Home network searching when roaming in wireless communications networks

A method in a wireless communications device including determining whether the device is operating in a network other than a home network, determining whether to search for the home network when not operating in the home network by comparing network record information associated with the network in which the device is operating to reference information. In some embodiments, the device indicates that it is operating in a network other than the network in which it is operating.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to wireless communications and, more particularly, to determining whether a wireless communications device, for example, a mobile cellular telephone, should search for its home network when operating in other networks, for example, when roaming in a virtual Home Public Land Mobile Network (H-PLMN), and methods therefor.

BACKGROUND

It is common for wireless communications network operators to offer service plans, for example, nationwide calling plans, with coverage in geographical areas that are served by third party network operators but not by the operator offering the service plan. To do this, network operators enter into network sharing agreements with other network operators so that operators may provide service to subscribers in areas where the operators do not actually own and operate network infrastructure.

In some mobile stations, the display indicates that the mobile station is operating in a home network when the mobile station is actually in a third party operator network, thus making it appear to the user as though the mobile station is camped on its home network when in fact the mobile station is roaming, i.e., operating in a third party network. For example, the Global System for Mobile Communications (GSM) specification defines a feature called Extended Operator Name String (EONS) enabling a GSM Subscriber Identification Module (SIM) card issuer, for example, a network operator, to control the displayed idle-mode operator name using a set of rules and associated name strings stored on the SIM card. The rules are known as the Operator PLMN List (OPL) and the associated name string is known as the PLMN Network Name (PNN) list. The EONS feature makes it possible for the phone to display a particular name other than that of the actual network where the mobile station operating. Some GSM network operators use the EONS feature to provide “virtual” nationwide coverage by programming the SIM to make the mobile station display the operator's name in all or in particular portions of third party networks. Under these circumstances, the mobile station is said to be in a “virtual” home network.

Wireless communications devices, or mobile stations, operating in third party networks are actually roaming outside the home operator's network, regardless of what may be indicated to the user by the mobile station. A roaming mobile station periodically scans for its home network, for example, its Home PLMN (H-PLMN). The network scanning procedure however consumes power, which significantly reduces battery life compared to the power consumed when the mobile station is not roaming and scanning for its home network.

Release 99 of the 3rdGeneration Partnership Project (3GPP) GSM specifications allows networks to specify a list of equivalent PLMNs that are treated by recipient mobile stations as though they were the same network. Under Release 99, a mobile station will not perform periodic H-PLMN searches when camped on networks that are equivalent to the mobile station's H-PLMN. However, the Release 99 specification is a significant change that will require some time to implement fully, rendering the equivalent PLMN feature substantially unavailable for near term use. Moreover, the equivalent PLMN feature is available only in Release 99 specification compliant networks that elect to utilize the equivalent PLMN data field in messages responding to location area updates from the mobile station. Particularly, the Release 99 equivalents PLMN feature is dependent upon competing network operators configuring network information in a manner that reduces unnecessary H-PLMN searching by roaming mobile stations. If there is no indication that the roaming PLMN is equivalent to the mobile station's home PLMN, the roaming mobile station will continue searching for its H-PLMN.

The various aspects, features and advantages of the disclosure will become more fully apparent to those having ordinary skill in the art upon careful consideration of the following Detailed Description thereof with the accompanying drawings described below.

DETAILED DESCRIPTION

FIG. 1illustrates a geographical region100including a first communications network “A” and a second communications network “B” operated by different operators that provide wireless communications services to mobile communications devices, for example, mobile station102inFIG. 1. The exemplary networks “A” and “B” include overlapping portions, though generally the networks need not overlap. Some networks include one or more location areas, which are typically defined by the corresponding network operators. The exemplary network “B” includes location area codes: LAC01, LAC02& LAC03. A wireless communications device reports changes in it current location area to the network.

The exemplary wireless communications networks generally include communications subsystems comprising a controller communicably coupled to one or more transceiver stations that provide service coverage for corresponding areas, for example, cellular areas. In some network architectures, one or more communications subsystems serve corresponding location areas in networks that include multiple location areas. The communications networks may provide circuit and/or data services. Exemplary cellular communications networks include 2ndGeneration (2G) Global System for Mobile Communications (GSM) radio access networks, 2.5 Generation GSM and CDMA networks, and 3rdGeneration (3G) Universal Mobile Telephone System (UMTS) W-CDMA networks, other communications networks, and combinations of these networks. The infrastructure architecture of these and other networks are known generally and not discussed further herein.

