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A Gateway Approach for Mobility Integration of GPRS and Wireless LANs

Jyh-Cheng ChenNational Tsing Hua University

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Outline

IntroductionGateway approachTestbed and experimental analysisSummaryDemo

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IntroductionDivergence

2~50Mbps20~170KbpsData Rate

5m~100m10KmRadio Coverage

WLANGPRS

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Radio Coverage

WLAN

WLAN

WLAN

WLAN

WLAN

WLAN

GPRS

MS

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Integration

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Any Problems?

Both GPRS and WLANs are in the market alreadyShould not change the standardsShould be easy to deploy and get into the market quickly

Most GPRS and WLANs are owned and operated by different providers

Loose coupling may be more feasibleBoth GPRS and WLAN may be a user’s home network

WLAN standards are in PHY and MAC onlyShould we integrate based on IP? IPv4 or IPv6?

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Gateway Approach

GGSN

GGSN

SGSN

BSS

Internet

MS

GPRSCNGp

MS

WLAN

FA

Gn Gi

GW

other PLMN

PLMN:GGSN:SGSN:BSS:HA:FA:CN:MS:

Public Land Mobile NetworkGateway GPRS Support NodeServing GPRS Support NodeBase Station SystemHome AgentForeign AgentCorrespondent NodeMobile Station

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Summary

Place a gateway in the conjunctional point of GGSN and WLAN system

No change to existing infrastructuresNo lengthy standardization process

Mobile IPv4 on top of WLANWLAN could be IEEE 802.11, HYPERLAN, etc.

User’s home network is either GPRS or WLANThe gateway should function like GGSN, FA, and HA

Implemented in the GPRS network of Taiwan Cellular Corporation (TCC)

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Home in WLAN System

The gateway functions like GGSN/FAEnhances GGSN with FA functionality as defined in 3GPP

FA helps decapsulate incoming packets and GGSN transmit them to the target SGSN by GTP tunneling

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Mobile IP Support for GPRS

Defined in 3GPP TS 29.061For interworking with other PLMN or PDNGGSN/FA is considered as an integrate nodeMIP-FA service request identified by APN (Access Point Name)

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PDP Context Activation

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Home in WLANCN outside GRPS

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Home in WLANCN inside GPRS

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Home in GPRS

The gateway functions like GGSN/HAGGSN must be aware of the attachment point of MS to transmit packets properlyHA informs GGSN current location of MS when HA receives the registration from MS

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PDP Context Activation

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Home in GPRSCN outside GPRS

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Home in GPRSCN inside GPRS

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Handoff Management

WLAN-preferredUser-trigger

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Requirements for MS

GPRS signaling is still enabled when WLAN-attachment

LA updateCircuit-switch service

PDP context activationRequest with a specified APN (MIPv4HA)Activate previous PDP context to reduce handoff latency when MS hands off from WLANs back to GPRS

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Protocol Stack in MS

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Testbed Components

Mobility: Hut Dynamics Mobile IPSoftware for MSSignaling: SIPQoS: Traffic conditionerMultimedia applicationsGPRS system

ITRITCC

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GPRS by ITRIRadio interface of BTS & MS simulated by 802.11Trillium’s code for SNDCP/LLC ported into Linux kernel

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Foreign Network

Private Foreign Network

VLRMSC/HLR

GatewayGGSNSGSNBSC

FA

FA

NAT

Home Network

AAARouter

Testbed Architecture

BTS

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Experimental Analysis

ScenarioGPRS-WLAN1-WLAN2-WLAN1-GPRSPlace access points of GPRS and WLAN1 closelyGPRS-WLAN1 handoff is user-triggered

Various experiments including:Handoff-latencyTCP packet delayUDP packet lostThroughput

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Home in GPRSCN outside GPRS

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Home in GPRSCN inside GPRS

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Home in WLANCN outside GPRS

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Home in WLANCN inside GPRS

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Summary

Leverage Mobile IP to integrate heterogeneous networksMinimize the impact on existing systemsA testbed is constructed Various experiments