ABSTRACT
Contents 10.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 10.2 Routing in Multichannel Multihop Non-CRN Networks. . . . . . . . . . . 261 10.3 Routing in Multichannel Multihop CRN Networks . . . . . . . . . . . . . . . . 264
10.3.1 Decoupled Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264 10.3.2 Coupled Designs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
10.4 Discussion and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276
10.1 Introduction As we discussed in previous chapters, a cognitive radio network (CRN) is a network that performs communication through dynamic channels. Each channel is composed of different characteristics (corner frequency, bandwidth, power, etc.). The channel borders are defined by their frequency widths, possibly changing with time as primary and secondary users access/release portions of the spectrum. When a frequency range is unused, there exists a possibility for channel assignment. In a typical CRN environment a spectrum-agile radio (SAR) is used to scan a large frequency range
and operate on a number of small channels within a specified frequency band. When the SAR detects an unused frequency band, called a “hole,” it can begin sharing the frequency with other CRN radios, as long as a path exists from source to destination. Given a selection between optimal bands, the ones chosen for operation are based on variables such as the number of secondary accesses at the source or destination and the activity of licensed users.
