US006243581B1
`(10) Patent No.
`a2) United States Patent
`US 6,243,581 B1
`Jawanda
`(45) Date of Patent:
`Jun. 5, 2001
`
`
`(54) METHOD AND SYSTEM FOR SEAMLESS
`ROAMING BETWEEN WIRELESS
`COMMUNICATION NETWORKSWITH A
`MOBILE TERMINAL
`Inventor:
`Jastinder Jawanda, Plano, TX (US)
`(75)
`(73) Assignee: Nortel Networks Limited, Montreal
`(CA)
`
`(*) Notice:
`
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`US.C. 154(b) by 0 days.
`
`(21) Appl. No.: 09/209,581
`.
`Filed:
`(22)
`Dec. 11, 1998
`(51)
`Int. C17 oe H04Q 7/20; H04Q 7/24;
`HO4L 12/28; HO4L 12/56
`(52) US. Ch. eessnessenene 455/432; 455/437; 455/557;
`370/338; 370/401; 370/913
`(58) Field of Search 0... 455/466, 426,
`455/432, 436, 442, 550, 556, 557, 437
`440. 11 re 370315. 323, 331, 332, 338.
`349, 401, 913
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`5,457,680 * 10/1995 Kamm et al. cesses 455/432 x
`5,600,707 *
`2/1997 Miller, II ...........
`we 455/434
`
`8/1998 Seazholtz et al. eee 455/432
`5,790,952 *
`
`5,796,727 *
`8/1998 Harrison et al. wo. 370/338
`5,878,343 *
`3/1999 Robert et al. we 455/424
`
`oerar : sw/1900 siesrrseeeeneennnrenseraneenan;seusx
`
`chaefers .....
`.
`3961,
`*
`
`4/2000 Persson et al. wees 455/433
`6,052,589 *
`* cited by examiner
`
`Primary Examiner—Iracy Legree
`(74) Attorney, Agent, or Firm—Bruce E. Garlick; James A.
`Harrison
`(57)
`
`ABSTRACT
`
`A mobile computer system capable of seamless roaming
`between wireless communication networks includes data
`processing resources for executing software, a plurality of
`wireless interfaces that supports simultaneous wireless con-
`nections with first and second wireless communication
`networks, and a network access arbitrator that routes data
`Communicated between the software executed by the data
`processing resources and the first and second wireless com-
`munication networks. ‘To permit seamless roaming, the net-
`work access arbitrator routes the data to the first wireless
`communication network via a first wireless interface and
`then seamlessly reroutes the data to a second wireless
`.
`.
`.
`.
`communication network via a second wireless interface.
`According to one embodiment, the network access arbitrator
`reroutes the data in response to the data bandwidths of the
`connections with the first and second wireless communica-
`«(HOnetworks.
`
`11 Claims, 4 Drawing Sheets
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`10
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`12
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`a 34
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`HLR
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`WWAN
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`NSSSiL
`NSS
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`1
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`SAMSUNG 1019
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`SAMSUNG 1019
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`1
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`

`

`U.S. Patent
`
`Jun.5, 2001
`
`Sheet 1 of 4
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`US 6,243,581 B1
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`24
`
`12
`
`WLAN
`
`=
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`WLAN-G
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`IWFH 8
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`22
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`WWAN
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`10
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`2
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`

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`Sheet 2 of 4
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`US 6,243,581 B1
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`JOIAIGONILNIEd=f
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`Jun. 5, 2001
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`

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`U.S. Patent
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`d/|NVIM
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`Sheet 3 of 4
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`US 6,243,581 B1
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`Jun. 5, 2001
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`¢‘Pry
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`4
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`

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`U.S. Patent
`
`Jun.5, 2001
`
`Sheet 4 of 4
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`US 6,243,581 B1
`
`ESTABLISH WIRELESS
`
`DATA CONNECTION WITH
`WWANVIA MOBILE PHONE
`
`102
`
`BEGIN
`
`100
`
`(108
`NO
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`
`
`
`
`
` TRANSFER DATAGRAMS
`
`
`BETWEEN MOBILE TERMINAL
`
` SESSION
`AND WLAN VIA WWAN
`
`TERMINATED ?
