GB2481395A

GB2481395A - Call set-up management in a mobile radio communications network

Info

Publication number: GB2481395A
Application number: GB1010392.7A
Authority: GB
Inventors: Caroline Jactat; Anand R Prasad
Original assignee: NEC Corp; NEC Casio Mobile Communications Ltd
Current assignee: NEC Corp; NEC Casio Mobile Communications Ltd
Priority date: 2010-06-21
Filing date: 2010-06-21
Publication date: 2011-12-28
Also published as: GB201010392D0; WO2011162167A1

Abstract

When a legacy UE 38 (with a SIM rather than a USIM) tries to access an LTE network 40 for an emergency call, the network sends an authentication request 16 which cannot be fulfilled by the UE. The UE replies with a failure signal 44 indicating its lack of capability such that the network can deduce that there is a failure due to a legacy UE. The network sends a NAS registration reject message 36 rather than repeated authentication requests. This releases the UE to attempt emergency call set-up via a circuit-switched (CS) domain without delay.

Description

CALL SET-UP MANAGEMENT IN MOBILE

RADIO COMMUNICATIONS NETWORK

The present invention relates to the management of call set-up within a mobile radio communications network and to network devices configured for use therein and, in particular, for use in scenarios in which emergency call set-up might be required and, yet further, where different networks of different service capabilities might be available for attempted connection by a mobile radio communications device handset.

As mobile radio communications networks and systems evolve, and the capabilities exhibited are extended and improved, there is inevitably potential for scenarios in which a mobile radio communications device such as a cell phone handset having a certain level of capability, may seek connection to a network exhibiting greater capability.

In such a scenario the "legacy" handset might not be able to connect to the improved-capability network.

However, although establishing such connection may not prove possible, ongoing network signalling commonly arises which can represent a waste of network resources.

Yet further, if the attempted connectivity has some desirable quality, or urgency, for example if it is part of the emergency call set-up, then the potentially delayed/prevented connectivity is contrary to the urgency required of the emergency situation.

While it is known to offer various authentication and security procedures in environments where multiple networks might be available, for example in CN- 10165328, EP-A-2139175, WO-A-2010/041 135 and US-A-2010/088516, the current art nevertheless remains disadvantageous in exhibiting the potential delay-related problems noted above.

The present invention therefore seeks to provide for a mobile radio communications network devices, such as handset and network node devices, and methods of managing the same, for providing communications network management in general, having advantages of known such devices and methods.

According to a first aspect of the present invention there is provided a mobile radio communications device arranged for seeking connection to network nodes of a mobile radio communications network and for receiving connectivity signals from nodes of networks having differing service capabilities, and arranged, upon receipt of a connectivity signal from a node of a network exceeding the mobile radio communications device capability, to return a failure signal confirming the device capability is exceeded such that network signalling can proceed responsive to that failure cause.

The present invention can prove advantageous insofar as unnecessary network signalling can be avoided and the appropriate handling of urgent connectivity, such as on an emergency call set-up basis, can be achieved.

Yet further, the invention can provide for a mobile radio communications network node device of a mobile radio communications network exhibiting a service capability and arranged to receiving signalling from a plurality of mobile radio communication devices having differing service capabilities, and to provide connectivity signalling responsive to attempted connection from a mobile radio communications device, the node device further being arranged for receipt of a failure message returned from the radio communications device in reply to the connectivity signalling, wherein the failure message can indicate that the capability of the mobile radio communications device is less than that of the network, and the subsequent network signalling preceding responsive to that failure cause.

Preferably, the mobile radio communications network can comprise a 3GPP network and in particular a Long Term Evolution (LTE) network which can take the form of a E-UTRAN.

Further, the said connectivity signals, or connectivity signalling, can comprise authentication signalling.

The device can be arranged such that the said differing capabilities are defined by differing LIE capabilities.

Also, the said differing capabilities can be defined by differing management and/or memory capabilities within different mobile radio communication devices, in this manner, the said differing capabilities are defined in accordance with the provision of either of a SIM or USIM.

Advantageously, the said failure signal can serve to indicate that the mobile radio communications device does not have the specific capability required.

The failure signal can serve to confirm that authentication of the mobile radio communications device is not possible.

Preferably, receipt of the failure signal can cause the network node to abort and authentication procedures.

