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Overview of Mobile Networking Overview of Mobile Networking Initiatives at WINLABInitiatives at WINLAB

Internet (IP-based)

Infostationcache

WLANAccess Point

WLANHot-Spot

VOIP(multi-mode)

Low-tier clusters(e.g. low power 802.11 sensor)

Ad-hocnetwork

extension

Public Switched Network(PSTN)

BTS

High-speed data & VOIP

Broadband Media cluster(e.g. UWB or MIMO)

BTS

BSC

MSC

CustomMobileInfrastructure(e.g. GSM, 3G)

CDMA, GSMor 3G radio access network

Generic mobile infrastructure

Today Future

GGSN,etc.

Voice(legacy)

High-speed data & VOIP

Relay node

Introduction: The Next GenerationIntroduction: The Next Generation

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Introduction: Future Protocol ArchitectureIntroduction: Future Protocol Architecture

Research OverviewResearch Overview

Future Wireless Networks

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Research Topics Multimedia Networking

Ad Hoc Networking

Sensor Networking

Security and Privacy

Testbeds and Validation

MultimediaNetworking

Wireless Multimedia MulticastingWireless Multimedia Multicasting

Challenges

• Limited Bandwidth• Time-varying, error-prone

channels• Receiver heterogeneity

Issue: What strategies can we employ to overcome the challenges of the wireless scenario?

FEC

ARQ

Simulcast

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Layers

Tools Proposed strategy being examined:1. Employ multiple resolutions of video transmitted to different

multicast groups2. Clients subscribe to multicast groups based on their channel

conditions3. Centralized and distributed strategies for deciding appropriate

group

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Network Coding:�� Incorporate coding at intermediate network nodes• Achieves higher throughput in a multicast network• Challenge: Transmission rate is limited by the minimum capacity of all receivers

Multiple Description Network Coding:• Multimedia MDC can ensure reliable media delivery• MDs are transmitted at a rate of the maximum capacity of all receivers!• Receivers with less capacity receive fewer descriptions• Graceful reduction in media quality

Multiple Description Network CodingMultiple Description Network Coding

Ad HocNetworking

BTS A

AP1

FN1

FN2

FN3

FN4

AP2

AP3Wired Radio Access Network Infrastructure AP beacon(ID, frequency, power, ,bit-rate,service capabilities...)

FN beacon

BTS radiobeacon

BTS serviceadvertisement (into wired net)AP service

advertisement (into wired net)

End-user:seek (FN*, AP*)associate (FN1, AP2)routing update (FN1)routing update (AP2)send data

med-tier radio(e.g. 802.11x)

low-tier radio(e.g. 802.15.x)

Forwarding Node:seek (FN*, AP*)associate (FN3, AP3)routing update (FN3)routing update (AP3)forward data

Protocols needed:Ad-hoc discovery (enhanced beacons, etc.)Ad-hoc MACAd-hoc network routing (extended metrics including energy)handoff, QoS control, multicast (..features)

ad-hocwireless networkinfrastructure

may receiveBTS beaconfor wide-areaservice

laptop

sensor node

Access Point:Seek (AP*, BTS*)Associate (AP2, BTS A)handoff update (AP2)handoff update (BTS A)..forward data & handoff

Discovery and Routing in Ad Hoc NetworksDiscovery and Routing in Ad Hoc Networks

AdAd--Hoc MAC: Hoc MAC: DD--LSMA SchedulingLSMA Scheduling

� Link scheduling to allow parallel transmissions, solves “exposed node”� useful for QoS on ad-hoc FN-FN infrastructure in hierarchical systems

� Distributed scheduling algorithm (upper MAC), using 802.11-based lower MAC

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B

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to C to ERTS retransmit

to C to Cto E to Eto C

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A

DE

B C RTS

CTSDATA

Upper MACScheduler

D-LSMA

Classified flows

Lower MAC

……

Sensor Networking

AdAd--Hoc Network: Hoc Network: 33--Tier Sensor NetTier Sensor Net� Self-organizing hierarchical ad-hoc wireless network (SOHAN)

under consideration at WINLAB– Tier 1: low-tier mobile nodes, e.g. low-power sensors (MN)– Tier 2: forwarding nodes (FN) with multiple radio interfaces

