a2) United States Patent
`US 6,771,635 B1
`(10) Patent No.:
`Aug.3, 2004
`(45) Date of Patent:
`Vilanderet al.
`
`US006771635B1
`
`(54)
`
`IPADDRESS ALLOCATION FOR MOBILE
`TERMINALS
`
`(75)
`
`Inventors: Harri Tapani Vilander, Espoo (FD;
`Tom Mikael Nordman, Kirkonummi
`(FI)
`
`(73) Assignee: Telefonaktiebolaget LM Ericsson
`(publ), Stockholm (SE)
`
`(*) 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.: 09/536,015
`
`(22)
`
`Filed:
`
`Mar. 27, 2000
`
`(30)
`
`Foreign Application Priority Data
`
`OTHER PUBLICATIONS
`
`R. Hindon, S. Deering; IP Version 6 Addressing Architec-
`ture, RNC 2373; Jul. 1998.*
`Guidelines for 64-bit Global Identifier (EUI-64) Registra-
`tion Authority; IEEE Standards.*
`Proceedings of the Conference on Computer Communica-
`tions (INFOCOM), US, New York, IEEE, vol. CONF. 11,
`1992, pp. 626-632, XP000300088, ISBN: 0-7803-0602-3,
`D. Cohen et al., “IP Addressing and Routing in a Local
`Wireless Network”.
`IEICE Transactions on Communications, JP, Institute of
`Electronics Information and Comm. Eng., Tokyo, Japan,
`vol.. 80-B, No.
`8, Aug.
`1,
`1997, pp. 1132-1137,
`XP000723080,
`ISSN: 0916-8516, F. Teraika, “Mobility
`Support with Authentic Firewall Traversal in IPV6”.
`IEEE Network, vol. 12, No. 4, Jul. 1, 1998, pp. 4-10,
`XP002142781, Bo Ryu, Jun Wei, Yongguang Zhang, & Son
`Dao, “Managing IP Services Over a PACS Packet Network”.
`
`Mar. 31, 1999
`
`(GB) cee cece cece ceeeeeeeeeneaees 9907335
`
`* cited by examiner
`
`Tint, C0eee ceeeceeeseeneeneneeneenens HO4J 3/24
`(SL)
`(52) US. Ch. cece cteecceeteeceeeenenenecneenseceraes 370/349
`(58) Field of Search 000.0000: 370/349, 328,
`370/310.1, 310.2, 321, 322, 379, 455, 466
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`5,572,528 A * 11/1996 Shuen ...... eee 370/402
`6,147,986 A * 11/2000 OFSic we. eeeeecee enone 370/349
`FOREIGN PATENT DOCUMENTS
`
`EP
`WO
`WoO
`
`0 883 266 A
`WO 99/16266
`WO 99/17568
`
`12/1998
`1/1999
`8/1999
`
`Primary Examiner—Wellington Chin
`Assistant Examiner—Mark A Mais
`(74) Attorney, Agent, or Firm—Nixon & Vanderhye P.C.
`
`(57)
`
`ABSTRACT
`
`A method of allocating an Internet Protocol (IP) address to
`a mobile wireless terminal within a mobile telecommunica-
`
`tions network. During the establishment of the radio link
`between the terminal and the network, a negotiation is
`conductedto provide the mobile terminal with a hostpart for
`an IP address, wherethe host part is unique within the radio
`network. In the case of a UMTS network,the host partis the
`Radio Network Terminal Identity (RNTI).
`
`9 Claims, 2 Drawing Sheets
`
`Begin
`
`
`
`Mobile terminal switched on or enters
`coverage area of mobile network
`
`
`
` Y.
`(Mobite terminal receives routing prefix on broadcast channel
`
` —_¥
`
`Duringestablishment ofradio link, mobile
`network transmits RNTI to mobile terminal
`
` ¥.
