In year 2007, out of 2.85 billion cellular network users world-wide, only 295 million i.e. approximately 10% used high speed mobile data services. In the next few years, with rapid adoption of smart phones that allow end-users any-time, any-where Internet access, mobile data traffic is expected to increase exponentially. The wireless service providers face two main challenges as they address this new trend: (1) as the peruser throughput requirements scale to multi-Mbps, how to scale the networks to achieve dramatic improvements in wireless access and system capacity, and (2) in the face of declining ARPU and increasing competition, how to reduce cost of deploying and operating the network. In this paper, we highlight how cognitive radio technologies, specifically Dynamic Spectrum Access (DSA) and Self-X will help meet these challenges and usher in a new transformation in cellular networks. We discuss in detail technologies in the following key areas: (1) DSA for capacity augmentation in macrocells, (2) Ultra-broadband small and femto cells using spectrum white spaces, (3) Self-X (X=configure, monitor, diagnose, repair and optimize) for LTE networks, and (4) Energy management. We show that the application of cognitive radio ideas to infrastructure cellular networks can bring great benefits by achieving a balance between complexity, practical realizability, performance gains and true market potential.