Title of Invention

METHOD FOR CONFIGURING CONTEXT FOR CONNECTION DELIVERING PACKET DATA SERVICE TO MOBILE TERMINAL VIA TARGET WIRELESS ACCESS NETWORK, AUTHENTICATION SERVER AND PACKET DATA GATEWAY THEREFOR

Abstract The invention relates to a method for configuring a context for a connection delivering a packet data service to a mobile terminal via a target wireless access network, wherein the mobile terminal is initially connected to an originating wireless access network, the method comprising the steps of providing the packet data service to the mobile terminal via the originating wireless network, attaching the mobile terminal to a core network connected to the target wireless access network by an authentication server to enable a reception of the packet data service via the target wireless access network, and initiating by the authentication server the establishment of a context within the core network connected to the target wireless access network, wherein the context is established prior to an attachment of the mobile terminal to the target wireless access network.
Full Text FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENTS RULES, 2003
(See Section 10; Rule 13)
TITLE
METHOD FOR CONFIGURING CONTEXT FOR CONNECTION DELIVERING PACKET
DATA SERVICE TO MOBILE TERMINAL VIA TARGET WIRELESS ACCESS
NETWORK, AUTHENTICATION SERVER AND PACKET DATA GATEWAY THEREFOR
APPLICANT
PANASONIC CORPORATION
A JAPANESE COMPANY
OF 1006, OAZA KADOMA, KADOMA-SHI,,OSAKA 571-8501,
JAPAN
The following specification particularly describes the nature of the invention and
the manner in which it is performed.

FIELD OF THE INVENTION
The invention relates to a method for configuring a context for a connection delivering a
packet data service to a mobile terminal via a target wireless access network. The mobile
terminal is initially connected to an originating wireless access network and the packet
data service may be provided to the mobile terminal via the originating wireless network.
Moreover, the invention provides an authentication server, a packet data gateway and a
packet data service support node which participate in the context configuration method.
TECHNICAL BACKGROUND
W-CDMA (Wideband Code Division Multiple Access) is a radio interface for IMT-2000
(International Mobile Communication), which was standardized for use as the 3rd
generation wireless mobile telecommunication system. It provides a variety of services
such as voice services and multimedia mobile communication services in a flexible and
efficient way. The standardization bodies in Japan, Europe, USA, and other countries
have jointly organized a project called the 3rd Generation Partnership Project (3GPP) to
produce common radio interface specifications for W-CDMA.
The standardized European version of IMT-2000 is commonly called UMTS (Universal
Mobile Telecommunication System). The first release of the specification of UMTS has
been published in 1999 (Release 99). In the mean time several improvements to the
standard have been standardized by the 3GPP in Release 4 and Release 5 and
discussion on further improvements is ongoing under the scope of Release 6.
Another issue becoming more and more important for future mobile communication
networks is the interworking between different access network technologies in
heterogeneous networks.
It has been recognised that WLANs (Wireless Local Area Networks) are, and will
continue to be deployed by independent operators and that these WLANs may or may
not be interworked with a mobile communication systems, such as 3GPP systems.
Further, these WLANs may overlap partially or completely with WLANs that are
interworked with Home and/or Visited mobile communication systems. Lastly, WLANs
interworked with Home and Visited 3GPP systems may also overlap each other, as well

as the radio access networks for each mobile communication system. These situations
create multiple permutations of coverage areas and service states which will need to be
carefully understood and managed.
In this respect the 3GPP has standardized the interworking of 3G networks and WLAN
(see 3GPP TR 22.934: "Feasibility study on 3GPP system to Wireless Local Area
Network (WLAN) interworking", 3GPP TS 22.234: "Requirements on 3GPP system to
Wireless Local Area Network (WLAN) interworking" and 3GPP TS 23.234: "3GPP
system to Wireless Local Area Network (WLAN) interworking; System Description", all
available at http://www.3gpp.org).
There are number of different possible operating environments where interworking of the
3GPP system and the WLANs may be desired. The 3GPP operates universally in
Public, Corporate, or Residential environments. WLANs may also be deployed in any of
these environments and it would be advantageous if the standards for 3GPP to WLAN
interworking could accommodate all of these environments. Such capability would
further enhance the ease of use for the mobile system user and virtually extend the
effective coverage areas of each system.
The different environments may involve different administrative domains and wide
diversity of WLAN technical capabilities. As an example, the security capabilities and
policies may differ between public, corporate and residential WLANs. These differences
may lead to different interworking methods between 3GPP and WLANs.
Different scenarios are identified describing different levels of interworking. E.g. scenario
2 describes 3GPP-based access control and charging, scenario 3 relates to accessing
3GPP PS based services, e.g. IMS, scenario 4 and 5 consider the access to 3GPP PS
based services with service continuity.
The protocol details are separated in several documents. In 3GPP TS 24.234: "3GPP
system to Wireless Local Area Network (WLAN) interworking; UE to Network protocols"
the details of the protocols between WLAN UE and the network are described. In 3GPP
TS 29.234: "3GPP system to Wireless Local Area Network (WLAN) interworking; Stage 3
Description" protocols for several network reference points are specified and in 3GPP TS
33.234: "Wireless Local Area Network (WLAN) interworking security" the security
architecture, i.e. trust model and security requirements for the interworking of the 3GPP
System and WLAN Access Networks are discussed.