`
`
`HIGHER
`BANDWIDTH CONNECTION
`
`
`AVAILABLE ?
`
`
`
`SEAMLESSLY HANDOFF
`
`TRANSFER OF DATAGRAMS
`
`
`FROM WWAN CONNECTION
`ESTABLISH WIRELESS DATA
`
`TO WLAN CONNECTION
`CONNECTION WITH WLAN
`
`
`WHILE OPTIONALLY
`VIA WIRELESS LAN IF
`
`
`CONNECTION IS NOT
`MAINTAINING WWAN
`
`CONNECTION
`ALREADY ACTIVE
`
`
`
`
`
`
`
`
`
`
` TRANSFER DATAGRAMS
`
`
`BETWEEN MOBILE TERMINAL
`
`
`AND WLAN VIA WLAN
`
`
`
`
`SESSION
`INTERFACE
`
`TERMINATED?
`
`TRANSFER ?
`
`
`NEED TO
`HANDOFF DATAGRAM
`
`
`CLOSE ALL ACTIVE DATA
`CONNECTIONS
`
`110
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` ESTABLISH WIRELESS DATA
`Ceo
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`CONNECTION WITH WWAN
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`VIA MOBILE PHONE,IF
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`DATA CONNECTION IS NOT
` 132
`ALREADY ACTIVE
`SEAMLESSLY HANDOFF
`TRANSFER OF DATAGRAMS
`
`FROM WLAN CONNECTION
`
`TO WWAN CONNECTION
`
`WHILE OPTIONALLY
`
`
` Fig. 4
`MAINTAINING WLAN
`
`
`CONNECTION
`
`
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`5
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`

`

`US 6,243,581 B1
`
`1
`METHOD AND SYSTEM FOR SEAMLESS
`ROAMING BETWEEN WIRELESS
`COMMUNICATION NETWORKS WITH A
`MOBILE TERMINAL
`
`BACKGROUND OF THE INVENTION
`
`1. Technical Field
`
`The present invention relates in general to data commu-
`nication and in particular to a method and system for
`wireless data communication. Still more particularly,
`the
`present invention relates to a method and system for seam-
`less roaming between wireless data communication net-
`works with a mobile terminal.
`
`2. Description of the Related Art
`Connectivity to wired networks continues to experience
`exponential growth. Likewise, recent years have seen rapid
`growth in the market for portable electronic devices, includ-
`ing portable computers and mobile telephones.It is expected
`in view of the growing use of portable electronic devices and
`the pervasive use of wired networks for entertainment,
`communication, and commerce that there will soon be a
`large demand for wireless data access to wired networks
`such as intranets and the Internet and World Wide Web.
`
`Already, some standards have emerged for wireless data
`communication. For example, an overlay technology called
`CDPD (Cellular Digital Packet Data) assigns channels of an
`underlying radio telephony system, for example, an AMPS
`(Advanced Mobile Phone Service) or TDMA (Time Divi-
`sion Multiple Access) system, for wireless data communi-
`cation. In this manner, a user of a portable electronic device
`(e.g., a portable computer) can establish wireless data access
`to the local wireless data network, whichis in turn connected
`by a landline to the target wired network (e.g., the Internet).
`Another technology called GPRS (General Packet Radio
`Service) is integrated into the GSM (Global System for
`Mobile communications) protocol in order to provide wire-
`less data access.
`
`While the mobility of portable computer users is greatly
`enhanced by the availability of wireless data
`communication,
`the mobility of a portable computer is
`currently restricted whenthe user has an active session. That
`is,
`the user cannot move out of the service area of the
`wireless data communication network through which the
`user is connected to the target network without terminating
`the session. Thus, if the portable computer user has initiated
`a time consuming operation such as a download ofa large
`file, the heretofore mobile user must remain within a con-
`fined service area if the operation is to complete success-
`fully.