The device can be arranged such that, subsequent to aborting the authentication procedure, the node seeks to continue with a registration procedure.

Advantageously, the mobile radio communications device can proceed subsequent to a failure signal to seek alternative to ensure connectivity.

Of course, such alternative connectivity can comprise that found within the Circuit Switched (CS) domain.

In one particular embodiment the connection sought by the mobile radio communications device can be part of an emergency set-up procedure.

Yet further, the connectivity signalling can relate to an authentication procedure between the source and target network.

For example, the source and target network can comprise a source PLMN and a target PLMN.

According to a further aspect of the present invention there is provided a method of seeking connection of a mobile radio communications device to one of a plurality of network nodes of different mobile radio communication networks having differing network capabilities, and including the steps of, subsequent to receipt of a connectivity signal from a node of a network exceeding the mobile radio communications device capability, returning a failure signal to the node confirming that the mobile radio communications device capability is exceeded such that network signalling can proceed responsive to that failure indication.

Within yet another aspect of the present invention, there is provided a method of managing attempted connection of mobile radio communication devices having differing service capabilities to a network node of a network having a service capability, and including the steps of, responsive to an attempted connection by a mobile radio communications device, providing connectivity signalling to the mobile radio communications device and receiving and processing a failure message returned from the mobile radio communications device in reply to the connectivity signalling, the failure message indicating the capability of the mobile radio communications device is less than that of the network, and proceeding with subsequent network signalling at the node responsive to that failure indication.

As above, but when considering the methods of the present invention, the said connectivity signals or connectivity signalling can comprises authentication signalling.

The said differing capabilities can again be defined by differing LTE capabilities such as differing management and/or memory capabilities within different mobile radio communication devices and can be defined in accordance with the provision of a SIM or USIM.

The said failure signal can serve to indicate whether the mobile radio communications device has the specific capability required.

As above, the failure signal can serve to confirm that authentication of the mobile radio communications device is not possible and also receipt of the failure signal can cause the network node to abort the authentication procedures.

The method can include steps, subsequent to a failure signal, to seek alternative connectivity and which can be found within the Circuit Switched domain.

A method can of course be part of an emergency set-up procedure.

Alternatively, the connectivity signalling can relate to an authentication procedure between a source and target network and the source and target network can comprise a source PLMIN and a target PLMN.

Yet further, the invention can provide for a computer program, computer program product or computer program medium comprising instructions for carrying out a method as discussed above.

As will therefore be appreciated, the present invention can advantageously relate to Evolved Packet System (EPS) Non-Access Stratum (NAS) authentication of mobile radio communications device such as terminal equipment such as a User Equipment or Mobile Equipment and having limited service capability with regard to one of the potential networks to which connection might be attempted. As noted, such capability may be defined by operational functionality within the handset, such as the use of a Subscriber Identity Module (S1M) rather than, for example, a USIM.

In particular, the present invention provides an advantageous mechanism for dealing with IP Multimedia Service (IMS) emergency calls via a Packet Data Network (PDN) connection for emergency bearer services for Long Term Evolution (LTE) radio access.

The invention is described further hereinafter by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a signalling diagram according to operational characteristics of a UE and CN according to the current art; Fig. 2 is a further signalling diagram according to another example of the current art; Fig. 3 is a signalling diagram according to signalling arising in relation to embodiment of the present invention; and Fig. 4 is a schematic block diagram of a mobile radio communications device such as a mobile radio communications handset according to an embodiment of one aspect of the present invention.

The present invention is now described by reference to the accompanying drawings in relation to an embodiment in which a User Equipment (UE) having limited capability evidenced by the mere use of a SIM therein, is operating within an environment in which 3GPP LTE network such as a E-UTRAN are available, and which network has enhanced capability not found within the UE.

Examples of provided information within the current art are therefore illustrated in relation to such arrangement and, further, examples of advantageous features of an embodiment of the present invention are likewise illustrated in our reference to such a terminal device and network.

The particular scenario envisaged by way of the illustrated embodiment is that of the UE attempting an emergency call through attempted connectivity to a 3GPP LTE network.

Within this scenario, it should be appreciated that only IJEs including a Universal S1M (USIM) is permitted access to an EPS network for normal, i.e. non-emergency, connectivity. When, however, an emergency situation arises, and ILS emergency calls through the EPS network are required, aspects of network configuration tend to dictate that only authenticated UEs can achieve connectivity for such emergency calls.

