es of their choice. It supports gener- alized mobility that will allow consistent and ubiquitous provision of services to users. [17, 18] In other words, NGNs will provide an all-IP network which transports multiple services (voice over IP, video, etc.) in both fixed and wireless systems. Moreover the services will be broadband and use 4G, VDSL and fibre to the X to transport content to end-users. The systems are to have stringent quality of service (QoS) constraints to ensure delay and transmission rate sensitive ser- vices are supported, regardless of whether transmission networks use fixed or wireless links. Furthermore, NGNs propose to provide QoS control through recognising the application and routing accordingly. This can be accomplished by protocols which enable the router to recognise what kind of data are included in a packet, and switch according to a set priority. An important part of the vision of NGNs is independence between application provision and data transport mechanisms. This may be interpreted in two ways: one is that a network operator should not discriminate against services and applications that use its infrastructure. This is also referred to as net-neutrality, a concept which will be discussed in Chapter 14. The other interpretation is that the infrastructure and retail strata of broadband telecommunications service providers are separated. We have used this model in building the broadband telecom- munications ecosystem model. Infrastructure Convergence The objective of the Australian government in construction of its National Broadband Network (NBN) has been to create a monopoly infrastructure entity for fixed (as opposed to mobile) services. The NBN manages the infrastructure and leases capacity to retailers who manage service provision. However can the NBN fixed network model apply to wireless networks? Network Topologies, Design and Convergence Most operators have spent billions of dollars in rolling out 3G networks and are spending similar amounts on 4G networks and beyond. Infrastru