GB2428540A - Managing identities of forbidden PLMNs - Google Patents

Abstract

A mobile radio communications device, arranged for at least dual mode operation, stores the identity of a public land mobile network identified as forbidden in a first of the two modes in a first memory region and identifies the network as forbidden for both modes, and stores a forbidden public land mobile network identified in relation to a second of the two modes in a second memory region and identifies the network as forbidden only in relation to the second mode.

Description

Mobile Radio Communications Device and Method of Operation The present

invention relates to a mobile radio communications device and to a method of operation and, in particular, to a method of managing Forbidden Public Land Mobile Networks (FPLMNs) as identified by the device and to a device arranged for such management of the FPLMNs Mobile radio communication devices such as cellular phone handsets arranged for dual mode operation are increasingly provided so as to allow for operation in relation to socalled "third generation" (3G) services. The so-called third generation partnership project (3GPP) specifications however do not tend to associate Radio Access Technologies (RATs) to public land mobile networks that, for some reason are identified as forbidden for use by the handset, hereinafter FPL1VIIN5. The list of FPLMINs is stored within the Universal Subscriber Identity Module (USIM) which generally comprises part of a Universal Integrated Circuit Card (UICC) mounted within the handset. However, some network operators provide for rejection of registration to a 3G service by way of a so-called "cause #11" rejection, issuing a "PLMN not allowed" instruction even if the network subscriber owning the handset is in fact allowed to operate on the same PLMN but in connection with a second generation (2G) service.

Thus, connectivity to the 2G service which, in many instances may be sufficient to provide for the particular requirements of the user at that time, may be disadvantageously prevented While some dual mode cellular phone handsets have, in addition to the USIM, also implemented an area of Non-Volatile Memory (NVM) in which a list of FPLMINS for 3Gservjces is stored, operation of such devices in relation to the two lists then available, i.e the 3G FPLMINS list stored in the NVM, and the remaining list stored in the USIM, is disadvantageously limited even though the cellular phone handset is arranged not to attempt to attach to the listed PLMNs in relation to a 3 G service, but may attempt to attach to such PLMNS in relation to a 2G service since the FPLMNs list in relation to 2G services is read from the USIM Reference to the NVM list therefore permits attempted connection to a 2G service which might be available on a PLMN which, with regard to 3G services, is listed as forbidden.

The present invention seeks to provide for a mobile radio communications device and method of controlling the same, in particular in relation to management of FPLMN lists for dual mode operation and which exhibit advantages over known devices and methods.

In particular, the present invention seeks to provide for improvements to the management of FPLMIN lists for an at least dual mode mobile radio communications device According to a first aspect of the present invention, there is provided a method of managing the identity of forbidden public land mobile networks in a mobile radio communications device arranged for at least dual mode operation, and comprising the steps of storing the identity of a public land mobile network identified as forbidden in a first of the two modes in a first memory region and identifying the network as forbidden for both modes, and storing a forbidden public land mobile network identified in relation to a second of the two modes in a second memory region and identifying the network as forbidden only in relation to the said second mode The present invention provides for advantageous synchronjzaj0 between the two different Forbidden Public Land Mobile Networks (FPLJVIN5) lists in relation to inter-radio access technology cell-reselection and also in relation to PLMN selection.

The invention can advantageously provide for an algorithm arranged for the management of a list in the first memory area, and also the interaction between the FPLvThIs stored in the second memory area and, specifically, the treatment of so- called cause #11 rejections Preferably, the method is arranged such that the said first region is found on a USIM of the device Further, the said second memory region can advantageously comprise a nonvolatile memory region of the device Also, the respective two modes of operation advantageously comprise a 2G service and a 3G service, and in this manner, the said second of the modes comprises the 3G service As noted, the method is advantageously arranged to manage cause #11 rejections arising as specified in accordance with 3GPP specifications.