The details of the WLAN Access Authentication and Authorization procedure from the
architectural view are described in chapter 7.2 of 3GPP TS 23.234 and the W-APN
(WLAN Access Point Name) Resolution and Tunnel Establishment in chapter 7.9 of
3GPP TS 23.234.
The description of the GPRS architecture with its entities and functionalities can be found
in 3GPP TS 23.060: "General Packet Radio Service (GPRS); Service Descriptions;
Stage 2". Especially the logical architecture in chapter 5.4, the GPRS attach procedure in
chapter 6.5, the mobility management states in chapter 6.1.2, the location management
procedures in chapter 6.9.2, the PDP context activation procedure in chapter 9.2 and the
appropriate HLR GPRS subscription data, MM and PDP contexts in chapter 13 are
explained.
If a terminal hands over from a 3G network to WLAN and is afterwards in idle mode in
3G network. The terminal has to send periodic Routing Area Update (RAU) messages
over the 3G air interface to preserve the MM and PDP contexts in the 3G SGSN. This
requires the availability of 3G network coverage and a periodic 3G connection
establishment for performing the RAU. If 3G network coverage is not available (user is in
a shopping centre, at airport, in the subway) and the RA update timer expires, the MM
and PDP contexts are deleted in the SGSN. Further the 3G network connection
establishment for performing the RAU would increase 3G signalling overhead and UE
power consumption.
In addition, if the terminal starts a 3G service from WLAN coverage, there is no PDP
context established in the appropriate 3G SGSN. Thus if handover from WLAN to 3G is
initiated the 3G connection for the service must be initiated from scratch by performing
and GPRS Attach procedure and a PDP Context Activation which are time consuming
and imply a significant delay for service delivery through the 3G network.
SUMMARY OF THE INVENTION
The object of the invention is therefore to provide a method that allows establishing
connection for packet service delivery to a mobile terminal from a wireless access
network, as for example a UMTS, as fast as possible.
The object is solved by the subject matter of the independent claims. Advantageous
embodiments of the invention are subject matters to the dependent claims.

According to one embodiment of the invention a method for configuring a context for a
connection delivering a packet data service to a mobile terminal via a target wireless
access network is provided. The mobile terminal is initially connected to an originating
wireless access network and the packet data service may be provided to the mobile
terminal via the originating wireless network.
The authentication server may attach the mobile terminal to a core network connected to
the target wireless access network to enable a reception of the packet data service via
the target wireless access network. Further, the authentication server may initiate the
establishment of a context within the core network connected to the target wireless
access network wherein the context is established prior to an attachment of the mobile
terminal to the target wireless access network.
This operation allows to set-up and configure parameters associated for packet data
service delivery through the target wireless access network by establishing a context
within one or more network nodes within the core network connected to the target
wireless access network. Upon handover from the originating wireless access network to
the target wireless access network, the user of the mobile terminal may benefit from the
preconfiguration by a faster establishment of packet data service provision through the
target wireless access network.
According to a further embodiment the authentication server may determine an address
of a serving packet data service support node of the core network, wherein the serving
packet data service support node serves the mobile terminal when attaching to the target
wireless access network. Moreover, the attachment of the mobile terminal to the target
wireless access network comprises sending a packet data service attach message to the
serving packet data service support node.
In a variation of this embodiment the mobile terminal may be authenticated at the
authentication server and receiving location information of the mobile terminal may be
received at the authentication server, for example during the authentication procedure.
The determination of the serving packet data service support node may comprise a
mapping of the mobile terminal's location information to an identifier of the serving packet
data service support node.

In another embodiment of the invention the context is a PDP context and/or MM context,
the originating wireless access network is a WLAN, the target wireless access network is
a UMTS or GSM radio access network and the packet data service is a GPRS service.
According to another embodiment of the invention the establishment of the context in the
core network connected to the target wireless access network comprises the following
steps. A packet data gateway of a core network connected to the originating wireless
access network may receive an address of the serving packet data service support node
or an address of a gateway packet data service support node of the core network
connected to the target wireless network from the authentication server. The packet data
gateway may further determine context information based on the context information
associated to a connection used for providing the packet data service to the mobile
terminal via the originating wireless access network, and may transmit a context
activation message comprising the determined context information to the serving or
gateway packet data service support node to establish the context in the respective
packet data service support node. The packet data gateway relays packets of the packet
data service to/from the originating wireless access network.
In one embodiment of the invention, the core network connected to the originating
wireless access network and the core network connected to the target wireless access
network is a core network common to the target and the originating wireless access
network.
Further, in another embodiment of the invention the authentication server may determine
the address of the gateway packet data service support node based on the access point
name of an access point in the core network connected to the originating wireless access
network communicating via an air interface with the mobile terminal.
In further embodiment, the a context activation message comprising the context
information from the serving/gateway packet data service support node may be
transmitted to the gateway/serving packet data service support node to establish the
context at the respective packet data service support node.
For example, the context may comprise QoS requirement for delivery of the packet data
service and resource reservation information for reserving resources in the core network
connected to the target wireless access network and/or the target wireless access
network for delivery of the packet data service. According to this example, the packet

data gateway may determine resource reservation information based on the context
information associated to a connection used for providing the packet data service to the
mobile terminal via the originating wireless access network, and may transmit the
determined resource reservation information within the context activation message to the
serving or gateway packet data service support node to reserve resources within the
core network connected to target wireless access network and/or the target wireless
access network for delivery of the packet data service prior to an attachment of the
mobile terminal to the target wireless access network.
In a variation of this example the authentication server may indicate to the packet data
gateway whether to reserve resources for delivery of the packet data service.
According to a further embodiment of the invention, a service request for delivery of the
packet data service is received from the mobile terminal through the target wireless
access network by the serving packet data service support node, and the packet data
gateway may be requested to route data of the packet data service to the mobile terminal
via the core network connected to the target wireless access network and the target
wireless access network.
In a variation of this embodiment, the request to the packet data gateway comprises the
transmission of a context update message from the serving packet data service support
node to the gateway packet data support node.
Another embodiment of the invention foresees that the packet data gateway and the
gateway packet data support node are comprised within one core network element.
In a further embodiment the request mentioned above is a request for resources for
delivery of the packet data service through the target wireless access network.
Further, in a variation of the embodiment, a rerouting request message may be
transmitted from the gateway packet data support node to the packet data gateway to
request the routing of data of the packet data service to the mobile terminal via the target
wireless access network.
Another embodiment of the invention relates to an authentication server for initiating the
establishment of a context for a connection delivering a packet data service to a mobile
terminal via a target wireless access network. As before, the mobile terminal is initially
^connected to an originating wireless access network and is provided with a packet data

