ABSTRACT
Contents 12.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297 12.2 A Cross-Layer Framework for Cognitive Radio Networks . . . . . . . . 301
12.2.1 System Model and Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . 301 12.2.2 Cross-Layer Framework . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
12.3 Implementation Aspects of the Cross-Layer Framework . . . . . . . . . 304 12.3.1 Routing Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304 12.3.2 Channel Allocation and Power Control . . . . . . . . . . . . . . . . . . 305
12.4 Overhead Analysis for the Cross-Layer Framework . . . . . . . . . . . . . . 307 12.5 Performance Evaluation and Tradeoffs in Cross-Layering . . . . . . . . 310 12.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
12.1 Introduction Wireless networks are evolving toward networks of small, smart devices that opportunistically share the wireless spectrum with minimal infrastructure and coordination. The new generation of smart terminals can provide
intelligent adaptive services by adjusting to the environment thanks to the software-defined radio (SDR) technology. This intelligence is incorporated into a cognitive cycle,1 which allows the wireless device to gather information about its environment (“learn”) and make decisions (“act”) regarding its transmission parameters and possible access strategies. The development of this new technology is further motivated by the new paradigm of the FCC’s spectrum management policy2 that has adopted new rules to promote active spectrum sharing techniques in both licensed and unlicensed bands.
