Ulllted States Patent [19]
`La Porta et al.
`
`US006081715A
`[11] Patent Number:
`[45] Date of Patent:
`
`6,081,715
`Jun. 27, 2000
`
`[54] METHOD AND SYSTEM FOR DISTRIBUTED
`CONTROL IN WIRELESS CELLULAR AND
`PERSONAL COMMUNICATION SYSTEMS
`
`.
`[75] Inventors‘ ghYolttliil?‘alc‘gaggg? igtilrltt‘eveood’
`' "
`_
`J >
`Matavtfan; Malathl Veeraraghavam
`Atlantlc Hlghlandsa both of N1
`
`[73] Assignee: Lucent Technologies Inc., Murray Hill,
`
`N.J.
`
`0 512 962 A2 11/1992 European Pat. Off. ....... .. H04Q 7/04
`0 546 758 A2 6/1993 European Pat. Off. ....... .. H04Q 7/04
`0 562 374 9/1993 European Pat. Off.
`H04Q 7/04
`2 243 976 11/1991 United Kingdom ........... .. H04Q 7/04
`2 273 424 6/1994 United Kingdom ........... .. H04Q 7/04
`2 275 389
`8/1994 United Kingdom
`. H04Q 11/04
`2 309 607 7/1997 United Kingdom
`. H04B 10/18
`92/13428 8/1992 WIPO ..................... .. H04Q 7/04
`93/06685
`4/1993 WIPO
`H04M 11/00
`
`94/01978
`
`94/05129
`
`1/1994 WIPO . . . . .
`
`3/1994 WIPO
`
`. . . . . .. H04Q 7/04
`
`H04Q 7/04
`
`95/04420 2/1995 WIPO . . . . .
`. . . .. H04L 12/56
`95/14343
`5/1995 WIPO ......................... .. H04M 11/00
`
`[21] Appl. No.: 08/819,929
`[22]
`Filed:
`Mar.18, 1997
`
`Related US. Application Data
`
`Primary Examiner—Wellington Chin
`Assistant Examiner—Keith Ferguson
`
`[57]
`
`ABSTRACT
`
`[62] Division of application No. 08/324,427, Oct. 17, 1994.
`
`[51] Int. Cl.7 .............................. .. H04Q 7/20; H04Q 7/22
`[52] US. Cl. ........................ .. 455/445; 455/445; 455/432;
`455/433; 455/434; 455/435; 370/312; 370/331;
`370/338; 370/390
`[58] Field of Search ................................... .. 455/445, 432,
`455/433, 434, 435, 436, 437, 438, 439,
`440, 441, 442, 550, 561, 552, 422; 370/312,
`331, 338, 390, 396, 522
`
`[56]
`
`References Clted
`UASA PATENT DOCUMENTS
`
`5,408,419
`5’497’412
`5,528,583
`5,539,744
`
`4/1995 Wong .................................... .. 455/436
`3/1996 Lannen et a1‘
`455/432
`6/1996 Acampora et al.
`455/436
`7/1996 Chu et al. ............................. .. 455/422
`
`FOREIGN PATENT DOCUMENTS
`0 369 535 A2 5/1990 European Pat. Off. ....... .. H04Q 7/04
`0 426 269 A1 5/1991 European Pat. Off. ....... .. H04Q 7/04
`0 475 865 A2 3/1992 European Pat. Off. ....... .. H04Q 7/04
`
`A system for distributed control in wireless cellular and
`personal communication systems includes separate servers
`for performing call control and connection control functions,
`thereby obviating the need for a mobile switching or other
`switch to be anchored for the duration of a call. During a
`registration procedure, visiting location servers track only
`roaming mobiles, rather than tracking both roaming mobiles
`as well as mobiles located in their home network. Direct
`signalling links between servers and base stations, or other
`servers, located in different networks allow roaming mobiles
`to contact their home networks for service at all times,
`thereby obviating the need for passing signalling informa
`tion for mobiles when they are not involved in a call. The use
`of multicast signalling with asynchronous transfer mode
`Switches, permits Speci?ed Channel Control functions to take
`place concurrently in channel servers associated with base
`.
`.
