USOO7349695B2

(12) United States Patent (10) Patent No.: US 7,349,695 B2 Oommen et al. (45) Date of Patent: Mar. 25, 2008

(54) MULTIMODE MOBILE DEVICES 6,415,148 B1* 7/2002 Chiniga et al...... 455,434 2002fO160763 A1 10, 2002 Mittal et al. (75) Inventors: Paul Oommen, Irving, TX (US); 2003.0054809 A1 3, 2003 Bridges et al. Yichyun Mitch Tseng, Plano, TX (US) 2003, OO88539 A1 5/2003 Andrus et al. 2004/0043788 A1 3/2004 Mittal ...... 455,558 2004/0203745 A1* 10/2004 Cooper ...... 455,432.1 (73) Assignee: Nokia Corporation, Espoo (FI) 2004/0235475 A1* 11/2004 Ishii ...... 455,435.3 (*) Notice: Subject to any disclaimer, the term of this FOREIGN PATENT DOCUMENTS patent is extended or adjusted under 35 U.S.C. 154(b) by 154 days. Wo wo...A. S. (21) Appl. No.: 10/963,629 WO WO O2/O76131 A1 9, 2002 9 OTHER PUBLICATIONS (22) Filed: Oct. 14, 2004 Mazziotto, G., “The Subscriber Identity Module for the European (65) Prior Publication Data Digital Cellular System GSM', Jun. 26, 1990, pp. 1-9. US 2005/0282544 A1 Dec. 22, 2005 * c1tedcited bby examiner Primary Examiner Keith Ferguson (51) Int. Cl. (74) Attorney, Agent, or Firm—Squire, Sanders & Dempsey, H04O 7/20 (2006.01) LLP. H04O 7/32 (2006.01) (52) U.S. Cl...... 455/432.1; 455/432.2: (57) ABSTRACT 455/435.2:455/435.1; 455/432.3:455/550.1; 455/551:455/422.1s Acations mobile networks SE EEin different geographicalE. regions communi 1s pro (58) Field of ClasgSt.el, 3.45 a. vided. The mobile device includes an interface configured to 455/.435 3 422 i 403 418 419 420 445. transmit and receive signals over a wireless channel accord 455/500 517 574 5501 552 1 553 1. 558. ing to a communication mode using one of a plurality of 455/551 414 i 4142 414 3 4144 access technologies. The device also includes a store holding See application file for com lete search histor a preferred roaming list having a common block holding pp p ry. data common to the plurality of access technologies, and a (56) References Cited set of access technology-specific blocks each holding chan nel acquisition data specific to one of the plurality of access U.S. PATENT DOCUMENTS technologies for setting up the communication mode. 5.999,811 A * 12/1999 Molne ...... 455,432.3 6,223,028 B1* 4/2001 Chang et al...... 455,419 27 Claims, 3 Drawing Sheets

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US 7,349,695 B2 1. 2 MULTIMODE ROAMING MOBILE DEVICES mobile device would have no information about a CDMA network in its geographical region or vice-versa. FIELD OF THE INVENTION So-called multimode devices are currently being devel oped which should be capable of roaming in heterogeneous This invention relates to multimode roaming mobile network environments. For example, a device originally devices. provisioned in a CDMA network should be capable of roaming in a GSM, WLAN (Wide Local Area Network), BACKGROUND TO THE INVENTION UMTS (Universal Mobile Telecommunications Systems) or any other network. Service providers set up roaming agreements with other 10 service providers in different geographic regions so that SUMMARY OF THE INVENTION when the user is in a region where the home service provider does not offer a service, nevertheless the service can be It is an aim of the invention to enable selection of provided by a different service provider who has a billing preferred access technology in a geographical region for arrangement with the home service provider. Any particular 15 multimode mobile devices and to improve OTA manage region may support different systems and networks. For ment of preferred roaming lists for differing access tech CDMA (Code Division Multiplex Access) networks, a Pre nologies. ferred Roaming List PRL which is stored at the mobile According to one aspect of the invention there is provided device provides information about which system/network is a mobile device for roaming between wireless communica preferred in the region for that device. Over-the-air (OTA) tions networks in different geographical regions, the mobile Management protocols allow data to be transmitted to device comprising: an interface adapted to transmit and mobile devices via wireless transmission media. One receive signals over a wireless channel according to a example of OTA Device Management is the re-program communication mode using one of a plurality of access ming of the Preferred Roaming List (PRL). When a mobile technologies; and a store holding a preferred roaming list user is abroad and switches on the mobile device for the first 25 having a common block holding data common to said time, the mobile device performs a search for all available plurality of access technologies, and a set of access tech networks. The mobile device then reads from the PRL the nology-specific blocks each holding channel acquisition preferred networks and the order in which they should be data specific to one of the plurality of access technologies for offered to the user. Since preferred networks are constantly setting up said communication mode. changing as new roaming agreements are made, it is nec 30 Another aspect of the invention provides a method of essary to frequently update the PRL in the mobile device. selecting a communication mode for a mobile device roam This is achieved by downloading the revised PRL remotely ing between wireless communications networks in different using OTA technology. OTA protocols are defined for geographical regions, the