnets complete the process of discovering network,they can exchange information to complete the process of merging network.This paper focuses on the the process of discovering network.Its goal is increasing the probability of discovery between subnets and reducing the time of discovering network,without affecting the communication within network.It is pointed out that the nodes at the edge of network only needs to scan sending and receiving in the direction outside the network in idle time slots.A optimized algorithm calculating the direction outside network is proposed to reduce the number of directional antenna beams outside the network.According to the network load size three scanning algorithms are designed.Taking into account that relevant sequence can transmit farther distances,this paper use the relevant sequence to complete the three-way handshake process of the discovering network,speeding up the merging network and avoiding unnecessary conflicts.A mobile Ad Hocnetworks With Pure Directional Antennas model is established with OPNET simulation software in this paper,getting the discovering network time under different network scenarios.The simulation results show that the scanning algorithms can effectively accomplish discovering network under different network scenarios,and the optimized algorithm calculating the direction outside network can effectively reduce network discovery time.