Research On A Hybrid Multiple Access Protocol In Layered Ad Hoc Networks

With the rapid development of wireless networks, everyday life has been closely associated with the network. However, centralized networks have difficulty in recovery after disasters, therefore, ad hoc networks with distributed features have been widely used in wireless communication networks. Benefiting from the infrastructure-less set-up and self-healing ability, ad hoc networks can be applied to civilian areas as well as military battlefield. In order to satisfy the strict performance requirements for military communications, we develop a layered ad hoc network architecture to support the subnet division and node roaming in this paper. Moreover, we design a hybrid multiple access protocol based on time division multiple access(TDMA), frequency hopping(FH), and spatial multiplexing(SM). In particular, the main cotents are summarized as follow.1. A large-scale layered mobile ad hoc network(MANET) architecture supporting subnet division and node roaming has been proposed, which supports both single-level and multi-level ad hoc networks. In this network architecture, different FH pattern is utilized in each subnet aiming at enhancing the network capacity, whereas the public hopping pattern is leveraged in different subnets to guarantee the network interoperability.2. The multiple access problem when nodes move fast synchronously in the large-scale layered ad hoc network architecture has been investigated. First, a multi-granularity hybrid multiple access protocol combining TDMA, frequency hopping with spatial multiplexing technology has been proposed, which can sense the node density and guarantee quality of service. Second, a superframe structure, a slot allocation algorithm, and a time base unified program have been designed aiming to achieve the channel access at low latency in a large-scale scene. Then, a delivery mechanism based on the location information of gateway nodes has been proposed, which can effectively reduce the collision among subnets, and thus enhance the throughput of network. Finally, the feasibility and effectiveness have been verified by simulation.3. The problem of subnet division and nodes roaming when nodes move fast in the large-scale layered ad hoc network architecture has been investigated, aiming to enhance the network survivability. First, the selection strategies of dynamic maintenance nodes and gateway nodes have been formulated to ensure the rapid formation of dividing subnets. In addition, a delivery mechanism of gateway nodes based on the location information and probability has been proposed, which avoids the collision resulting from rapid increasement in the number of gateway nodes due to the division of subnets.Then, an access network program about an isolated roaming node and node sets off network has been designed so as to guarantee roaming nodes to access network safely, thus enhance the network survivability. Finally, extensive simulation results exihibit that the proposed protocol is able to reduce the traffic latency and improve the system throughput effectively. Meanwhile the network survivability can be enchanced.