`| Mobile terminal stores RNTI as IP addresshost part |
`
`APPLE 1011
`
`Mobile terminal combinesrouting part and hostpart
`to generate IP address for subsequent IP sessions
`
`Mobile terminalregisters with mobile network
`using information on broadcast channels
`
`
`
` 1
`
`
`
`APPLE 1011
`
`1
`
`

`

`U.S. Patent
`
`Aug. 3, 2004
`
`Sheet 1 of 2
`
`US 6,771,635 B1
`
`
`
`Figure1
`Prior Art
`
`<<tH
`
`64 bits
`
`64 bits
`
`wef| ts
`
`Routing prefix
`
`Host part
`
`Figure 2
`Prior Art
`
`2
`
`

`

`U.S. Patent
`
`Aug. 3, 2004
`
`Sheet 2 of 2
`
`US 6,771,635 B1
`
`Mobile terminal switched on or enters
`coverage area of mobile network
`
`Mobile terminal receives routing prefix on broadcast channel
`
`During establishment ofradio link, mobile
`network transmits RNTI to mobile terminal
`
`Mobile terminal stores RNTIas IP address hostpart
`
`Mobile terminal combines routing part and hostpart
`to generate IP address for subsequentIP sessions
`
`
`
`Mobile terminal registers with mobile network
`using information on broadcast channels
`
`End
`
`Figure 3
`
`3
`
`

`

`US 6,771,635 B1
`
`1
`IP ADDRESS ALLOCATION FOR MOBILE
`TERMINALS
`
`FIELD OF THE INVENTION
`
`invention relates to the allocation of IP
`The present
`addresses to mobile terminals and in particular to the allo-
`cation of a host part of an IP address to a mobile terminal.
`BACKGROUND TO THE INVENTION
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`Subscribers to existing mobile telecommunications net-
`works may under certain circumstances access the Internet
`using either an Internet enabled mobile telephone(a device
`often referred to as a “communicator”) or by coupling a
`palmptop or laptop computer to a conventional mobile
`telephone,
`for example using a software or hardware
`modem.
`
`In digital mobile telephone networks, such as the Euro-
`pean GSM (Global System for Mobile communications)
`system, a mobile telecommunications network can be
`divided into two parts. The first part is referred to as the
`“radio network” and consists of base stations (BSs) andbase
`station controllers (BSCs) where a single BSC controls a
`number of BSs. The second part of the network is referred
`to as the “core network” and comprises mobile switching
`centres (MSCs), each MSC being responsible for a number
`of BSCs. An MSC is analogous to an exchange of a
`conventional telephone network. Internet traffic is carried
`over a circuit switched connection established between the
`mobile terminal and an Internet Service Provider (ISP) via
`the core network.
`
`The development of future mobile communication stan-
`dards is currently ongoing. In particular, an enhancement to
`GSM known as General Packet Radio Service (GPRS)is
`being developed to introduce a packet switched service into
`GSM. The introduction of GPRS will effectively add an
`additional core network to GSM systems, with switching
`functions being performed in the GPRS core network by
`Serving GPRS Switching Nodes (SGSNs) and Gateway
`GPRSSwitching Nodes (GGSNs). A third generationdigital
`systemis also under developmentand is knownas Universal
`Mobile Telecommunications System (UMTS). UMTS is
`likely to incorporate GPRS or a similar packet switched
`system.
`Under current proposals, in both GSM GPRS and UMTS
`systems, Internet access will be obtained via the packet
`switched core network. When a mobile terminal requests
`Internet access, the request is directed via a BS and a Radio
`Network Controller (RNC, equivalent
`to the traditional
`BSC) to a GGSN. The GGSN mayact as an Internet Access
`Server (IAS)or direct the request to a separate IAS. Such a
`separate IAS is typically operated by an Internet Service
`Provider (ISP) which is independent from the operatorof the
`mobile network. However,
`the IAS may alternatively be
`operated by the mobile network operator. In any case, the
`integrated or separate IAS allocates to the calling mobile
`terminal an Internet Protocol (IP) address. According to the
`existing Internet Protocol version 4 (IPv4), the IP address
`has 32 bits. According to the proposed Internet Protocol
`version 6 (IPv6), the IP address is enlarged to 128 bits and
`comprises a 64 bit routing prefix which uniquely identifies
`the LASto the Internet, and also a 64 bit host prefix which
`uniquely identifies the mobile terminal to the IAS.