`Statton and swttches that form a Segment of the route for a
`call. Similarly, speci?ed call control functions are performed
`concurrently with mobile location functions, thereby
`decreasmg the delays “1 Settmg up a can‘
`
`17 Claims, 12 Drawing Sheets
`
`MOBILE GENERATES
`200’ REGISTRATION MESSAGE
`I
`205/ BASE STATION RECEIVES
`REGISTRATION MESSAGE
`
`210
`
`IS
`MOBILE LOCATED
`IN ITS HOME
`NETWORK 7
`
`FORWARD REGISTRATION
`230/ INFORMATION TO MOBILE‘S
`VISITOR LOCATION SERVER
`
`FORWARD REGISTRATION
`220/ INFORMATION TO MOBILE‘S
`HOME LOCATION SERVER
`
`DOES
`REGISTRATION
`
`225
`
`STORE MOBILE
`CLUSTER MAPPING
`
`245
`
`FORWARD REGISTRATION
`250 INFORMATION TO MOBILE'S
`HOME LOCATION SERVER
`
`STORE NETWORK
`IDENTIFIER AND VISITOR
`LOCATION SERVER
`255 ~"
`CORRESPONDING TO
`MOBILE LOCATION
`
`Bright House Networks - Ex. 1044, Page 1
`
`

`
`Bright House Networks - Ex. 1044, Page 2
`
`

`
`U.S. Patent
`
`Jun. 27, 2000
`
`Sheet 2 0f 12
`
`6,081,715
`
`MOBILE GENERATES
`200 “
`REGISTRATION MESSAGE
`I
`205 _/_ BASE STATION RECEIVES
`REGISTRATION MESSAGE
`
`210
`
`IS
`MOBILE LOCATED
`IN ITS HOME
`NETWORK '?
`
`V
`FORWARD REGISTRATION
`INFORMATION TO MOBILE'S
`230-’
`VISITOR LOCATION SERVER
`
`240
`
`DOES
`REGISTRATION
`MESSAGE INDICATE
`CLUSTER
`CHANGE '?
`
`YES
`
`V
`
`FORWARD REGISTRATION
`INFORMATION TO MOBILE’S
`220 -’
`HOME LOCATION SERVER
`I
`STORE MOBILE
`225 -’
`CLUSTER MAPPING
`
`NO
`
`STORE MOBILE
`CLUSTER MAPPING
`
`FORWARD REGISTRATION
`INFORMATION TO MOBILE'S
`250'”
`HOME LOCATION SERVER
`I
`STORE NETWORK
`IDENTIFIER AND VISITOR
`LOCATION SERVER
`255 ~"
`CORRESPONDING TO
`MOBILE LOCATION
`
`FIG. 2
`
`Bright House Networks - Ex. 1044, Page 3
`
`

`
`U.S. Patent
`
`Jun. 27,2000
`
`Sheet 3 0f 12
`
`6,081,715
`
`CALLING END SYSTEM
`GENERATES CALL
`300.,
`ORIGINATION MESSAGE
`III
`305/. BASE STATION RECEIVES
`CALL ORIGINATION MESSAGE
`
`310
`
`IS
`CALLING END
`SYSTEM A
`MOBILE '2
`YES
`
`FIG. 3
`
`i015
`SEND SETUP CALL
`MESSAGE TO CALL
`sERvER IN BASE
`STATION’S CLusTER
`
`NO
`
`Is
`CALLING
`MOBILE LOCATED
`IN ITS HOME
`NETWORK ?
`
`320
`
`YES
`
`325
`,
`I
`SEND SETUP CALL
`MESSAGE TO CALL
`sERvER IN BASE
`STATION’S CLUSTER
`
`330
`/
`,
`SEND SETUP CALL
`AND UPDATE MESSAGES
`TO ROAMER CALL
`sERvER IN MOBILE’S
`HOME NETWORK
`
`335
`\
`sTORE MOBILE-TO
`_ CALL sERvER MAPPING
`IN BASE STATION FOR
`CALLING MOBILE
`
`Bright House Networks - Ex. 1044, Page 4
`
`

`
`Bright House Networks - Ex. 1044, Page 5
`
`

`
`U.S. Patent
`
`Jun. 27,2000
`
`Sheet 5 0f 12
`
`6,081,715
`
`CALL sERvER FDR CALLING END SYSTEM
`500/ SENDS A FIND REQUEST TO HOME
`LOCATION sERvER FoR CALLED MOBILE
`+
`J HOME LOCATION SERVER FOR CALLED
`505
`MOBILE RECEIvEs FIND REQUEST
`
`507
`
`IS
`CALLED MOBILE
`LOCATED IN ITS HOME
`NETWORK ?