On this basis, a UE that does not include a USIM, i.e. a "legacy" UE having only a SIM therein is not going to be able to achieve access to the network.

Currently therefore, a UE with owner SIM will not proceed with the standard EPS authentication procedure employing Non-Access Stratum (NAS) signalling as part of authentication procedure. Although failure of such authentication will become apparent to the parties concerned the exact reason for failure will not be needed apparent to the network node and so the network will then not necessarily know whether the reason for failure is due to a "legacy" and said seeking connectivity to the network, or whether a handset of appropriate capability, i.e. one including a USIM, in attempt in connection but failure has occurred for some other reason.

As will be appreciated from the discussion as follows, within the illustrated embodiment of the present invention it is proposed that the UE is arranged to signal in the appropriate manner to connectivity signalling from the network node so that the network can determine that failure has occurred to the connectivity attempt originating from a "legacy" handset, rather than through failure of, for example, a USIM-loaded handset. In this manner and upon realisation that a "legacy" handset is involved, the network can proceed further as appropriate, for example through limiting its ongoing connectivity signalling and, also, the handset can be released to attempt its emergency call set-up in accordance with network in accordance to network characteristics appropriate to its capabilities, such as via the Circuit Switch (CS) domain.

Network signalling is therefore advantageously induced as is the emergency call set-up delay that would otherwise by experienced by the "legacy" handset.

Turning now to Fig. 1, there is illustrated a scenario for the current art in which a UE having limited capabilities exhibited by the use of a SIM therein is operating within an environment including a E-UTRAN and associated with LTE core network 12.

Assuming that the UE 10 is to establish a emergency call although the core network 12 has been configured to allow only authenticated emergency calls.

As illustrated, signalling commences with a NAS registration request 14 and can comprise an initial registration request to the LTE network, or a registration request to use mobility from a UMTS network, such a by way of a EPS tracking area update request.

The registration request signalling 14 includes temporary UE identity but the network cannot determine from this identity whether the UE 10 has a USIM or not. However, the network commences an authentication procedure by way of signalling 16 although the EU 10 is of course incapable with proceeding with the authentication request message 16. In view of the lack of response from the UE 10, the network is generally arranged to retransmit the NAS authentication request in region of every six seconds and for a total of six with five attempts. Thus, five NAS authentication request signals 16 are issued and this will require a total period in the order of 30 seconds since, each time, the UE 10 is incapable of responding to the request.

Of course, a delay some 30 seconds can prove particularly disadvantageous and problematic in emergency situations.

Subsequent to expiry of the timer controlling the resending of the NAS authentication requests 16, the authentication procedure is eventually aborted and a NAS registration request procedure is invoked.

This involves transmission of the NAS registration reject signalling 18.

Upon receipt of the NAS registration object signalling 18 the UE 10 can be arranged to proceed in an appropriate manner to satisfy its emergency call set-up requirements through some other means for example, if the UE 10 comprises a CS-UE an emergency call set-up procedure by way of the CS domain can be pursued.

As illustrated, connectivity via a CS domain core network 20 can then be achieved as indeed can a CS domain registration and CS emergency call set-up 22.

Although the requirement for emergency call set-up at the UE 10 is eventually satisfied, it will of course be appreciated that a relatively large delay has been experienced, and a waste of network resources has occurred in view of the unnecessary repeated authentication attempts.

Turning now to Fig. 2, a similar scenario is illustrated with registration request and authentication request signalling 14, 16 arising between a UE 10 and a LTE core network 12 wherein the UE 10 initially provides aNAS authentication failure signal 24 providing a reasoning for the failure, i.e. in this example, a Message Authentication Code MAC failure indication.

However, the network still does not know the UE 10 identity, or whether the UE employs a USIM or not and so ongoing network signalling 26 arises as illustrated between the UE 10 and the CN 12 and which comprises NAS identity request, NAS identity response, NAS authentication request and NAS authentication failure messages 28-34 as illustrated.

Again, after some substantial delay and unnecessary use of network resources, a NAS registration rejection 36 is delivered from the core network 12 to the UE 10 confirming that the network could not authenticate the UE 10.

As with the illustration of Fig. 1, the procedure then continues by way of a call set-up procedure within the CS domain, and again employing a CS domain core network 20 and CS domain registration and CS emergency call set-up procedures 22.

