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Mobile Networks Research: Area Review

I. Seskar, K. Tepe, M. Ott, D. Raychaudhuri

WINLAB IAB MeetingMay 20/21, 2002

5/02

MobiNet Project ObjectivesWINLAB initiated a new core research area on next-

gen mobile network arch & protocols in AY’01-’02

Experimentally-based activity centered around the new “MobiNets” lab (in CORE529)

Goals of research programnew concepts for next-gen (“4G”) wireless network protocols, applicable to future cellular, WLAN, sensor nets & pervasive computingexperimental evaluation of proposed protocols and related algorithmssystem prototyping capabilities for proof-of-concept demosadvances in network software architecture & implementationhands-on software prototyping experience for grad students

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MobiNet Research ChallengesSeveral basic issues still need to be addressed for next generation wireless networks:

Fast/reliable broadband radios (PHY/MAC) with QoS~100 Kbps 1-10 Mbps with adaptivity, link reliability & QoS

Scaling of radio networks for ubiquitous wireless devicesarchitectures that support ~10’s of devices/Sq-m, ~Gbps/Sq-Km,..

Integration of multiple radio technologies into single IP networkradio-independent generic mobile network, support for legacy protocols

Faster and simpler standardization process, feature evolution.....open-architecture networks, programmable features, etc.

New networking modes, e.g. multicast, multihop & peer-to-peer...lower-cost infrastructure, networks that grow organically

Truly “useful” mobile information services...beyond web browsing on phones/PDA’s, new portable devices

scalability,cost

networkflexibility

new services

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“4G” Network Evolution

WPAN radio

Today’s Wireless Systems The Future

Low-tier services

IP

802.11 Radio

Ethernet

Mobile ServiceMiddleware

IP

WLAN Services

3G/4GRadio

WLANradio

WPAN/low-tier radio

2.5G/3G Radio

GSM/GPRS

2.5G/3G Services

3G AccessNetwork

PSTN IP

WPAN networklayer (e.g. Bluetooth)

Generic Radio Access Network

Radio-specific vertically integrated systems withcomplex intetworking gateways

Security QoS VPN ContentDelivery

4G Services

Radio Independent modular system architecturefor heterogeneous networks

uniformradio API’s

genericnetwork API

uniform serviceAPI (Internet+)

Unified IP-based mobile network

incl supportfor multihop,mcast, etc,

servicefeaturemodules

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Potential “4G” Network IdeasA few techniques for achieving the 4G design goals discussed earlier:

3G/WLAN Hot-SpotsUse of WLAN in hot-spots for lower system cost, better end-user performance and more total capacity

InfostationsUse of opportunistic “radio caches” for significant reduction inaverage cost per bit, facilitating qualitatively new mobile services

Self-organizing wireless access networksAd-hoc wireless network protocols which support multihop and peer-to-peer service models, particularly for low-tier uses (in-home, sensors, etc.)

Content-based multicasting...new network service paradigms for location- and person-aware information delivery to mobiles

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Techniques for seamless service:

- Authentication, global roaming

- Security issues

- Dynamic handoff

- End-to-end QoS control

- Network management

- Service level agreements (SLA)

Bluetooth<-> 3G IWF

WLAN<->3G IWF

BluetoothUWB,

Bluetooth<->WLAN IWF

WLAN,HiperLAN,UWB,

Cellular/2.5G,3G

3G/WLAN interworking

Unified Mgmt Layer

Protocol stacks

PHY

linknet

IWF1 IWF2BT WLAN 3G

MobiNets: Multimode Networks

Multiple devices with various radio interfaces

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• Mobile user passes through Infostation in sec during which ~MB files are downloaded/uploaded– Requires modifications to conventional WLAN MAC, incl fast synch,

pre-authentication, etc. (...related to interworking discussed before)– Motivates 2-tier arch with ~10m service zone (for high-speed data

transfer) and ~50m access control zone (for sync, authentication, ..)

Transit time ~sec

Infostationsaccess pointData cache

~100 MB/sFast transfer

Low-speed control channel(for synch & service setup)

ServiceZone

Access ControlZone

Total transit time ~10sec

MobiNets: Infostations MAC

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• 802.11a MAC can be used for Infostations service– Pre-authenticate user in low-bit rate mode (~50m range)– Mobile terminal waits for modem to reach max 54 Mbps (~10m range)– High priority access mode used for Infostations access

MobiNets: Infostations via 802.11 MAC

APBeacon

IS Controlpacket

Terminalenters WLANcoverage area

Mobile requestsadvance authentication

........

Authenticationmessage exchange

PIFS

normal channelactivity

..

IS transferrequest*

PIFS

Infostationsfile transfer*

Terminalenters maxPHY speed zone

ACK

A1

A2

A3

PriorityAccessinitiated

*RTS/CTS msgsnot shown

time

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• Infostation caches contain location-aware and user-specific data to be downloaded opportunistically

proactive caching involves various strategies including locationcontext, user profiles, prediction of user location, etc.content multicasting (with XML classification) potentially useful

Infostation 1

Locally relevant+ user-specific data

Infostation cache

Movement of user

Router

Infostation cache

Infostation M

Server

Internet

MobiNets: Infostations Caching

Flow of cached data

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• New real-time, person- and location-aware information delivery paradigms need to be considered for 4G.

• Content multicasting based on XML investigated as possible option for delivering relevant info to mobiles.