`The allocated IP addressis returned to the mobile terminal
`via the packet switched core network and the radio network
`whereupon the mobile terminal
`is able to commence an
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`Internet session. Assuming that the mobile terminal is reg-
`istered with its home network when the Internet access is
`requested, the Internet sessionis routed via the GGSN ofthe
`home network. However, when a mobile terminalis “roam-
`ing” and is registered with a foreign network, the Internet
`session may be conducted via both a GGSN of the home
`network and a SGSNof the foreign network.
`As subscribers of existing digital networks may be aware,
`Internet access via a mobile terminal is generally extremely
`slowand unreliable. This is due in part to the need for a slow
`set-up phase, required each time a newtransfer session is
`commenced, during which session parameters including an
`IP address are negotiated. Another reason for slow speed (as
`well as unreliability) is the possibly large distance between
`the node (e.g. IAS) which allocates an IP address and the
`mobile terminal, possibly involving one or more intermedi-
`ate nodes. IP datagrams must be tunnelled between the two
`end points, often involving additional protocols (e.g. Point-
`to Point Protocol, Layer 2 Tunnelling Protocol, etc), con-
`suming extra processing and transmission capacity.
`Whilst the current proposals for GPRS and UMTSwill
`result in a faster and more reliable radio connection between
`a mobile terminal and the radio and core networks, they will
`not eliminate the need to negotiate the IP address prior to
`commencing an Internet session nor the need to route IP
`datagrams via one or more switching nodes of the packet
`switched core network(s).
`It is anticipated that in Pv6, two Internet Control Message
`Protocol (ICMP) messageswill be utilised for the purpose of
`negotiating a host part of an IP address for a mobile terminal
`connectedto a fixed line communications network. A mobile
`
`terminal proposes a host part which may be a host part
`permanently allocated to the mobile terminal or may be the
`host part last used by the mobile terminal. The proposed host
`part is included in a Neighbour Solicitation message which
`is sent by the mobile terminal to other mobile terminals
`currently connected to the same fixed line network. If it
`transpires that another of the connected terminals is cur-
`rently using the same host part,
`then that other mobile
`terminal responds byreturning a Neighbour Advertisement
`message to the newly connected mobile terminal. In the
`event that the newly connected mobile terminal receives
`such a Neighbour Advertisement message, it must reject the
`originally proposed host part and propose a new hostpart.
`The mobile terminal then includesthis newly proposed host
`part in a Neighbour Solicitation message and the processis
`repeated until a unique host part has been arrivedat.
`As already noted, the host part generation process of Pv6
`is concerned with mobile terminals connected to fixed line
`networks. However, the process is not necessarily easily
`appliedin the case of mobile wireless terminals connected to
`a mobile telecommunications network. Vor example, a
`mobile network will not necessarily provide for a mobile
`wireless terminal to broadcast Neighbour Solicitation mes-
`sages to other mobile terminals connected to the same
`network (GPRS and UMTS do not provide for mobile
`terminal to mobile terminal signalling). Whilst it may be
`possible to transmit a NeighbourSolicitation message to the
`mobile network and thereafter to broadcast the Neighbour
`Solicitation message to other mobile terminals, such a
`solution would be wasteful of radio interface resources.
