Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W48/00—Access restriction; Network selection; Access point selection
  • H04W48/18—Selecting a network or a communication service
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W8/00—Network data management
  • H04W8/18—Processing of user or subscriber data, e.g. subscribed services, user preferences or user profiles; Transfer of user or subscriber data
  • H04W8/183—Processing at user equipment or user record carrier

Definitions

• This invention relates to mobile stations such as cellular telephones and personal communicators and, more particularly, relates to methods and apparatus for managing a forbidden Public Land Mobile Network (PLMN) list in a mobile station.
• PLMN Public Land Mobile Network
• New GSM and other types of mobile networks are continually being deployed.
• a new operator typically has no roaming agreements with other operators, or at best just a few, when a new network is established. Also, existing roaming agreements between operators can change over time.
• the GSM standards require that once a network has indicated "PLMN Not Allowed", that operator code must be stored within a Subscriber Identity Module (SIM) in a forbidden PLMN list.
• SIM Subscriber Identity Module
• the techniques 1) and 2) are generally difficult ways to remove a network that has been placed in the forbidden PLMN list, while the technique 3) will not work at all if the mobile station is in an area where there are only forbidden networks available. For example, assume that a user has a Finnish SIM and is located in Ghana. Upon arrival in Ghana the user finds that the network there is forbidden. By the time of the user's next trip to Ghana a roaming agreement between the Finnish operator and the Ghana operator has been put in place. However, since the Ghana network is in the mobile station's forbidden PLMN list, the mobile station does not register there and, as a result, over-the- air updating of the forbidden PLMN list in the SIM is impossible to perform.
• a feature of the teachings of this invention is that forbidden PLMN list erasure (or modification) by a mobile station is accomplished so that, without user action or over-the-air interaction, the forbidden PLMN list is modified by the mobile station.
• Another feature of the teachings of this invention is that the operator issuing the SIM to a customer is given an option either to enable or disable the forbidden PLMN list management feature, and possibly also to affect how the erasure operates .
• One relatively simple method to manage the forbidden PLMN list is timer-based, where the mobile station erases the entire forbidden PLMN list at periodic intervals, such as once a month.
• the erasure of the forbidden PLMN lists is distributed evenly or substantially evenly over the population of mobile stations, so that not all mobile stations erase their respective forbidden PLMN lists on the same day.
• methods for ensuring the even distribution of forbidden PLMN list erasure are provided.
• a more complex method has the mobile station analyze the list of forbidden networks and select the one(s) to be erased. As this type of autonomous mobile equipment behavior may not be desirable to some network operators, the network operator can be given the prerogative as to whether to enable the use of this method.
• a presently preferred method employs the timer-based erasure of the forbidden PLMN list, but other methods where the mobile station decides automatically, without user intervention, to remove forbidden PLMNs from the SIM are also within the scope of the teachings of this invention.
• the disclosed embodiments provide at least the following advantages over the conventional techniques for managing the forbidden PLMN list.
• the timer-based method reduces greatly the opportunity to attempt to access forbidden networks . Furthermore, if an ERASURE TYPE argument is provided, such as "only erase network where the country is different from the home network", then unnecessary registration attempts may be removed altogether. This technique also does not require any user interaction.
• roaming agreements may be updated immediately (this solution can be accomplished also by correctly defining TRIGGERS for erasure) .
• User flexibility is also provided, as the user is enabled to control the network selection process according to his or her desires. For example, it becomes possible to place an expensive network into the forbidden PLMN list, even when there actually is a roaming agreement in place.
• a mobile station is disclosed, as is a method for operating the mobile station.
• the mobile station has a forbidden PLMN list stored in a memory that is accessible to a mobile station processor.
• the mobile station processor determines whether at least one predetermined criterion is met and, if the at least one predetermined criterion is determined to be met, erases all or a part of the forbidden PLMN list.