method comprising the steps of example in the over-the-air service provisioning/parameter receiving network parameters identifying wireless commu administration (OTASP/OTAPA) and Open Mobile Alliance 35 nications networks in the region where the mobile device is (OMA) device management standards. located; comparing said parameters with preferences among Current protocols developed in OMA (Open Mobile Alli a plurality of access technologies and selecting one of said ance) DM (Device Management) provide an integrated access technologies; and Scanning channel acquisition data framework for OTA management of mobile devices. The for the selected access technology to set up a communication existing OMA DM protocol defines a management frame 40 mode using the selected access technology. work and a set of messages exchanged between one mobile A further aspect of the invention provides a method of device and an entity in the network called the management managing a preferred roaming list of a mobile device server. A management session is set up between the man capable of transmitting and receiving signals using each of agement server and the mobile device, and an OTA message a plurality of access technologies, the method comprising: 45 transmitting a notification message from a mobile device to is constructed which is unique to the mobile device. a management server, said notification message including FIG. 1 illustrates the structure of a preferred roaming list parameters identifying the device and the access technology PRL for CDMA networks. There is a system table ST . . . of a current communication mode; and transmitting an ST, ... ST associated with each geographical region which contains a list of system descriptions keyed by System update message from the management server to the mobile 50 device according to said communication mode, for perform identifier/network identifier (SIN/NID) pairs and associated ing an update to access technology-specific blocks of a with an acquisition index. The acquisition index is used as preferred roaming list stored at the mobile device. a pointer to an acquisition table AT which contains an A further aspect of the invention provides a computer indexed list of RF channels for channel acquisition purposes program product comprising a code sequence which, when in the new network. 55 executed by a processor in a mobile device, carries out the According to the current standard, System acquisition can following steps: receiving network parameters identifying be carried out using frequency blocks with Personal Com wireless communications networks in the region where the munication Systems (PCS) assigned values, or by using mobile device is located; comparing said parameters with channel numbers with the highest priority channel first. preferences among a plurality of access technologies and To date preferred roaming lists are provided only in the 60 selecting one of said access technologies; and scanning context of CDMA operation, which includes system selec channel acquisition data for the selected access technology tion in analogue mode and CDMA mode. to set up a communication mode using the selected access Currently, for GSM mobile equipment, a list of preferred technology. Public Land Mobile Networks (PLMNs) is stored in the A further aspect of the invention provides a method of Subscriber Identity Module (SIM) of the mobile device. This 65 managing a preferred roaming list of a mobile device enables roaming through PLMN selection when the mobile capable of transmitting and receiving signals using each of equipment is outside the home network. However, a GSM a plurality of access technologies, the method comprising: US 7,349,695 B2 3 4 transmitting a notification message from a mobile device to the mobile station radio software can use this information to a management server, said notification message including access the preferred list and select a system in a region. parameters identifying the device and the access technology In a possible embodiment of the invention, the common of a current communication mode; and transmitting an update message from the management server to the mobile data block and the different preferred lists could be created device according to said communication mode, for perform and updated in the mobile station using over-the-air meth ing an update to a preferred roaming list stored at the mobile ods. device, said update message indicating whether it is per In a possible embodiment of the invention, the common forming an update to a common block of the preferred data block and different preferred lists can be retrieved from roaming list holding data common to said plurality of access 10 the mobile station using over-the-air method. technologies or performing an update to access technology In a possible embodiment of the invention, the retrieval specific blocks of the preferred roaming list. can be based on algorithms of tree encoding and compres Another aspect of the invention provides claim 28 Sion. In a possible embodiment of the invention, a common In a possible embodiment of the invention, over-the-air data block carrying data related to roaming in different 15 method can be based on the OMA DM protocol. networks (CDMA, GSM, WLAN, and future networks) is In a possible embodiment of the invention, over-the-air linked to preferred roaming lists for each network access method can