service through the originating wireless access network. The authentication server may
comprise a communication means for attaching the mobile terminal to a core network
connected to the target access wireless network to enable a reception of the packet data
service via the target wireless access network, and for initiating the establishment of a
context within a core network connected to the target wireless access network.
According to this embodiment, the authentication server is adapted to initiate the context
establishment prior to an attachment of the mobile terminal to the target wireless access
network.
In another embodiment of the invention the authentication server further comprises
means adapted to perform the steps of the method according to one of the various
embodiments outlined above.
Further, one embodiment of the invention relates to a packet data gateway for initiating
the establishment of a context for a connection delivering a packet data service to a
mobile terminal via a target wireless access network. Again, the mobile terminal is
initially connected to an originating wireless access network and is provided with a
packet data service through an originating wireless access network connected to the
packet data gateway.
The packet data gateway may comprise communication means for receiving an address
of the serving packet data service support node or an address of a gateway packet data
service support node within the core network connected to the target wireless access
network from an authentication server. Moreover the packet data gateway includes
processing means for determining context information based on the context information
associated to a connection used for providing the packet data service to the mobile
terminal via the originating wireless access network. The communication means may be
adapted to transmit a context activation message comprising the determined context
information to the serving or gateway packet data service support node to establish a
context in the core network connected to the target wireless access network prior to an
attachment of the mobile terminal to the target wireless access network.
Another embodiment of the invention relates to the packet data gateway which further
comprises means adapted to perform the method according to one of the various
embodiments outlined above.

One other embodiment of the invention foresees a packet data service support node in a
core network connected to a target access network for configuring a context for a
connection delivering a packet data service to a mobile terminal via the target wireless
access network. The mobile terminal is initially connected to an originating wireless
access network and is provided with a packet data service through an originating access
network connected. According to this embodiment the packet data service support node
comprises communication means for receiving a packet data service attach message
from an authentication server and processing means for attaching the mobile terminal to
a core network connected to the target wireless access network in response to the
packet data service attach message to enable a reception of the packet data service
through the target wireless access network: Further the communication means is
adapted to receive a context establishment request comprising context information from
a packet data gateway and the processing means is adapted to establish the context
based on the context information prior to an attachment of the mobile terminal to the
target wireless access network.
The packet data service support node according another embodiment of the invention
further comprises means adapted to perform the steps of the method according to one of
the various embodiments outlined above.
Other embodiments of the invention relate to the implementation of the different
embodiment of the invention in software. According to one of these embodiments, a
computer readable medium for storing instructions that, when executed by a processor of
an authentication server, cause the authentication server to initiate the establishment of
a context for a connection delivering a packet data service to a mobile terminal via a
target wireless access network is provided. The mobile terminal is initially connected to
an originating wireless access network and is provided with a packet data service
through the originating wireless access network.
The authentication server may be caused to initiate the establishment of the context by
attaching the mobile terminal to a core network connected to the target wireless access
network by the authentication server to enable a reception of the packet data service via
the target wireless access network, and initiating the establishment of a context within a
core network connected to the target wireless access network, wherein the context
establishment is initiated prior to an attachment of the mobile terminal to the target
wireless access network.

In another embodiment of the invention, the computer readable medium further stores
instruction that, when executed by the processor of the authentication server, cause the
authentication server to perform the steps of the method according to one of the various
embodiments outlined above.
Further, one embodiment of the invention relates to a computer readable medium for
storing instructions that, when executed by a processor of a packet data gateway, cause
the packet data gateway to initiating the establishment of a context for a connection
delivering a packet data service to a mobile terminal via a target wireless access
network. The mobile terminal is initially connected to an originating wireless access
network and is provided with a packet data service through an originating wireless
access network connected to the packet data gateway.
The packet data gateway may be caused to initiate the context establishment by
receiving an address of the serving packet data service support node or an address of a
gateway packet data service support node within the core network connected to the
target wireless access network for an authentication server, determining context
information based on the context information associated to a connection used for
providing the packet data service to the mobile terminal via the originating wireless
access network, and transmitting a context activation message comprising the
determined context information to the serving or gateway packet data service support
node to establish a context in core network connected to the target wireless access
network prior to an attachment of the mobile terminal to the target wireless access
network.
The computer readable according to another embodiment of the invention may further
store instruction that, when executed by the processor of the packet data gateway, cause
the packet data gateway to perform the method according to one of the various
embodiments outlined above.
A further embodiment of the invention encompassed a computer readable medium for
storing instructions that, when executed by a processor of a packet data service support
node, cause the packet data service support node in a core network connected to a
target access network to configure a context for a connection delivering a packet data
service to a mobile terminal via the target wireless access network. As before, the mobile
terminal is initially connected to an originating wireless access network and is provided
with a packet data service through an originating wireless access network.

