GM Tutorial on Ad-Hoc Networks From VA Tech

8/2/2019 GM Tutorial on Ad-Hoc Networks From VA Tech

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Mobile Ad Hoc Networks andAutomotive Applications

Luiz A. DaSilva, Jeff H. Reed, William Newhall

Mobile and Portable Radio Group

Virginia Polytechnic Institute and State University

Luiz DaSilva, 2002


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Ad Hoc Networks and Automotive

Applications2

Agenda Fundaments of Mobile Ad Hoc Networks (MANETs)

Advances in MANET

Research on MANET at Virginia Tech

Automotive applications


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Applications3

Fundaments of Mobile Ad HocNetworks (MANETs)

Definition and applications

Challenges

Standardization


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Applications4

Mobile Ad Hoc Networks (MANET)

Mobile nodes

Access points

Backbone

Wireless Mobile Network

MANET


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Applications5

Fundamental Concepts Ad hoc networks are autonomous networks operating

either in isolation or as stub networks connecting to a

fixed network

Do not necessarily rely on existing infrastructure

No access point

Each node serves as a router and forwards packets forother nodes in the network

Topology of the network continuously changes


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Applications6

Motivation Battlefield survivability

Must support mobility

Avoid single point of failure typical of centralized systems

Often unable to rely on existing communications infrastructure

Desire for a rapidly deployable, self-organizing network

Multi-hop packet routing used to exchange messages betweenusers who are not within LOS of each other


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Applications7

Applications Military

Rapidly deployable battle-site networks

Sensor fields

Unmanned aerial vehicles

Disaster management

Disaster relief teams that cannot rely on existing infrastructure

Neighborhood area networks (NANs)

Shareable Internet access in high density urban settings

Impromptu communications among groups of people Meetings/conferences

Wearable computing

Automobile communications (more on this later)


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Applications8

Characteristics Dynamic topology

Heterogeneity

Bandwidth-constrained variable-capacity links

Limited physical security

Nodes with limited battery life and storage capabilities


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Applications9

Standardization Internet Engineering Task Force (IETF) MANET working

group (http://www.ietf.org/html.charters/manet-

charter.html)

The primary focus of the working group is to develop and

evolve MANET routing specification(s) and introducethem to the Internet Standards track. The goal is to

support networks scaling up to hundreds of routers. ()

The working group will also serve as a meeting place andforum for those developing and experimenting with

MANET approaches.


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Applications10

Advances in MANET

Areas of current research

Routing

Cluster management


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Applications11

Research focus to date Routing protocols

Reactive, proactive, hybrid

Cluster management

To reduce overhead, to facilitate network management, to enable

QoS, etc.

Quality of service (QoS) Differentiating among different types of applications

Medium access

Closing the link, recognizing neighbors, scheduling transmission,etc.

Other

TCP performance in MANETs, etc.


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Applications12

Routing in MANETs Why is it different from routing in other types of network?

Because both end nodes and routers are mobile

Rate of link failure can be high if mobility is high

Unicast and multicast routing problems are being treated

No protocol has been standardized yet (but several under

consideration as Internet Drafts at the IETF)

Need new metrics to assess the effectiveness of the

protocol

Route stability Control overhead

Data rebroadcast overhead (for multicast)


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Applications13

MANET Routing Protocols Proactive

Establish routes in advance

Example: Optimized Link State Routing Protocol (OLSR)

Reactive

Establish routes as needed

Example: Dynamic Source Routing (DSR) Less routing overhead, but higher latency in establishing the path

Hybrid

Proactive within a restricted geographic area, reactive if a packetmust traverse several of these areas

Example: Zone Routing Protocol (ZRP)


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Applications14

Routing ExampleA

B

denotes neighbors


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Applications15

Dynamic Source Routing -- DSR (1) Suppose node A wishes to send a packet to node B, but

does not currently have a valid route to the destination

Need for route discovery

Node A broadcasts a ROUTE_REQUEST packet

Each node forwards the packet to its neighbors unless they are

the destination or have a valid route to the destinationAs the packet traverses the network, each intermediate node

adds its address to the header, establishing the reverse route

The destination, node B, sends a ROUTE_REPLY

packet to node A

If the links are not bi-directional, node B must perform its own

route discovery to respond to node A


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Applications16

DSR (2)A

B

ROUTE_REQUEST

packets


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Applications17

DSR (3)A

B

ROUTE_REPLY

packets


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Applications18

DSR (4) Intermediate nodes may cache accumulated route record

contained in the ROUTE_REQUEST packet headers in

order to reduce routing overhead Security concerns with this type of snooping

Confirmation of the receipt of a packet can be done by

passive acknowledgement Node overhears a downstream node forwarding the packet

DSR also contains provisions to avoid route reply storms


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Applications19

Optimized Link State Routing Protocol

(OLSR) Unlike DSR, a proactive routing scheme

Routers maintain awareness of current network topology

by exchanging beacons (HELLO messages)

