Research On Admission Control Algorithm In Cognitive Radio Networks

With the advent of the era of mobile Internet, the data flow increases explosively,thus inspired the people’s demand for high speed data business. According to statistics,the utilization of the spectrum resource is about 15% which is not efficient then aggravated serious shortage of spectrum resources. The cognitive radio technology is proposed at the historic moment. Cognitive radio technology refers to spectrum sensing to find spare spectrum and the use of spectrum appropriately, to be more specifically, the secondary user(SU) constantly perceive the spectrum around then access and use the licensed spectrum opportunistically without causing any interference to the primary user(PU). However, PU’s random arrival will cause collision between users which interrupts the transmission of the ongoing SU. Thus, the primary user and secondary user’s Qo S can’t be guaranteed, so admission control(AC) technology is proposed. Admission control technology can effectively balance system performance parameters which are the dropping probability and the blocking probability.The main contribution of this paper is to propose and analyze the three kind of admission control algorithm under centralized cognitive radio network(CRN), and obtain the best one. These three admission control algorithms are: admission control algorithm based on integer channel reservation, admission control algorithm based on fractional channel reservation and admission control algorithm based on the probability of acceptance. In this paper, using the stochastic process and related probability theory, we setup a model to simulation the process of dynamic spectrum allocation and set up a scalable, programmable Continuous-time Markov Chain(CTMC) to analyze the system performance(including the throughput of the secondary users, dropping probability and blocking probability) in CRN. What’s more, admission control algorithm based on the channel reservation find out the best reserved channel number under the conditions which limit the dropping probability strictly and maximize the throughput of secondary users.Compared to other algorithms, admission control algorithm based on the probability of acceptance can maximize the throughput of the secondary users by solving a nonlinear optimal problem under the condition of the strictly ensured dropping probability. Finally the analysis and simulation with the traditional admission control algorithm prove the feasibility and effectiveness of the proposed admission control algorithms.