The packet data service support node may be caused to configure the context by
receiving a packet data service attach message from an authentication server, attaching
the mobile terminal to the core network connected to the target wireless access network
in response to the packet data service attach message to enable a reception of the
packet data service via the target wireless access network, receiving a context
establishment request comprising context information from a packet data gateway and
establishing the context base on the context information prior to an attachment of the
mobile terminal to the target wireless access network.
In another embodiment the computer readable medium further stores instruction that,
when executed by the processor of the packet data service support node, cause the
packet data service support node to perform the steps of the method according to one of
the various embodiments outlined above.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
In the following the invention is described in more detail in reference to the attached
figures and drawings. Similar or corresponding details in the figures are marked with the
same reference numerals.
Fig. 1 shows an architecture for a 3GPP system to WLAN interworking supporting
a handover of mobile terminals between the heterogeneous networks,
Fig. 2 shows a flow chart of a context establishment procedure according to an
exemplary embodiment of the invention, and
Fig. 3 to 5 show details of different procedures indicated in the flow chart of a context
establishment procedure as shown in Fig. 2 according different exemplary
embodiments of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The following paragraphs will describe various embodiments of the invention. For
exemplary purposes only, most of the embodiments are outlined in relation to a UMTS
communication system interworking with a WLAN. Also the terminology used in the
subsequent sections mainly relates to the UMTS terminology and WLAN terminology.
However, the used terminology and the description of the embodiments with respect to
the UMTS to WLAN interworking architecture is not intended to limit the principles and
ideas of the inventions to such systems.

Also the explanations given in the Technical Background section above are merely
intended to better understand the mostly UMTS and WLAN specific exemplary
embodiments described in the following and should not be understood as limiting the
invention to the described specific implementations of processes and functions in the
mobile communication network or WLAN.
One main aspect of the invention is to enable an authentication server to initiate the
establishment of a context in a target network for a packet data service while the mobile
terminal is connected to the originating network and receives the packet service through
this originating network.
For exemplary purposes the following case may be considered. If the terminal has WLAN
coverage and an activated 3G service over WLAN, the appropriate 3G SGSN may be
determined by the AAA server by the use of location information and a mapping function.
The AAA performs the GPRS Attach and Routing Area Update and initiates the PDP
Context Activation on behalf of the terminal before the terminal connects to the 3G
network. This reduces 3G signalling overhead and terminal power consumption and
further does not depend on 3G coverage.
A possible architecture for 3GPP system to WLAN interworking with handover support is
shown in Fig. 1. In addition to the current 3GPP system to WLAN interworking
architecture for scenario 2 and 3, this architecture comprises an interface between the
packet data gateway (PDG) and the GGSN for routing/relaying data packets from the
GGSN to the PDG and vice versa. It should be noted that the functionality of the PDG is
to a large extend similar to the one of the GGSN.
Further an interface between an authentication server, according to the exemplary
architecture an AAA Server and the SGSN to establish the MM (Mobility Management)
and PDP (Packet Data Protocol) context for a user is incfuded.
For a 3GPP/WLAN dual mode mobile terminal it is possible to access 3G services from
an active 3G connection and also from an active WLAN connection.
In one embodiment of the invention the mobile terminal may perform a GPRS attach
procedure in the 3G network in order to access GPRS services. After completing the
GPRS attach procedure the mobile terminal is in the so-called "PMM connected state"
and the MM context may be created in the SGSN. This context may inter alia comprise
the IMSI of the user, the current MM state and the Routing Area that identifies one or

several cells of the mobile terminal's current location. The routing area identifier (RAI)
may be broadcasted to the mobile terminals in RRC Idle mode and mobile terminals in
RRC Connected mode may be notified on established RRC (Radio Resource Control)
connections.
If the user wants to start a 3G service (e.g. SMS, MMS, IMS) on its terminal, a service
activation may be initiated by the PDP context activation procedure. In the PDP context
activation procedure, the Access Point Name (APN) and the requested QoS is signaled.
The APN may identify the GGSN, the Packet Data Network and optionally a service to be
offered. If the PDP context activation is accepted, a PDP context is established for
example in the SGSN and the GGSN and PDP PDUs (Protocol Data Units) can be
transferred between the mobile terminal and the GGSN.
If the mobile terminal has established a 3G service and detects WLAN coverage by
scanning of WLAN beacons each WLAN beacon comprising a SSID identifying the
respective WLAN, the handover from 3G to WLAN could be advantageously in terms of
higher data rates and lower delay. The mobile terminal may for example select one of the
available WLANs based on the received SSIDs.
Further the mobile terminal could be provided with a list of preferred WLANs which may
be used to a WLAN in case more than one beacon is received by the mobile terminal.
The mobile terminal may establish a connection with the target wireless access network,
i.e. the chosen WLAN. This connection establishment to the WLAN is also referred to as
the mobile terminal associating to the WLAN.
After associating to the WLAN, the mobile terminal may need to be authenticated in the
WLAN. For example the WLAN Access Authentication (Re-authentication) may be
initiated for this purpose. During this WLAN Access Authentication procedure EAP
(Extensible Authentication Protocol) messages are commonly exchange between the
mobile terminal, the WLAN access network (AN) and the 3GPP AAA Server. For the
authentication of the user the user identity may be provided to the AAA Server in a NAI
format (NAI = Network Access Identifier, see RFC 2486: "The Network Access Identifier",
available at http://www.ietf.org) in the EAP messages.
It should be noted that the mobile terminal is commonly assigned an IP address within
the WLAN after being authenticated. Therefore, the mobile terminal does not yet have an
IP Address assigned which implies that the WLAN should support means to transport