`it would be desirable to
`As should thus be apparent,
`provide a method and system for data communication that
`permit a portable computer user to move outside the service
`area of a wireless data communication network through
`which a connection to a computer network is established
`without terminating an active session.
`SUMMARYOF THE INVENTION
`
`In accordance with the present invention, a mobile com-
`puter system capable of seamless roaming between wireless
`communication networks includes data processing resources
`for executing software, a plurality of wireless interfaces that
`supports simultaneous wireless connections with first and
`second wireless communication networks, and a network
`accessarbitrator that routes data communicated between the
`
`software executed by the data processing resources and the
`
`2
`first and second wireless communication networks. To per-
`mit seamless roaming, the network access arbitrator routes
`the data to the first wireless communication network via a
`
`first wireless interface and then seamlessly reroutes the data
`to a second wireless communication network via a second
`
`wireless interface. According to one embodiment, the net-
`work access arbitrator reroutes the data in response to the
`data bandwidths of the connections with the first and second
`wireless communication networks.
`
`All objects, features, and advantages of the present inven-
`tion will become apparent in the following detailed written
`description.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The novel features believed characteristic of the invention
`
`are set forth in the appended claims. The invention itself
`however, as well as a preferred modeof use, further objects
`and advantagesthereof, will best be understood by reference
`to the following detailed description of an illustrative
`embodiment when read in conjunction with the accompa-
`nying drawings, wherein:
`FIG. 1 depicts an illustrative embodiment of a wireless
`data communication environment in accordance with the
`
`present invention;
`FIG. 2 is a more detailed block diagram of the mobile
`terminal shown in FIG. 1;
`FIG. 3 is a data flow diagram illustrating the interrela-
`tionship of the software utilized to implement the present
`invention in a preferred embodiment; and
`FIG. 4 is a high level logical flowchart depicting a method
`of wireless data communication in which a data communi-
`
`cation session is seamlessly handed off between wireless
`data communication networks.
`
`DETAILED DESCRIPTION OF ILLUSTRATIVE
`EMBODIMENT
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`With reference now to the figures and in particular with
`reference to FIG. 1, there is depicted an illustrative embodi-
`ment of a wireless data communication environment
`in
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`invention may advantageously be
`which the present
`employed. The wireless data communication environment
`shown in FIG. 1 includes a wireless wide area network
`(WWAN)10 and a wireless local area network (WLAN) 12
`coupled by an external network 13, which may comprise, for
`example, the Internet or a public switched telephone net-
`work (PSTN).
`WLAN 12, which may form, for example, the intranet of
`a business, has at least one wireless network adapter 20, a
`wireless LAN gateway (WLAN-G) 22, and one or more
`fixed terminals 24 that are all interconnected by a conven-
`tional (e.g., Ethernet) network. Wireless LAN gateway 22
`forms the demarcation point of WLAN 12 and performsall
`necessary protocol conversions so that entities within
`WLAN 12 can communicate with entities coupled to exter-
`nal network 13. As discussed further herein below, data-
`grams are preferably communicated between WWAN 10
`and WLAN 12 across external network 13 utilizing the
`mobile internet protocol (IP) described in detail in Perkins,
`C., “IP Mobility Standard,” RFC 2002, October 1996 avail-
`able from the Internet Engineering Task Force (IETF) and
`incorporated herein by reference. Wireless network adapter
`20 is in all respects like the conventional network adapter
`cards utilized to interface fixed terminals 24 to WLAN 12,
`except that one or more mobile terminals 14 can obtain a
`high bandwidth wireless connection to WLAN 12 via wire-
`less network adapter 20.