`
`A further disadvantage of the proposed IPv6 in so far as
`it relates to IP addressallocation,is that, if a mobile terminal
`is permanently allocated a host part, it may be possible for
`third parties to track the movementof a mobile terminal and
`hence of the user of a mobile terminal. Assuming that such
`
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`

`

`US 6,771,635 B1
`
`4
`a parameter transmitted from the mobile network to the
`mobile terminal for the purpose of setting-up the radio link
`between the terminal and the network.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`For a better understanding of the present invention and in
`order to show how the same maybe carried into effect
`reference will now be made, by way of example, to the
`accompanying drawings, in which:
`FIG. 1 illustrates schematically a mobile telecommunica-
`tions system;
`FIG. 2 illustrates the structure of an IP address according
`to an IPv6; and
`FIG. 3 is a flow diagramillustrating a method of allocat-
`ing the host part of the IP address of FIG. 2 in the system of
`FIG. 1.
`
`DETAILED DESCRIPTION OF CERTAIN
`EMBODIMENTS
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`A GSM based telecommunication system incorporating
`the proposed General Packet Radio Service (GPRS)
`is
`illustrated schematically in FIG. 1 and comprises a number
`of radio networks 1 which may or maynot have overlapping
`invention enable an IP
`Embodiments of the present
`radio coverage. Each radio network 1 has its own unique
`address to be made available at a mobile terminal prior to
`radio network identity (ID1 to ID4) and comprises a plu-
`commencing an Internet session. Thus, there is no need for
`rality of Radio Network Controllers (RNCs) 4, each RNC4
`a further IP address negotiation immediately prior to the
`being responsible in turn for a plurality of Base Stations
`Internet session. Furthermore, as the initial negotiation
`(BSs) 5. Each RNC4effectively comprises an integrated
`forms part of the radio link establishment, data transfer
`IAS (or the functionality thereof), which enables the RNCs
`requirements are likely to be optimised.
`4 to be coupled directly to the Internet.
`FIG. 1 illustrates a mobile terminal 7 which is located
`Preferably, the host part is proposed by the radio network.
`Morepreferably, the host part is an identifier allocated to the
`within a cell associated with a given radio network 1. When
`mobile terminal in connection with one of the standardised
`the mobile terminal 7 is switched on, or first enters the
`geographical area covered by the radio network 1,
`the
`terminal 7 begins scanning the broadcast channel(s) of that
`network 1. By listening to the broadcast information, the
`mobile terminal 7 is able to select a suitable network(if there
`are several networks available),
`to synchronise with the
`selected network, and to initiate layers of the radio link
`(namely the CDMAphysical layer and the medium access
`control,
`radio link control, and radio resource control
`layers). Each RNC 4 of the radio network 1 broadcasts over
`a predefined broadcast channel an IP routing prefix which
`has previously been allocated to that RNC 4 and whichis
`worldwide unique to the RNC 4. Typically, the routing prefix
`correspondsto the RNC ID or may be a combination of RNC
`ID and network ID. Bylistening to the broadcast channel,
`the mobile terminal 7 is able to identify the routing prefix of
`the controlling RNC 4 and is subsequently able to generate
`an IP address using the routing prefix.
`FIG. 2 illustrates the structure of an IP address according
`to IPv6. The address comprises a 64 bit prefix (MSBs)
`containing the routing prefix. This prefix is used by routers
`in the Internet to route IP datagramsto the originating RNC
`4. The second part of the address (LSBs) is also 64 bits in
`length, and represents a host part which uniquely identifies
`the originating mobile terminal 7 to the RNC4.
`A suitable host part
`is negotiated between the mobile
`terminal 7 and the radio network 1 during the establishment
`of (lower) communication layers over the air interface (ie.
`CDMAphysical layer; medium access control layer; radio
`link control layer; and radio resource control layer). The
`negotiation is initiated by the radio network proposing a
`suitable host part which it knows is unique within its
`coverage area. The proposed host part may be a dedicated
`
`3
`a third party is aware of the host part allocated to a given
`mobile terminal, and has knowledge of the unique routing
`prefixes allocated to the various networks, then he could
`determine the current location of a mobile terminal.