Preferably, the method includes a step of storing the identity of the PLMIN in the USIM list and removing it, if present, from the NVM list, should a cause #11 rejection be received in relation to a 2G service Yet further, the method is arranged such that successful manual selection on either the 3 G or 2G RAT provides for the step of removing the PLMIN from the USIM list Further, successful manual selection on the 3G radio access technology leads to the Step of removing the PLMN identified from the NVM list, if present, and, successful manual selection on the 2G radio access technology leads to no interaction with the N\TM list According to another aspect of the present invention, there is provided a mobile radio communications device arranged for at least dual mode operability and having storage means for storing the identity of forbidden public land mobile networks, the device being arranged to store the identity of a Forbidden Public Land Mobile Network relating to a first of the two modes within a first memory region of the storage means and for determining the network as forbidden for both modes and the device further being arranged for storing the identity of a forbidden public land mobile network relating to the second mode within a second memory region of the storage means and for determining the network as forbidden only in relation to the said second mode.

As with the method defined above, the said two modes can comprise a 2G and 3 G mode of operation and the two memory regions can comprise a portion of the USIM and also a non volatile memory region. In particular, the nonvolatile memory comprises the said second memory region in which the identify of networks forbidden for one mode is stored, and the USIM comprises the said first memory region in which the identity of networks forbidden for both modes is stored. Also, the device is arranged to manage so-called cause #11 rejections and when such a cause #11 rejection is received in relation to the 2G service, the handset is arranged to store the identity of the PLMN in the USIM list and to remove it, if present, from the NVM list.

The device is further arranged such that successful manual selection on either the 3G or 2G radio access technology leads to removal of the identity of the PLMIN from the US1IM list, if present and successful manual selection on 3G radio access technology leads to removal of the identity of the PLMN from the non-volatile memory list, if present.

Further, the device is arranged such that successful manual selection on the 2G radio access technology has no affect on the identities of the PLMNs stored within the NVM list.

Yet further, the device is arranged such that, when seeking to roam in relation to 3G services, the device first considers the contents of the US1M FPLMjs list.

In particular, the handset is arranged such that if the seemingly available PLMN for roaming purposes is found within the FPLMINs list on the USIM then no attempt to register to the this PLMN is made.

If, however, the seemingly available PLMN is not in the list of FPLMINS found on the US1IM, but is found in the NVM list, likewise the device is arranged such that no attempt to register to this particular PLMN is made. Attempted connection to a corresponding 2G service on this PLMN however remains possible.

Further if the seemingly available PLMN is not found in the list of FPLMJS found on the USIM nor even within the NVM, then an attempt to register to the 3G service on this PLtvJIN can be made.

As should therefore be appreciated, the present invention can provide for an enhancement to the management of, cause #11 rejections arising in relation to typical 3GPP implementations etc The invention can advantageously provide for the integrated management of information stored in both the USIM and the NVM which assists in enhancing the success, efficiency and accuracy of connectivity to a 2G service should connection to a 3G service on the same PLMN not be permitted Specifically, the invention can provide for an algorithm arranged to manage the NVM list, the interaction with a list of FPLIvrNs stored on a (JSIM within, for example, as cell phone handset, and thus the treatment of cause #11 rejections.

The invention is described further hereinafter by way of example only, with reference to the accompanying drawing in which: Fig I is a schematic block diagram of a mobile radio communications device embodying the present invention; Fig 2 is a flow diagram illustrating operation of an embodiment of the present invention in relation to such a device as that of Fig. I in relation to rejection of a PLMN, Fig 3 is a similar flow diagram illustrating a manual PLMIN selection procedure arising in accordance with an embodiment of the present invention; and Fig. 4 is a similar flow diagram illustrating automatic PLMIN selection according to an arrangement embodying the present invention.

Turning first to Fig. 1, there is illustrated in schematic form a block diagram of the mobile radio communications device 10 comprising a cellular phone handset 12 arranged for dual mode operation and having standard functionality as provided by an antenna 14, receive/transmission circuitry 16, a communications cpu 18 and associated operational memory 20. The handset 12 further includes a USJItvf 22 within which the identity of a PLMN which is considered to be forbidden for all RATs will

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be stored, and an area of non-volatile memory 24 within which the identity of PLMN in respect of which access is only considered forbidden to a 3G radio access technology is to be stored and as described further hereinafter.

