Research Of Dynamic Spectrum Sharing Model With Multiple Secondary Users

The spectrum resources become more and more precious than before.The scarcity of spectrum has been taken seriously and it was caused by traditional spectrum allocation.Most of the spectrums were unoccupied in a majority of the time but many wireless devices cannot be used to transmission information because of the spectrums were allocated to the licensed users.It causes a great influence to the wireless communication and limits the development of the information society in future.The pattern of traditional allocation unable to satisfy the requirements of technology and society in nowadays.So we need a better a way to solve the problems of spectrum scarcity which was caused by low utilization.At the present time,there are some ways to solve the matters of spectrum scarcity and low utilization.Such as raise the efficiency of spectrum sharing by competitive price game.We can make full use of TV White Space for spectrum sharing,and using queuing theory to solve the problem of sharing.The spectrum detected by cognitive radio before access channel opportunistically.An author also raised a two-phase spectrum sharing protocol on account of an analog network coding strategy in cognitive two-way relay networks.Each one has its own characteristic aforementioned,we study on another method,which is more simple and effective.It is hybrid spectrum sharing in dynamic spectrum access networks.Now the proposed hybrid spectrum access scheme which combines overlay and underlay spectrum sharing schemes by using continuous time Markov chain,reduces the complexity in modelling the dynamics of primary and secondary user.We derive the model of proposed scheme from 2 secondary users to 3 secondary users when it has multiple secondary users.We derive the steady state probability for these states and also calculate the throughput of the aforementioned spectrum sharing schemes with the use of Shannon channel capacity.By comparison,it shows the throughput of hybrid spectrum sharing which has 3 secondary users is greater than which has 2 secondary users.In order to consummate the scheme,an access probability for secondary users by importing a desired datarate to secondary users which improves the fairness in the system.At the same time,the numerical results validated the performance of adjusting system balance scheme,the results showed that the desired datarate higher,the probability of secondary users access lower.