hybrid 3g and 802.11 network for the open-access …trappe/prashant/sanjoyccwtalk-2004-10-15.… ·...

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Hybrid 3G and 802.11 Network for theHybrid 3G and 802.11 Network for theOOpenpen--AccessAccess RResearchesearch TestBedTestBed for Nextfor Next--GenerationGeneration WWIIrelessreless NeNeTTworksworks ((ORBITORBIT))

Dr. Sanjoy Paul ([email protected])Dr. Sanjoy Paul ([email protected])Research DirectorResearch Director

Wireless Networking Research Wireless Networking Research Bell LaboratoriesBell Laboratories

Lucent TechnologiesLucent Technologies(Team: John Lin, Sampath Rangarajan, Li (Team: John Lin, Sampath Rangarajan, Li LiLi, Xue Li), Xue Li)

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Outline of the PresentationOutline of the PresentationORBIT Testbed

Field Trial Network: Hybrid 3G and WiFi

ArchitectureComponentsHandoff in 3G cellular network

PPP State MigrationHandoff in 802.11 network

New Micro-mobility ProtocolHandoff between 3G cellular and 802.11 network

Conclusion

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What is ORBIT?What is ORBIT?ORBIT stands for Open-Access Research Testbed for Next-Generation Wireless Networks

NSF-funded project for 4 years

Collaboration between industry and academia

Two components of ORBITTestbedExperiments on the Testbed

Two components of TestbedLab EmulationField Trial Network

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Focus of the Presentation is theFocus of the Presentation is theField Trial NetworkField Trial Network for ORBITfor ORBIT

OurFocus

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Field Trial NetworkField Trial Network

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New Micro-mobility ProtocolHandoff between 3G cellular and 802.11 networkPotential Extensions to the Architecture

Conclusion

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Field Trial Network: HighField Trial Network: High--Level ViewLevel View

When the 802.11 network is unavailable, user requests and responses routed through the 3G Network.

As soon as 802.11 connectivity is established, packets routed through the 802.11 network.

802.11Network

Internet Gateway

3G Network

http://images.google.com/imgres?imgurl=www.wavepage.com/images/compaq.jpg&imgrefurl=http://www.wavepage.com/wireless.aspx&h=273&w=165&prev=/images%3Fq%3D802.11%2BPDA%26svnum%3D10%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8



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Field Trial Network: ArchitectureField Trial Network: ArchitectureBase Station Router (BSR)MWG (Mobile Wireless Gateway)RP (Rendezvous Point)AG (Access Gateway) 3G Carrier

Network

RP

TheInternet

Campus Network

MWG

AG

3G Network

MWG MWG

RP

RP Network

Bus/Train

BSR

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Access via MWG and 3GAccess via MWG and 3G

3G CarrierNetworks

RP

TheInternet

RP Network

MWG

WiFi Mobile

AG

192.168.1.200

68.85.1.100(assigned by 3G)

• IP address for MWG assigned by 3G network

• MWG tunnels packets from WiFi mobile to the AGthrough the 3G Network

192.168.1.1

http://images.google.com/imgres?imgurl=service.pcconnection.com/images/inhouse/290907.jpg&imgrefurl=http://www.pcconnection.com/scripts/productdetail.asp%3Fproduct_id%3D278967&h=150&w=150&prev=/images%3Fq%3D802.11%2Baccess%2Bpoint%26svnum%3D10%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8

http://images.google.com/imgres?imgurl=pdahandyman.com/images/devices/pico-picoblue.gif&imgrefurl=http://www.pdahandyman.com/archives/000270.html&h=323&w=242&prev=/images%3Fq%3Daccess%2Bpoint%26start%3D140%26svnum%3D10%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3DUTF-8%26sa%3DN




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Access via MWG and RPAccess via MWG and RP

3G CarrierNetwork

RP

TheInternet

MWG

WiFi Mobile

AG

192.168.1.200

128.6.1.100(Campus Net)

• IP address of MWG assigned by AG

• MWG tunnels packets from WiFi Mobile to the AGthrough the RP Network

192.168.1.1

Campus Network







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Current 3G Network ArchitectureCurrent 3G Network Architecture

Packet core

TheInternet

MWG

AG

3G Network

BSC PCFPDSN

BTS

BTS: Base Transceiver Station (Radio Interface)

BSC: Base-station Control

PCF: Packet Control Function

PDSN: Packet Data Serving Node –Interface to the IP Network

ATM/IP

PPP connection between MWG and PDSN

IP interface




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Conclusion

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BaseBase--Station Router (BSR)Station Router (BSR)

TheInternet

MWG

3G Network

PPP connection between MWG and BSR

AGBSR

RadioInterface

IPInterface

• Simplifies disparate network integration

• Ideal for hot-spot and in-building high-speed data markets

• Scalable: pico- to wide-area cellular



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MWG RPMWG RPForwards packets between the MWG and the wired network.