`6
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`6
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`

`

`US 6,243,581 B1
`
`3
`As further illustrated in FIG. 1, WWAN 10 is a cellular
`communication system that can be utilized for both voice
`and data communication. For example, WWAN 10 includes
`a base station 30, which transmits wireless signals to and
`receives wireless signals from one or more mobile phones
`16. For data connections, such wireless signals can be
`transmitted according to any currently available or future
`wireless data protocol such as code division multiple access
`(CDMA), CDPD, or GPRS. Base station 30 is further
`coupled to a network subsystem (NSS) 32, which in the
`illustrative embodimentis implemented as a single computer
`system that executes software performing the conventional
`functions of a base transceiver station (BTS), a base station
`controller (BSC), and a mobile switching center (MSC).
`NSS 32 is in turn coupled to home location register 34,
`whichis a database storing information related to the voice
`connection services provided to mobile phones 16 having
`WWAN 10 as their home communication network.
`In
`addition, NSS 32 is coupled by interworking function (TWF)
`36 to a wireless network gateway (WNG) 38 that connects
`WWAN 10 to external network 13. IWF 36 contains a
`database storing information related to the data connection
`services that WWAN 10 will provide to mobile phones 16
`having WWAN 10 as their home communication network.
`WNG 38 performs both routing and protocol conversion
`functions for datagrams transmitted between external net-
`work 13 and WWAN 10.
`
`there is illustrated a more
`Referring now to FIG. 2,
`detailed block diagram of mobile terminal 14. As shown,
`mobile terminal 14 has a system bus 50 connected to a
`central processing unit (CPU) 52, which executes software
`instructions and controls the operation of mobile terminal
`14. A read-only memory (ROM) 54 and dynamic random
`access memory (DRAM) 56 are also connected to system
`bus 50 in order to provide storage for data and instructions
`that may be accessed by CPU 52. System bus 50 is further
`coupled to PCI local bus 60 via Peripheral Component
`Interconnect (PCI) host bridge 62. PCI host bridge 62
`provides both a low latency path through which CPU 52 may
`directly access PCI devices mapped to bus memory and/or
`I/O address spaces and a high bandwidth path through which
`PCI devices may directly access DRAM 56.
`The PCI devices connected to PCI local bus 60 include a
`wireless LAN adapter 64, which handles network commu-
`nication between mobile terminal 14 and WLAN 12, and a
`PCI-compatible audio controller 66 and graphics controller
`68, which drive speaker(s) 70 and flat-panel display 72,
`respectively. PCI bus 60 is further coupled to an expansion
`bus 74 via expansion bus bridge 76. Coupled to expansion
`bus 74 is an input/output (I/O) adapter 78, which provides an
`interface to mobile terminal 14 for both conventional input
`devices, such as a keyboard and pointing device, and mobile
`phone 16. The link connecting mobile phone 16 and I/O
`adapter 78 may be a conventional RS-232 connection, for
`example. A hard disk 80 for providing non-volatile storage
`for software and data is also be connected to expansion bus
`74. In a preferred embodimentof the present invention, the
`software stored on hard disk 80 includes operating system,
`application, and communication software, as discussed
`below in greater detail with respect to FIG. 3. Of course, in
`other embodiments of mobile terminal 14, such communi-
`cation software may be encoded within other computer
`usable media, including both transmission media (e.g., com-
`puter and telephone networks) and storage media (e.g.,
`floppy disks and CD-ROMs).
`With reference now to FIG. 3, there is depicted a data flow
`diagram illustrating the relationship between the various
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`4
`software components utilized to facilitate data communica-
`tion in accordance with the present invention. As illustrated,
`a first application 90 is executed by mobile terminal 14, and
`a second application 91 is executed by fixed terminal 24 of
`WLAN 12. Applications 90 and 91, which may be the same
`or different applications, are compatible in the sense that
`data can be shared between applications 90 and 91 via
`program-to-program transfer. In addition to application 90,
`mobile terminal 14 executes communication software
`
`including network access arbitrator 92, cellular access inter-
`face (CAT) 94 and WLAN interface 96. As discussed further
`below, network access arbitrator 92 routes datagrams output
`by application 90 to either CAI 94 or WLAN interface 96
`and transfers datagrams received from CAI 94 and WLAN
`interface 96 to application 90. CAI 94 and WLAN interface
`96 form the lowest level of the communication software and
`
`provide software support within mobile terminal 14 for data
`transfer with CAI 94 executed by WNG 38 and WLAN
`interface 96 executed by WLAN-G 22,respectively.