SX

SX

User

Content Provider

SemanticRouter

A

SemanticRouter

B

XMLDescriptor

Interest profile

MobiNets: Content Multicast

Mobile interestprofile contains:(user, location, terminal capability,..)

contentmulticast

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• Hierarchical, self-organizing network concepts currently under consideration, based on:

3 service tiers (cellular, WLAN, personal area)BS’s, AP’s, FN’s (forwarding radio nodes), user devicesautomatic discovery and power mgmt protocolshierarchical, ad-hoc multihop routing and spatial MAC

MobiNets: Self-Organizing “4G” Network

InternetInternet

Forwarding node

low-tier(e.g. sensor)user nodes

Access Point

FN

APBTS

3G cell

personal-areapico-cell

WLANmicro-cell

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AccessPoint (AP)

ForwardingNode (FN)

SensorNode (SN)

Third Tier (AP)IP Network

First Tier SN

Second Tier (FN)

MobiNets: Hierarchical Ad-Hoc Net

MAC cluster

Ad-hoc FN/AP backbone

wiredAP backbone

Note: not astrict

hierarchySN

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IP Network

MAC/Flooding

Ad-hoc routing

Ad-hoc& IP routingλ6

λ5

λ4

λ1

λ2

λ=f (Tx power,battery life,

congestion, etc.)

MobiNets: Routing in Hierarchical Ad-Hoc Network

λ3

routingmetrics

Need to consider PHY power, MAC and routing in an integrated

way to optimize the system

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• A flexible, open-architecture mobile network testbedhas been set up during the ’01-’02 academic year– open-source Linux routers and AP’s (commercial hardware)– Linux and embedded OS forwarding and sensor nodes (custom)– radio link and global network monitoring/visualization tools

PC-basedLinux router

MobiNets Lab: Experimental Network

P C

Router networkwith arbirtrary topology

AP

Compute& storageservers

Managementstations

Radio Monitor

Forwarding Node/AP(custom)

Sensor Node(custom)

802.11bPDA

802.11bLinux PC

Commercial 802.11

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MobiNets Lab: Network NodeEach router node has 3 general purpose PCs:• 1U form factor • Single or dual CPU configuration with up to 1

GB of memory• Quad 100 Mb/s Ethernet

Single/DualCPU

IDEController

HD

DualEthernet

DualEthernet

802.11Card

BluetoothCard

PC Card(PCMCIA)Memory

Controller

DDR Memoryup to 1 GB

BusControllers

Display Controller

Peripherals(USB, etc.)

PCI bus

P C

P CP C

to other nodes

Node can be used as:

• Router

• Server/Cache

• Access point

• Combination of above

control links

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MobiNets Lab: Software platform

Main SW features:• Open Linux OS• By using packet filters

minimizes driver development

• Multiple independent developers each with separate protocol stack

• Uses existing TCP/IP stack for control only

• Java based for ease of reuse and feature addition

802.11 Bluetooth Ethernet

Driver Driver Driver

Packet filter

Ext Ext Ext

LL Open API

Custom protocol stack

Kernelprotocolstack

Applications

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CerfBoard-SA:• Intel® StrongARM™ 1110 microprocessor @ 206 MHz • 16 MB ROM (FLASH)• 32 MB RAM• Compact Flash Interface• 16 Digital I/O lines

Wireless Interface: 802.11b -Lynksys WCF11

OS: Linux 2.4.9

Typical power consumption: 450 mW

Small, low-power platform with good hardware feature set sharing the same software platform with other node types

MobiNets Lab: Sensor Module

5/02

MobiNets Lab: Forwarding/AP node

CompuLab 586CORE:• AMD ElanCS520 CPU – 133 MHz• 32 MB ROM (FLASH)• 32-64 MB RAM• 2 x 100BaseTx Ethernet• VGA/XGA, IDE - Hard Disk Interface, Dual PCMCIA SlotWireless Interface: 802.11b • PRISM-2 PCMCIA Card with external antenna• Cisco 350 with internal antennaOS: Linux 2.4.17 kernel with both Infrastructure / Add-hoc mode supportTypical power consumption: 8 W

Multi-purpose embedded platform with radio in/out, processing, routing and storage capabilities

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MobiNets Lab: RF Monitoring NodeOff-the-shelf Access Point running modified Linux OS with the wireless interface in RF Monitoring mode – used for spectrum monitoring and management support.

Eumitcom WL11000SA-N:• AMD ELAN SC400 CPU• 1 Megabyte ROM (FLASH)• 4 Megabytes RAM• NE2000 Ethernet ControlerWireless Interface: 802.11b Generic PRISM-2 PCMCIA Card with external antennaOS: Linux 2.4.17 kernel with Infrastructure mode supportTypical power consumption: 4.0 W

5/02

MobiNet Project Status & Future Work

Initial goal of establishing the lab and getting control of router/AP/FN/SN platform software achieved

Early research-level demo system of discovery in self-organizing network completed

Infostations (with content multicast) demo for emergency/disaster recovery applications being developed for potential “tech transfer” uses

Future work during 2003:continue with discovery, power control, MAC and routing in hierarchical ad-hoc network prototoypeWLAN/2.5G interworking proof-of-concept prototypestart examining security and information flow in pervasive computing scenariosinitiate experiments on spectrum collaboration (..new ITR)

5/02

MobiNets Lab: Emergency Infostation Prototype

Forwarding node/Access Point with:•30 GB Hard Disk for caching•High-gain directional antenna for backbone connectivity•Omni-directional antenna for local coverage•3 hour battery •Photovoltaic (solar) panels with the controller as a continuous power/battery charging sourceLinux 2.4.17 kernel with:•Infrastructure 802.11b support•IP Bridging support•JAVA Application support

Typical power consumption: 20 W