  Increasing mobile data demands in current cellular networks and proliferation
of advanced handheld devices have given rise to a new generation of dynamic
network architectures (DNAs). In a DNA, users share their connectivities and
act as access points providing Internet connections for others without
additional network infrastructure cost. A large number of users and their
dynamic connections make DNA highly adaptive to variations in the network and
suitable for low cost ubiquitous Internet connectivity. In this article, we
propose a novel collaborative cognitive dynamic network architecture (CDNA)
which incorporates cognitive capabilities to exploit underutilized spectrum in
a more flexible and intelligent way. The design principles of CDNA are
perfectly aligned to the functionality requirements of future 5G wireless
networks such as energy and spectrum efficiency, scalability, dynamic
reconfigurability, support for multi-hop communications, infrastructure
sharing, and multi-operator cooperation. A case study with a new resource
allocation problem enabled by CDNA is conducted using matching theory with
pricing to illustrate the potential benefits of CDNA for users and operators,
tackle user associations for data and spectrum trading with low complexity, and
enable self-organizing capabilities. Finally, possible challenges and future
research directions are given.
