Method Of Adaptive Communication Based On Cognition Forwireless Network

Modern wireless communication networks are moving towards broadband, information-digitizing and intelligent. In which, how to make network be adaptive to the dynamically changing environment and provide communications supporting the carried packet data service in military confrontation, disaster reliefemergency and communications, is a wide spread concern.Cognitive radio technology has the "adjustable and flexible communication parameters " and "opportunistic dynamic spectrum access" features, is considered to be an effective solution to the above problem of wireless communication technology. However, using cognitive radio technology in complex environment to achieve adaptive communication still faces many technical challenges. Therefore, on the basis of the analysis of domestic and foreign literature, the present dissertation research the resource time-varying influence on the traffic flow from the angle of resources and traffic propagation. And specific research the following problem from the aspects of QoS-guarantee, lower collision probability and lower routes disruption probability:First, hierarchical distributed network architecture and model of service transmission. At present，with the features of clustering and easy expansibility, the hierarchical and distributed network structure is widely used in the networks which has the character of hierarchical command, for example, the tactical networks and the emergency network. Therefore, the present dissertation first analysis the hierarchical distributed network architecture. And then, discussed the adaptive function mechanism with this framework, discussed the channel availability and link availability in this complex environment, as well as IP characteristics of packet service transmission with hierarchical distributed network architecture.Second, admission control method facing aggregation service QoS constraints. Complex environment will lead to uncertainty spectrum resources, and will lead to the fragments of traffic flow in transmitting and aggregating process, and has important influence on aggregation service queueing performance. Therefore, this dissertation building up the functional relationship between buffer-size service-rate packet loss ratio and queuing time-delay. And by the use of multi-objective optimization method research the admission control method facing the QoS constraint of packet loss rate and queuing delay.Third, dynamic channel adaptive switching method based on probability prediction. For the diversification of interference type in complex environment, this dissertation from the statistical law for duration type classified the interference as: continuous, periodic and random several kinds, and study a prediction method of channel idle state’s duration probability under a variety of styles interval. Its outstanding feature is the ability to give an estimate of the prediction error, thus take advantage of the ability of interval prediction to reduce the negative impact of the prediction error. And based on the results of probability prediction, which leads specific dynamic channel allocation and adaptive switching by setting the threshold of probability selection. On one hand, this can make node early exit current channel to avoid the collision generating during the arrival of interference. On the other hand, nodes can make a reasonable choice of switching target channel to reduce the switching probability.Forth, adaptive routing method based on link ability. First, research the link usability under multi-channel combination, and further research routing metric based on link availability under complex environment. And treat this routing metric as criterion, using adaptive routing algorithm with global dynamic optimization study demand routing selection method in complex environments, in order to reduce service blocking probability on the path. Among them, time-varying factors and reliability factors of channel and link are under serious consideration, and the channel switching times and channel switching frequency problem on communication path of both transmitter and receiver which caused by it. In the aspect of routing selection method, selecting the link with high reliability on statistical significance to form route, thereby avoiding unnecessary link reconstruction and route reconstruction.