TECHNICAL FIELD The present invention generally relates to systems and methods and, more particularly, to mechanisms and techniques for arranging disposal of high resolution location information in a Circuit Switched network for a User Equipment located in an Evolved Packet System EPS network.

BACKGROUND

3 ^rd Generation Partnership Project 3GPP is defining specifications allowing a 2G/3G Circuit Switched CS network to be connected to an Evolved Packet System EPS. CS fallback gives the possibility to provide CS services where a User Equipment UE is attached to E-UTRAN. 3GPP TS 23.272 V9.2.0 (2009-12) discloses an architecture enhancement for functionality to enable fallback from E-UTRAN access to UTRAN/GERAN CS domain access, and functionality to reuse of voice and other CS-domain services by reuse of CS infrastructure. A CS Fallback capable UE, which is attached to E-UTRAN, may use GERAN or UTRAN to establish CS services. A pre-requisite is that E-UTRAN coverage is overlapped by either GERAN coverage or UTRAN coverage. Another pre-requisite for CS Fallback is that the UE is registered in a Mobile Switching Center MSC while the UE is attached to E-UTRAN and registered in a Mobility Management Entity MME node. The MSC registration is achieved by using combined Mobility Management procedures for EPS and CS. A specific new interface called SGs has been standardized for this scope. The CS fallback in EPS function is realized by using the SGs interface mechanism between the MSC Server and the MME. SGs interface functionality is based on a mechanism specified for the Gs interface, see 3GPP TS 23.060 v.9.3.0 (2009-12) "General Packet Radio Service (GPRS)" or 3GPP TS 29.018 v9.0.0 (2009-12). Additionally, 3GPP has specified a special SMS handling. SMS can be sent via the SGs-interface without doing a fallback to CS. UEs that are interested in SMS but not in other CS services (like e.g. Laptop cards) have the possibility to attach with an SMS only option to E-UTRAN. The standards don't consider to transport information at cell level over SGs interface in case of International Mobile Subscriber Identity IMSI attach / Location Update operations but only Location Area Identity LAI is transferred. Even if the LAI info is enough to allow registration of UE in MSC server (IMSI Attach/Location Update) in case of CS fallback, it is not a complete info for Lawful Interception purposes where, according to standards, cell information shall be provided over H2 interface to a Law Enforcement Agency LEA. Figure 1A is part of the prior art and discloses an Intercept Mediation and Delivery Unit IMDU, also called Intercept Unit. The IMDU is a solution for monitoring of Interception Related Information IRI and Content of Communication for the same target. The different parts used for interception are disclosed in current Lawful Interception standards (see 3GPP TS 33.108 and 3GPP TS 33.107 - Release 9). In figure 1, a Law Enforcement Monitoring Facility LEMF is connected to Mediation Functions MF and MF2 respectively for an Administration Function ADMF and a Delivery Function DF2. The Administration Function and the Delivery Functions are each one connected to the LEMF via standardized handover interfaces HI1-HI2, and connected via interfaces Xl_l and X2 to an Intercepting Control Element ICE in a telecommunication system. Messages REQ sent from LEMF to ADMF via HI1 and from the ADMF to the network via the Xl_l interface comprise identities of a target that is to be monitored. The Delivery Function DF2 receives Intercept Related Information IRI from the network via the X2 interface. DF2 is used to distribute the IRI to relevant Law Enforcement Agencies via the HI2 interface.

While Lawful Interception is a real-time exercise, data from the past is used when Data Retention is practiced. Figure IB belongs to the prior art and shows the Handover Interfaces between a Data Retention System DRS (see ETSI DTS/LI-00033 V0.8.1 and ETSI DTS/LI-0039) at a Communication Service Provider CSP, and a Requesting Authority RA. The figure shows an Administration Function AdmF used to handle and forward requests from/to the RA. A Mediation and Delivery function MF/DF is used to mediate and deliver requested information. Storage is used to collect and retain all possible data from external data bases. The generic Handover Interface adopts a two port structure such that administrative request/response information and Retained Data Information are logically separated. The Handover Interface port 1 HIA transports various kinds of administrative, request and response information from/to the Requesting Authority and the organization at the CSP which is responsible for Retained Data matters. The HIA interface may be crossing borders between countries. This possibility is subject to corresponding national law and/or international agreements. The Handover Interface port 2 HIB transports the retained data information from the CSP, to the Requesting Authority. The HIB interface may be crossing borders between countries. This possibility is subject to corresponding national law and/or international agreements.

As already mentioned even if the LAI info is enough to allow registration of UE in MSC server (IMSI Attach/Location Update) in case of CS fallback, it is not a complete info for Lawful Interception or Data Retention. SUMMARY

An aim of the invention is to overcome above identified limitations of the prior art. The invention focuses on modification of SGs interface to allow transferring of enhanced cell information from an MME node to an MSC server when mobility management events are signalled over the interface. In addition the invention proposes modification of Lawful Interception interfaces to allow reporting the enhanced cell information from the MSC server to a Monitoring Function via the Lawful Interception interfaces.

