"Advanced Wireless Networks 4G Technologies". New E-Book. In the wireless communications community we are witnessing more and more the existence

of the composite radio environment (CRE) and as a consequence the need for reconfigurability

concepts. The CRE assumes that different radio networks can be cooperating components

in a heterogeneous wireless access infrastructure, through which network providers

can more efficiently achieve the required capacity and quality of service (QoS) levels. Reconfigurability

enables terminals and network elements to dynamically select and adapt

to the most appropriate radio access technologies for handling conditions encountered in

specific service area regions and time zones of the day. Both concepts pose new requirements

on the management of wireless systems. Nowadays, a multiplicity of radio access

technology (RAT) standards are used in wireless communications.