AAA messages from the mobile terminal to an AAA Server. On WLAN side specific
means as e.g. specified by the WLAN standards IEEE 802.11i could be used. The
transport of EAP messages from the WLAN access network to the AAA Server could be
accomplished over RADIUS or Diameter.
When transporting EAP messages via RADIUS or Diameter an identifier of the WLAN
access network is included in the messages. This identifier can for example be included
implicitly by including the optional sender IP address of the Network Access Server
(NAS-IP) serving as a RADIUS client for the mobile terminal to a RADIUS message.
Alternatively, the WLAN access network identifier may also be included explicitly, for
example by including the WLAN access point's MAC address (link identifier) or the
access router's address (APID) to an EAP message by the mobile terminal or by an
entity in the WLAN access network.
For service activat00000ion in a WLAN, the W-APN resolution and Tunnel establishment
procedure for setting up a tunnel between the UE and the PDG is performed. For the
Tunnel QoS setup, i.e. the setup of the tunnel QoS parameters, the QoS requirements
may be either directly included in the establishment messages or the QoS signalling may
be performed independently before or after the tunnel establishment. Further, the PDG
could also determine the QoS requirements on basis of the specified service.
An identifier of the WLAN Access Network may also be included in the messages
exchanged between MS and PDG during tunnel establishment. For example, the WLAN
AN identifier may be included explicitly, for example the 3G RAI, the AP MAC address
(link identifier), a notified AR address (APID), a GPS retrieved position or the transport IP
address assigned to the MS in the WLAN access network is included to the messages by
the MS or by an entity in the WLAN AN. This identifier may for example be transmitted
during the authentication and authorization check from the PDG to the AAA Server.
After tunnel establishment and QoS setup the GGSN is triggered to route/relay the
packets to the PDG and the PDG may tunnel the packets to the MS in WLAN. Please
note that it is also possible that GGSN and PDG are physically located in one single
network element. Further the 3G radio bearers to the MS may be released and the MS is
moved to 3G idle mode.
As already indicated above, in case the terminal has to send periodic Routing Area
Update (RAU) messages over the 3G air interface to preserve the MM and PDP contexts

in the 3G SGSN, if 3G network coverage is not available (user is in a shopping centre, at
airport, in the subway) and the RA update timer expires, the MM and PDP contexts may
be deleted in the SGSN.
Also in case the MS activates a service in WLAN first, may result in a situation where the
MS is not GPRS attached and has no PDP contexts established in the 3G network. Here
the GGSN may not be involved in the delivery process of data packets to/from the MS,
since the PDG may be directly connected to the external network or service provider as
illustrated in Fig. 1.
Because WLAN coverage can get lost suddenly, it is of advantage to have faster service
activation in the 3G network after/during handover from WLAN back to 3G. For this
purpose one embodiment of the invention suggests to establish the PDP (and MM)
contexts in the GGSN and SGSN in advance, i.e. before the MS attaches to the 3G
network.
If the user is subscribed to support of seamless service handover between
heterogeneous networks, e.g. from WLAN to 3G, the establishment of MM and PDP
context in the Core Network nodes during WLAN connection can be performed in
different levels. In dependence on the subscription level the user may be allowed to have
no, low or full resource reservation for a packet data service delivery in the 3G without
the MS being connected to the 3G network.
According to an embodiment of the invention the GPRS attach procedure and RA update
is performed in case no resources have been reserved in the 3G network. Low
reservation may mean that the PDP context is activated within the Core Network
elements of the 3G network, but no QoS is negotiated, i.e. no resources (0 kbit/s) are
reserved in the network for service delivery. In case of a 'full reservation' the PDP context
may be activated, resources in the 3G network according to negotiated QoS parameters
are reserved and optionally also RABs for service delivery may be setup before the MS
is actually handing over to the 3G network.
In order to maintain the MM and PDP context in the SGSN and to keep the MS GPRS
attached, a preservation function can be used. This function allows to preserve active
PDP contexts in the SGSN for released radio bearers (which are released for example
by the RAN because of a break of the radio connection) and to re-establish the radio
bearers later. As outlined previously, this may require that periodic RA Updates are sent

to the SGSN. Otherwise the mobile reachable timer in the SGSN expires and the GPRS
detach procedure would be initiated for the MS. Alternatively, a special WLAIM RAI may
be sent from the MS to the SGSN so that the Timer controlling the duration of the
activation is set to a very high value or the mobile reachable timer may even not be used,
i.e. no timeout of MM and PDG contexts may be foreseen. However, this latter option
may cause further problems in that e.g. all network elements activating a MM or PDP
context would have to keep track of its deactivation as well.
For the transmission of RA Updates from the MS it is required that 3G coverage is
available, that the MS is continuously listening to broadcast messages and that a RRC
connection is established.
In one exemplary embodiment, it is assumed that the MS has an active WLAN
connection and the AAA Server is informed about the current location of the MS (due to
the implicitly/explicitly transmitted WLAN identifier). Thus, is no need for the MS to
occupy 3G radio resources and to actively send messages on a 3G connection to
preserve a state in the SGSN. This situation is for example depicted in Fig. 2 where the
WLAN Connection Setup and 3G Service activation 201 is intended to exemplarily
illustrate the connection of the MS to a WLAN and the activation of a GPRS service.
According to this embodiment, the AAA Server in the 3G network may have access to a
location mapping function. This mapping function may be employed to determine 202 the
possible SGSN serving the terminal when a handover to the 3G network would occur
and the matching Routing Area in the 3G network in the same coverage of the current
WLAN.
Every time the MS moves and changes the location, the AAA Server may be informed
about the new location through an authentication procedure of the MS. When the
location of the MS is changing, the AAA Server may determine the corresponding SGSN
and RAI again and in case of a change the AAA Server may signal an update to the
appropriate 3G network nodes.
Optionally the AAA Server may also check first if there is a SGSN registered for the MS
within the HLR/HSS 203. If there is a registered SGSN that differs from the determined
SGSN, the PDP contexts in that SGSN may be deleted 204. This check may be
performed for example by the AAA server querying the HLR/HSS of the MS.

