Study On Real-Time Communication Networks And Simulation

At present, real-time systems has been widely applied in the field of military affairs and civil affairs. Distributed real-time systems emerged as the continuously in-depth development of real-time applications. Distributed real-time system can be divided into two parts: local real-time process and real-time communication. We consider the assignment of the process resource according to the priority of the tasks in local real-time process. And similarly, in real-time communication, we care about the network resource. In real-time communication networks, based on the different application field, we choose the corresponding network topology and protocol. For example, multimedia services on demand are always provided on point-to-point packet-switching network; but real-time measure and control systems are always based on bus network. Today, the study on the real-time communication has become a hotspot. Some of these studies made amelioration to Ethernet, field-bus, and some reserve bandwidth for real-time messages in packet-switching networks. Under such background, our research aimed at small scale distributed real-time systems. We designed the crossed bus network architecture and the protocol which could transmit messages among lots of processors in real-time. These processors can execute their own tasks independently and they can finish large mission through cooperate with each other by real-time communication. To achieve the design of real-time communication network, we have done some research on the contents as follows:(1) Real-time communication network: the network architecture and the protocol.We designed crossed bus architecture. The nodes in the network can be classified into two types: function nodes and communication nodes. Function nodes undertake the tasks of the application and they connect to communication nodes. Communication nodes undertake transferring and receiving message between buses and function nodes, and they connect to the crossed points of the bus. Communication nodes implement real-time protocol, which guarantees every message could be sent to other nodes by the order of priority.(2) The way to denote priority.Priority is very important for real-time systems. For different applications, we should consider different factors that will influence the priority of the task. For example, deadline, the importance of the task itself and the cost caused by the task missed its...