• the memory is contained in a SIM having an ERASURE TYPE stored within for specifying at least one of: erase the entire forbidden PLMN list; erase only networks that are from a different country than a home network; erase only networks from the country the mobile station is visiting or roaming in; and erase only networks from countries other than where the mobile station is currently roaming.
• the SIM also has an ERASURE TRIGGER stored within for specifying at least one of: a timer-based erasure trigger; erasure when, after switch-on, only forbidden networks are found and the mobile station is visiting another country than its home country; erasure when, after switch-on, only forbidden networks are found regardless of the country; erasure when returning to the home network, after roaming; erase when roaming after being in home network; and never erase.
• a timer-based erasure trigger the erasure time is preferably temporally distributed over the population of mobile stations.
• the at least one predetermined criterion, to erase all networks from the forbidden PLMN list, can be when a user has manually selected a forbidden network and obtained service .
• a method is disclosed to clear all or a part of the forbidden PLMN list stored in the memory accessible to the mobile station processor.
• the method has steps of (a) calculating a time at which to clear all or a part of a forbidden PLMN list; (b) comparing the calculated time to a current time; and (c) if not already erased, erasing all or a part of the forbidden PLMN list if the calculated time equals or is greater than the current time.
• the current time may be obtained from a calendar function or it may estimated. In the preferred embodiment the current time and the calculated time are expressed as a day of the month, and the calculated time is determined from the mobile station IMSI or from the mobile station IMEI .
• An initial step sets an indicator in the mobile station for indicating that clearing the forbidden PLMN list is one of enabled or disabled.
• Fig. 1 is block diagram of a wireless telecommunications system that is suitable for practicing this invention.
• Fig. 2 is logic flow diagram that illustrates a method in accordance with the teachings herein.
• FIG. 1 there is illustrated a simplified block diagram of an embodiment of an exemplary wireless telecommunications system 1 that includes a plurality of mobile stations 10.
• MSs mobile stations
• Fig. 1 also shows an exemplary network operator 2 having, for example, a mobile switching center (MSC) 3 for connecting to a telecommunications network, such as the Public Switched Telephone Network or PSTN, at least one base station controller (BSC) 4, and a plurality of base transceiver stations (BTS) 5 that transmit in a forward or downlink direction both physical and logical channels to the mobile stations 10 in accordance with a predetermined air interface standard.
• MSC mobile switching center
• BSC base station controller
• BTS base transceiver stations
• the air interface standard conforms to a Time Division Multiple Access (TDMA) air interface known as GSM and variants thereof, but the use of a GSM or GSM- like air interface standard is not a limitation upon the practice of this invention.
• TDMA Time Division Multiple Access
• the network operator 2 can include a Message Service Center (SMSC) that receives and forwards messages for the mobile stations 10, such as Short Message Service (SMS) messages, or any wireless messaging technique including e-mail and Supplementary Data Services.
• SMS Short Message Service
• MMS Multimedia Messaging Service
• the mobile station 10 typically includes a data processor embodied in a microcontrol unit (MCU) 12 having an output coupled to an input of a display 14 and an input coupled to an output of a keyboard or keypad 16.
• MCU microcontrol unit
• the mobile station 10 may be considered to be a handheld radiotelephone, such as a cellular telephone or a personal communicator, and may have a microphone and a speaker (not shown) for conducting voice communications.
• the mobile station 10 could also be contained within a card or module that is connected during use to another device.
• the mobile station 10 could be contained within a PCMCIA or similar type of card or module that is installed during use within a portable data processor, such as a laptop or notebook computer, or even a computer that is wearable by the user.
• the MCU 12 is assumed to include or be coupled to some type of a memory 13, including a read-only memory (ROM) for storing an operating program, as well as a random access memory (RAM) for temporarily storing required data, scratchpad memory, received data packets and data packets prepared for transmission, etc.
• ROM read-only memory
• RAM random access memory
• a separate, removable SIM 26 that is accessible to the MCU 12 by being bidirectionally coupled to the MCU 12 can be provided as well, the SIM storing, for example, a preferred Public Land Mobile Network (PLMN) list 26B, a forbidden PLMN list 26A, as well as other subscriber-related information.