Provides support for the WiFi client (and MWG) to move between RPsusing micro-mobility protocols.

Uses IP-in-IP tunneling to the AG (Access Gateway) to support micro-mobility

Forwards packets between a WiFimobile client and the 3G Network or the 802.11 Network (the RP network)

Can detect a nearby RP if connectivity is available and use it for 802.11 access to the Internet.

Informs WiFi mobile clients about the availability of the high speed WiFi link so that data can be actively fetched by the client

Supports mobility of the WiFi client between different RPs

3G CarrierNetwork

RP

TheInternet

Campus Network

MWG

AG

3G Network

MWG MWG

RP

RP Network

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Access Gateway (AG)Access Gateway (AG)

3G CarrierNetwork

RP

TheInternet

Campus Network

MWG

AG

3G Network

MWGMWG

RP

RP Network

Packets from/to the mobile routed to the AG by the MWG through the 3G or 802.11 network

AG can distinguish packets received over the 3G network from packets received over the 802.11 network

This decision made on source IP address on packets from the MWG

Supports micro-mobility protocols by serving as an end point for the IP-in-IP tunnels from the RPs

Serves as the application (HTTP, e-mail etc.) access gateway for all the WiFiclients.

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Conclusion

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Handoff between BaseHandoff between Base--Station RoutersStation Routersis a challengeis a challenge

• Smaller coverage area per base station increases frequency of handoffs

• Re-initiating a PPP connection with the new BSR takes significant time

•Tunneling packets from old BSR to new BSR is inefficient

• Need for PPP state transfer

TheInternet

AG

MWG

3G Network

BSR

RadioInterface

IPInterface

BSRRadio

Interface

MWG

Migrate PPP State

Serving Cell

Target Cell

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PPP State Migration: PPP State Migration: Call flowCall flowNew/TargetBSR (FA)

1. PPP Migration Request

Old/Source BSR (FA)

2. PPP Migration Response

3. PPP Migration Confirm

4. PPP Migration Ack

MS HA

5. MIP Agent Adv

6. MIP Registration Request

7. MIP Registration Reply

P-P Release

New messageStandard message

Research work of:Research work of:

Sarit MukherjeeSarit MukherjeeAnand KagalkarAnand Kagalkar

Sampath RangarajanSampath Rangarajan

From Bell LabsFrom Bell Labs

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PPP State Info for MigrationPPP State Info for Migration

Parameters Size (Linux Implementation) Frequency of change

LCP 70 Bytes (approx) Once during setup

PAP* 100 Bytes (approx) Once during setup

CHAP* 150 Bytes (approx) Once during setup (may change during session)

Header Compression

Depends on Compression Scheme With every data packet

Total About 300 Bytes

CCP 10 Bytes (approx) Once during setup

IPCP 30 Bytes (approx) Once during setup

*Only one is used in a session

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PPP State Migration: PPP State Migration: Data flowData flowNew/Target

BSR (FA)

1. PPP Migration Request

Old/SourceBSR (FA)

2. PPP Migration Response

3. PPP Migration Confirm

4. PPP Migration Ack

MS HA

IP Packet in TunnelPPP frame in GRE

PPP frame in GRE

IP Packets in GRE

New messageStandard message

Data flow

• Holds IP packets from HA• Sends all the PPP state related parameters

• Recreates and activates PPP state• Processes PPP frames on hold and those coming new from MS• Sends IP packets to Old- Serving BSR

• Sends IP packets on hold and those coming new from HA

5. MIP Agent Adv

6. MIP Registration Request

7. MIP Registration Reply

IP Packets in Tunnel

P-P Release

• Holds PPP frames from MS

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PPP State Migration PPP State Migration vsvs ReRe--initiationinitiation

0100020003000400050006000700080009000

10000

280 375 525 725 1490

PPP Re-initiationTime (in ms)

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6 7 8 9 10

PPP MigrationTime (in ms)

PPP State Migration is significantly faster than PPP State Migration is significantly faster than PPP new session initiation (50 ms vs. 5000 ms)PPP new session initiation (50 ms vs. 5000 ms)

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PPP State Migration + IPCP negotiation PPP State Migration + IPCP negotiation vsvs ReRe--initiationinitiation

050

100150200250300350400450500

280 375 525 725 1490PPP migrationtime (in ms)

IPCP negotiationtime (in ms)

0100020003000400050006000700080009000

10000

280 375 525 725 1490

PPP Re-initiationTime (in ms)

Even considering IPCP negotiation, PPP State Migration is signiEven considering IPCP negotiation, PPP State Migration is significantly ficantly faster than PPP new session initiation (250 ms vs. 5000ms)faster than PPP new session initiation (250 ms vs. 5000ms)

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Filed Trial Network: Hybrid 3G and WiFi




Conclusion

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Fast Layer 3 Fast Layer 3 Handoff between Handoff between RPsRPs is a Challengeis a Challenge

RP

TheInternet

Access Gateway(AG)

Campus Network

128.6.230.1128.6.231.1

128.6.232.1

RP

10.1.1.1 10.1.1.2 10.1.1.3

Mobile: 10.2.1.1Default Router: 10.0.0.1




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A new microA new micro--mobility protocolmobility protocolMobile-IP or one of its variants not a feasible approach for inter RP mobility.

