Cognitive Radio Network
In all our previous discussions, we focused on point to point communications using cognitive radio technology. Having solved the problem of two-party communications, we can now focus on using the cognitive radio link to form a network. Wireless networking has been widely studied for decades. However, the revolutionary new spectrum access mechanism in cognitive radio incurs substantial challenges for the design of networks. In this chapter, we provide a brief introduction to the basics of general networks; more details about networks can be found in . Then, we will study the special design suitable for cognitive radio in different layers in a bottom-up manner.
Intuitively, a network is an ensemble of parties that can communicate with each other, directly or indirectly. Usually, a network can be represented by a graph, in which each node represents a communication party while each edge means that the two incident nodes can communicate with each other.
There are typically two types of architectures for networks, as illustrated in Figure 11.1, both having plenty of applications.