`Referring now to FIG. 4, there is depicted a high level
`logical flowchart of a method of wireless data communica-
`tion in which a data communication session is seamlessly
`handed off between wireless data communication networks.
`
`For illustrative purposes, the process will be described with
`respect to an exemplary processing scenario in which the
`service area of WWAN 10 includes a business premises or
`campus housing WLAN 12 and in which a user of mobile
`terminal 14 travels from a location distant from WLAN 12
`into the service area of WLAN 12 andthen returns to the
`remote location.
`
`As illustrated, the process begins at block 100 and there-
`after proceeds to block 102, which illustrates mobile termi-
`nal 14 first establishing a wireless data connection with
`WWAN 10 via mobile phone 16 while located outside the
`service area of WLAN 12. The wireless data connection to
`
`WWAN 10 can be established, for example, as part of the
`power-on procedures of mobile terminal 14 or in response to
`a user input while interacting with application 90. In any
`event, a signal is transmitted via I/O adapter 78 to mobile
`phone 16, which responds to the signal by establishing the
`wireless data connection utilizing a conventional technique,
`for example, by requesting a connection from the MSC
`within NSS 32 using a message transmitted to base station
`30 via a control channel. As indicated at block 104, data-
`grams may thereafter be transferred between application 90
`executed by mobile terminal 14 and application 91 executed
`by a fixed terminal 24 within WLAN 12. As discussed above
`with respect to FIG. 3, at the higher layers of connectivity
`the outward-bound datagrams are passed from application
`90 to network access arbitrator 92, which routes the data-
`grams to CAI 94. CAI 94 transmits the datagrams via I/O
`adapter 78, mobile phone 16, base station 30, NSS 32 and
`IWF36 to the CAI 94 executed by WNG 38. The CAI 94
`executed by WNG 38 in turn transmits the datagrams to
`WLAN-G 22utilizing the mobile IP protocol. In response to
`receipt of datagrams by WLAN-G 22, WLAN-G 22 converts
`the datagramsto the appropriate protocol for WLAN 12 and
`forwards them to the fixed terminal 24 executing application
`91. Datagrams transmitted from application 91 to applica-
`tion 90 follows the reverse data path.
`As depicted at block 106, a determination can be madeat
`any time following block 102 whether or not a higher
`bandwidth data connection is available. The determination
`
`illustrated at block 106 can be made by WLAN interface 96,
`for example, which may periodically poll
`to determine
`whether a connection can be obtained directly with WLAN
`12 via wireless network adapter 20. This polling behavior
`7
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`

`

`US 6,243,581 B1
`
`5
`may entail WLAN interface 96 periodically determining
`whether an “advertisement” message has been received by
`wireless LAN adapter 64 from wireless network adapter 20.
`Alternatively, and less preferably since mobile terminal 14
`is typically powered by a limited life battery, the determi-
`nation illustrated at block 106 can represent WLAN inter-
`face 96 detecting whether an “advertisement” message
`transmitted by wireless LAN adapter 64 has received a
`response from WLAN interface 96. If a determination is
`madeat block 106 that no higher bandwidth data connection
`is available, the process passes to block 108, which illus-
`trates a determination of whetheror not the session has been
`terminated by the user or by application 90. If not,
`the
`process simply returns to block 104, which has been
`described.If, however, a determination is made at block 108
`that the session has been terminated, the process passes to
`block 110, which illustrates network access arbitrator 92
`terminating all active wireless data connections. The process
`then ends at block 150.