As will be appreciated, the present invention seeks to pride for an improved and efficient management of, in particular, international roaming situations in which the network sends reject cause #11 on a 3G RAT but when the user can however operate on the 2G RAT for that network. Through employment of an algorithm embodying the invention, the User Equipment will be able to connect to the 2G RAT for the same PLMN as for the failed 3G RAT The specific embodiment is described in relation to the synchronization of two different FPLMN lists for inter-RAT cell reselection and PLMN selection, and the usage of these two lists for a dual-mode mobile radio communications device such as a cellular phone handset.

A particular aspect of the invention is the manner in which a cause #11 rejection received on a 3G RAT is considered as if it were a rejection for the 3G RAT only, and to consider a cause #11 rejection on a 2G RAT as a rejection applicable to both RATs.

Thus the handset when receiving a rejection with cause #11 on a 2G RAT will consider the PLMN as forbidden for all RATs and will store the identity of that PLMN within the USIM.

However, when a cause #11 rejection is received on a 3G RAT, the PLMN will be considered as forbidden for the 3G RAT only and will store the identity of the PLMIN id in the NVM list only Reception of such a cause #11 rejection will then be treated as already known from the 3GPP specification, leading to PLMN selection and possibly eventually to the selection of the same PLMN on 2G depending on the PLMN/RAT priority defined on LJSIM. If no RAT priority is given, this would lead to selection of the same PLMN for the 2G service just after being rejected on the 3G service.

In operation, the algorithm embodying the invention should allow for the handset to first consider the contents of USIM FPLMINs lists when trying to roam on 3G services. If the available PLJvTh is in this FPLMN list on LJSIM, then no attempt need be made to register on this PLMN If however, the available PLMN is not in the FPLMNs list within the USIM but is in the 3G FPLMIN NVIvI list, then no attempt to register to this PLMIN will be made.

Further, if the available PLMN is not in the FPLMNs list within the USIM nor within the NVM list, then an attempt to register to this PLM1N can be made.

If the handset receives a cause #11 rejection on a 3G service, the handset should store the PLMIN identity in the NVM list. When being rejected with cause #11 manage on 2G however, the handset stores the PLMIN in the USIIvI list and removes it, if present, from the NVM list.

A successful manual selection on either the 3G or the 2G RAT, can lead to removal of the PLMN from the USIM list, while successful manual selection on the 3G RAT can lead to removal of the PLMIN identity from the NVM list Successful manual selection on 2G RAT should not however lead to removal of the identified PLMIN from the N\TM list.

Also, a change of USIM is arranged to lead to re-initialization of the NVM list and inter-RAT cell reselect jon to 3G is to be achieved on a PLMN found within the NVM FPLMNS list It should be noted that since PLMNs are declared as forbidden for a given subscription, then for a given International Mobile Subscriber Identity (IMSI) it can prove important to associate the NVM FPLMNS list to an IMSI in order to re- initialize the NYIvI list when a change of occurs.

Rather than simply deleting the FPLMJ'45 list in NVM when the USIM is changed, the invention can be advantageously arranged to manage two different FPL1V[Ns lists, for example one list associated with IMSI from USIM 1 and another associated with IMSI 2 from USIM 2. In this manner, a temporary change of(U)S1M (change USIM I for USIM 2, then insert back USIM 1, which is likely to be one of the more usual cases of USIM change) would not necessarily lead to re-initialisation of the NVM FPLMNs list For example, if there is a list in NVM associated to current IMSI from USI1M, then this NVM list will be used when necessary, that is upon cause #11 reception in 3G. Also, if there is no list in NVM associated to current IMSI from USIZM, either the two lists in NYM are already used, in which case the device will use the NVM region associated to the latest IMSI used, first performing re- initialisation, or at least one NVM region for FPLMNs list is not used, in which case this region will be used.