After determining the SGSN serving the coverage area of the WLAN in the 3G network,
the AAA Server may initiate a GPRS attach procedure 205. An GPRS attach procedure
according to an illustrative embodiment of the invention is shown in Fig. 3. In this
exemplary procedure the AAA Server may transit 301 a GPRS attach message to the
determined SGSN. Further, the AAA Server or the SGSN may update 302, 305 the
location of the WIS in the HLR/HSS and the HLR/HSS is triggered to send 303, 304 the
subscriber data for the user to the SGSN. If the MS was already GPRS attached at this
SGSN the messages may be ignored. Finally the network initiated GPRS attach is
accepted 306 and the MM context is established in the SGSN.
After completion of the AAA Server initiated GPRS attach 205, the AAA Server may
(optionally) perform a routing area update procedure 206. In this procedure, the AAA
Server may send a routing area update to the SGSN in order to indicate to the SGSN to
maintain the PDP and MM context for the UE. Furthermore the routing area update may
be sent by the AM Server every time the location of the MS in the WLAN changes such
that the corresponding 3G RAI is also changing. Moreover, the AAA server may transmit
routing area updates to the SGSN to restart the Routing Area Update Timer before
expiry.
As mentioned above, the PDG may be informed on the service for the user and the QoS
of the tunnel for the MS in WLAN. Next, the AAA Server may initiate 207 the PDP
context establishment in the network nodes of the core network. An exemplary context
establishment procedure 207 is illustrated in Fig. 4. The AAA Server may request 401
the PDG to activate PDP contexts related to the tunnels established for a user in the 3G
network. For this purpose the PDG may determine 402 the PDP context parameters from
the WLAN tunnel settings, such as the QoS parameters associated thereto. It should be
noted that this context activation in the GSNs of the 3G network may not only based on
the QoS parameters of the tunnel in the WLAN for the user but also based on the
subscription level of the individual user.
Additional parameters for performing the PDP context activation may be included in the
message (see 401) from the AAA Server to the PDG. The PDG may aggregate amongst
others the IMS), SGSN address, APN, PDP address, QoS Requested and QoS
Negotiated in a request message and may send 403 the request to the GGSN to create
and activate a PDP context. The GGSN's address may for example be determined by the
PDG based on the APN received from the AAA Server. The GGSN may create a PDP

context for the 3G idle user according to the received parameters and in addition a PDP
context activation is initiated 404, 406 from the GGSN to the SGSN.
On reception of the PDP context activation message from the GGSN, the SGSN
establishes the contexts for the user. Moreover, based on the I subscription level of the
user the SGSN may optionally establish 405 RABs in the RAN for the user, i.e. may
reserve resources for service provision to the user through the 3G network. Upon
receiving 407 a PDP Context Activation Response message reporting on the context
establishment, the PDG may inform 408 the AAA Server that the context has been
established in the GSNs.
Alternatively, the PDG may send the request message to the SGSN directly. The
address of the SGSN may be made known to the PDG from the AAA server, which
would no longer need to resolve the GGSN address from the APN in this case. The
SGSN may create and activate the context(s) and may also trigger a context
establishment at its SGSN.
If the MS loses WLAN coverage or if there is another trigger to handover the MS to the
3G network, a 3G radio connection will be (re-)established 208. Generally there may be
the following three scenarios to consider in this respect.
If there are already RABs established in the RAN and resources for service provision
have been reserved, only the radio bearers from the RAN to the MS must be set up
which will further improve the performance of the handover between the heterogeneous
networks.
Otherwise the MS may initiate a service request procedure to the SGSN to (re-
establishes RABs and radio bearers. In case the RABs and radio bearers have been
configured and established before handover of the MS but no resources have been
reserved in the core network, the PDP Context Modification procedure may be initiated to
change the assigned QoS.
A third option may be that the RABs have been set up but no resources in the RAN have
been reserved. In the network nodes of the core network a PDP context comprising
reserved QoS and required QoS parameters may be established. If the reserved QoS
parameters "reserve" no resources (0 kbit/s) this means that no resources are reserved
within the core network but the PDP context is established in the network nodes. A
similar mechanism may also be used in the RAN. Thus, in case of establishing RABs

there may be no resources reserved in the RAN but a context associated to the RABs
may be established prior to the MS attaching to the 3G network.
After completion of (or during) the 3G connection establishment 208, the MS may initiate
a 3G Service Setup procedure 209. An exemplary procedure is shown inn Fig. 5.
According to this procedure a Service Request 501 for a GPRS service is received by
the SGSN. The SGSN may inform 502 the GGSN by a PDP Context Update Request
that the MS desires to receive the GPRS service through the 3G network. This message
may for example also be used to allocate resources in the 3G network for service
delivery if not done previously, Upon receiving the message, the GGSN may send
downlink packets to the SGSN.
For example, if the initial service activation procedure was directly to the PDG, the PDG
may further be informed 503 to relay the packets to the GGSN and no longer to the
downstream nodes in the WLAN. The messages exchanged between MS (UE), SGSN,
GGSN and PDG may be confirmed or acknowledged 504, 505, 506 by respective
messages.
Another embodiment of the present invention relates to the implementation of the above
described various embodiments using hardware and software. It is recognized that the
various above mentioned methods as well as the various logical blocks, modules, circuits
described above may be implemented or performed using computing devices, as for
example general purpose processors, digital signal processors (DSP), application
specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other
programmable logic devices, etc. The various embodiments of the present invention may
also be performed or embodied by a combination of these devices.
Further, the various embodiments of the present invention may also be implemented by
means of software modules which are executed by a processor or directly in hardware.
Also a combination of software modules and a hardware implementation may be
possible. The software modules may be stored on any kind of computer readable storage
media, for example RAM, EPROM, EEPROM, flash memory, registers, hard disks, CD-
ROM, DVD, etc.


