erent latency and throughput char- acteristics, as well as incremental infrastructure deployment. WiMAX network supports phased deployment of IP services that in turn scale with increasing number of active users and concurrent IP services per user. The architecture supports the integration of base stations of varying coverage and capacity - for example, pico, micro, and macro base stations - and allows flexible decomposition and integration of ASN functions in ASN network deployments, in order to enable use of load balancing schemes for efficient use of radio spectrum and network resources. Inter-working with existing wireless networks (e.g., 3GPP, 3GPP2) or wireline networks (e.g., DSL) is supported where the interworking function is based on standard IETF and IEEE protocol suites. The WiMAX network supports global roaming across WiMAX operator networks including support for credential reuse, consistent use of Authentication, Authorization, and Accounting (AAA) protocols for accounting and charging, and consolidated/common billing and settlement. A variety of iv Admission control is the ability to admit or control admission of a user to a network based on the user's service profile and network performance parameters, such instantaneous load and average delay. If a user requests access to network services but the incremental resources required to provide the grade of service specified in the user's service profile are not available, the admission control function rejects the user's access request. Note that admission control is implemented to ensure service quality and is different from authentication and authorization, which are also used to admit or deny network access. 2.2 Network reference model user authentication credential formats, such as username/password, digital certificates, Subscriber Identity Module (SIM), Universal SIM (USIM), and Removable User Identify Module (RUIM) are supported. Furthermore, WiMAX network accommodates a variety of online and offline client- provisioning, enrollment, and managem