Research Of Csma Scheme Based On Grouping In Cognitive Radio Networks

Recently, with the rapid development of information industry, the mobile telecommunication industry faces grate serious challenge, such as the increasing broadband communication demands and the shortage of spectrum. Therefore how to improve the networks spectrum efficiency is the key to promote the development of network. Consequently, CR technology has become an effective way to solve the problem of scarce spectrum resources. In the acknowledged wireless network, if the primary users don’t use the spectrum, it can be used by the SUs with the permission of the network which can also improve the network efficiency. This thesis will discuss the function of CSMA scheme based on grouping interception in the un-slotted construction. The dissertation will also analysis throughout capability, forced termination probability and packet transmission delay.Firstly, this thesis propose a scheme consider about throughout capability and terminal consumption in the multichannel distribution acknowledged network The program will separate the whole channel into group A and group B. Intercept group A channel when every SUs wants to transmit packet. If the SUs find vacancy channel, they will choose one of the vacancy channels randomly to transmit there packets. If the SUs can’t find any vacancy channels, they will stay back-off period. After back-off period, intercept group B channel and repeat. This scheme can both reduce terminal consumption and keep the throughout capability.Secondly, based on the grouping scheme, this thesis models the system by 3-dimensional continuous time Markov process, calculate the steady state probability of the system, and obtain several performance measures such as throughput, forced termination probability, transmission delay of SUs by queuing analysis method.Last, with the given system parameter, this thesis compared the CSMA program based on grouping with hybrid sensing, random m-sensing and all sensing scheme.The result of the comparison test shows that CSMA scheme based on grouping has better performance in transmission delay than m-sensing scheme. Throughout capability and forced suspend probability are lower than that in the m-sensing scheme, barely different but shows lower consumption.