We Claim :
1. A method for configuring a context for a connection delivering a packet data
service to a mobile terminal via a target wireless access network, wherein the
mobile terminal is initially connected to an originating wireless access network,
the method comprising the steps of:
providing the packet data service to the mobile terminal via the originating
wireless network,
attaching the mobile terminal to a core network connected to the target wireless
access network by an authentication server to enable a reception of the packet
data service via the target wireless access network, and
initiating by the authentication server the establishment of a context within the
core network connected to the target wireless access network,
wherein the context is established prior to an attachment of the mobile terminal to
the target wireless access network.
2. The method as claimed in claim 1, which involves the step of determining by an
authentication server an address of a serving packet data service support node
of the core network, wherein the serving packet data service support node serves
the mobile terminal when attaching to the target wireless access network, and
wherein attachment of the mobile terminal to the target wireless access network
comprises sending a packet data service attach message to the serving packet
data service support node.
3. The method as claimed in claim 2, which involves the steps of authenticating the
mobile terminal at the authentication server, and
receiving location information of the mobile terminal at the authentication server
and
wherein the determination of the serving packet data service support node
comprises mapping the mobile terminal's location information to an identifier of
the serving packet data service support node.

4. The method as claimed in any one of claims 1 to 3, wherein the context is a
PDP context, the originating wireless access network is a WLAN, the target
wireless access network is a UMTS radio access network and the packet data
service is a GPRS service.
5. The method as claimed in any one of claims 2 to 4, wherein the establishment
of the context in the core network connected to the target wireless access
network comprises the steps of:
receiving at a packet data gateway of a core network connected to the originating
wireless access network an address of the serving packet data service support
node or an address of a gateway packet data service support node, wherein the
packet data gateway relays packets of the packet data service to/from the
originating wireless access network,
determining context information by the packet data gateway based on the context
information associated to a connection used for providing the packet data service
to the mobile terminal via the originating wireless access network, and
transmitting a context activation message comprising the determined context
information to the serving or gateway packet data service support node to
establish the context in the respective packet data service support node.
6. The method as claimed in claim 5, which involves the step of determining the
address of the gateway packet data service support node at the authentication
server based on the access point name of an access point in the core network
connected to the originating wireless access network communicating via an air
interface with the mobile terminal.
7. The method as claimed in claim 5 or 6, which involves the step of transmitting a
context activation message comprising the context information from the
serving/gateway packet data service support node to the gateway /serving packet
data service support node to establish the context at the respective packet data
service support node.
8. The method as claimed in any one of claims 5 to 7, wherein the context
comprises QoS requirement for delivery of the packet data service and resource
reservation information for reserving resources in the core network connected to

the target wireless access network and/or the target wireless access network for
delivery of the packet data service, and
the method comprises the steps of determining resource reservation information
by the packet data gateway based on the context information associated to a
connection used for providing the packet data service to the mobile terminal via
the originating wireless access network, and
transmitting the determined resource reservation information within the context
activation message to the serving or gateway packet data service support node
to reserve resources within the core network connected to target wireless access
network and/or the target wireless access network for delivery of the packet data
service prior to an attachment of the mobile terminal to the target wireless access
network.
9. The method as claimed in claim 8, which involves the step of indicating by the
packet data gateway whether to reserve resources for delivery of the packet data
service.
10. The method as claimed in any one of claims 1 to 9, which involves the steps of
receiving a service request for delivery of the packet data service from the mobile
terminal through the target wireless access network by a serving packet data
service support node, and
requesting a packet data gateway to route data of the packet data service to the
mobile terminal via the core network connected to the target wireless access
network and the target wireless access network .
11. The method as claimed in claim 10, wherein the request to the packet data
gateway comprises the step of transmitting a context update message from the
serving packet data service support node to the gateway packet data support
node.
12. The method as claimed in claim 10 or 11, wherein the packet data gateway and a
gateway packet data support node are comprised within one core network
element.

13. The method as claimed in any one of claims 10 to 12, wherein the request
comprises a request for resources for delivery of the packet data service through
the target wireless access network.
14. The method as claimed in claim 11, which involves the step of transmitting a
rerouting request message from the gateway packet data support node to the
packet data gateway to request the routing of data of the packet data service to
the mobile terminal via the target wireless access network.
15. An authentication server for initiating the establishment of a context for a
connection delivering a packet data service to a mobile terminal via a target
wireless access network, wherein the mobile terminal is initially connected to an
originating wireless access network and is provided with a packet data service
through the originating wireless access network, the authentication server
comprising:
communication means for attaching the mobile terminal to a core network
connected to the target access wireless network to enable a reception of the
packet data service via the target wireless access network, and
for initiating the establishment of a context within the core network connected to
the target wireless access network,
wherein the authentication server is adapted to initiate the context establishment
prior to an attachment of the mobile terminal to the target wireless access
network.
16. The authentication server as claimed in claim 15, comprising means adapted to
perform the steps of the method as claimed in any one of claims 1 to 14.
17. A packet data gateway for initiating the establishment of a context for a
connection delivering a packet data service to a mobile terminal via a target
wireless access network, wherein the mobile terminal is initially connected to an
originating wireless access network and is provided with a packet data service
through an originating wireless access network connected to the packet data
gateway, the packet data gateway comprising:
communication means for receiving an address of the serving packet data
service support node or an address of a gateway packet data service support

node within the core network connected to the target wireless access network
from an authentication server, and
processing means for determining context information based on the context
information associated to a connection used for providing the packet data service
to the mobile terminal via the originating wireless access network,
wherein the communication means is adapted to transmit a context activation
message comprising the determined context information to the serving or
gateway packet data service support node to establish a context in the core
network connected to the target wireless access network prior to an attachment
of the mobile terminal to the target wireless access network.
18. The packet data gateway as claimed in claim 17, comprising means adapted to
perform the method as claimed in one of claims 5 to 14.
19. A packet data service support node in a core network connected to a target
access network for configuring a context for a connection delivering a packet
data service to a mobile terminal via the target wireless access network, wherein
the mobile terminal is initially connected to an originating wireless access
network and is provided with a packet data service through an originating access
network connected, the packet data service support node comprising:
communication means for receiving a packet data service attach message from
an authentication server.
processing means for attaching the mobile terminal to the core network
connected to the target wireless access network in response to the packet data
service attach message to enable a reception of the packet data service through
the target wireless access network, and
wherein the communication means is adapted to receive a context establishment
request comprising context information from a packet data gateway and
wherein the processing means is adapted to establish the context based on the
context information prior to an attachment of the mobile terminal to the target
wireless access network.

