PDF of this tutorialThe resulting communications architecture is designed to deliver greater functionality to wireless networks by delivering value-added services coupled with superior performance. This architecture consists of the following elements:
- radio access network
- core network
- end-user services network
The architecture assures that these functional elements are seamlessly interconnected and facilitates connecting additional networks to the core network. These additional networks include the Internet and other packet-switched IP networks; traditional telephone service networks, including public switched telephone network (PSTN) and integrated services digital network (ISDN); and legacy signaling system 7 (SS7), interim standard–41 (IS–41) mobile application part (MAP) and Global System for Mobile Communications (GSM) MAP information transport networks (see Figure 4).
Figure 4. Wireless IP Network Architecture
Functional Components
The architecture defines the following three service planes that contain specific functional components:
Radio Access Plane
This contains the radio access functional network elements that work together for providing the mobile subscriber network access over an air interface. The radio access network (RAN) provides the basic transmission, radio control, and management functions needed for the mobile subscriber to access the resources of the core network and the end-user services network. It is this access network that terminates the air interface to the mobile station (MS) and converts the air frames to packet format for transporting traffic between mobile subscribers or extending the reach of the mobile subscriber to other RANs and external networks. The network topology for provisioning the RAN is a key element in terms of defining the flexibility for backhaul options from the base transceiver station (BTS) to include bandwidth options that are higher than the current T1 and E1 deployments. Also, given that T1 and E1 backhaul rates will require continued support in the foreseeable future, the choice of protocol for backhaul transport becomes an important criteria for assuring maximum efficiency on the lower-speed T1 and E1 links (see Figure 5).
Figure 5. Detailed Architecture
Core Network Plane
This contains the functional network elements that work together for linking subscribers with feature servers and internetworking gateways to external networks such as the Internet, PSTN, corporate enterprise intranet, and other RANs. The core network also provides the interface into network management and connects RANs with mobility management, security, and signaling functions. For third-generation network deployments, the core network will be recognized as the key investment operators make for securing a superior competitive position by offering an extensive variety of services.
The core network is designed to be access technology–independent. The core network leverages IP for control and transport. The peer-to-peer network is enhanced by using client/server technology within the network, presenting the mobile subscriber with a network environment that is already familiar because of its Internet feel. The core network is designed to leverage the enhancements available by moving to packet with the definition of open interfaces to provide the operator the ability to enhance the system offering, commission features from third parties, and reduce overall operating costs. The network is a unique combination of functions that leverages the individuality imposed by a mobile network with the proven concepts of IP. The core network is designed with the understanding that an active subscriber may have multiple active sessions but may not be physically connected, thus enabling an always-connected, always-on subscriber experience. The importance of a services client acting on behalf of the subscriber and its awareness of all of the different sessions is one of the unique features found in this network architecture. The aim of the architecture is to repeat the success of open interfaces found in wireline networking. These objectives will be achieved via a core and RAN network architecture that leverages existing standards but permits the possibility of extending newly defined open interfaces for new, mobile-oriented, end-to-end services that will range from multimedia, mobile video, Web browsing, and electronic commerce.
End-User Services Plane
This plane hosts a variety of services that is available to mobile subscribers based on their access profiles. These services may be provided by operators and third-party content and service providers and include Internet and private value-added network content such as news and information, video, and other media that can be delivered to consumers through their wireless subscriber devices. The end-user services network contains specific functions and, when interoperating with core network functions, the mobile subscriber will experience the feel of a wireline network with the added value of being completely unrestricted by the bounds imposed by the wireline network. The services delivered to the subscriber will include the expected voice mobility enhanced by the expanded ability to execute any IP–based application transparently in the eyes of the subscriber. This experience will be enhanced even further with the anticipated deployment of new IP–based services specifically designed to leverage the concept of mobility.
These three architecture planes work harmoniously as layered networks for delivering complete end-to-end service to mobile subscribers.
Network Service Functionality
The fundamental premise driving the new communications architecture is the convergence of the voice and data realms. However, there are basic differences in the traditional regulation and provisioning of these services. In this model, the core network plays a central role in connecting a myriad of host services to subscriber access networks.
The architecture permits services to drive the functionality and added value of the wireless network. A key set of common functions and basic services must be supported to have a viable service offering. This key set of functions and services includes the ability for subscriber terminals to register, originate, receive, maintain (i.e., hand off or hand over), and clear voice and data sessions via one or more different media types. It also includes an initial set of supplementary services that add features to these basic call capabilities. The set of services offered will be expanded as value-added services, developed by third parties, and added to the network through open interfaces.
The common set of services enabled by the architecture is as follows:
- packet services—This is the data transport, providing carriage for services such as voice and data, that facilitates the delivery of wireless services. IP services include transparent support of existing IP applications and new value-added IP services that specifically leverage the advantages of a mobile environment.
- common functions—This is the base layer of functions, such as call registration and origination, that supports all subsequent layers of services and upon which all other layers of functions are based.
- teleservices—These are the basic services delivered to the end user, such as voice calls and data sessions.
- supplementary services—These are the enhanced teleservices, such as caller ID and teleconferencing, plus new supplementary services enabled by an IP–based services model.
- operations, administration, maintenance, and provisioning (OAM&P)—These are the supervisory functions, such as network monitoring and billing tracking, that keep the network operating efficiently and effectively.
- value-added services—These are the services residing outside the alliance architecture’s core network offering that are supplied by the network operator, content provider, and enterprise and endpoint applications and services (see Figure 6).
Figure 6. Service Provisions