Each node tells the entire network about its immediate

neighbors

So each node forms a picture of the entire network topology

Each node can then calculate the best route to any destination

Flooding the network with HELLO messages incurs too

much overhead OLSR uses multi-point relay (MPR) nodes to decrease the

number of unnecessary broadcasts (only selected nodes

broadcast HELLO)


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Applications20

Other routing protocols Zone Routing Protocol (ZRP)

Proactive within the nodes local neighborhood, reactive for inter-

zone routing

Temporally Ordered Routing Algorithm (TORA)

Structured reaction to link failures by temporally ordered

sequence of searches for alternative routes Multicast routing protocols

Protocol Independent Multicast (PIM)

Multicast Zone Routing (MZR)

Multicast Optimized Link State Routing (MOLSR)

On-demand Multicast Routing Protocol (OMRP)

And many more


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Applications21

Clustering Transforms the physical network into a virtual network of

interconnected node clusters

Cluster controllers act on behalf of other members of the

cluster to make control decisions

Gateways establish communication between clusters

The objective is to improve efficiency of resource use by

Reducing channel contention

Forming routing backbones to reduce network diameter

Abstracting network state information to reduce its quantity andvariability


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Applications22

Link-Clustered Architecture (1)gateway

ordinary node

cluster head

cluster


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Applications23

Link-Clustered Architecture (2) Must have a protocol for electing clusterheads, choosing

gateways

Provides a natural routing backbone consisting of

clusterheads and gateways

However, may reduce throughput and network robustness (single

point of failure) Another option is to use the clusterhead for control

purposes but not for routing

Each node distributes and collects routing information andchooses routes

Neither inter-cluster nor intra-cluster routing requires clusterhead

traversal

Cl t i f b kb f ti


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Applications24

Clustering for backbone formation

Gateway and Head the Same(1)

ordinary node

cluster head

cluster

backbone

Cl t i f b kb f ti


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Applications25

Clustering for backbone formation

(2) May create a backbone, reducing delay related to

multiple hops

Long distance backbone links may be provided by increasedtransmit power for the clusterheads

Need a protocol to elect clusterheads, decide cluster

affiliation For fault-tolerant connectivity and load balancing, may

create multiple disjoint routing backbones

Virtual Subnet Architecture


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Applications26

Research on MANET at Virginia

Tech

Smart antennas in ad hoc networks

Policy-based management for ad hoc

mobile networks

Game Theory

Adaptive MACs


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Applications27

Smart antennas in ad hoc networks Potential benefits in closing the link, reaching distant

notes through a direct link, directional multicasting, etc.

Simulation of smart antenna controller, with dynamic

beam forming and null steering

Development of an integrated Matlab/OPNET Modeler

simulation including layers 1 (signal degradation and attenuation,optimum assignment of antenna weights), 2 (medium access) and

3 (routing) considerations

Application of directed beams to increase the efficiency

of medium access algorithms in ad-hoc environments

Multi-hop request-to-send/request-to-orient


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Applications29

Policy-based Management Policy-based Networking (PBN)

Automating network management

Abstraction of complex low-level policies to simple high-levelpolicies

Multiple policy disciplines

QoS, network security, IP address allocation etc.

QoS policy QoS means incentive to steal resources?!

Need for Authentication, Authorization, Accounting

Policy-based Admission Control (PAC) Not just based on available resources (bandwidth)

IETF/DMTF Standardization

Common Open Policy Service (COPS) protocol etc.


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Applications30

Management of Ad Hoc Networks Autonomous networks operating in

isolation or as stub networks

Extremely challenging Severe bandwidth constraints

Limited battery life

Dynamic topology

Heterogeneity Limited survivability

Need a robust, adaptive, and

efficient management framework

Are wireless mobile networks

another venue for policy-based

management?


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Applications32

Testbed A R INetw ork Virg in ia AT M

Campus ne twork

Linux router

CISCO router 3660

Linux router

CISCO router 3660

Linux router

CISCO router 3660

Linux router

CISCO router 3660

H ubSwitch

P C PC PC PC802.11b

Laptop

Laptop

H ub

CISCO router 3620

100 Mbps

Sniffer

OC3c

100 Mbps

PC

K VM

Patch panel

H ub

Switch


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Applications33

Automotive Communications

Issues and applications

Performance and feasibility assessment


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Applications34

Automotive communications

In-vehicle devices

Under the hood (brakes, transmission, engine, )

Passenger cabin (dashboard, seatbelt, air bags, )