• PLMN Public Land Mobile Network
• the ROM is assumed, for the purposes of this invention, to store a program enabling the MCU 12 to execute the software routines required to operate in accordance with the presently preferred forbidden PLMN list 26A management methods .
• the mobile station 10 also contains a wireless section that includes a digital signal processor (DSP) 18, or equivalent high speed processor, as well as a wireless transceiver comprised of a transmitter 20 and a receiver 22, both of which are coupled to an antenna 24 for communication with the network operator 1.
• DSP digital signal processor
• This invention provides for the automatic erasure of the forbidden PLMN list by the mobile station 10, and to the definition of rules as to whether (and when) to make the erasure, and whether to erase the entire forbidden PLMN list 26A or only a portion thereof.
• One location to configure whether the forbidden PLMN list erasure feature is enabled or disabled is in the SIM 26. This can be done by defining a new datafield in the SIM 26 and, if the datafield exists in the SIM 26, then the feature is enabled.
• the datafield may also store additional information related to the forbidden PLMN erasure method, such as whether to erase the entire list of forbidden networks or only certain networks, such as outside of the home country.
• the datafield may also store an erasure interval which functions as a trigger to make the automatic erasure, such as once a month, or when there are only forbidden networks available when outside of home country, or when there are only forbidden networks available, as described in further detail below.
• an EASY ERASURE trigger may be made part of the applicable standards. For example, if the user manually selects a network which is in the forbidden PLMN list 26A, and obtains service there, according to current GSM standards only this manually selected network is removed from the forbidden PLMN list 26A.
• the inventor has realized that in actuality the ability to obtain service from a formally forbidden network is an indication of the fact that the operator has made at least one new roaming agreement, and thus it may be desirable to trigger the erasure of the entire forbidden PLMN list 26A (i.e., the list may be out of date) .
• This EASY ERASURE may also be configurable .
• erasure TYPES and TRIGGERS can be made a function of the roaming status of the mobile station 10 (e.g., roaming or not roaming, location where mobile station is roaming, roaming history, etc.)
• the timer-based method may be made configurable, so that the timer interval is made programmable and stored in the SIM 26, e.g., 1-255 days, where 0 specifies basically the same operation as ERASURE TRIGGER 1 or 2.
• Fig. 2 depicts a logic flow chart of a presently preferred embodiment of the teachings of this invention.
• the erasure date for this particular mobile station 10 would thus be the (14+1) or 15th of each month. If the current day of the month is equal to the calculated date (or past the calculated date) then it may be time to clear the forbidden PLMN list 26A (Step 106) .
• the mobile station 10 needs to "remember” whether it has already cleared the forbidden PLMN list 26A in the current day (and month) . If it is time to clear the forbidden PLMN list 26A list, and if it has not yet been cleared, then the list is cleared at Step 110.
• the current date may also be obtained, in some embodiments, from the network operator 2 , or from some other source external to the mobile station 10 (e.g., the mobile station 10 includes a GPS reception capability) .
• the date calculation techniques described above are exemplary, and those skilled in the art may derive other suitable techniques to determine a particular time for the mobile station 10 to automatically clear the PLMN list 26A. In all such cases it is desirable and preferred that not all mobile stations 10 (e.g., MS#1 and MS#2) clear their respective forbidden PLMN lists 26A on the same day. It is desirable to temporally distribute the clearing of the forbidden PLMN lists 26A for different mobile stations to minimize the risk that on some particular date many network operators do not experience a large number of failed registration attempts.
• Step 112 if the mobile station 10 does not have a built-in calendar function, control passes to Step 112 where, for example, a switch-on counter (typically a memory 13 location) is tested to determine if the mobile station 10 has been turned on some predetermined number (e.g., 100) times. If Yes, control passes to Step 110 to clear the forbidden PLMN list 26A. Also, a mobile station 10 timer function can be used, such that after some number of hours (e.g., 12) the switch-on counter is increased by one. In this case, if the mobile station 10 is left on continuously the forbidden PLMN list 26A will be cleared every 50 hours. The interval may be programmable and may be obtained from a SIM datafield defined for this purpose.
