Abstract
We propose an access control scheme in cognitive radio networks with prioritized Secondary Users (SUs). Considering the different types of data in the networks, the SU packets in the system are divided into SU1 packets with higher priority and SU2 packets with lower priority. In order to control the access of the SU2 packets (including the new arrival SU2 packets and the interrupted SU2 packets), a dynamic access threshold is set. By building a discrete-time queueing model and constructing a three-dimensional Markov chain with the number of the three types of packets in the system, we derive some performance measures of the two types of the SU packets. Then, with numerical results, we show the change trends for the different performance measures. At last, considering the tradeoff between the throughput and the average delay of the SU2 packets, we build a net benefit function to make optimization for the access threshold.
Highlights
In conventional cognitive radio networks, two types of users, namely, Primary Users (PUs) and Secondary Users (SUs), share the spectrum resource in the system
In order to control the access of the SU2 packets, an access threshold is set for the SU2 packets
We find that as the access threshold T increases, the blocking rate β22 of the SU2 packets will decrease and the throughput θ22 and the average delay δ22 of the SU2 packets will increase. This is because the higher the access threshold is, the more the SU2 packets can be admitted to join the system and the more the SU2 packets will wait in the system
Summary
In conventional cognitive radio networks, two types of users, namely, Primary Users (PUs) and Secondary Users (SUs), share the spectrum resource in the system. It is necessary to consider the different types and prioritization among the SUs in cognitive radio networks. The above researches about cognitive radio networks with prioritized SUs did not consider the access control for the SU packets with lower priority. Larger number of SU packets with lower priority which access the system without any restriction will disturb the transmission of the PUs and the SUs with higher priority. We can find that the researches about cognitive radio networks with priority SUs mentioned above were analyzed by using continuous-time models.
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