The wireless communications device is, for example, a mobile cellular communications handset that operates pursuant to one or more applicable communications protocols corresponding to the communications networks in which it operates, for example, TDMA, GSM, CDMA, UMTS W-CDMA, among other protocols. More generally, the wireless communications device may be a personal digital assistant, or a wireless enabled laptop or notebook computer, or some other wireless communications device that operates in different networks, for example, in networks “A” and “B” inFIG. 1.

The wireless communications device102is usually associated with a corresponding home network referred to as an H-PLMN in some communications standards, for example, network “A” inFIG. 1. Generally, wireless communications devices may also operate in networks other than the home network, for example, through contractual agreements made by the home network operator with other operators, thereby providing substantially seamless communications services to roaming wireless communications devices. And some wireless communications devices, for example, some GSM mobile stations, are programmed to indicate that the mobile station is operating in a home network when it is roaming.

In some embodiments, the wireless communications device includes a subscriber information module including subscriber identity and other information on a removable integrated circuit (IC) card. Exemplary identification modules, also referred to generally as “smart cards”, include the GSM Subscriber Identification Module (SIM), SIM for UMTS, also known as a User Services Identity Module or a Universal Subscription Identity Module (U-SIM), or equivalent modules used in CDMA 1x compliant devices and other communications devices.

Some subscriber information modules include, among other information, wireless communications device identification information, for example, an International Mobile Subscriber Identity (IMSI), which is used by communications networks to identify subscriber devices. Subscriber information modules may also include preferred service provider information for use by the mobile station when operating in networks other than the home network, i.e., when roaming.

In one embodiment, the wireless communications device includes, stored thereon, extended operator name string information. This information may be stored, for example, on a SIM card or on some other smart card of the wireless communications device.FIG. 2illustrates a modified GSM Extended Operator Name String (EONS) comprising Operator PLMN List (OPL) information andFIG. 3illustrates modified PLMN Network Name (PNN) information. In GSM devices, the EONS information is stored in a SIM card. In other embodiments, similar or equivalent information may be stored on some other smart card or medium.

The OPL specifies rules for what network name to display on the wireless communications device.FIG. 2illustrates an exemplary OPL information file200, in tabular form for ease of illustration. Each of the exemplary OPL information file records, identified inFIG. 2by corresponding record numbers210, includes network identification information, for example, a PLMN-ID,220, location area information, for example, a range of location areas230, and a reference to corresponding PNN record information240. In one embodiment, the ordering of the records in the OPL information file200implies a record number in the absence of explicit record number data.FIG. 3illustrates an exemplary PNN information file300, also in tabular form for ease of illustration, including multiple records, identified inFIG. 3by a corresponding record number310, having corresponding network name information320. In one embodiment, the ordering of the records in the PNN information file300implies a record number in the absence of explicit record number data.

The PNN record information240of the OPL information table200is used to reference corresponding name information320in the PNN information table300. The identity of the network in which the wireless communications device is operating is generally obtained from the network. In practice, the wireless communications device uses the network identity and any location area information to locate the corresponding record in the OPL file, which is used to cross-reference the corresponding PNN record. Using the EONS information ofFIGS. 2 and 3, for example, a wireless communications device operating in LAC0002-0003of PLMN-ID 318261 would display network name “A”, rather than some other network name that may be affiliated with PLMN-ID 318261. When the device is operating in LAC0001of PLMN-ID 318261, it would display network name “B”.

InFIG. 1, when the wireless communications device102, is roaming in location area code (LAC)03of network “B”, the wireless communications device will not find its home network “A”, since it is unavailable. Under these circumstances, it is unnecessary in at least some applications for the wireless communications device to search for its home network, which is unavailable. At least one reason for not searching for the home network is to conserve resources, for example, battery power.

According to one aspect of the disclosure, in some applications, a mobile wireless communications device operating in a network other than the home network of the wireless communications device determines whether to search for its home network when roaming by comparing network record information corresponding to the network in which the wireless communications device is operating to reference information, examples of which are discussed further below.

