* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download WLAN-GPRS Integration for Next-Generation Mobile Data Network
Survey
Document related concepts
Deep packet inspection wikipedia , lookup
IEEE 802.1aq wikipedia , lookup
Extensible Authentication Protocol wikipedia , lookup
Distributed firewall wikipedia , lookup
Wake-on-LAN wikipedia , lookup
Computer network wikipedia , lookup
Zero-configuration networking wikipedia , lookup
Network tap wikipedia , lookup
IEEE 802.11 wikipedia , lookup
Recursive InterNetwork Architecture (RINA) wikipedia , lookup
Wireless security wikipedia , lookup
Airborne Networking wikipedia , lookup
Transcript
WLAN-GPRS Integration for Next-Generation Mobile Data Network Apostolis K. Salkintzis, Chad Fors, and Rajesh Pazhyannur Motorola IEEE Wireless Communications Magazine October 2002 報告人:李偉晟 18 / 6 / 2003 1 Outline • Motivation • The general aspects of integrated WLAN-cellular network • Interworking architecture Tight Couple Architecture Loose Couple Architecture • Conclusion 2 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. 3 The general aspects of integrated WLAN-cellular network • Who owns the WLAN? Cellular operator Wireless Internet Service Provider(WISP) • Session Mobility 4 Interworking Architecture • The Tight Couple Architecture • The Loose Couple Architecture HLR Loose coupling point Gr Gc Mobiel station MS Iu-ps UTRAN Gi SGSN Uu MS Um GRPS RAN Gb Gn/p GGSN External Packet data network Gn/p SGSN Tight coupling point HLR:Home location register SGSN:Serving GPRS support node GGSN:Gateway GPRS support node 5 The Tight Couple Architecture 6 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 7 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 (RA:group of cells) in the system 8 Radio Access Network (UTRAN/ GPRS RAN) Feature Servers HLR (AuC) Operator's IP network GPRS core SGSN Internet GGSN Firewall CG Billing mediator Gb 48-bit 802 MAC GIF address Billing system WLAN network Distribution system AP Dual mode MS All mobile terminals and the GIF use MAC address Beacon (SSID) BSS-1 Beacon (SSID) BSS-2 Beacon (SSID) BSS-3 GIF:GPRS Interworking function CG:Charging gateway HLR:Home location register AuC:Authentication center SGSN:Serving GPRS support node GGSN:Gateway GPRS support node BSS:Basic service set AP:Access point 802.11 standar service set(ESS) 9 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 10 WLAN access network Defined by 802.11 Dual-mode MS WLAN Adaptation Function (WAF) LLC WLAN access network WLAN radio subsystem GPRS radio subsystem GPRS Interworking Function (GIF) Um GPRS access network Gb GPRS core network Gb New interworking componets 11 Protocol Architecture User data GMM/SM SNDCP SGSN LLC WAF WAF BSSGP NS RLC/MAC 802.11 MAC 802.11 MAC GPRS PHY 802.11 X PHY 802.11 X PHY 802.3 MAC 10Base-T or other 802.3 MAC FR 10Base-T or other PHY (e.g. G.703/704) Um Dual-mode MS Gb Access point GPRS interworking Function (GIF) 12 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 13 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 14 WLAN Adaptation Function (cont.) 15 GIF/RAI 5.Discovery Procedure Then the Start 1. MS’s WAF send Discovery Request ,SA=MS ,DA=Broadcast ,IMSI 2. Data is directed to the AP with BSSID GIF's WAF Responds Discovery Response ,GIF's MAC Address, WLAN's RAI 6. The MS receives this response , stores the GIF address and the RAI 7. The 4. The GIF receive this message ,associate the IMSI with the MS's MAC address MS notifies the GMM layer that the current GPRS RA has changed 8. The GMM 3. The AP broadcast this message to the DS layer notifies the SGSN that the MS has change RA End 16 The Loose Couple Architecture 17 System Description • The WLAN network is coupled with the GPRS network in the operator’s IP network 18 Radio Access Network (UTRAN/ GPRS RAN) CAG HLR (AuC) GPRS core FA Operator's IP network Internet Firewall GGSN SGSN Feature Servers HA CG Billing mediator Billing system WLAN network FA Firewall AAA Dual mode MS AP CAG:Cellular acess gateway CG:Charging gateway HLR:Home location register AuC:Authentication center SGSN:Serving GPRS support node GGSN:Gateway GPRS support node AAA:Authentication, authorization, accounting FA:Foreign agent HA:Home agent 19 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 20 AP MS CAG (AAA server) HLR 1. EAPOW-start 2. EAPOW-request/identity 3. EAPOW -response/identity (IMSI) 4. RADIUS access-request (IMSI) 5. Send authentication info 6. Send authentication info ack 7. RADIUS access-challenge 8. EAP-request(RAND) RAND XRES 9. EAP-response(SRES) [Signed Result] 10. RADIUS access-request 11. RADIUS access-accept if XRES == SRES 12. EAP-sucess 13. EAP-key 21 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 22 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 23 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 24 Sesson Mobility (cont.) Start When the MS move from one system to another system The MS performs a MIP registeration via the FA The FA then associates the care-of address with that of the MS The FA acts as the proxy on behalf of the MS for the life of the registeration The FA provides a care-of address to the HA to completes the registeration End 25 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 26 The End ! 27