`
`T0 FIG- 5B
`
`HOME LOCATION SERVER
`FOR CALLED MOBILE SENDS
`A FIND RESPONSE
`(SPECIFYING THE CALL
`520, SERVER, CONNECTION
`SERVER AND GATEWAY
`SWITCH FOR THE CALLED
`MOBILE) TO THE CALL
`SERVER FOR THE
`CALLING END SYSTEM
`
`HOME LOCATION SERVER FOR
`CALLED MOBILE SENDS PAGE
`522 _,4 REQUEST AND UPDATE MESSAGE
`TO ALL BASE STATIONS IN THE
`CLUSTER IN WHICH CALLED
`MOBILE IS LOCATED
`I
`EACI-I BASE STATION IN
`, THE CLUSTER GENERATES
`523' PAGE ORDER TO LOCATE
`THE CALLED MOBILE
`I
`IF A BASE STATION RECEIvEs
`PAGE RESPONSE, lT SENDS
`PAGE REsPoNsE TO HOME
`524 / LOCATION sERvER AND
`STORES MOBILE-TO-CALL
`sERvER MAPPING FoR THE
`CALLED MOBILE
`I
`HOME LOCATION SERVER FOR
`CALLED MOBILE SENDS AN
`526 -/ UPDATE MESSAGE TO THE
`CONNECTION SERVER FOR
`THE CALLED MOBILE
`
`521
`/
`I
`COMMUNICATE WITH CALL
`SERVER IDENTIFIED IN
`STEP 520 TO INVOKE
`IMPLICIT SERVICES FOR
`THE CALLED END SYSTEM
`
`FIG- 5A
`
`Bright House Networks - Ex. 1044, Page 6
`
`

`
`Bright House Networks - Ex. 1044, Page 7
`
`

`
`U.S. Patent
`
`Jun. 27,2000
`
`Sheet 7 0f 12
`
`6,081,715
`
`mw>mmm
`
`EwSEOE
`
`
`
`4.30 \. mvm
`
`/ mom
`
`vEOEwZ
`
`EmFmDJO
`
`Pow
`
`0 .0E
`
`wwo /
`
`E5602
`mzwemoz
`
`Fmm
`\ EMT»
`
`ZOFOwZZOO
`
`:
`
`4
`
`\ Eb
`
`Bright House Networks - Ex. 1044, Page 8
`
`

`
`U.S. Patent
`
`Jun. 27,2000
`
`Sheet 8 0f 12
`
`6,081,715
`
`CONNECTION SERVER RECEIVES A
`700" SETUP CONNECTIONS MESSAGE
`+
`FIND AN
`705 ,
`END-TO-END ROUTE
`I
`y
`CONNECTION SERVER SENDS \
`RESERVE CHANNEL
`MESSAGE TO CHANNEL
`710 / SERVERS ASSOCIATED wITH
`BASE STATIONS AND
`SWITCHES |N THE ROUTE
`AND WITHIN ITS DOMAIN
`I
`CHANNEL SERVERS PERFORM
`712 -/'
`CHANNEL RESERVATION
`FUNCTIONS CONCURRENTLY
`I
`SEND RESERVE CHANNEL
`714 / RESPONSES TO THE
`CONNECTION SERVER
`
`720
`I
`i
`CONNECTION SERVER SENDS
`A RESERVE SEGMENT MESSAGE
`TO THE NEXT CONNECTION
`SERVER IN THE ROUTE
`;,
`F|ND THE SWlTCHES
`REQUIRED TO
`CONNECTION
`ESTABLISH THE
`ADMISSION
`SEGMENT OF
`ROUTINE
`THE ROUTE
`_,_
`I,
`722
`PERFORM THE CONNECTION
`ADMISSION ROUTINE WITH
`RESPECT TO NEXT CONNECTION
`SERVER AND THE ASSOCIATED
`CHANNEL SERVERS
`4'
`
`}
`,
`724
`
`FIG. 7
`
`730 T‘
`
`SEND RESERVE
`726 ’ SEGMENT RESPONSES
`l
`
`T
`ACCEPT
`CONNECTION
`
`CONNECTION SERVER SENDS \
`740 J SETUP TRANSLATION
`MESSAGE TO THE
`CHANNEL SERVERS
`I
`CHANNEL SERVERS PERFORM >COgNE$S|TJ°N
`742 / SETUP TRANSLATION
`ROUTINE
`FUNCTIONS CONCURRENTLY
`+
`SEND SETUP
`744 ’ TRANSLATION RESPONSES }
`
`SEND SETUP SEGMENT
`750 / MESSAGE TO THE NEXT
`CONNECTION SERVER
`IN THE ROUTE
`I,
`PERFORM THE
`CONNECTION
`SETUP ROUTINE
`WITH RESPECT
`TO NEXT
`752 ’
`CONNECTION SERVER
`AND THE
`ASSOCIATED