Turning now to Fig. 3 as illustrated an embodiment of the present invention.

Aspects of this illustrated embodiment again involves signalling arising between a UE 38 and core network 40 and wherein the UE 38 is again considered a "legacy" device and employs simply a SIM.

The signalling procedure commences with delivery of a NAS registration request 14 as part of an attempted emergency call set-up procedure and which again can comprise an initial registration request to the LTE network, or registration arising due to UE mobility from a UMTS network.

Again, the network does not know the UE identity and so nor whether the UE includes a USIM or simply a SIM but in any case, the network seeks to perform an authentication procedure assuming that the UE 38 includes a USIM.

The illustrated embodiment of Fig. 3 then advantageously enters a signalling period 42 embodying advantageous aspects of the present invention.

As is, in response to the NAS authentication request 16, the UE 38 delivers aNAS authentication failure signal 44 providing clear indication that, for example, "EPS authentication is not possible". Thus, a clear indication is provided by the failure message 44 from the UE 38 that the capability of the LTE core network is not matched by the UE38.

Advantageously, and at the LTE core network 40, upon receipt of the NAS authentication failure signal 44, the network can really determine that the UE 38 will not be able to perform the required authentication procedure and so no repeated authentication attempts are made and so the disadvantageous delays and ongoing signalling and use of network resources such as illustrated in Fig. 1, does not occur.

Also, as compared with the illustration of current art applied by Fig. 2, it is clear to the LTE core network 40 that the basis for the failure is the mismatch in capabilities between the handset and the network and so the LTE core network 40 can move simply to delivery of an NAS registration reject signal 36 to the UE 38. As before, and upon receipt of the NAS registration objection 36, the UE 38 can proceed with an emergency call set-up but this time by way of the CS domain employing the CS domain core network 20 and concluding in the successful CS domain registration and CS emergency call set-up 22.

Thus, although, as when compared with the current art illustrated by Figs. I and 2, the CS domain emergency call set-up procedure is eventually achieved, the signalling control of the present invention allows the "legacy" UE 38 to arrive at this situation without the disadvantageous delay, and ongoing signalling requirements, arising in the current art.

Turning lastly to Fig. 4, there is provided a schematic illustration of a mobile radio communications device comprising a UE handset 46 and including the standard

II

interface functionality provided by an antenna 48 and transmitter 50, and standard processor 52 and storage 54 functionality as illustrated.

Also, the handset 46 is currently in the context of the present invention, a "legacy" handset can employ simply a SIM 58.

Also illustrated schematically within Fig. 4 is the protocol stack within the handset and from which the NAS signalling described herein is derived.

As will be appreciated from the above mentioned description, the present invention can prove particularly advantageous employed within network scenarios in which a IMS emergency features employed to establish an emergency call using the IP domain. The IMS emergency feature is achieved by establishing an emergency PDN connection between the radio access network and the core network and where the core network is connected to the PDN that is arranged to deliver the IMS emergency services.

Typically, this PDN connection for emergency bearer services can be set-up with a core network such as a so-called evolved packet core employing LIE radio access.

The present invention advantageously allows for the handling of EPS authentication requests sent to a liE employing simply a SIM, rather than a USIM.

In one arrangement therefore, the invention can be advantageously employed within a scenario wherein the UE is performing an emergency attach procedure and is faced with a network that requires performance of an authentication procedure for IMS emergency calls. As noted above, since the network does not know at the time of receipt of the IMS included in the Attach Request message, or the EPS temporary UE identity in the Tracking Area Update Request message whether the UE employs a USIM or not, further dispatch of authentication requests occur. However, the controlled signalling of the present invention provides a means by which the network can readily reply with a NAS Tracking Area Update Registration Reject message so that the UE can then attempt to establish the required emergency call by way of the CS domain.

Yet further, the present invention can find use within a scenario involving inter-network, i.e. Public Mobile Network (PLMN) idol mode mobility when a target PLMN is not able to retrieve the UE context from the source PLMN and in situations in which the UE has already achieved a PDN connection for emergency bearer services. In situations where the target PLMN forms an authentication procedure due to this PLMN allowing only authenticated emergency calls or allowing unauthenticated emergency calls subsequent to initial performance of the authentication procedure, the inclusion of the controlled arrangement whereby the UE can reject the authentication request through the dispatch of a dedicated "failure" message again proves particularly advantageous. That is, instead of attempting a UE identity request or reattempting the authentication procedure with the UE, the network can then, in a straightforward and simply manner, reply with an NAS Tracking Area Update Registration Reject message such that the UE can again attempt to establish an emergency call by way of the CS domain.