20. The packet data service support node as claimed in claim19, comprising means
adapted to perform the steps of the method as claimed in any one of claims 1 to
14.


The invention relates to a method for configuring a context for a connection delivering a
packet data service to a mobile terminal via a target wireless access network, wherein the
mobile terminal is initially connected to an originating wireless access network, the method
comprising the steps of providing the packet data service to the mobile terminal via the
originating wireless network, attaching the mobile terminal to a core network connected to the
target wireless access network by an authentication server to enable a reception of the packet
data service via the target wireless access network, and initiating by the authentication server
the establishment of a context within the core network connected to the target wireless
access network, wherein the context is established prior to an attachment of the mobile
terminal to the target wireless access network.

Documents:

00617-kolnp-2007-assignment-1.1.pdf

00617-kolnp-2007-correspondence-1.1.pdf

0617-kolnp-2007 abstarct.pdf

0617-kolnp-2007 assignment.pdf

0617-kolnp-2007 claims.pdf

0617-kolnp-2007 correspondence others.pdf

0617-kolnp-2007 description(complete).pdf

0617-kolnp-2007 drawings.pdf

0617-kolnp-2007 form-1.pdf

0617-kolnp-2007 form-3.pdf

0617-kolnp-2007 form-5.pdf

0617-kolnp-2007 international publication.pdf

0617-kolnp-2007 international search authority report.pdf

0617-kolnp-2007 pct form.pdf

0617-kolnp-2007 priority document.pdf

617-KOLNP-2007-(07-10-2011)-CORRESPONDENCE.pdf

617-KOLNP-2007-(27-03-2012)-CORRESPONDENCE.pdf

617-KOLNP-2007-ABSTRACT.pdf

617-KOLNP-2007-AMANDED CLAIMS.pdf

617-KOLNP-2007-ASSIGNMENT-1.1.pdf

617-KOLNP-2007-ASSIGNMENT.pdf

617-KOLNP-2007-CORRESPONDENCE-1.1.pdf

617-KOLNP-2007-CORRESPONDENCE-1.2.pdf

617-KOLNP-2007-CORRESPONDENCE-1.3.pdf

617-KOLNP-2007-CORRESPONDENCE.pdf

617-KOLNP-2007-DESCRIPTION (COMPLETE).pdf

617-KOLNP-2007-DRAWINGS.pdf

617-KOLNP-2007-EXAMINATION REPORT REPLY RECIEVED-1.1.pdf

617-KOLNP-2007-EXAMINATION REPORT.pdf

617-KOLNP-2007-FORM 1-1.1.pdf

617-KOLNP-2007-FORM 1.pdf

617-KOLNP-2007-FORM 13.pdf

617-kolnp-2007-form 18.pdf

617-KOLNP-2007-FORM 2.pdf

617-KOLNP-2007-FORM 3-1.1.pdf

617-KOLNP-2007-FORM 3-1.2.pdf

617-KOLNP-2007-FORM 3.pdf

617-KOLNP-2007-FORM 5-1.1.pdf

617-KOLNP-2007-FORM 5-1.2.pdf

617-KOLNP-2007-FORM 5.pdf

617-KOLNP-2007-GPA.pdf

617-KOLNP-2007-GRANTED-ABSTRACT.pdf

617-KOLNP-2007-GRANTED-CLAIMS.pdf

617-KOLNP-2007-GRANTED-DESCRIPTION (COMPLETE).pdf

617-KOLNP-2007-GRANTED-DRAWINGS.pdf

617-KOLNP-2007-GRANTED-FORM 1.pdf

617-KOLNP-2007-GRANTED-FORM 2.pdf

617-KOLNP-2007-GRANTED-SPECIFICATION.pdf

617-KOLNP-2007-OTHERS-1.1.pdf

617-KOLNP-2007-OTHERS.pdf

617-KOLNP-2007-PA.pdf

617-KOLNP-2007-PETITION UNDER RULE 137.pdf

617-KOLNP-2007-REPLY TO EXAMINATION REPORT-1.1.pdf

617-KOLNP-2007-REPLY TO EXAMINATION REPORT.pdf

617-KOLNP-2007-TRANSLATED COPY OF PRIORITY DOCUMENT.pdf


Patent Number 252358
Indian Patent Application Number 617/KOLNP/2007
PG Journal Number 19/2012
Publication Date 11-May-2012
Grant Date 09-May-2012
Date of Filing 20-Feb-2007
Name of Patentee PANASONIC CORPORATION
Applicant Address 1006, OAZA KADOMA, KADOMA-SHI, OSAKA 571-8501, JAPAN
Inventors:
# Inventor's Name Inventor's Address
1 BACHMANN JENS REIFENBERGER STR. 6, 61440 OBERUSEL, GERMANY
2 HAKENBERG ROLF SCHEPP ALLEE 47, 64295 DARMSTADT,GERMANY
PCT International Classification Number H04L 12/56
PCT International Application Number PCT/EP2005/007005
PCT International Filing date 2005-06-29
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 04023829.7 2004-10-06 EUROPEAN UNION