`CHANNELSERVERS
`i
`SEND SETUP SEGMENT RESPONSE
`754 -’ TO THE CONNECTION SERVER THAT
`SENT THE SETUP SEGMENT MESSAGE
`I
`
`i
`760 A SEND SETUP CONNECTIONS RESPONSE TO
`CALL SERVER FOR THE CALLING END SYSTEM
`
`Bright House Networks - Ex. 1044, Page 9
`
`

`
`Bright House Networks - Ex. 1044, Page 10
`
`

`
`U.S. Patent
`
`Jun. 27, 2000
`
`Sheet 10 0f 12
`
`6,081,715
`
`900 -’
`
`END SYSTEM SENDS A
`RELEASE-ORDER MESSAGE
`+
`BASE STATION SENDS A
`RELEASE-CALL MESSAGE TO
`905 -’
`THE END SYSTEM’S CALL SERVER
`i
`CALL SERVER SENDS RELEASE
`CALL MESSAGES TO OTHER CALL
`910"
`SERVERS INVOLVED IN THE CALL
`
`FIG. 9
`
`ONE OF THE CALL SERVERS SENDS
`A RELEASE-CONNECTION MESSAGE TO
`915-’
`CORRESPONDING CONNECTION SERVER
`
`930
`I
`i
`CONNECTION SERVER SENDS
`DROP-SEGMENT MESSAGE
`TON
`EXT CONNECTION
`SERVER IN THE ROUTE
`I
`PERFORM RELEASE
`CONNECTION ROUTINE
`WITH RESPECT TO
`NEXT CONNECTION
`SERVER AND
`ASSOCIATED
`CHANNEL SERVER
`I
`SEND SEGMENT
`DROPPED RESPONSE TO
`CONNECTION SERVER
`THAT SENT DROP
`SEGMENT MESSAGE
`
`1
`
`920 -’
`
`i
`CONNECTION SERVER SENDS
`DROP-CHANNEL
`MESSAGE TO CHANNEL
`SERVERS IN THE
`SEGMENT OF THE ROUTE
`WITHIN ITS DOMAIN
`I
`CHANNEL SERVERS RELEASE
`922 f
`RESOURCES CONCURRENTLY
`I
`CHANNEL DROPPED
`SENT BY
`924 /‘ RESPONSES
`CHANNEL SERVERS
`
`RELEASE
`CONNECTION
`ROUTINE
`
`I
`
`932 -"
`
`934 -’
`
`V
`SEND CONNECTIONS-RELEASED
`940 -"
`RESPONSE TO CALL SERVER
`
`1021
`
`SWITCH
`
`1012
`
`CURRENT
`BASE STATION
`
`1001-’
`
`NEW
`BASE STATION
`
`Bright House Networks - Ex. 1044, Page 11
`
`

`
`U.S. Patent
`
`Jun. 27,2000
`
`Sheet 11 0f 12
`
`6,081,715
`
`Bright House Networks - Ex. 1044, Page 12
`
`

`
`Bright House Networks - Ex. 1044, Page 13
`
`

`
`1
`METHOD AND SYSTEM FOR DISTRIBUTED
`CONTROL IN WIRELESS CELLULAR AND
`PERSONAL COMMUNICATION SYSTEMS
`
`This is a divisional of copending application(s) Ser. No.
`08/324,427 ?led on Oct. 17, 1994.
`
`FIELD OF THE INVENTION
`
`The present invention relates generally to communication
`systems using wireless cellular and personal communication
`networks, and, in particular, to methods and apparatus for
`distributed control in such networks.
`
`10
`
`BACKGROUND OF THE INVENTION
`
`In current cellular networks, three functions are per
`formed in order to establish a call or connection to a mobile
`unit or mobile in such a network: (1) locating the mobile; (2)
`handling any implicit services to which a user may have
`subscribed; and (3) establishing the connection. These
`functions, may be referred to, respectively, as mobile
`location, call control, and connection control. In some
`networks, authentication functions are also performed.