be based on the IOTA-HCM (Handset Configu system. ration Management) protocol, described in GPP2 C.S0040–0 In a possible embodiment of the invention, preferred v1.0. roaming lists for each access system as well as the common data block can be stored in the R-UIM or SIM card. In a possible embodiment of the invention, over-the-air In a possible embodiment of the invention, preferred method can be based on the OTASP/OTAPA protocol. roaming lists for each access system as well as the common In a possible embodiment of the invention, over-the-air data block can be stored in the mobile equipment. method can be based on pure air-interface messaging. In a possible embodiment of the invention, the common 25 In a possible embodiment of the invention, the informa data block stores access level information, enabling the tion created or updated or retrieved from the mobile station mobile station to decide which access system is preferred in can be stored in a network location, associated with the a given geographical region. E.g. to decide whether CDMA management station. or GSM is preferred in a region. In a possible embodiment of the invention, the informa In a possible embodiment of the invention, the common 30 tion stored in the network location can be sent to another data block stores parameters related to accessing the man network, to a management station in that network. agement station, as well as security parameters. In a possible embodiment of the invention, the informa In a possible embodiment of the invention, there may be tion sent to another network can be created and updated in a common identity parameter, which can identify the mobile a mobile station of the same user in that network. As an station in each access network. 35 example, a user visits a new network, and he lost his mobile In a possible embodiment of the invention, the common station afterwards, this mechanism helps creating and updat data block stores parameters related to identity of the mobile ing roaming related data in the new mobile station. station, Such as a common identity that can be used in all In a possible embodiment of the invention, in order to networks. Currently we have ESN (Electronic Serial Num 40 have control of managing preferred lists in the mobile ber), MEID (Mobile Equipment Identifier) etc. in CDMA, station, the mobile station stores a current mode parameter and IMEI (International Mobile Equipment Identity) in value and sends it to the management station. The manage GSM for equipment id. There can be a future id common to ment station uses this information to update the correct all access system or a common id designed for the purpose Preferred Roaming List. of multi-mode roaming. Such an id can be stored in the 45 In a possible embodiment of the invention, a management common block. station associated with a network can update also preferred In a possible embodiment of the invention, the preferred lists corresponding to other access networks. For example roaming lists linked to the common data block stores infor the security parameters in the common data block can be set mation specific to each radio network. For example, there is to allow this. This allows a management station in the GSM a preferred list that stores preferences of system and channel 50 network to update also CDMA preferred lists. for operation in CDMA mode, another one for storing For a better understanding of the present invention and to preference list of systems and channels in GSM network and show how the same may be carried into effect, reference will another similar list for WLAN. now be made by way of example to the accompanying In a possible embodiment of the invention, there can be drawings. Such preferred lists for future access technologies. 55 In a possible embodiment of the invention, the common BRIEF DESCRIPTION OF THE DRAWINGS data block and various preferred lists may be represented and implemented using a hierarchical tree which is imple FIG. 1 is a schematic diagram of an existing preferred mented in the mobile station and stored either in the mobile roaming list; equipment (ME) or the R-UIM/SIM card. The hierarchical 60 tree is used for over-the-air management purpose, especially FIG. 2 is a schematic diagram illustrating a roaming when OMADM and similar protocols are used for managing mobile device; multi-mode roaming data. FIG. 3 is a schematic diagram illustrating a preferred In a possible embodiment of the invention, the common roaming list in accordance with one embodiment of the data block carries pointers to or the address of location in the 65 invention; and R-UIM/SIM or the hierarchical tree where the actual pre FIG. 4 is a schematic diagram illustrating use and updat ferred list for a specific access system is stored. For example, ing of the preferred roaming list in a roaming mobile device. US 7,349,695 B2 5 6 DESCRIPTION OF THE PREFERRED 4, the mobile equipment ME arriving in the second region EMBODIMENTS Region 2 where the CDMA network NW3 causes a base station BTS2 to transmit a broadcast message 20 identifying FIG. 2 is a schematic diagram illustrating the principle of the system and network parameters to all users in the region; a user roaming between networks. A mobile device is 5 in the case of CDMA these are SID/NID pairs for the referred to in the following as a mobile equipment ME and available CDMA systems. The mobile equipment compares