As a further exemplary, illustration, reference is made to a device having two different N\TM FPLMNs lists Case 1: USIM I, containing IMSI 1, is inserted in device and the 2 NVM lists, List A and List B, are empty (i e. never used before). The device will then store a new FPLMN found in 3G (FPLJVIN1) in one or the two lists, associated with IMSI 1, hereinafter List A. Case 2: USIM is removed from device in case I, and USIM 2 (containing IMSI 2) is inserted. A new FPLMIN is found, FPLMN2, which is stored in the second NVM list, associated to IMSI 2, List B. At this stage, the two NVM lists are used with at least one FPLMN stored in both lists Case 3: USIM 2 is removed from device in case 2, and USIM I (containing IMSI 1) is reinserted. A new FPLMN is found, FPLMN3, which is stored in the first NYM list associated to IMSI I, List A Case 4 USJIM 1 is removed again from device in case 2, and a new USIM 3 (containing IMSI 3) is inserted. A new FPLMN is found, FPLMN4. This FPLMJ'4 will be inserted in the second NYM list, List B, after re- initialization of this list.

Turning now to Fig. 2, there is illustrated an embodiment of the present invention relating to the receipt of a cause #11 rejection. Thus, at step 26 attempted registration is rejected with a cause #11 and it is first determined, at 28, whether or not a rejection is received in relation to a 3G service.

If it is determined that the relevant service is in fact a 3G service, the PLMN relating to that service is stored within the non-volatile memory 24 as illustrated at step 30 and, subsequently at step 32, a new PLMN selection is performed.

If, however, at step 28 it was determined that the cause #11 rejection message was not received in relation to a 3G service, the PLMN is then stored at step 34 within the USIM FPLMIN list provided on the USIM 22. Subsequent to such addition to the USIM FPLMN list, it is determined at step 36 whether that particular PLMIN was also present within the nonvolatile memory 3G FPLMN list. If it was present, the identity of that PLMN is removed from that NYM 3G FPLMIN list. Subsequent to removal, the procedure then continues to step 32 as noted above for performance of a new PLMN selection.

With regard to Fig. 3, the attempted manual selection of a PLMIN within the handset 12 is illustrated.

First, during manual selection of the PLMN as attempted at step 38 and subsequent to identification of an appropriate 2G or 3G service, registration should be possible to both 3G and 2G RATs. Determination of successful registration as indicated by steps 40, 42, is then conducted at step 44. If so, the relevant RAT is identified and the PLMN is removed from the appropriate list such as the NVM 3G FPLMN list within the nonvolatile memory and also from the USIM FPLMN list within the USIM If, however, it is determined at step 44 that no such successful registration on 3G can be achieved, an attempted registration onto a 2G service available on that network is attempted at step 42. The identity of the RAT on which the successful registration was performed is then obtained so that the identity of the PLMN can be removed from the appropriate list as illustrated at step 44.

Turning lastly to Fig 4, the operation of a handset embodying the present invention in relation to automatic PLMIN selection is illustrated.

First of all at step 50, automatic selection mode is chosen and any stored PLrv[NS are sorted into appropriate priority order.

Then, at step 52, it is determined whether or not the candidate PLMN is located within the FPLMN list stored on the USIM.

If the candidate PLMIN is in fact stored in that list, then no registration is possible in relation to 2G or 3G service as illustrated at 54 and the processing returns as indicated by arrow 56 to the list of available PLMINs.

If, however, at step 52 it is determined that the candidate PLI'vIN is not within the FPLMN list stored in the USIM, then it is subsequently determined at step 58 whether or not the candidate PLMIN is stored in the FPLMIN list within the non- volatile memory If it is determined that the candidate PLMN is stored within that list on the non-volatile memory, then no registration on 3G is attempted even though registration may be possible in relation to a 2G service as illustrated at step 60. If, however, at step 58 it is determined that the candidate PLMIN is not in the list within the non- volatile memory then it is determined at step 62 that registration is possible on either the 3G or the 2G service.

Variations to the details discussed above are also encompassed within the concept of the present invention. For example, the invention can allow for the provision of two different NVM lists provided for two USIIMs respectively. Upon insertion of a new EJSIM, it is found that either there is, or is not, an NVM list associated therewith. If there is association, the NVM list can be used as required If not, the contents of the oldest NYM list is deleted and the NVM area is then re-used for this new USIM Thus, as illustrated in the above-mentioned figures, while the invention advantageously allows for the ready set-up and management of automated FPLMN lists relevant to both services within a dual mode device, further advantages also arise from the manner in which the data within those lists is handled, and indeed serves to control attempted PLMIN selections within the handset.