`During registration of a mobile in current cellular
`networks, a user pro?le is sent from a home network to a
`Visitors’ Location Register (VLR) in the network in which
`the mobile user is currently located. A Mobile Switching
`Center (MSC) then obtains the user’s pro?le from the VLR
`either during registration or during call delivery in order to
`provide signalling services for the mobile user. One disad
`vantage of this technique is that sending the user pro?le
`requires the sharing of competitive information between
`different networks. A second disadvantage is that signalling
`traf?c is generated even when the mobile is not involved in
`a call.
`Also, in typical current cellular networks, the function of
`locating the mobile is performed, in a sequential manner,
`prior to the function of performing call control and estab
`lishing the connection. The sequential nature of current
`procedures leads to long setup delays.
`Finally, in typical current cellular networks, the MSC, is
`required to be an anchor for the duration of the call. The
`MSC thus remains involved for the duration of a call even
`if there exists a more efficient route for the user information
`path.
`
`SUMMARY OF THE INVENTION
`
`The present invention comprises a system and methods
`for distributed control in wireless cellular and personal
`communication systems. The system includes separate serv
`ers for performing call control and connection control
`functions, thereby obviating the need for a mobile switching
`or other switch to be anchored for the duration of a call.
`During a registration procedure, visiting location servers
`track only roaming mobiles, rather than tracking both roam
`ing mobiles as well as mobiles located in their home
`network. Direct signalling links between servers and base
`stations, or other servers, located in different networks allow
`roaming mobiles to contact their home networks for service
`at all times, thereby obviating the need for passing signalling
`information for mobiles when they are not involved in a call.
`The use of multicast signalling with asynchronous transfer
`mode switches, permits speci?ed channel control functions
`to take place concurrently in channel servers associated with
`base station and switches that form a segment of the route
`for a call. Similarly, speci?ed call control functions are
`
`15
`
`25
`
`35
`
`45
`
`55
`
`65
`
`6,081,715
`
`2
`performed concurrently with mobile location functions,
`thereby decreasing the delays in setting up a call.
`The system of the present invention may suitably com
`prise a plurality of networks each of which includes a home
`location server, a visitor location server, a roamer call server,
`and a plurality of clusters. Each cluster may comprise a call
`server, a connection server, a plurality of base stations each
`having a channel server associated with it, a plurality of
`switches each of which has a channel server associated with
`it, and a plurality of signalling transfer points. The system
`also may comprise a plurality of end systems, including a
`plurality of mobiles, where each mobile has a home net
`work.
`Other features and advantages of the present invention
`will be readily apparent by reference to the following
`detailed description and accompanying drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a block diagram illustrating a cluster-based
`multi-network system for the transfer of data or voice.
`FIG. 2 is a How diagram showing the steps of a mobile
`location tracking routine for use in the present invention.
`FIG. 3 is a How diagram illustrating the initial steps of a
`call control routine for a call originating in a mobile.
`FIG. 4 is a How diagram showing further steps in the call
`control routine.
`FIGS. 5A and 5B are a How diagram illustrating in greater
`detail several of the steps of the call control routine and a
`base station location routine.
`FIG. 6 illustrates the use of several direct signalling, links
`used in the call control routine of FIGS. 4 and 5 for a
`roaming mobile according to the principles of the present
`invention.
`FIG. 7 is a How diagram showing the steps of a connection
`establishment routine according to the principles of the
`present invention.
`FIG. 8 illustrates an exemplary route for connecting a call
`from one end system to another end system.
`FIG. 9 is a How diagram showing the steps of a release
`call routine according to the principles of the present inven
`tion.
`FIG. 10 illustrates a handoff routine according to the
`principles of the present invention.
`FIGS. 11A, 11B and 11C show exemplary values of input
`parameters used in an analysis of the system of FIG. 1.
`FIG. 12 shows exemplary resulting values of certain
`parameters based upon the exemplary input values in FIGS.
`11A—11C.
`
`DETAILED DESCRIPTION
`
`FIG. 1 is a block diagram illustrating a cluster-based
`multi-network system 100 for the transfer of data or voice.