`
`SUMMARY OF THE INVENTION
`
`It is an object of the present invention to overcomeor at
`least mitigate the above noted disadvantages of existing
`systems and methods of allocating IP addresses to mobile
`terminals. This and other objects are achievedat least in part
`bynegotiating a temporary host part during the establish-
`mentof a radio link between a mobile terminal and a mobile
`
`telecommunications network. The temporary host part may
`beused for subsequent IP sessions whilst the mobile termi-
`nal is within the mobile network.
`
`According to a first aspect of the present invention there
`is provided a method ofallocating an IP address to a mobile
`wireless terminal within a mobile telecommunications
`
`network, the method comprising conducting a negotiation
`between the mobile terminal and the network during the
`establishmentof a radio link, to determine a host part of the
`IP address, wherein said host part maybe used by the mobile
`terminal to generate an IP address for use in subsequent
`Internet sessions.
`
`air interface protocol layers. More preferably, and in the case
`of UMTS, the Radio Network Temporary Identity (RNTI)is
`used as the host part.
`Alternatively,
`the host part may be proposed bythe
`mobile terminal. For example,
`the mobile terminal may
`generate a random proposed host part. During the
`negotiation, the network may accept or reject the proposal
`depending upon whether or not a mobile terminal, having
`the samehost part, is currently registered with the network.
`According to a second aspect of the present invention
`there is provided apparatus for allocating an IP address to a
`mobile wireless terminal within a mobile telecommunica-
`
`tions network, the apparatus comprising means distributed
`between a mobile wireless terminal and a mobile telecom-
`
`munications network for conducting a negotiation between
`the terminal and the network during the establishment of a
`radio link,
`to determine a host part of an IP address, the
`mobile terminal further comprising means for generating an
`IP address incorporating said hostpart for use in subsequent
`Internet sessions.
`
`According to a third aspect of the present invention there
`is provided an Internet enabled mobile wireless terminal, the
`mobile terminal being arranged to conduct a negotiation
`with a mobile telecommunications network to determine a
`
`hostpart of an IP address, the mobile terminal being further
`arranged to generate an IP address incorporating said host
`part for use in subsequent Internet sessions.
`According to a fourth aspect of the present invention there
`is provided a method ofallocating an IP address to a mobile
`wircless terminal within a mobile telecommunications
`network, wherein the IP address comprises a routing part and
`a host part, the method comprisingutilising as said host part
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`US 6,771,635 B1
`
`5
`identifier or may serve some other purpose associated with
`one of the layers of the radio link. For example, in UMTS,
`it is currently proposed that the radio network controller
`(RNC) allocates to cach mobile terminal, during registration,
`a Radio Network Temporary Identity (RNTI) which is
`unique to the registering mobile terminal. Alternatively,
`some other unique identity maybe used. In anycase, the
`mobile terminal receives the proposed host part and is able
`to combine this with the received routing prefix to form an
`IP address for use in subsequent Internet sessions.
`In the case where RN'I'is used as the host part, it is noted
`that in inter-RNC handovers, i.e. when control of a mobile
`terminal is passed from one RNC to another, a new RNTI is
`assigned to the mobile terminal and in consequence a new IP
`address is generated. Datagrams directed to a previous IP |
`address may be tunnelled to the newaddress by the radio
`network 1.
`
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`The exact form of future generation digital mobile tele-
`communication standards, such as GPRS and UMTS, are not
`yet finally specified. In the event that no suitable identity,
`such as the RNTI, is available in the final protocols, an
`alternative solution to allocating a host part to a mobile
`terminal 7 maybeto allow the mobile terminal 7 to generate
`a temporary host part upon registering with a radio network
`1. For example,
`the mobile terminal 7 may generate a
`random 64 bit identity which is transmitted to the radio
`network 2. The radio network 1 is then able to check whether
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`6
`conducting a negotiation between the mobile terminal and
`the network to determine a host part of the IP address,
`wherein the host part is an identifier allocated to the
`mobile terminal by the mobile telecommunications
`network in connection with a standardized air interface
`protocol layer, and
`using the host part may be used byat the mobile terminal
`to generate an IP address for use in a subsequent
`Internet session.
