WLANGPRS Integration for NextGeneration Mobile Data Network

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WLAN-GPRS Integration for Next-Generation Mobile
Data Network
Apostolis K. Salkintzis, Chad Fors, and Rajesh
Pazhyannur
Motorola
IEEE Wireless Communications Magazine
October 2002

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18 / 6 / 2003
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Outline

• Motivation
• The general aspects of integrated WLAN-cellular
  network
• Interworking architecture
• Tight Couple Architecture
• Loose Couple Architecture
• Conclusion

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Motivation

• The operator has the large investments made for
  new spectrum in which to offer 3G services, but
  3G data technology is not available
• And 2.5G(GPRS) cellular data technology is
  available in large coverage, but can't meet
  business and multimedia application requirement
• The recent evolution and successful deployment of
  WLAN systems worldwide, and its high data rate
• An integrated network combines the strenghths of
  each, provides users with ubiquitous data service.

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The general aspects of integrated WLAN-cellular
network

• Who owns the WLAN?
• Cellular operator
• Wireless Internet Service Provider(WISP)
• Session Mobility

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Interworking Architecture

• The Tight Couple Architecture
• The Loose Couple Architecture

HLRHome location register SGSNServing GPRS
support node GGSNGateway GPRS support node
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The Tight Couple Architecture
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Benefits

• Seamless service continuation across WLAN and
  GPRS
• Reuse of GPRS AAA
• Authentication, Authorization, and Accouting
• Reuse of GPRS infrastructure
• Access to core GPRS services

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WLAN System Description

• A WLAN network is deployed with one or more
  off-the-shelf access ponts(APs)
• APs are connected by means of a distribution
  system(DS)
• In the system, DS is a LAN (IEEE 802.3)
• APs behave like base stations
• The service area of a AP
• is a basic service set (BSS)
• Each WLAN composes many BSSs,
• all form an ESS
• The WLAN is considered like any other GPRS
  routing area (RAgroup of cells) in the system

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GIFGPRS Interworking function CGCharging
gateway HLRHome location register AuCAuthenticat
ion center SGSNServing GPRS support
node GGSNGateway GPRS support node BSSBasic
service set APAccess point
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New Component

• GPRS interworking function (GIF)
• Is connected to a DS and to a serving GPRS
  support node (SGSN)
• Provide a standardized interface to the GPRS core
  network
• Hides the WLAN particularities
• WLAN adaptation function (WAF)
• Identifies when the MS associates with a valid AP
• Informs the LLC layer , which subsequently
  redirects signaling and data traffic to the WLAN

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(No Transcript)
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Protocol Architecture
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WLAN Adaptation Function

• Functions
• Signals the activation of WLAN interface when the
  mobile enters a WLAN area
• Supports the paging procedures (SGSN pages the
  MS)
• Transfers PDUs (Packet Data Unit) between mobiles
  and GIF
• Supports QoS (transmission scheduling in GIF and
  the MS)
• Transfers the TLLI and QoS information in the WAF
  header

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WLAN Adaptation Function (cont.)

• TLLI ( Temporary Logical Link Identifier )
• Is used by GIF to update an internal mapping
  table that correlates TLLI and MS's MAC addresses
• The SGSN uses TLLI as MS address informatioin,
  whereas the WLAN utilizes MAC addresses

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WLAN Adaptation Function (cont.)
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GIF/RAI Discovery Procedure
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The Loose Couple Architecture
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System Description

• The WLAN network is coupled with the GPRS network
  in the operators IP network

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CAGCellular acess gateway CGCharging
gateway HLRHome location register AuCAuthenticat
ion center SGSNServing GPRS support
node GGSNGateway GPRS support node AAAAuthentica
tion, authorization, accounting FAForeign
agent HAHome agent
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Authentication

• The Extensible Authentication Protocol(EAP)
• Performs authentication of the MS
• Passing the subscriber identity
• Passing SIM-based authentication data
• Encrypted session key
• The cellular accesss gateway(CAG) acts as an
  authenticator for WLAN users

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(AAA server)
Signed Result
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Encryption

• Weakness of the 802.11 WLAN standard in its
  encryption technology
• Wired Equivalent Privacy(WEP)
• is a relatively inefficient encryption scheme
• With the use of EAP, WEP may be enhaced by the
  use of a unique session key (EAPOW-Key) for each
  user of the WLAN

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Billing

• Integrated billing is achieved via the billing
  mediator function
• The billing mediator
• convert accounting statistics from both the GPRS
  and WLAN access networks into a format of the
  particular billing system used by the operator
• The AP in the WLAN will report accounting
  statistics to the CAG
• The GPRS core will report accounting statistics
  (via CG) pertaining to GPRS usage

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Sesson Mobility

• Mobile IP (MIP) can be used to provide seeion
  mobility across GPRS and WLAN domain
• The MIP framework contains
• A MIP client (MS)
• A foreign agent (FA)
• A home agent (HA)
• The FA in the GPRS resides in the GGSN in the
  WLAN can reside in an access router
• The HA is located in the operator's network

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Sesson Mobility (cont.)
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Conclusion

• The recent evolution and successful deployment of
  WLAN sustems worldwide has fueled the need for
  interworking mechanisms between WLANs and cellar
  data networks such as GPRS
• Tight coupling is fit for the cellular operator
  having WLAN
• Loose coupling is fit for the wireless network
  composed of a large number of WLAN operators and
  cellular operators
• WLAN technology will play an important role in
  supplementing wide-area cellular network

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The End !