As will no doubt be appreciated, the present invention finds particularly advantageous use in relation to products supporting LTE and IMS emergency procedures.

Of course, the emergency is not restricted to the details of the specific embodiment discussed above and can be employed in any scenario in which any potentially unnecessary delays might arise due to a possible mismatch in terminal device and network capabilities.

Claims

CLAIMS: 1. A mobile radio communications device arranged to seek connection to network nodes of a mobile radio communications network and for receiving connectivity signals from nodes of networks having differing service capabilities, and arranged, upon receipt of a connectivity signal from a node of a network exceeding the mobile radio communications device capability, to return a failure signal confirming the device capability is exceeded such that network signalling can proceed responsive to that failure calls.
2. A mobile radio communications network node device of a mobile radio communications network exhibiting a service capability and arranged to receiving signalling from a plurality of mobile radio communication devices having differing service capabilities, and to provide connectivity signalling responsive to attempted connection from a mobile radio communications device, the node device further being arranged for receipt of a failure message returned from the radio communications device in reply to the connectivity signalling, wherein the failure message can indicate that the capability of the mobile radio communications device is less than that of the network, the subsequent networks signalling preceding responsive to that failure calls.
3. A device as claimed in Claim 1 or 2, wherein the mobile radio communications network can comprise a 3GPP network and in particular a Long Term Evolution network which can take the form of a E-UT RAN.
4. A device as claimed in Claim 1,2 or 3, wherein the said connectivity signals or connectivity signalling comprises authentication signalling.
5. A device as claimed in any one or more of the preceding claims, wherein the said differing capabilities are defined by differing LTE capabilities.
6. A device as claimed in any one or more of Claims 1-5, wherein the differing capabilities are defined by differing management and/or memory capabilities within different mobile radio communication devices.
7. A device as claimed in Claim 6, wherein said differing capabilities are defined in accordance with the provision of a SIM or USIM.
8. A device as claimed in any one of Claims 1-7, wherein the said failure signal serves to indicate that the mobile radio communications device does not have the specific capability required.
9. A device as claimed in Claim 8, wherein the failure signal serves to confirm that authentication of the mobile radio communications device is not possible.
10. A device as claimed in any one or more of Claims 1-9, wherein receipt of the failure signal causes the network node to abort the authentication procedure.
11. A device as claimed in Claim 10, wherein subsequent to aborting the authentication procedure, the node seeks to reject the registration procedure.
12. A device as claimed in any one or more of Claims 1-11, wherein the mobile radio communications device proceeds subsequent to a failure signal to seek alternative to ensure connectivity.
13. A device as claimed in Claim 12, wherein the said alternative connectivity is found within the Circuit Switched domain.
14. A device as claimed in Claim 10, and arranged, subsequent to aborting the authentication procedure, to communicate with a node seeking to continue with a registration procedure.
15. A device as claimed in Claim 14, wherein the node activates security context with no integrity protection.
16. A device as claimed in any one or more of Claims 1-15, wherein the connection sought by the mobile radio communications device is part of an emergency set-up procedure.
17. A device as claimed in any one or more of Claims 1-16, wherein the connectivity signalling relates to an authentication procedure between the source and target network.
18. A device as claimed in Claim 17, wherein the source and target network comprise a source PLMN and a target PLMN.
19. A method of seeking connection of a mobile radio communications device to one of a plurality of network nodes of different mobile radio communication networks having differing network capabilities, and including the steps of, subsequent to receipt of a connectivity signal from a node of a network exceeding the mobile radio communications device capability, returning a failure signal to the node confirming that the mobile radio communications device capability exceeded such that network signalling can proceed responsive to that failure indication.
20. A method of managing attempted connection of mobile radio communication devices having differing service capabilities to a network node of a network having a service capability, and including the steps of, responsive to an attempted connection by a mobile radio communications device, providing connectivity signalling to the mobile radio communications device and receiving and processing a failure message returned from the mobile radio communications device in reply to the connectivity signalling, the failure message indicating the capability of the mobile radio communications device is less than that of the network, and proceeding with subsequent network signalling at the node responsive to that failure indication.