Our Implementation:

Mobiles keep a constant IP address and a constant default IP router IP address, both acquired from the AG (DHCP server)

AG maintains location information in a location table

Once Layer 2 handoff is completedRP sends a gratuitous ARP to the mobile and takes over as default router.RP updates location of the mobile at the AG.

Layer 3 handoff in the order of sub msec.max(one-way delay to the AG, one-way delay to the mobile)

Key Idea: Use Ethernet address as a key to the Location Table at the AG.

Handoff latency using firmware (default) LayerHandoff latency using firmware (default) Layer--2 (L2) handoff2 (L2) handoff

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Re-association of the mobile with a new access point (AP) is the dominant component of the delay (L2 handoff)

T1 = L2 handoff delay due to re-association with new AP

T2 = Time to update ARP cache at mobile

T3 = Ping latency between sending the first probe and getting the ping response from AP

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Handoff latency using manual LayerHandoff latency using manual Layer--2 handoff2 handoff

Manual Re-association of the mobile with a new Access Point (AP) reduces L2 handoff delay from 350ms to 4ms

T1 = L2 handoff delay due to re-association with new AP

T2 = Time to update ARP cache at mobile

T3 = Ping latency between sending the first probe and getting the ping response from AP

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Packet loss count for each experiment during handoffPacket loss count for each experiment during handoff

Faster L2 handoff reduces Ping Replay packet loss dramatically.Reasons for packet loss: (1) weak signal strength (20%); (2) wrong physical address of the destination

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Mobility Protocol ComparisonMobility Protocol ComparisonScheme Mobile-IP

CompliantAnticipation of Link-Layer Handoff

Wireless Mode Protocol Layer

Latency

Daedalus No Yes Infrastructure Network 8-15 ms

MosquitoNet Modified No ----- Network > 250ms

Domain Foreign Agent

No Yes Infrastructure Network ~10ms

NeighborCasting Modified Yes Infrastructure Network NA

End-to-End Approach

No No ----- Transport RoundTrip(peer-to-peer)

Dynamics Mobile-IP

Yes Yes Ad-hoc Network 10-50 ms

FSHWI Modified Yes Infrastructure Network ~10ms

Low-Latency Handoff

Yes No Infrastructure Link & Network

< 100ms

Our protocol No No Infrastructure Link & Network

< 1ms(within a campus)

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Conclusion

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Handoff between 3G BSR and 802.11 RPHandoff between 3G BSR and 802.11 RP

MWG hides transport-level Mobility

MWG terminates PPP while Handset terminates TCP

When MWG moves from 3G to 802.11 network, it gets a new IP address but that is transparent to the handset

IP address of TCP End-points remain the same

3G Network

TheInternet

AG

RP

Campus Network

MWG MWG

BSR

PPP end-point

TCP end-point

TCP end-point

TCP end-point







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Conclusion

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Extending the Field Trial Network: AdExtending the Field Trial Network: Ad--hoc Relayshoc Relays

3G CarrierNetwork

RP

TheInternet

RP Network

MWG(3G Proxy)

AG

MWG

Ad-Hoc Network

(RP Proxy)

3G Network












Extending Field Trial Network with AdExtending Field Trial Network with Ad--Hoc NetworkHoc Network

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When the 802.11 network is unavailable, user requests and responses routed through the 3G Network.As soon as 802.11 connectivity is established, packets routed through the 802.11 network.

An Ad-Hoc 802.11 network willExtend the coverage for 3G and Fixed 802.11 NetworksMake the 3G access more efficient by routing packets through proxy node(s) that have the best channel quality to the 3G base-station.

Fixed 802.11Network

Ad-hoc 802.11Network

Internet Gateway

R-P Proxy

3G Network

3G Proxy






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New Micro-mobility Protocol

Conclusion

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ConclusionConclusionORBIT Testbed:

Hybrid 3G and WiFi Network is operational in Bell Labs Holmdel Lab where 3G is currently emulated using 802.11 access

Hybrid 3G and WiFi Network with 3G Base Station Router (BSR) is expected to be operational in Bell Labs Holmdel Lab by early 2005

Field Trial Hybrid 3G and WiFi Network is expected to be operational in Rutgers campus by mid 2005

Several New Research ideas:

Fast handoff in 3G BSR architecture using PPP state migration

Micro-mobility in outdoor WiFi Networks

Extending WiFi networks using Ad-Hoc networks

Multicast in Hybrid 3G/WiFi networks

hybrid 3g and 802.11 network for the open-access …trappe/prashant/sanjoyccwtalk-2004-10-15.… ·...

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