`FIG. 1 shows (G+1) networks 101, 102 and 103, each having
`at least one and as many as n clusters, where G and n are
`positive integers. For example, network1 101 has n clusters,
`three of which are labelled clusters 110, 111 and 112. Each
`cluster, such as cluster1 110 has a call server 120, a con
`nection server 130, and a plurality of base stations. For
`example, cluster1 110 has r base stations, two of which are
`labelled in FIG. 1 with reference numbers 150 and 159. In
`FIG. 1, the subscript r is a positive integer. Although only
`one call server 120 and one connection server 130 are shown
`in cluster1 110 of FIG. 110, it should be understood that each
`cluster may have multiple call servers and multiple connec
`
`Bright House Networks - Ex. 1044, Page 14
`
`

`
`3
`tion servers. In any event, each cluster has at least one call
`server and at least one connection server.
`Each cluster, such as the cluster1 110, also has a plurality
`of sWitches for establishing a voice or data path betWeen tWo
`end systems. Cluster1 110, for example, has m sWitches, tWo
`of Which are labelled in FIG. 1 With reference numbers 140
`and 149. In FIG. 1, the subscript m is a positive integer. In
`a preferred embodiment of the present invention the
`sWitches, such as the sWitches 140, 149 are asynchronous
`transfer mode (ATM) sWitches. Alternatively, hoWever, they
`may be synchronous transfer mode (STM) sWitches.
`Within each cluster, such as cluster1 110, there also may
`be one or more end systems, including ?xed and mobile end
`systems. FIG. 1, for example, shoWs s end systems currently
`located Within cluster1 110, Where the subscript 5 is a
`positive integer. Three of the end systems currently located
`in cluster1 110 of netWork1 101 are labelled With reference
`numbers 160, 161 and 169. For exemplary purposes, the end
`systems 160 and 161 are mobile end systems or mobiles,
`such as cellular telephones, and the end system 169 is a ?xed
`end system. Each mobile end system is assigned a home
`netWork, so that, at any given time, a particular mobile end
`system either may be located in its home netWork or may be
`roaming in another netWork. In addition, each mobile is
`assigned an address, Which uniquely identi?es it. The end
`systems, such as the end systems 160, 161 and 169, and the
`base stations, such as the base stations 150, 159, use Wireless
`or Wired transfer of voice or data.
`The transfer of inter-node signalling messages, such as
`messages or signals sent betWeen a base station and a server
`or betWeen servers, takes place via either ATM sWitches,
`Which may by any of the sWitches 140, 141 or 149 imple
`mented as ATM sWitches, or signalling transfer points
`(STPs) 135. Each cluster has a plurality of signalling transfer
`points. The links interconnecting the nodes or servers in
`FIG. 1, such as the servers 120, 130, 170, 180 and 190,
`therefore, may be, for example, connection-oriented ATM
`signalling virtual channel connections (VCCs) or datagram
`oriented links interconnecting servers through routers.
`Additionally, at least some of the signalling links are mul
`ticast signalling links.
`In a preferred embodiment of the present invention,
`provisioned direct signalling or ATM virtual channel con
`nections (VCCs) provide the links betWeen base stations and
`servers in the same netWork, Whereas datagram-oriented
`links are used for the connections betWeen nodes, or servers,
`and base stations located in different netWorks Wherever
`needed. An exception is made for the links from base
`stations and connection servers of one netWork to roamer
`call servers in all other netWorks, in Which case ATM VCCs
`are also used in the preferred embodiment.
`The functions performed by a call server, such as the call
`server 120, are cumulatively referred to as call control. For
`cellular phone and data applications, the call control func
`tions include maintaining a basic call state model for a call,
`de?ned as a communication session involving users and
`servers, and triggering implicit services subscribed to by the
`users in the call. The call control functions also include
`handling multiple connections, or end-to-end user informa
`tion paths, per call, such as multiple audio connections,
`multiple data connections, or a mixture of audio and data
`connections.
`The functions performed by a connection server, such as
`the connection server 130, are cumulatively referred to as
`connection control. The connection control functions
`include ?nding routes to establish an end-to-end connection,
`
`45
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`25
`
`4
`computing end-to-end quality of service measurements for
`the connection, establishing, modifying and releasing
`connections, and handling segments of a connection. A
`segment is de?ned as any part of the connection, in other
`Words, a concatenation of channels.
`Each sWitch, such as the sWitch 140, and each base
`station, such as the base station 150, has an associated
`channel server (not shoWn in FIG. 1). The functions of a
`channel server include managing channels or user informa
`tion links on a physical interface of a base station or sWitch.
`The functions of a channel server further include setting up
`translation tables to enable the proper routing of user infor
`mation across the base station or sWitch With Which the
`channel server is associated. A channel server associated
`With a base station also maps virtual channel identi?ers
`(VCIs) to the next sWitch in the connection to air interface
`resources, such as frequency, time-slot or code, depending
`upon the Wireless access scheme used.