A purpose with the invention is to facilitate transferring of enhanced location information to a Monitoring System in case of Circuit Switched fallback. The solution in one exemplified embodiment is a method for disposal of high resolution location information in terms of enhanced cell identity in a Circuit Switched CS network. The information is related to a User Equipment that is located in a cell area in an Evolved Packet System EPS network. The user is able to trigger fallback to CS services. An interface between a Mobility Management Entity and a Mobile Switching Center is hereby modified to allow transferring of enhanced cell identity in case a location update request related to the user equipment is signalled from the Mobility Management Entity to the Mobile Switching Center.

The solution in another exemplified embodiment is a method for disposal high resolution location information in a Circuit Switched CS network for a User Equipment located in a cell area in an Evolved Packet System EPS network, to a Monitoring System. The User Equipment attaches to the EPS network which attachment indicates that the User Equipment is configured to use CS fallback. A location update request signal comprising an enhanced cell identity is sent from a Mobility Management Entity to the Mobile Switching Center and the enhanced cell identity is forwarded from the Mobile Switching Center to the Monitoring System.

In yet another exemplified embodiment is described a first node for disposal of high resolution location information in a Circuit Switched CS network for a User Equipment located in a cell area in an Evolved Packet System EPS network. The user is able to trigger fallback to CS services and the node comprises means to modify an interface between the node and a Mobile Switching Center to allow transferring of enhanced cell identity. Computer readable program code may be adapted in the node to perform the disposal.

In yet another exemplified embodiment is described a second node for disposal of high resolution location information in a Circuit Switched CS network for a User Equipment located in a cell area in an Evolved Packet System EPS network. The user is able to trigger fallback to CS services. The node comprises means to receive enhanced cell identity related to the user equipment and means to forward the received cell identity and/or Mobility Management Entity identity. Computer readable program code may be adapted in the node to perform the disposal.

In yet another exemplified embodiment is described a third node for disposal of high resolution location information in a Circuit Switched CS network for a User Equipment located in a cell area in an Evolved Packet System EPS network. The user is able to trigger fallback to CS services. The node comprises means to modify an interface to allow transferring of enhanced cell identity and/or Mobility Management Entity identity from the node to a Law Enforcement Monitoring Facility.

An object of the invention is to dispose high resolution location information to a Monitoring System. This object and others are achieved by systems, methods, arrangements, nodes and articles of manufacture.

An advantage of the invention is that existing LI functionalities can be maintained in terms of reporting location information for a target subscriber in case fallback to CS services is invoked in a mixed EPS/CS network.

The invention will now be described more in detail with the aid of preferred embodiments in connection with the enclosed drawings .

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1A is part of the prior art and discloses a block schematic illustration of an Intercept Mediation and Delivery Unit attached to an Intercepting Control Element.

Figure IB is part of the prior art and discloses a block schematic illustration of a Data Retention System attached to a Requesting Authority.

Figure 2 is a block schematic illustration of an Evolved Packet communication System wherein monitoring information is triggered by a user capable of using CS fallback, and sent to a Lawful Interception System.

Figure 3 discloses a signal sequence diagram representing a method to monitor high resolution location information by utilizing the system configuration disclosed in figure 2.

Figure 4 discloses a block schematic illustration of an Evolved Packet communication System wherein monitoring information is triggered by a user capable of using CS fallback, and sent to a Data Retention System. DETAILED DESCRIPTION

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular circuits, circuit components, techniques, etc. in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well known methods, devices, and circuits are omitted so as not to obscure the description of the present invention with unnecessary detail.

Long Term Evolution LTE is advancement to current mobile telecommunications networks, designed to significantly improve data rates. System Architecture Evolution SAE is the core network architecture of 3GPP' s future LTE wireless communication standard. The main component of the SAE architecture is the Evolved Packet Core that is a part of an Evolved Packet System EPS. The Evolved Packet Core will serve as equivalent of GPRS networks via a Mobility Management Entity MME.