Mobile devices

Palmtop, laptop, Blackberry, pager,

External communications Satellite radio, AM/FM radio

Positioning information, directions, road assistance

Notification of traffic information, general Internet access

Diversity of needs implies multiple communications solutions


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Applications35

Communications solutions

IEEE 802.11

Bluetooth Cellular

(2G/2.5G/3G)

Infrared

IN VEHICLE EXTERNAL

Ad hoc networks

CANIEEE 1394


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Applications36

Existing initiatives

Several projects dealing with automobile communications

(primarily in Europe)

Project COMCAR (Communication and Mobility by CellularAdvanced Radio)

Dynamic Radio for IP Services in Vehicular Environments

(DRiVE)

Multimedia Car Platform (MCP)

Note that all rely on infrastructure-based wireless

systems (not ad hoc)


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Applications37

Project COMCAR

www.comcar.de

Communication and Mobility by Cellular Advanced Radio

Asymmetrical, interactive, high quality IP multimedia services

Application to automobiles and trains

Uses cellular infrastructure

W-CDMA, OFDM, GPRS Project developed in Germany

Ericsson, Daimler Chrysler, Sony


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Applications38

DRiVE

www.ist-drive.org

Dynamic Radio for IP-Services in Vehicular

Environments Uses cellular infrastructure

Dynamic frequency allocation and coexistence of different radio

technologies (GSM, GPRS, UMTS, etc.) Cooperation among network elements and applications

European IST (Information Society Technologies)

program started in 2000


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Applications39

Multimedia Car Platform (MCP)

http://mcp.fantastic.ch

IP-based, using GSM/GPRS

Project partners include BMW, Volkswagen, France

Telecom, Nokia and others


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Applications40

Ad hoc automotive network

Each automobile participating in the network would

contain a low power data transceiver

Enable communications with other automobiles in the vicinity Each vehicle serves as both an end point (to receive/transmit

data) and a router (to relay data to/from other vehicles)

Some fixed sites serve as gateways to the Internet Vehicle dealerships, other partners

Feasibility

Use unlicensed frequency bands low cost deployment Must determine achievable performance as a function of density

of vehicles


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Applications41

Applications

Weather and hazard alerts

Safety and security

Travel information and m-commerce (car is your credit

card)

Interactive navigation

Diagnostic data

Maintenance support

Instant messaging Data mining

General Internet access


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Applications42

Performance Assessment

Factors deal primarily with very dynamic nature of the

topology

Latency of transmissions Probability of success

Throughput

Control traffic overhead Route stability

and impairments due to the wireless medium

Error rate

Spectrum utilization


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Applications43

Network architecture

Mobile nodes (vehicles)

Transceiver

In-vehicle devices, mobile consumer devices

Existing infrastructure

Cellular/PCS, public data network, etc.

New infrastructure Car dealerships

Gas and service stations

Drive-through windows Fixed points along highways


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Applications44

Network components

Radio

Power requirements and power control

Bandwidth Memory requirements

Programmability

Antenna requirements Backhaul strategies

Wireline, fixed wireless, satellite

IP-based, PSTN,

Protocols

Physical, MAC and transport layers

Ad-hoc routing protocols for unicast and multicast


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Applications45

Evolutionary path

Migration to new standards and technologies

Compatibility with existing standards

Challenges

Development and product life cycle is very different for

automobiles versus communications devices

Market penetration of proposed new technology in new vehiclesand existing vehicles will impact network density and therefore

performance


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Applications46

Technology assessment

Analysis and simulation

Network capacity

Network performance as a function of node density

Demonstrations

Experimental statistics

Application demonstration


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Applications47

Benefits of Research

Benefits to GM

Clear understanding of feasibility of vehicular ad-hoc network and

performance of such a network Fill a gap in vehicular communications research on external

networking and communications

Future research to provide more detailed descriptions of realizing

the network on a broad scale

Future work could include prototypes to be demonstrated


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Applications48

Readings and References (1)

Books on MANET

C. K. Toh,Ad Hoc Mobile Wireless Networks: Protocols and

Systems, Prentice Hall, 2001. C. E. Perkins,Ad Hoc Networking, Addison Wesley, 2000.

IETF MANET working group for RFCs with details of

proposed routing protocols http://www.ietf.org/html.charters/manet-charter.html


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Readings and References (2)

For a summary of unicast and multicast routing protocols

M. Christman, Extensions for Multicast in Mobile Ad-hoc

Networks (XMMAN): the Reduction of Data Overhead in WirelessMulticast Trees, M.S. Thesis, Virginia Tech, July 2002.

For a discussion of automotive communications

W. Kellereret al., (Auto) Mobile Communication in a

Heterogeneous and Converged World, IEEE Personal

Communications, December 2001.

GM Tutorial on Ad-Hoc Networks From VA Tech

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