(UWB, WLAN, cellular…)– Tier 3: wired base stations and access points (BS or AP)– Research on new protocols for: ad-hoc discovery, MAC and

routing

InternetInternet

Forwarding node

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

Access Point

FN

AP

Wide-AreaCell

personal-area pico-cell

WLANmicro-cell

BTS

Sensor Energy Conservation via AdaptationSensor Energy Conservation via Adaptation

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���Active nodes: forwarding packets

Backup nodes: Sleep + Wakeup

Question: How to determine the sleep interval?

�Tradeoff between energy conservation and responsiveness

Current solution: � Use a fixed sleep interval that is small enough� Energy conservation = sleep interval / wakeup time

Proposed Solution:� Adaptive sleep interval

Issue: Network Lifetime

WirelessSecurity andPrivacy

Authentication in Hierarchical Authentication in Hierarchical Ad Hoc Sensor NetworksAd Hoc Sensor Networks

� Public key certificates are not suitable for flat ad hoc networks– To check certificate requires

expensive public key operations

� Three tier architecture:– Varying levels of computational

power within the sensor network– Sensors do not communicate with

each other– Forwarding nodes are radio-relay

� TESLA Certificates– Alternative to PK certificates– Uses symmetric key cryptography– Delayed key disclosure

AP

FN

SN

� Authentication framework:– Access points provide filter to

application– TESLA certificates provide efficient

sensor node handoff– Weak and assured data

authentication provided

3G Multicast Security3G Multicast Security

� Keys must be shared by multicast group participants� As users join and leave, keys must be changed� 3GPP has proposed a new entity, the BMSC for managing broadcast and

multicast services� The BMSC can perform key management

Node B

Node B

Radio Network Subsystem (RNS)

GGSN

SGSNRNC

Node B

UMTS Terrestrial Radio Access Network

BMSC

UMTS Core Network

Internet

TestbedsAndValidation

Emergency Response Infostation� Outdoor Infostations for Rapid

Deployment– For first responders to set up

wireless communications infrastructure at disaster site

– Provides WLAN & sensor net services

– Infostations for caching large files (maps, etc.)

– Wireless backhaul link

� Prototype incorporates:– 802.11 MAC+ for Infostations pass-

through mode– Content caching algorithm & software– Solar panels, antennas and

embedded processor with WLAN card– Can be integrated with 802.11 ad-hoc

sensorsWINLAB’s Emergency Infostation 2002

Medical Sensor with 802.11 WLAN

� First system-level MUSE prototype completed 11/03– New ECG interface board– CerfCube platform with 802.11b

(off-the shelf components)– WINLAB drivers & networking

software

� Next steps– Make this prototype available to

BioMed and UMDNJ collaborators– Integrate with ZnO devices– Continue work towards MUSE

sensor SoP/SoC with low-power 802.11b

ORBIT Testbed� Open-access next-generation wireless network testbed being

developed for NSF network research testbeds (NRT) program

� Large scale “radio grid emulator” for evaluating new concepts for future wireless networks, e.g. ad-hoc sensor nets, pervasive systems...

� Also, outdoor “field trial network” covering RU Busch & NB campuses for real-world application work

Mobile node(robotic control)

Static radio node

Radio link emulation

1. Radio Grid for Lab Emulation

Dual-mode Radio device

2. Field Trial Network

“Open”APIAccess Point(802.11b)

End-user devices

Ad-hoclink

3Gaccess

link

HighSpeed

Net

Firewall

MobilityServer

Wiredrouters

EmulatorMapping

“Open”API

3G BTS

Global InternetGlobal Internetns-2+ scripts

&code

downloads

ResearchUser of Testbed

ORBIT ORBIT TestbedTestbed: : Radio GridRadio Grid