Figure 2 discloses an Evolved Packet System EPS. The EPS disclosed in figure 2 comprises UTRAN 5 and GERAN 6 networks. Universal Terrestrial Radio Access Network - UTRAN is a conceptual term identifying parts of a 3G network which consists of one or more RNC (Radio Network Controller) . GSM Edge Radio Access Network - GERAN is supporting the EDGE (Enhanced Data rates for Global Evolution) modulation technique. The architecture allows two BSS (Base Station Subsystem) to be connected to each other. The EPS futher comprises Evolved UMTS Terrestrial Radio Access Network E- UTRAN 7. Compared to traditional GSM and UMTS networks, the E-UTRAN does not include a BSC (Base Station Controller) or RNC (Radio Network Controller) functional entity. Instead, many of the controlling functions have been moved towards an eNodeB 3 which interconnects directly with the Evolved Packet Core. The eNodeB includes a Radio Resource Controller function and therefore provides access and mobility control. A User Equipment 1 is in figure 1 located within a cell area 2 that is handled by the eNodeB 3. The identity of the cell area is called an E-UTRAN Cell Global identity E-CGI. The cell area is part of a Tracking Area 4. As have been mentioned in the background part of this application, A CS Fallback capable UE, which is attached to E-UTRAN, may use GERAN or UTRAN to establish CS services. A pre-requisite is that E-UTRAN coverage is overlapped by either GERAN coverage or UTRAN coverage. The User Equipments capability to attach, during CS fallback, to a Radio Base Station in the GERAN network has been shown by an interface Urn 16 in figure 2.

A Mobility Management Entity MME 9 is the key control-node for the Long Term Evolution LTE access-network. It is responsible for idle mode User Equipment UE tracking and paging procedure. When the subscriber successfully attaches to the EPS network, the MME provides the User Equipment UE with a "Tracking Area List" which includes one or more Tracking Areas. In addition, a default bearer is activated and, as part of the signaling, the MME may be required to report change of location for the involved subscriber. When this happens for a specific subscriber, each time that the MME detects a change of location due to a Tracking Area Update or any other network procedure involving the subscriber, the updated location is reported. This function, which is called MS Info Change Reporting { [3GPP TS 23.401, "General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access"], [3GPP TS 23.060, "General Packet Radio (GPRS) ; Service description"] ) , may be used e.g. for Location Dependent Charging. The MME is attached to a Mobile Switching Center MSC 10 via an interface called SGs 11. The SGs has been briefly explained in the background part of this application. The CS fallback in EPS function is realized by using the SGs interface mechanism between the MSC Server and the MME.

The Mobile Switching Center MSC 10 is a telecommunication switch or exchange within cellular network architecture. The MSC is part of a Circuit Switched CS domain. The MSC is attached to a Law Enforcement Monitoring Facility LEMF 15 (also called Monitoring System) via a Delivery Function DF2 14 and interfaces X2 12 and HI2 13. These entities have all been explained in the background part of this application together with figure 1. The MSC in figure 2 corresponds to the Intercepting Control Element ICE in figure 1.

A method according to an embodiment of the invention will now be explained together with figure 3. The entities UE, MME, MSC, DF2/MF2, ADMS and LEMF have all been explained earlier together with the figures 1 and 2. The method will show how an enhanced resolution of location information of the mobile user 1 located in the cell area 2 in the Evolved packet System EPS network, during CS fallback, is sent to the Law Enforcement Monitoring Facility 15. The method comprises the following steps:

• An agency activates Lawful Interception of a target, i.e. of the User Equipment 1 attached to the Evolved Packet System EPS, requiring also location information to be reported, by an activation message 20,21 according to the prior art.

• According to the prior art, the target subscriber 1 attaches 22 to the Evolved Packet System EPS through 3GPP access and the MME node is hereby the node in the Evolved Packet Core EPC which is the most location aware in the network. The User Equipment UE initiates the attach procedure by the transmission of an Attach request message to the MME. The Attach Type indicates that the UE requests a combined EPS/IMSI attach and informs the network that the UE is capable and configured to use CS fallback.

When UE successfully attaches, the MME is required to report change of location. The SGs interface is according to the invention modified 23 to be able to transport an enhanced E-UTRAN Cell Global Identity E- CGI over the SGs interface. This modification will be explained more in detail later in the description.

E-CGI is according to the invention sent 24 in a location update request. The location update request is a mobility management event that is sent over the SGs from the Mobility Management Entity MME 9 to the MSC 10. The location update request comprises, according to prior art, also an identity of the MME.

The X2 interface 12 is according to the invention modified 25 to be able to transport the enhanced E- UTRAN Cell Global Identity E-CGI and the identity of the MME. This modification will be explained more in detail later in the description.

The mediation function MF2 14 will provide to send the cell info and MME identity towards LEMF via standard HI2 interface 13. According to the invention, in order to allow reporting to the LEMF of the E-CGI received from the MME, the existing HI2 interface for CS will be enhanced by adding the E-CGI and MME name as parameters which can be carried. This enhancement will be explained more in detail later in the description. • The enhanced E-UTRAN Cell Global Identity E-CGI and the identity of the MME is received by the LEMF 15.

