Client Mobility Support

The components for Client Mobility Support have the role of interacting with the Core Network Mobility Management Components and providing a seamless experience for the applications running on the client devices, such that operations like network attachment or hand-overs would be transparently handled. To perform these operations, the Mobility Manager (MM) component, as the background application running on the mobile device, will orchestrate the normal network management procedures. For providing value-added functionality, the Access Network Discovery and Selection Function situated in the core network assists the Mobility Manager with information and operator pushed policies.

1. OpenEPC Release 1 Access Network Discovery and Selection Function (ANDSF)

The Access Network Discover and Selection Function component has the purpose of communicating with a Mobility Manager running on the mobile endpoint device and exchanging information which would enhance both the Always Best Connected concepts, but also allow the network operator to manage and enhance connectivity on a multi-access environment. In the Release 1 implementation, the ANDSF behaves in the spirit of the  3GPP TS23.402 Ch. 4.8, with the use of an ANDSF Management Object similar (but extended) to that presented in  3GPP TS24.312.

The ANDSF features a database back-end for storing both the Access Network Discovery Information and the Inter-system Client Mobility Policies with their specific 3GPP, 3GPP2, WiMAX and WiFi parameters. The provisioned Inter-System Client Mobility Policies can be pushed towards the UE from the web interface. A remote triggering of this "push" operation is also possible, yet this remains largely unstandardized.

A Working Policies Policy Engine is built in the ANDSF, which allows for delivery of dynamic and subscriber specific Inter-System Client Mobility Policies. The operator can configure dynamic behavior, by checking various conditions (e.g. subscriber category, IPCAN type, RAT type, events, APN, access restrictions etc) and accordingly providing parametrized action (e.g. time-based) to reorder and to indicate its prioritized access network hand-over policies to the UE.

Further, each Inter-System Mobility Policy can contain various parameters (e.g. validity areas, time intervals, etc). Once the UE receives a set of such policies, it will apply it's current parameters to find the matching policy with the highest priority. From this, the UE can extract directly an operator-ordered list of Access Networks, which indicate the operators suggested solution for the given client's profile, location and time of day.

Limitations:

• currently there is no limitation of the Access Network Discovery Information, but the complete provisioned coverage map is relied to the UE. Future releases will add parametrized filtering support for particular locations or UE capabilities.

2. The OpenEPC Release 1 S14 Reference Point

The ANDSF and the Mobility Manager communicate through the S14 interface. This follows the data models and specifications from  3GPP TS24.312. The transport mechanism is currently limited for Release 1 to a simple XML exchange over TCP interface, with an additional triggering mechanism by simple UDP alerting.

The Mobility Manager "registers" each hand-over operation to the ANDSF through this interface, during which the UE pushes its connectivity information and the ANDSF pushes its coverage maps for discovery purposes and access network policies for hand-over triggering purposes. The ANDSF can also trigger an immediate exchange, by alerting the UE at its latest known location.

Limitations:

• full  SyncML support is deferred for future releases
• authentication, encryption and attacks mitigation are not present
• automatic ANDSF discovery is not yet present.

3. OpenEPC Release 1 Mobility Manager

The Mobility Manager has the role of orchestrating the mobile client attachment/detachment procedures during the hand-over operations from one Access Network to another. As such, it allows for a seamless experience for the EPC clients, by managing the IP connectivity layer operations. It provides wrapper functions to connect and disconnect from each individual access network available, by reusing the client device's standard Layer 2 and 3 attachments. For orchestrating smooth hand-overs, the actual connection and final selection of a connection are provided with a fine-grain control mechanism to be used from the application layers, or managed transparently by the Mobility Manager based on Inter-System Mobility Policies, received from the ANDSF.

The Mobility Manager implements the  ANDSF S14 interface, which allows for exchange of information between the core network and the clients. With this mechanism in place, the Mobility Manager can provide to the ANDSF its updated network location and connectivity information and can receive from the ANDSF coverage maps in the form of Access Network Discovery Information and hand-over indications in the form for Inter-System Client Mobility Policies.

Based on the operator pushed Inter-System Mobility Policies, the MM can handle transparently (if configured as such by the subscriber) the operator's indications and requests. Besides this network-triggered hand-over mechanism, of course, manually triggered hand-overs on subscriber request are supported and have the highest priority over the network-triggered ones.

For performing all this operations and for retrieving IP connectivity information, the MM exports an open API towards the client application layer, which allows for easy integration with existing and future applications, mobile frameworks and platforms.

The supported client platforms for Release 1 of OpenEPC are mainly desktop/netbook operating systems: Linux, Microsoft Windows XP/Vista/7 (tm). Solutions for Android(tm), Maemo/MeeGo(tm), Symbian(tm), Windows Mobile(tm), Mac OS X (tm) etc are under development and will be prioritized based on customer requests.

4. OpenEPC Release 1 Mobility Manager GUI

The Mobility Manage GUI is an open source reference implementation of a network manager and generic client application, which demonstrates the use of the Mobility Manager. As the Mobility Manager runs typically completely in the background and should do most of its tasks transparently, the Mobility Manager GUI has the role of exposing to the user all the IP connectivity and operator pushed (over the S14 interface) informations, as well as providing the user interface for configuring the behavior of the Mobility Manager and for triggering manual hand-overs.

This GUI is limited in scope to demonstrative purposes and as code reference for development of mobile platform integrated functionality or mobile application add-ons. As such, the Mobility Manager can run also entirely without it and the client applications should connect themselves directly to the Mobility Manager API.

5. myMONSTER EPC add-on

The  MONSTER EPC add-on is a plugin which was developed to demonstrate the integration of a mobile client framework with the Mobility Manager. It has similar capabilities with the reference Mobility Manager GUI, but also extra support for a demonstrative video-streaming application. The added value is that it directly integrates with a Telco Communication Suite and as such demonstrates the way to link between EPC and a client application framework.