21. A method as claimed in Claim 19 or 20, wherein the mobile radio communications network can comprise a 3GPP network and in particular a Long Term Evolution network which can take the form of a E-UTRAN.
22. A method as claimed in Claim 19,20 or2l, wherein the said connectivity signals or connectivity signalling comprises authentication signalling.
23. A method as claimed in Claim 22, wherein the said differing capabilities are defined by differing LTE capabilities.
24. A method as claimed in Claim 23, wherein the differing capabilities are defined by differing and/or memory capabilities within different mobile radio communication devices.
25. A method as claimed in Claim 24, wherein said differing capabilities are defined in accordance with the provision of a SIM or USIM.
26. A method as claimed in any one or more of Claims 19 to 25, wherein the said failure signal serves to indicate that the mobile radio communications device does not have the specific capability required.
27. A method as claimed in Claim 26, wherein the failure signal serves to confirm that authentication of the mobile radio communications device is not possible.
28. A method as claimed in Claim 27, wherein receipt of the failure signal causes the network node to abort the authentication procedure.
29. A method as claimed in Claim 28, wherein subsequent to aborting the authentication procedure, the node seeks to reject the registration procedure.
30. A method as claimed in Claim 29, wherein the mobile radio communications device proceeds, subsequent to a failure signal, to seek alternative to ensure connectivity.
31. A method as claimed in Claim 30, wherein the said alternative connectivity is found within the Circuit Switched domain.
32. A method as claimed in Claim 28, wherein subsequent to aborting the authentication procedure, the node seeks to continue with the registration procedure.
33. A device as claimed in Claim 32, wherein the node activates security context with no integrity protection.
34. A method as claimed in Claim 31, 32 or 33, wherein the connection sought by the mobile radio communications device is part of an emergency set-up procedure.
35. A method as claimed in any one or more of Claims 19 to 34, wherein the connectivity signalling relates to an authentication procedure between source and target networks.
36. A method as claimed in Claim 35, wherein the source and target network comprise a source PLMN and a target PLMN.
37. A mobile radio communications system including a mobile radio communications device as claimed in any one or more of Claims I and 3-18, and a mobile radio communications network device as claimed in any one or more of Claims 2 and 3-18.
38. A method of managing network connectivity comprising a method as claimed in any one or more of Claims 19 and 2 1-35, and a method as claimed in any one or more of Claims 20 and 2 1-35.
39. A computer program, computer program product or computer program medium comprising instructions for carrying out a method as claimed in any one or more of Claims 19-36 or 38.
40. A mobile radio communications device substantially as hereinbefore described with reference to, and as illustrated in the accompanying drawings.
41. A mobile radio communications network node device substantially as hereinbefore described with reference to, and as illustrated in the drawings.
42. A method of seeking connection of the mobile radio communications device to a plurality of network nodes of mobile radio communications networks and substantially as hereinbefore described with reference to the accompanying drawings.
43. A method of managing an attempted connection of a mobile radio communications device to a network node and as substantially as hereinbefore described with reference to the accompanying drawings.*::r: INTELLECTUAL 20 . ... PROPERTY OFFICE Application No: GB1010392.7 Examiner: Gareth Griffiths Claims searched: 1, 2, 19 & 20 Date of search: 8 October 2010 Patents Act 1977: Search Report under Section 17 Documents considered to be relevant: Category Relevant Identity of document and passage or figure of particular relevance to claims A -W02009/1 16691 Al (NEC) A -US2007/123231 Al (LG ELECTRONICS) A -US2O1O/014508A1 (HUAWEI TECH) Categories: X Document indicating lack of novelty or inventive A Document indicating technological background and/or state step of the art.Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of before the filing date of this invention.same category.& Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:Search of GB, EP. WO & US patent documents classified in the following areas of the UKCX Worldwide search of patent documents classified in the following areas of the IPC HO4W The following online and other databases have been used in the preparation of this search report WPI, EPODOC, XP3GPP International Classification: Subclass Subgroup Valid From HO4W 0004/22 01/01/2009 HO4W 0048/18 01/01/2009 HO4W 0076/02 01/01/2009 Intellectual Property Office is an operating name of the Patent Office www.ipo.gov.uk