`Each netWork, such as netWork1, also has a roamer call
`server 170, a home location server 180, and a visitor location
`server 190. The functions of the location servers 180 and 190
`include tracking the location of an assigned set of mobile
`users and responding to requests for the location of these
`users. The home location server 180 tracks the cluster for its
`mobiles located in the home netWork and tracks the visiting
`netWork for its mobiles that are roaming. The visitor location
`server 190 tracks the cluster in Which each visiting mobile
`is located, in contrast to existing netWorks, in Which a VLR
`tracks both home and visiting mobiles. The roamer call
`server 170 handles calls for users of netWork1 101 Which are
`roaming or visiting another netWork. Although only one
`roamer call server 170, one home location server 180, and
`one visitor location server 190 are shoWn in cluster1 110 of
`FIG. 1, it should be understood that some netWorks may
`have multiple roamer call servers, home location servers or
`visitor location servers. In any event, each netWork prefer
`ably has at least one roamer call server, at least one home
`location server, and at least one visitor location server.
`The location server responsible for tracking the location
`of a particular mobile is identi?ed by the address of the
`mobile. The call server handling the calls for a mobile
`located in its home netWork and the connection server
`handling the connections for a particular mobile are identi
`?ed by the cluster in Which the mobile is located. The call
`server handling the calls for a mobile visiting another
`netWork is identi?ed by the netWork in Which the mobile is
`visiting. In a preferred embodiment of the present invention,
`the servers 120, 130, 170, 180 and 190 occur in pairs in order
`to increase reliability.
`FIG. 2 is a How diagram shoWing the steps of a mobile
`location tracking routine in accordance With the present
`invention. As shoWn in step 200, a mobile, such as the
`mobile end system 160, generates a registration message
`identifying itself When it turns its poWer on or off, or When
`it changes clusters by moving from one cluster to another
`cluster. Each base station, such as the base station 150,
`periodically transmits a message identifying the cluster in
`Which it is located. These messages transmitted by the base
`stations alloW a mobile to determine When it changes
`clusters. Upon receiving a registration message from a
`mobile as indicated by step 205, a determination is made as
`to Whether the mobile that generated the registration mes
`sage is located in its home netWork, as indicated by 210.
`As shoWn in step 220, if the mobile that generated the
`registration message is in its home netWork, then the base
`station that received the registration message forWards the
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`registration information to the home location server for t hat
`mobile. Next, as indicated in step 225, the home location
`server Would then store information indicating the cluster in
`Which the mobile is currently located by storing the mobile
`to-cluster mapping.
`If on the other hand, the mobile that generated the
`registration message is not located in its home network,
`then, as shoWn in step 230, the base station that received the
`registration message forWards the registration information to
`a visitor location server located in the same netWork as the
`base station and currently tracking the mobile. As indicated
`by 240, the next step depends upon Whether the registration
`message indicates a cluster change, in other Words, that the
`mobile has moved from one cluster to another cluster Within
`the netWork. If the registration message indicates a cluster
`change, then, as shoWn in step 245, the visitor location
`server, to Which the registration information Was forWarded,
`stores the cluster in Which the mobile is currently located by
`storing the mobile-to-cluster mapping. If the registration
`message indicates that the mobile is poWering up or poW
`ering doWn, then, as indicated in step 250, the visitor
`location server that received the registration information
`forWards the registration information to the home location
`server in the mobile’s home netWork. Finally, as shoWn in
`step 255, the home location server in the mobile’s home
`netWork Would store a netWork identi?er and visitor location
`server identi?er corresponding to the location of the mobile.
`The steps illustrated in FIG. 2 thus represent the mobile
`location tracking routine.
`In a preferred embodiment of the present invention, the
`base station that received the registration message from a
`mobile uses bicast signalling VCCs to update both location
`servers in the pair assigned to the mobile. Also, a timer
`based registration occurs in addition to the registration
`procedures explained above. Timer-based registration mes
`sages are generated at a relatively sloW rate, for example
`once each day, and are processed by the visitor location
`servers for roaming mobiles and by the home location
`servers for mobiles located in their respective home net
`Works. If, for example, a visitor location server does not
`receive a timer-based registration from a mobile that previ
`ously Was roaming Within its domain, it deletes the entry for
`the previously registered mobile. This timer-based registra
`tion procedure obviates the need for a registration cancel
`lation procedure from the home location server to a previous
`visitor location server, as is presently done in the current
`15-41 and GSM standards.