`
`Returning to block 106, in response to a determination
`that a higher bandwidth data connection (i.e., a direct
`connection to WLAN via wireless network adapter 20) is
`available, for example, due to mobile terminal 14 being
`moved into the service area of WLAN 12,
`the process
`proceedsto block 120. Block 120 depicts mobile terminal 14
`establishing a second wireless data connection by logging on
`to WLAN 12 via wireless network adapter 20. To logon to
`WLAN 12, mobile terminal 14 performs the conventional
`registration procedures dictated by the network and followed
`by fixed terminals 24, except
`that
`logon information is
`conveyed between mobile terminal 14 and wireless LAN
`adapter 64 by wireless communication. Thus, following
`block 120, the user has concurrent wireless data connections
`with both WWAN 10 and WLAN 12. Then, as depicted at
`block 122, network access arbitrator 92 causes the transfer
`of datagrams to be seamlessly handed off from the wireless
`connection with WWAN 10 to the wireless connection with
`
`WLAN 12 while maintaining the session between applica-
`tions 90 and 91. Thus, following block 122, datagrams are
`routed between application 90 and application 91 utilizing
`the higher bandwidth data path between WLAN interfaces
`96 rather than between CAIs 94, as shownat block 124.
`Next, as illustrated at block 126, network access arbitrator
`92 determines whether or not the transfer of datagrams
`should be handed off to the connection with WWAN 190,for
`example, in response to mobile terminal 14 being moved out
`of range of WLAN 12 due to the user leaving the business
`premises housing WLAN 12. The determination made at
`block 126 can be based on one or morefactors, including the
`numberof transmission errors detected by WLAN interface
`96 and the received signal strength (RSS) ofsignals received
`by wireless LAN adapter 64. In response to a determination
`at block 126 that the transfer of datagrams should not be
`handedoff, the process passes to block 128, whichillustrates
`a determination of whetheror not the user or application 90
`has terminated the session with application 91. If so, net-
`work access arbitrator 94 closes all active wireless data
`connections at block 110, and the process ends at block 150.
`If, on the other hand, a determination is made at block 128
`that the session has not been terminated, the process returns
`to block 124, which has been described.
`Returning to block 126, in response to a determination by
`network access arbitrator 92 that the transfer of datagrams
`should be handedoff, the process passes to block 130. Block
`130 illustrates network access arbitrator 92 causing a wire-
`less data connection to be reestablished with WWAN 10 in
`
`the manner described above with respect to block 102, if
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`such a connection is not already active. Thereafter, network
`access arbitrator 92 reroutes the flow of datagrams from
`WLAN interface 96 to CAI 94. As indicated at block 132,
`the data wireless connection with WLAN 12 can thereafter
`optionally be maintained, if possible, until such time as the
`condition that prompted the handoff is no longer present and
`datagram transfer can again be handed off to the high
`bandwidth connection with WLAN 12. The processillus-
`trated in FIG. 4 then returns to block 104, which has been
`described.
`
`As has been described, the present invention provides an
`improved method and system for wireless data communi-
`cation in which the transfer of datagrams may be seamlessly
`handed off between multiple concurrent wireless data con-
`nections while maintaining an application-level session.
`While the invention has been particularly shown and
`described with reference to a preferred embodiment, it will
`be understood by those skilled in the art that various changes
`in form and detail may be made therein without departing
`from the spirit and scope of the invention.
`Whatis claimedis:
`1. A mobile computer terminal, comprising:
`data processing resources for executing software;
`a first wireless interface directly coupled to the data
`processing resources that interfaces the mobile com-
`puter terminal to a cellular wireless communication
`network;
`a second wireless interface directly coupled to the data
`processing resources that interfaces the mobile com-
`puter terminal to a wireless local area network;
`a network accessarbitrator that routes data communicated
`between said software executed by said data processing
`resources andthe cellular wireless communication net-
`work via the first wireless interface; and
`wherein the network access arbitrator seamlessly hand-off
`said data from said cellular wireless communication
`network via the first wireless interface to the wireless
`local area network via the second wireless interface in
`
`response to said mobile computer terminal having a
`higher bandwidth connection to the wireless local area
`network than to the cellular wireless network.