• a switch-on counter typically a memory 13 location
• the operator may define the interval to be zero in order to disable the automatic forbidden PLMN list 26A erasure function.
• This may be a default value, i.e., information is stored in the SIM 26 in the form of a datafield to enable periodic forbidden PLMN list 26A clearing, and if this data is not present the periodic forbidden PLMN list clearing is disabled.
• the entire forbidden PLMN list 26A or portions of it may be cleared when the mobile station 10 is switched off (those portions corresponding to networks from other countries or networks from the visited country.
• the list is cleared (i.e., in the case where the mobile station 10 did not access any network) .
• the roaming-based approach has more drawbacks than the other methods described above, as it is more likely to cause unnecessary registration attempts for forbidden networks .
• the mobile station 10 is operated to delete either the entire forbidden PLMN list 26A or a selected portion of the forbidden PLMN list 26A based on the assumption that a forbidden network ceases to be a forbidden network as operators make new roaming agreements.
• the method for the timer-based solution may be a value 1-28 (30 or 31) that is calculated based on the IMEI or the IMSI.
• the forbidden PLMN list 26A erasure date is dependent on the unique identity of the mobile station 10.
• the mobile station 10 stores the month in which it erased the forbidden PLMN list 26A (for instance May) , and when June arrives it checks when the date is equal to or greater than the calculated date. If the date is equal to or greater than the erasure date, and the SIM 26 requires the timer-based erasure, the erasure is performed (by using any appropriate erasure method) .
• the mobile station 10 also stores June (e.g., it stores a 6 in a month datafield in the SIM 26) as the month when the erasure was done. In this manner the mobile station 10 will not again erase the forbidden PLMN list 26A during June.
• a long timer e.g., 12 hours
• the switched-on timer can be used, either alone or in combination with the switched-on timer, for estimating the time.
• this approach is not as accurate, as the mobile station 10 can be switched off for several days.
• Another method may employ a datafield in the SIM 26 which is decreased (or increased) by one every day (24 hours) . Based on this day counter the erasure of the forbidden PLMN list 26A is made. In this case the SIM 26 may perform the erasure automatically.
• the SIM 26 datafield may just indicate the month when the erasure was made. In this case the mobile station 10 performs the next erasure if the date is one month (or more past) the date or, in the case where the interval is configurable, the mobile station 10 may calculate whether the erasure should be made at this time. In the case where the SIM 26 datafield includes the month when the erasure was made, the algorithm is basically the same as the fixed interval method.
• a value 1-28 (30 or 31) is calculated based on the IMEI or on the IMSI .
• the forbidden PLMN list 26A erasure date is dependent on the identity of the mobile station 10. This value could also be given by the SIM 26 so that the mobile station 10 can calculate it from the IMSI or given directly in some datafield.
• the SIM 26 stores the month it has erased the list (for instance May) and when it June arrives the mobile station 10 again checks if the date is equal or greater than the calculated date. If it is, and if the SIM 26 requires timer-based erasure of the forbidden PLMN list 26A, the erasure is performed using an appropriate erasure method.
• the mobile station 10 also stores June in the SIM 26 as the month when the erasure was performed to SIM.
• the SIM 26 is enabled itself to clear the forbidden PLMN list 26A or portions thereof .
• the SIM 26 is enabled itself to clear the forbidden PLMN list 26A or portions thereof at appropriate times.

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• Engineering & Computer Science (AREA)
• Computer Security & Cryptography (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Mobile Radio Communication Systems (AREA)
• Telephone Function (AREA)

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• 2000
  • 2000-07-13 EP EP00961988A patent/EP1195069A2/de not_active Withdrawn
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