  Cognitive radio (CR) has emerged as a promising technology to improve
spectrum utilization. Capacity analysis is very useful in investigating the
ultimate performance limits for wireless networks. Meanwhile, with increasing
potential future applications for the CR systems, it is necessary to explore
the limitations on their capacity in a dynamic spectrum access environment.
However, due to spectrum sharing in cognitive radio networks (CRNs), the
capacity of the secondary network (SRN) is much more difficult to analyze than
that of traditional wireless networks. To overcome this difficulty, in this
paper we introduce a novel solution based on small world model to analyze the
capacity of SRN. First, we propose a new method of shortcut creation for CRNs,
which is based on connectivity ratio. Also, a new channel assignment algorithm
is proposed, which jointly considers the available time and transmission time
of the channels. And then, we derive the capacity of SRN based on the small
world model over multi-radio multi-channel (MRMC) environment. The simulation
results show that our proposed scheme can obtain a higher capacity and smaller
latency compared with traditional schemes in MRMC CRNs.