In a first particular exemplary embodiment, illustrated in the process diagram400ofFIG. 4, at block410, the wireless communications device determines whether it is operating in, or camped on, its home network, for example, its Home Public Land Mobile Network (H-PLMN) or in some other network. InFIG. 4, at block420, when the wireless communications device is operating in its home network, the wireless communications device does not scan for the home network. In embodiments where the wireless communications device includes a roaming indicator, the roaming indicator is also disabled when the device is operating in its home network.

In one embodiment, a mobile wireless communications device operating in a network other than the home network of the wireless communications device determines whether to search for its home network by comparing network name information associated with the network in which the wireless communications device is operating to reference information. The network name information is a network name other than the name of the network in which the device is operating, for example, the home network name to be displayed on the wireless communications device when roaming.

InFIG. 4, at block430, the wireless communications device determines network name information. InFIG. 3, for example, the wireless communications device obtains a PLMN Network Name (PNN), e.g., “A”, “B”, “C”, etc., from the PNN information300using the PNN record information240from the OPL information200ofFIG. 2. InFIG. 4, at block440, the wireless communications device determines the name of the reference network, for example, using the EONS information, CPHS ONS, alternative name table information, or some other information etc. In one embodiment, the reference network name is the home network name. At block450, the name obtained at block430is compared to the reference name obtained at block440. If the names are identical, or match, the wireless communications device does not scan for its home network while roaming, as indicated at block420. Under these circumstances any roaming indicator would also be disabled.

Thus in at least some variations of the exemplary process ofFIG. 4, the wireless communications device uses prior art EONS information to determine whether it should scan for its home network when roaming. If the network name to be displayed using EONS matches the home operator name string as defined, for example, by the CPHS ONS file, then the wireless communications device does not search for its H-PLMN. Since the home network operators provision the SIM for EONS, the operator knows where the mobile should and should not search for its home network.

In an alternative embodiment, the network name information is compared to reference network name information obtained from the EONS file. Particularly, the network name information is obtained from the PNN information file300ofFIG. 3using the OPL information file200inFIG. 2, as discussed above in connection with block430inFIG. 4. According to this alternative embodiment, in some cases, the reference network name may be obtained from the OPL information file200ofFIG. 2as follows: The wireless communications device uses its home network identification, for example, its H-PLMN identity, to identify a corresponding record in the OPL information table200ofFIG. 2. In one embodiment, the H-PLMN ID is obtained from the International Mobile Subscriber Identity (IMSI), known formerly as the International Mobile Station Identity. The reference network name is obtained by referencing a network name320from the PNN information file300ofFIG. 3using the PNN record information240associated with the IMSI. In some instances, however, the H-PLMN ID may have multiple records in the OPL information file200, with references to corresponding network names in the PNN information file, resulting in an ambiguous reference to the network name in the PNN information file.

In another alternative embodiment, the network name information is compared to reference network name information obtained from a PLMN text table on the wireless communications device. PLMN text tables are known generally and used in the prior art for correlating PLMN identification information with network name information to display when in a corresponding PLMN. According to this alternative embodiment, the wireless communications device uses its home network identification, for example, its H-PLMN identity, to identify a corresponding record in the PLMN text table. And the network name or PLMN text table record number is used as the reference information.

InFIG. 4, in some embodiments, at block420, the wireless communications device indicates, for example, on an LCD display, that it is operating in its home network, when in reality the device is roaming. In one embodiment, the network name displayed is the network name obtained from the PNN table300using the OPL table200. Thus in at least some variations of the process ofFIG. 4, the same information used to display virtual home network information when the wireless communications device is roaming is also used to determine whether to search for the home network when roaming. In some embodiments, this same information is also used to determine the states of the roaming indicator.

InFIG. 4, at block460, if there is not a match between the names obtained at blocks430and440, the wireless communications device scans for its home network. At block460, the device may also indicate that it is roaming and display the name of the roaming network.

In an alternative embodiment, illustrated in the process diagram500ofFIG. 5, at block510, the wireless communications device determines whether it is operating in, or camped on, its home network, for example, its Home Public Land Mobile Network (H-PLMN), or in some other network. At block520, when the wireless communications device is operating in its home network, the wireless communications device does not scan for the home network. Any roaming indicator on the wireless communications device is also disabled.

In the alternative embodiment, the mobile wireless communications device operating in the network other than its home network determines whether to search for its home network when roaming by comparing network record information associated with the network in which the device is operating to reference information. In one embodiment, the network record information is a network record number for a network other than the network in which the device is operating, for example, a record number corresponding to virtual home network information to be displayed on the wireless communications device when roaming.