`FIGS. 3 and 4 are How diagrams illustrating the steps of
`a call control routine for use in conjunction With the present
`invention. As shoWn in step 300 of FIG. 3, a calling end
`system, such as the mobile 160 or the ?xed end system 169,
`generates a call origination message indicating that it Wishes
`to call a particular called end system. The remaining steps of
`FIG. 3 and FIG. 4, With the exception of step 422 in FIG. 4,
`illustrate the call control routine. As illustrated in step 305,
`the base station covering the area in Which the end system
`is located receives the call origination message. A determi
`nation is made as to Whether the end system that generated
`the call origination message is a mobile, as shoWn by 310.
`If the calling end system is not a mobile, but rather is ?xed,
`then, as indicated in step 315, the base station sends a setup
`call message to the call server covering the cluster in Which
`the base station is located. If, on the other hand, the calling
`end system is a mobile, then a determination is made as to
`Whether the calling mobile is located in its home netWork, as
`indicated by 320. A setup call message is sent to the call
`server serving the calling mobile. More particularly, if the
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`calling mobile is located in its home netWork, then, as
`illustrated in step 325, the base station sends a setup call
`message to the call server covering the cluster in Which the
`base station and mobile located. In contrast, if the calling
`mobile is not located in its home netWork, then the base
`station sends a setup call message to the roamer call server
`located in the mobile’s home netWork as shoWn in step 330.
`In this latter situation, the base station also sends an update
`message to the roamer call server indicating the identity of
`the connection server in the cluster Where the mobile is
`presently located. The identity of the connection server
`received in the update message is used by the roamer call
`server, as explained further beloW, to request that the con
`nections needed to connect the call be set up. Finally, as
`indicated in step 335, When the calling end system is a
`mobile, the base station stores the mobile-to-call server
`mapping needed to handle subsequent requests from the
`mobile.
`FIG. 4 illustrates additional steps Which are performed as
`part of the call control routine. As indicated in step 400, a
`call server for the calling end system receives the setup call
`message. As explained above, this call server Will be either
`the call server in the cluster in Which the base station is
`located or the roamer call server that is associated With the
`end system’s home netWork. Upon receiving the setup call
`message, a call server instantiates or creates a state machine
`for the call, as shoWn in step 410. Next, as indicated in step
`411, the call server invokes implicit services for the calling
`end system. Then, the call server creates a record for
`mapping connections to the call as shoWn in step 412.
`The call server that received the setup call message
`additionally performs several steps concurrently With the
`steps 410—412. Speci?cally, as indicated by step 420, the call
`server that received the setup message identi?es the call
`server, the connection server and the gateWay sWitch for the
`called end system. A gateWay sWitch is the sWitch that
`interconnects tWo netWorks. When the called end system is
`a ?xed end system, then this information may be retrieved
`from a database. When the called end system, hoWever, is a
`mobile, then further processing is required to obtain this
`information, as explained beloW With reference to FIG. 5.
`Next, as indicated in step 421, the call server that received
`the setup message communicates With the call server iden
`ti?ed in step 420 to invoke implicit services for the called
`end system.
`According to the principles of the present invention, if the
`called end system is a mobile, then a base station location
`routine is performed concurrently or in parallel With step
`421, as indicated by step 422. The base station location
`routine, as explained further beloW, determines Which base
`station, Within the cluster Where the called mobile is cur
`rently located, is serving the called mobile. This information
`is subsequently used When the connections for the call are
`established. By performing the base station location routine
`in parallel With the call control functions of step 421 the
`delays in establishing the connections for the call are
`decreased.
`Once the steps 410—412 and 420—421 have been
`performed, the call server that received the setup message
`sends a setup connections message to the connection server
`for the calling end system, as shoWn in step 430. The
`connection server for the calling end system is the connec
`tion server covering the cluster in Which the calling end
`system is currently located. In a setup connections message,
`the call server sending the message speci?es the connection
`server and gateWay sWitch for the called end system Which
`Were identi?ed in the step 420.
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`FIGS. 5A and 5B are a How diagram illustrating in greater
`detail several of the steps of the call control routine and the
`base station location routine. In particular, FIGS. 5A and 5B
`illustrate the details of the steps 420 and 422 When the called
`end system is a mobile. First, as shoWn in step 500, the call
`server for the calling end sys