Claims (1)

1. Claims 1. A method of managing the identity of forbidden public land

   mobile networks in a mobile radio communications device arranged for at least dual mode operation, and comprising the steps of storing the identity of a forbidden public land mobile network relating to a first of the two modes in a first memory region and identifying the network as forbidden for both modes, and storing a forbidden public land mobile network identified in relation to a second of the two modes in a second memory region and identifying the network as forbidden only in relation to the said second mode.

   2. A method as claimed in Claim 1, wherein the said first region is provided on a 1.JSIM of the device.

   3 A method as claimed in Claim I or 2, wherein the said second memory region advantageously comprises a non-volatile memory region of the device 4. A method as claimed in Claim 1, 2 or 3 and including the step of reinitializing a list of the second memory region if the memory providing the first memory region is changed 5. A method as claimed in Claim 1, 2, 3 or 4, wherein the respective two modes of operation comprise a 2G service and a 3G service, and wherein the said second of the modes comprises the 3G service.

   6 A method as claimed in Claim 5, and arranged to manage cause #11 rejections arising as specified in accordance with 3GPP specifications.

   7 A method as claimed in Claim 6, and including the step of storing the identity of the PLMN in a USIM list and removing it if present for a NYM list, should a cause #11 rejection be received in relation to a 2G service 8. A method as claimed in Claim 5, 6 or 7, and wherein successful manual selection on either the 3G or 2G radio access technology provides for the step of removing the PLMN from the said first memory region.

   9. A method as claimed in Claim 5, 6, 7 or 8, and wherein successful manual selection on the 3G radio access technology leads to the step of removing the PLMN identified from the second memory region and, successful manual selection on the 2G radio access technology leads to no interaction with the said second memory region.

   A method as claimed in any one or more of the preceding claims, and including the step of controlling 2G to 3G inter-RAT cell reselection by the said second memory region 11. A mobile radio communications device arranged for at least dual mode operability and having storage means for storing the identity of forbidden public land mobile networks, the device being arranged to store the identity of a Forbidden Public Land Mobile Network relating to a first of two modes within a first memory region of the storage means and for determining the network as forbidden for both modes and the device further being arranged for storing the identity of a forbidden public land mobile network relating to the second mode within a second memory region of the storage means and for determining the network as forbidden only in relation to the said second mode.

   12. A device as claimed in Claim 11, wherein the said two modes comprise a 2G and 3G mode of operation.

   13 A device as claimed in Claim 11 or 12, wherein the two memory regions are provided in a portion of the USIM and also a non-volatile memory.

   14 A device as claimed in Claim 11, 12 or 13, and wherein a list within the second memory region is arranged to be re-initialized if the memory providing the first memory region is unchanged A device as claimed in Claim 13 or 14, wherein the non-volatile memory comprises the said second memory region and the USIM comprises the said first memory region.

   16 A device as claimed in Claim 11, 12, 13, 14 or 15, and arranged to manage cause #11 rejections 17. A device as claimed in Claim 16, and arranged such that when a cause ll rejection is received in relation to the 2G service, the identity of the PLMIN is stored in the USIM list and is removed, if present, from the NVM list 18 A device as claimed in Claim 16 or 17, and further arranged such that successful manual selection on either the 3G or 2G radio access technology leads to removal of the identity of a PLMN from the first memory region and successful manual selection on 3G radio access technology leads to removal of the identity of a PLIV[N from the second memory region.

   19 A device as claimed in Claim 16, 17 or 18 and arranged such that successful manual selection on the 2G radio access technology has no affect on the identities of the PLJV[Ns stored within the second memory region 20. A device as claimed in any one or more of Claims 11 to 19, wherein the said second memory region is arranged to control 2G to 3G inter-RAT cell reselect ion.

   21. A method of managing the identity of forbidden public land mobile networks as a mobile radio communications device substantially as hereinbefore described with reference to Figs. 2, 3 and 4 of the accompanying drawings.

   22. A mobile radio communications device arranged for at least dual mode operability substantially as hereinbefore described with reference to Figs 1, 2, 3 and 4 of the accompanying drawings