In the exemplary process ofFIG. 5, at block530, the wireless communications device determines network record number information. InFIG. 2, for example, the wireless communications device obtains a PLMN Network Name (PNN) record number, e.g., “1”, “2”, “3”, etc., from the PNN record information240of the OPL file. InFIG. 5, at block540, the wireless communications device determines whether the record number matches a reference number by comparing the record number with the reference number. In one embodiment, the reference number is a record number corresponding to the home network name. The reference number may be stored on the wireless communication device, e.g., in non-volatile memory during manufacture, or it may be stored on a smart card, e.g., on a SIM, or USIM, etc. More generally, multiple reference numbers are stored on the wireless communications device or on a smart card thereof. If the network record number matches any one of the multiple reference numbers, the wireless communications device does not scan for its home network (or indicate that it is roaming), as indicated at block520.

Thus in at least some variations of the exemplary process ofFIG. 5, the wireless communications device uses prior art EONS information to determine whether it should scan for its home network when roaming. If the EONS network record number corresponding to the roaming network matches at least one reference number, then the wireless communications device does not search for its H-PLMN, and any roaming indicator is disabled.

InFIG. 5, in some embodiments, at block520, the wireless communications device indicates that it is operating in its home network, when in reality the device is roaming. In one embodiment, the network name displayed is the network name obtained from EONS information. Thus in at least some variations of the process ofFIG. 5, the record number of the OPL and/or PNN information used to display virtual home network information when the wireless communications device is roaming is also used to determine whether to search for the home network when roaming and to control the state of any roaming indicator. InFIG. 5, at block550, if there is not a match between the record-number obtained at block530and the reference number, the wireless communications device scans for its home network.

In another alternative embodiment, illustrated in the process diagram600ofFIG. 6, at block610, the wireless communications device determines whether it is operating in, or camped on, its home network, for example, its Home Public Land Mobile Network (H-PLMN), or in some other network. At block620, when the wireless communications device is operating in its home network, the wireless communications device does not scan for the home network.

In the alternative embodiment ofFIG. 6, the mobile wireless communications device operating in a network other than its home network determines whether to search for its home network when roaming based on search information, for example, a binary flag, associated with network record information associated with the network in which the device is operating. The search information may be stored on a smart card, for example, with EONS information on a SIM or USIM card of the wireless communications device, as discussed further below.

InFIG. 6, at block630, the wireless communications device determines network record information for the network in which the wireless communication device is operating. In one embodiment, a record in the OPL information file200ofFIG. 2is identified corresponding to the network in which the device is operating as discussed above. In another embodiment, a record in the PNN information file300ofFIG. 3is identified using the PNN record information240in the OPL file. At block640, the wireless communications device obtains search information from a smart card, for example, a SIM, USIM, etc. on the wireless communications device.

In one embodiment, the search information is part of the modified OPL information file200illustrated inFIG. 2. In this embodiment, a new OPL reference record data field250is utilized. The reference record data field accommodates search information, for example, a binary bit which is set or not set, indicating whether to search for the home network. In an alternative embodiment, the search information is in a new PNN record data field340that is part of the PNN information file300ofFIG. 3. In another embodiment, the search information is in a discrete file having multiple records that correspond, for example, by virtue of an explicit or implied record number, to records in the OPL and/or PNN information files.

InFIG. 6, at block650, the wireless communications device interprets and acts upon the search information obtained at block640. In the exemplary embodiment where the search information is a binary flag, the device either searches for the home network or does not search for the home network depending on the state of the flag. If the flag indicates that home network searching is not required, the algorithm proceeds to block620. In some embodiments, at block620, the wireless communications device may also indicate that it is in its home network when it is roaming. If the flag indicates that home network searching is required, the algorithm proceeds to block660. At block660, the wireless communications device resumes scanning for its home network and in some embodiments may indicate that it is roaming.

While the present disclosure and the best modes thereof have been described in a manner establishing possession by the inventors and enabling those of ordinary skill in the art to make and use the same, it will be understood and appreciated that there are many equivalents to the exemplary embodiments disclosed herein and that modifications and variations may be made thereto without departing from the scope and spirit of the disclosure, which is to be limited not by the exemplary embodiments but by the appended claims.