The modification 23 of the SGs interface according to the invention to be able to transport an enhanced E-UTRAN Cell Global Identity E-CGI over the SGs interface will now be further explained. The idea consists in the modification of SGs interface. In particular the E-UTRAN cell information (E-CGI) shall be included by MME (also called a first node) in "LOCATION UPDATE REQUEST" message [3GPP TS 29.118 "Mobility Management Entity (MME) - Visitor Location Register (VLR) SGs Interface specification"] sent over SGs interface from MME to MSC Server, as shown below (the additional parameter is marked by bold text) :

The modification 25 of the X2 interface 12 according to the invention to be able to transport the enhanced E-UTRAN Cell Global Identity E-CGI and the identity of the MME will now be further explained. The MSC Server (acting as ICE) (also called a second node) shall provide to send EPS cell information and MME identity towards mediation function via X2 interface.

The Location Update message specified by 3GPP TS 33.107, "Lawful Interception architecture and functions" will carry the parameters as shown below (the modified/new parameters are marked by bold text) :

Parameter location information is currently defined by 3GPP TS 33.107, "Lawful Interception architecture and functions" as "the service area identity and/or location area identity that is present at the 3G SC Server at the time of event record production"; such definition will need to be extended in order to allow location information to carry the E-CGI.

The enhancement of the mediation function MF2 (also called a third node) to send the cell info and MME identity towards LEMF via standard HI2 interface 13 will now be further explained. The mediation function will provide to send the cell info and MME identity towards LEMF via standard HI2 interface. In order to allow reporting to the LEMF of the E-CGI received from the MME, the existing HI2 interface for CS will be enhanced by adding the E-CGI and MME name as parameters which can be carried. A possible way to enhance the ASN.l is shown below (modifications are marked by bold text, not relevant parameters are excluded for simplicity) :

The reported MME-NAME can be used to identify at the LEMF the MME node currently handling the subscriber.

Figure 4 discloses a Data Retention configuration. Figure 4 shows the Handover Interfaces 48 and 49 between an Automatic Data Retention System ADRS 44 at a Communication Service Provider, and a Requesting Authority RA 50. This configuration including the AdmF 45, MF/DF 46, STORAGE 47, HIA 48, HIB 49 and RA 50 has been explained earlier in the background part of this application. In figure 4 can schematically be seen how User Equipments UEs 41 according to the invention upon EPS access trigger MMEs 42 to forward enhanced location information to Mobile Switching Centers MSCs 43. The Mobile Switching Centers are in this embodiment acting as data retention sources. The transportation of data from the MSCs to the MF/DF is schematically shown with a thick arrow in figure 4. Data records are transferred to the mediation function in the Data Retention System, and data fulfilling configured filtering criteria are mediated from MF/DF to the Storage. Updating of the Storage depends on the policy regulating the notifications with the user, session or operator related data, from the data retention sources towards the storage. Accordingly, the transportation of the data from the sources to the storage via the MF/DF is handled by an automatic data retention system. The transported data is user location information with high resolution that has been detected in the MSC after a User Equipment service request procedure. A method to request/receive high resolution information comprises the following steps:

- A monitoring request regarding user location information with high resolution is determined by the requesting Authority RA 50 and sent to the AdmF 45 via the interface HIA 48.

- The AdmF 45 informs the Mediation and Delivery function MF/DF of the request.

- The requested data is fetched by the Mediation and Delivery function MF/DF 46 from the Storage.

- The found data is sent as Message Data Records from the MF/DF on the interface HIB 49, to the RA. The reciprocal signaling between the above different Data Retention entities is to be seen just as example. For example can the STORAGE be an integrated part of the MF/DF. In this example the criteria are sent from the RA but may also be communicated by an intermediary, such as a human operator who receives the command from an authorized source, and then inputs the criteria to the ADRS.

Items are shown in the figures as individual elements. In actual implementations of the invention however, they may be inseparable components of other electronic devices such as a digital computer. Thus, actions described above may be implemented in software that may be embodied in an article of manufacture that includes a program storage medium. The program storage medium includes data signal embodied in one or more of a carrier wave, a computer disk (magnetic, or optical (e.g., CD or DVD, or both), non-volatile memory, tape, a system memory, and a computer hard drive.

The invention is not limited to the above described and in the drawings shown embodiments but can be modified within the scope of the enclosed claims. The systems and methods of the present invention may be implemented for example on any of the Third Generation Partnership Project (3GPP), European Telecommunications Standards Institute (ETSI), American National Standards Institute (ANSI) or other standard telecommunication network architecture. Other examples are the Institute of Electrical and Electronics Engineers (IEEE) or The Internet Engineering Task Force (IETF) .

Individual function blocks are shown in one or more figures. Those skilled in the art will appreciate that functions may be implemented using discrete components or multi-function hardware. Processing functions may be implemented using a programmed microprocessor or general-purpose computer. The invention is in other words not limited to the above described and in the drawings shown embodiments but can modified within the scope of the enclosed claims.