`2. A method according to claim 1, wherein the mobile
`network is a UMTS network, and the Radio Network
`Temporary Identity (RNTI) is used as the host part.
`3. A method according to claim 1, wherein an authenti-
`cation or authorization certificate, sent between the mobile
`terminal and the mobile network during the set-up phase of
`the radio link, is used as the host part or is used to generate
`the host part.
`4. Amethod according to claim 1, wherein the negotiation
`is conducted during the establishment of a radio link
`between the mobile terminal and the mobile network.
`5. A method according to claim 1, wherein the mobile
`network comprises a radio network part and the allocation of
`a host part to the mobile terminal is controlled by the radio
`network.
`6. A method according to claim 5, wherein the allocation
`of a host part to the mobile host is controlled by a Radio
`Network Controller (RNC) of the radio network.
`7. Apparatus for allocating an IP address to a mobile
`wircless terminal within a mobile telecommunications
`network,
`the apparatus comprising means distributed
`between a mobile wireless terminal and a mobile telecom-
`
`another mobile terminal 7 currently registered with the radio
`network 1 is using the proposed part. If not, then the radio
`network 1 is able to transmit an Accept message to the
`munications network for conducting a negotiation between
`mobile terminal 7 and, if a conflict does exist, then the radio
`the terminal and the network to determine a host part of an
`network 2 transmits a Deny message to the mobile terminal
`IP address, the host part being an identifier allocated to the
`7. In the latter situation, the mobile terminal 7 may propose
`mobile terminal by the mobile telecommunications network
`an alternative randomhostpart or the radio network2itself
`in connection with a standardized air interface protocol
`may propose an alternative host part. However, given that
`layer,
`the mobile terminal further comprising means for
`the 64 bit length of the host part provides for 2°* different
`generating an IP address incorporating the host part for use
`alternatives, the possibility of a conflict is small.
`in a subsequent Internet session.
`Still another possibility is for the RNC to utilise an
`the
`8. An Internet enabled mobile wireless terminal,
`authentication or authorisation certificate, provided by the
`mobile terminal being arranged to conduct a negotiation
`mobile terminal, as the IP address host part. This certificate
`with a mobile telecommunications network to determine a
`is generally ciphered, and may be intended for the mobile
`terminal’s home Internet Service Provider (ISP) to authen-
`ticate the terminal to the ISP. Alternatively, the certificate
`maycorrespondto an electronic cash payment. Theciphered
`certificate may beused directly to provide the required host
`part, or some function(c.g. a hash function) may be applied
`to the certificate.
`
`host part of an IP address, the host part being an identifier
`allocated to the mobile terminal by the mobile telecommu-
`nications network in connection with a standard air interface
`protocol
`layer, and the mobile terminal being further
`arranged to generate an IP address incorporating the host
`part for use in a subsequent Internet session.
`9. Apparatus for allocating an IP address to a mobile
`wireless terminal within a mobile telecommunications
`
`the apparatus comprising means distributed
`network,
`between a mobile wireless terminal and a mobile telecom-
`munications network for conducting a negotiation between
`the terminal and the network to determine a host part of an
`IP address, the host part being an identifier allocated to the
`mobile terminal by the mobile telecommunications network
`in connection with a standardized air interface protocol
`layer, the mobile terminal further configured to generate an
`IP address incorporating the host part for use in a subsequent
`Internet session.
`
`Yet another possibility is to use some other message sent
`between the mobile terminal and the RNC during the set-up
`phase of the radio link. Again, a hash function may be
`applied to the message, with the resulting check sum being
`used as the host part.
`It will be appreciated by the person ofskill in theart that
`various modifications may be made to the above described
`embodiment without departing from the scopeof the present
`invention.
`What is claimed is:
`
`1. A method of allocating an IP address to a mobile
`wireless terminal within a mobile telecommunications
`network, the method comprising:
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