Research On Key Technologies Of MANET Based On Cooperative Communication

Mobile ad hoc networks（MANET）is a centerless multi hop mesh network that does not depend on the existing network infrastructure.Because of its advantages of distribution,low deployment cost and strong adaptability,it is more and more widely used in military communication,emergency response and environmental monitoring.However,in practical application,the fading and time-varying characteristics of wireless channel lead to the decline of transmission performance,which makes the traditional ad hoc network unable to meet the needs of high-speed communication.Cooperative communication technology can make full use of spatial diversity to improve transmission performance,but its harsh cooperative conditions greatly limit the application of cooperative technology in mobile ad hoc networks.The cooperative communication technology based on random phase rotation,combined with error correction coding and phase jitter,can avoid channel conflict and bring spatial diversity gain at a low cooperative cost.Under this background,thesis studies the MANET based on cooperative communication technology,and optimizes and improves the network scheme in unicast and broadcast scenarios.Barrage relay networks（BRNs）combines the cooperative communication technology based on random phase rotation and establishes the cooperative path through the controlled barrage regions（CBR）establishment algorithm.It is a MANET unicast network with low delay,low overhead and high reliability.However,too many cooperative nodes in the cooperative path bring the problems of low user capacity and high average power consumption.Thesis combines the concept of "routing pipeline" in VBF（vector based forwarding）geographic routing protocol with the establishment algorithm of controlled interception area in BRNs,limits too many forwarding nodes through geographic location parameters,and puts forward an optimization scheme of relay blocking network based on geographic routing protocol.The simulation results show that the optimization scheme can significantly increase the user capacity and reduce the average power consumption of the BRNs.At present,most broadcasting schemes in MANET are based on Carrier Sense Multiple Access Protocol（CSMA）to avoid channel conflict.These broadcasting schemes have good network performance under low task load.However,when the transmission load increases or the node density is high,the performance of broadcasting schemes decreases significantly due to problems such as data redundancy and channel conflict.To solve these problems,thesis proposes a broadcast network scheme based on cooperative communication.Combined with cooperative communication technology and dynamic slot allocation technology,the broadcast network scheme is divided into three stages:competition,slot allocation and data transmission.In the competition stage,the transmission advantage of CSMA based broadcast network under low load is used to flood a small number of competitive messages and allocate broadcast permissions;In the time slot allocation stage,the dynamic time slot allocation algorithm combined with cooperative communication technology is used to complete the time slot allocation of nodes;In the data transmission stage,taking advantage of the transmission advantages brought by cooperative communication,nodes can avoid channel conflict and make full use of channel resources for data transmission.The three stages are cyclized to solve the problem of dynamic transformation of network topology caused by node movement.The simulation results show that the broadcast network scheme based on cooperative communication has obvious advantages in network load,delivery rate and transmission delay compared with the traditional broadcast scheme.