GPRS Auto-Configuration in Wireless Wide Area Networks
Updated: May 5, 2003
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Microsoft is investigating wireless wide area network (WWAN) services that rely on General Packet Radio Services (GPRS) technology. GPRS is a packet-based wireless data communication service that promises continuous connection to the Internet for mobile phone and computer users.
Microsoft and the hardware industry have long shared a goal to design Microsoft Windows operating systems and edge devices (mobile phones, network adapters, wireless access points, and so on) that require little or no intervention on the part of end users. The idea, known as auto-configuration, is that the devices “just work” without complex manual configuration. Auto-configuration is being extended from todays enterprise data networks to WWANs. By supporting the proposed GPRS Auto-Configuration Service in Windows Vista, vendors can achieve Ethernet-style connectivity between PCs, phones, and the WWAN networks.
GPRS Auto-Configuration benefits independent hardware vendors (IHVs) and original equipment manufacturers (OEMs) who create GPRS devices and interfaces that interoperate with Windows operating systems. Through this service, vendors can streamline a configuration task that today is overly complicated for operators and users alike. The approach outlined in this white paper offers several advantages:
The benefits of GPRS Auto-Configuration are available for the following:
This document provides preliminary information to IHVs and OEMs about how to design devices and interfaces that take advantage of the GPRS Auto-Configuration Service in future Windows operating systems.
Overview of GPRS and Configuration Services
The proposed GRPS Auto-Configuration Service is an extension to the next generation of the Wireless Zero Configuration (WZC) service in Windows XP for wireless local area networks (WLAN). The WZC service dynamically selects a wireless network with which to attempt connection, based either on a users preferences or on default settings. This process includes automatically selecting and connecting to a more preferred wireless network when it becomes available. If none of the preferred wireless networks are found nearby, the WZC service configures the wireless adapter so that there is no accidental connection until the wireless client roams within the range of a preferred network.
In the same way that the WZC service automatically locates all available access points, the GPRS Auto-Configuration Service automates wireless configuration and authentication between a PC and a phone. The interface can use the Bluetooth wireless technology specification.
WWANs and GPRS
WWAN technologies enable users to establish wireless connections over remote public or private networks. Some of the current WWAN technologies based on second-generation (2G) systems have limited roaming capabilities and are incompatible with each other. Still in development are the third-generation (3G) technologies that will follow a global standard to provide worldwide roaming capabilities.
GPRS bridges the gap between 2G and 3G systems by providing a continuous connection to the Internet for mobile phone and computer users. Through the GPRS Auto-Configuration Service, future Windows operating systems can gain access to a GPRS network as a connectionless network. The GPRS Auto-Configuration Service connects a local GPRS network adapter or a remote GPRS phone to a GPRS network. The service then activates the required packet data protocol (PDP) contexts.
The GPRS Auto-Configuration Service is designed for any 2.5G Global System for Mobile Communications (GSM) and later technologies, such as handsets based on the Universal Mobile Telecommunications System (UMTS), a popular 3G mobile technology.
Connections by RADIUS Servers
If the APN requests a connection to a private network, that network is likely to handle authentication, in which case the credentials are taken from the active context request and passed to a RADIUS client. The NAI from the username is then used by the RADIUS client to send a request to the correct corporate RADIUS server. The server can specify the IP configuration, which is passed to the phone by means of the active context response. This IP configuration information does not include the DNS servers IP address.
The active context request is routed to a Gateway GPRS Support Node (GGSN). After the GGSN accepts the PDP context, it routes IP packets from the phone to the selected network. When the phone receives the IP configuration, it passes this information to the computer. Then IP packets can be sent over the phone, which forwards them to the GGSN, which in turn routes them to the correct network.
GPRS Miniport Driver Communication
To use the WZC services, a wireless network adapter and its Network Driver Interface Specification (NDIS) driver must support the NDIS object identifiers (OIDs) that are used to query and set device and driver behavior.
To use the GPRS Auto-Configuration Services, vendors must also support the following:
Figure 1. GPRS Network Adapter Miniport Driver
GPRS Auto-Configuration Service Architecture
The following sections describe the basic components of the GPRS Auto-Configuration Service and their interfaces. Figure 2 illustrates the overall architecture.
Figure 2. Top-level Architecture of the GPRS Auto-Configuration Services
Any interaction with a local miniport driver or remote phone is through the media-specific layer, which does the following:
The media layer for Bluetooth-enabled phones uses UPnP to exchange control and status information over Internet Protocol version 6 (IPv6). The phone, in effect, serves as an IPv6 router that provides a Bluetooth interface on one side and a GPRS interface on the other. However, if a cellular network is not IPv6-enabled, the phone will use both v6 and v4. IPv6 nodes on the same link use the neighbor discovery protocol to discover each other's presence, determine each other's link-layer addresses, find routers, and maintain reachability information about the paths to active neighbors.
The IP configuration is sent differently depending on the version used:
Media-Independent Layer and Controller
The media-independent layer provides a set of functions as a single interface to the upper layers of the architecture. The media-independent layer receives GPRS indications from the media-specific layers and passes them to the interface manager, which uses the interface to issue commands to the local or remote GPRS devices.
The media-independent layer also provides an interface for the controller, notifying it of new GPRS device arrivals and departures. The controller controls the overall behavior of the service for each GPRS device by tracking the currently available interfaces, keeping them connected and appropriately configured. The controller receives and responds to interface events from the media-specific layer as well as the interface manager.
Data Configuration and Control
The interface manager is central to the GPRS Auto-Configuration. For each of the configured GPRS interfaces (local and remote), the interface manager maintains all the configuration data and control mechanisms in a single structure. The interface manager provides some notifications to the controller, including bad interface behavior and changes in interface characteristics. However, for the most part its management is passive, driven by a client or the controller and also by indications from the media layers.
The interface manager initializes the auto-configuration state machine, which attaches a GPRS device to a GPRS. Through the interface manager, the state machine receives events from the media as well as from internally generated events, and it issues commands to the media layers to request that the GPRS devices perform certain actions.
In addition, the interface manager drives the registry persistence component, which handles the persistence of all configuration data associated with a GPRS interface in the registry.
Benefits of the GPRS Auto-Configuration Service
Support in future versions of Windows for the GPRS Auto-Configuration Service will provide IHVs and OEMsand end userswith the following benefits:
Call to Action and Resources
Call to Action:
Microsoft Hardware and Driver Developer Information
Microsoft Platform Software Development Kit (SDK)
Microsoft Windows Driver Development Kit (DDK)
Microsoft Windows Logo Program System and Device Requirements
Windows XP Application Compatibility Toolkit