is illustrated located in a first region, Region 1 and in this with data in the common PRL data block 4 and identifies communication with a first network NW1 over a radio link the preferred access technology and system. This compari RL. As is well know, the radio link constitutes a physical son is done by appropriate client software at the mobile signalling channel over the air interface between the mobile 10 equipment ME1. Using the pointer to the access technology equipment ME and the network. In this case, the network specific PRL block for the preferred access technology, the that the mobile equipment ME is in communication with is mobile equipment ME can access the PRL corresponding to a CDMA (Code Division Multiplex Access) network, and the preferred access technology, and can then scan that PRL the communication mode for the radio link is CDMA. block for channel acquisition. This is faster than using a However, the Region 1 also supports a second network 15 single large preferred roaming list which combines param NW2, which in the illustrated case is a GSM network. eters for all of the possible access technologies. In GSM So-called multimode mobile devices can operate using dif networks, the base station transmits beacon frequencies, and ferent access technologies such as CDMA, GSM, WLAN, the mobile equipment compares the signal strength of any UMTS etc. To this end, they are provided with a wireless beacon frequencies listed in the common PRL block 4 to interface for receiving and transmitting signals according to locate the preferred GSM system, in the case that GSM is each of a plurality of different access technologies Supported preferred or no CDMA network is available. by appropriate client Software operating in the mobile equip Initial provisioning of the PRL in the home network can ment. Different geographical regions can provide one or be done using Internet Protocol (IP) based over-the-air more networks or systems of different access technologies, device management (IOTA-DM) or over-the-air service pro though in any particular region it is likely that one of the 25 visioning/parameter administration (OTASP/OTAPA) pro networks or systems will be preferred. tocols, depending on the chosen method and in particular When the mobile equipment ME moves to a second whether the data is to be supplied via an IP-based protocol region, Region 2, that region similarly provides more than in data bursts or using pure air-interface signalling in the one network with different access technologies (NW3 home network. Alternatively, initial provisioning can be CDMA, NW4-GSM). In Region 2, the mobile equipment 30 implemented through the manufacturing or distribution pro ME needs to determine which would be the preferred access cess by placing roaming information and parameters onto technology for that particular region. devices such as SIM cards or R-UIMs at the time of As is well known, the mobile equipment includes a manufacture. At the time of the initial provisioning, common memory 2. Amongst other things, the memory 2 stores a parameters are stored in the common data PRL block 4 so preferred roaming list PRL. In some types of mobile equip 35 that these parameters (related to the roaming list in multi ment ME, a replaceable user identity module (R-UIM) is mode operation) can be accessed regardless of the access used to store the preferred roaming list PRL instead of the technology. memory 2. Although in many cases the mobile equipment is Management of the preferred roaming list PRL is carried a mobile telephone, it will be appreciated that other types of out in the following way. Effective roaming requires up-to mobile equipment can be utilised, in particular a mobile 40 date management of the PRLs when carrier and user pref computer. erences change. FIG. 3 illustrates the structure of the preferred roaming Management of roaming lists is effected using a manage list which is stored at the mobile equipment ME. The ment server (MS) in the network. preferred roaming list PRL illustrated in FIG. 3 has a As explained above, the PRL initially provisioned in the common PRL data block 4 which stores preferences regard 45 home network enables the mobile equipment ME to select a ing which access technology and system is preferred in a preferred access technology for the region where it is given region. For example, the common PRL data block 4 located. After the preferred access technology has been can include preferences for geographical regions, for selected, a device information tree at the mobile equipment example CDMA can be the first preference for the first ME is updated with the “current mode’ parameter cmp. As region Region 1. The common PRL block 4 can also store 50 illustrated in FIG. 4, a notification message 22 is sent any other parameters common to the different access tech according to a communication mode using the selected nologies. Such parameters can include, for example, loca access technology from an OTA management client 18 in the tion of the provisioning server or security parameters. mobile equipment ME to the management server MS in the The PRL illustrated in FIG. 3 also has a set of access geographical region where the mobile equipment is now technology specific PRL blocks including a CDMA PRL 55 located, the notification message 22 including current mode block 6, a GSM PRL block 8, and a PRL block 10 for other parameters