`2. The mobile computer terminal of claim 1, wherein:
`the network access arbitrator interfaces with the first
`
`wireless interface to setup a communication with the
`cellular wireless communication network;
`the network access arbitrator interfaces with the second
`
`wireless interface to setup a communication with the
`wireless local area network; and
`wherein the setup of the communication with the cellular
`wireless communication network is distinct and sepa-
`rate from the setup of the communication with the
`wireless local area network.
`3. The mobile computer terminal of claim 1, and further
`comprising data storage that stores said software.
`4. The mobile computer terminal of claim 1, wherein the
`first wireless interface includes a mobile telephone in data
`communication with the cellular wireless communication
`network.
`
`5. The mobile computer terminal of claim 1, wherein:
`the first wireless interface comprises a cellular telephone
`coupled to an input/output adapter of the mobile com-
`puter terminal; and
`the second wireless interface comprises a wireless net-
`work adapter coupled to a local bus of the mobile
`computer terminal.
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`US 6,243,581 B1
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`7
`6. A method of wireless data communication within a
`mobile computer terminal, said method comprising:
`establishing a wireless connection with a cellular wireless
`communication network via a first wireless interface
`directly coupled to the mobile computer terminal;
`establishing a wireless connection with a wireless local
`area network via a second wireless interface directly
`coupled to the mobile computer terminal, the wireless
`connection with the local area network enabled con-
`
`currently with the wireless connection with the cellular
`wireless communication network;
`routing data between the mobile computer system and the
`cellular wireless communication network via the first
`wireless interface; and
`seamlessly handing-off data from the cellular wireless
`communication network via the first wireless interface
`to the wireless local area network via the second
`
`wireless interface in response to said mobile computer
`terminal having a higher bandwidth connection to the
`wireless local area network than to the cellular wireless
`network.
`7. The method of claim 6, wherein the setup of the
`wireless connection with the cellular wireless communica-
`tion network is distinct and separate from the setup of the
`wireless connection with the wireless local area network.
`8. The method of claim 6, and further comprising execut-
`ing software within said mobile computer terminal
`that
`communicates with both the cellular wireless communica-
`tion network and the wireless local area network.
`
`9. The method of claim 6, and further comprising com-
`municating said data between said mobile computer terminal
`and the cellular wireless communication network utilizing a
`mobile telephone connected to said mobile computer termi-
`nal as the first wireless interface.
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`8
`10. The method of claim 6, and further comprising
`communicating said data between said mobile computer
`terminal and the wireless local area network utilizing a
`wireless network adapter as the second wireless interface.
`11. A computer usable medium that stores a plurality of
`software instructions for execution by a mobile computer
`terminal to support seamless roaming of a mobile computer
`terminal between wireless communication networks, said
`computer usable medium comprising:
`a plurality of instructions that are executable by the
`mobile computer terminal
`to support simultaneous
`wireless connections between the mobile computer
`terminal and a cellular wireless communication net-
`
`work via a first wireless interface directly coupled to
`the mobile computer terminal and a wireless local area
`network via a second wireless interface directly
`coupled to the mobile computer terminal;
`a plurality of instructions that are executable by a network
`access arbitrator of the mobile computer terminal to
`cause the network access arbitrator to route data com-
`
`municated between the mobile computer terminal and
`the cellular wireless communication network and the
`wireless local area network, wherein said network
`access arbitrator routes said data to the cellular wireless
`communication networkvia the first wireless interface;
`and
`
`wherein the network access arbitrator seamlessly hand-off
`said data from said cellular wireless communication
`network via the first wireless interface to the wireless
`local area network via the second wireless interface in
`
`response to said mobile computer terminal having a
`higher bandwidth connection to the wireless local area
`network than to the cellular wireless network.
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