01 adhocnet overview

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TextbookC. Siva Ram Murthy and B. S. Manoj, Ad Hoc Wireless

Networks: Architectures and Protocols, Prentice HallPTR, 2004.

ReferencesCarlos de Morais Cordeiro and Dharma Prakash

Agrawal, Ad Hoc & Sensor Networks: Theory andApplications, World Scientific Publishing Co., 2006.

Feng Zhao and Leonidas Guibas, Wireless Sensor

Networks: An Information Processing Approach,Elsevier, 2004.

Edgar H. Callaway, Jr., Wireless Sensor Netwoks:Architectures and Protocols, Auerbach, 2004.


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Related Sites

Advanced Network Technologies Division, NIST,Wireless Ad Hoc Networks,

http://w3.antd.nist.gov/wahn_home.shtml

Autonomous Networks Research Group, USCWSN bibliography,

http://ceng.usc.edu/~anrg/SensorNetBib.html

IETF MANET WGhttp://www.ietf.org/html.charters/manet-charter.html

IEEE 802 WGhttp://grouper.ieee.org/groups/802/dots.html

Zigbeehttp://www.zigbee.org

TinyOShttp://www.tinyos.net/
http://w3.antd.nist.gov/wahn_home.shtmlhttp://ceng.usc.edu/~anrg/SensorNetBib.htmlhttp://www.ietf.org/html.charters/manet-charter.htmlhttp://grouper.ieee.org/groups/802/dots.htmlhttp://www.zigbee.org/http://www.tinyos.net/http://www.tinyos.net/http://www.zigbee.org/http://grouper.ieee.org/groups/802/dots.htmlhttp://www.ietf.org/html.charters/manet-charter.htmlhttp://www.ietf.org/html.charters/manet-charter.htmlhttp://www.ietf.org/html.charters/manet-charter.htmlhttp://ceng.usc.edu/~anrg/SensorNetBib.htmlhttp://w3.antd.nist.gov/wahn_home.shtml


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Wireless Network Technology


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Ad Hoc Networks vs.

Ad hoc networks vs. Wireless mobile networksInfrastructureless vs. Infrastructured Network

All devices of an ad hoc network are likely to have similarconstraints

Ad hoc networks vs. Peer-to-peer networks

P2P devices use existing networked structures such asInternet

All P2P networks are not ad hoc network

Because NOT all ad hoc network utilize an existing structure forthe communication among devices

Ad hoc computing vs. Pervasive computingThe devices for pervasive computing are usually very small

and can be embedded in any type of objects

Users are sometimes not even aware of the existence of theembedded electronic chips


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Ad hoc networks (1)

Temporary network composed of mobile nodes

without preexisting communication infrastructure,such as Access Point (AP) and Base Station (BS).Each node plays the role of router for multi-hop routing.

Self-organizing network without infrastructurenetworks

Started from DARPA PRNet in 1970 Cooperative nodes (wireless)Each node decode-and-forward packets for other nodes

Multi-hop packet forwarding through wirelesslinks

Proactive/reactive/hybrid routing protocolsMost works based on CSMA/CA to solve the

interference problem IEEE 802.11 MAC


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Ad hoc networks (2)

But, there is no links

Nodes simply radiate energy

Nodes can be cooperative in many other ways (complex)

Amplify and forward

interference cancellation to increase SINR

There may be many things out there that we can takeadvantage of across layers for improvement!

F

D

E

C

A

B


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Cellular Net vs. Ad Hoc Net (1)

Cellular Net Ad Hoc Net

Fixed infrastructure-based Infrastruxture-less

1-hop wireless links Multi-hop wireless links

Guaranteed bandwidth Shared radio channel

Centralized routing Distributed routing

Seamless connectivityFrequent path breaks due tomobility

High cost and time of deployment Quick and cost-effectivedeployment

Frequency reuse throughgeographical channel reuse

Dynamic frequency reuse basedon CSMA

Time sync: easier to achieve. Difficult and consume BW


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Cellular Net vs. Ad Hoc Net (2)

Cellular Net Ad Hoc Net

BW reservation: easier Requires complex MAC

App. Domain: civilian andcommercial sector

Battlefields, emergency operations,collaborative computing

High cost of net maintenanceSelf-organization and maintenanceis built into net

MHs: low complexity More intelligence

Major goal of routing: max call

acceptance, min call drop

Find paths with min overhead,quick reconfiguration of broken

paths

Widely deployed

Several issues are to be addressedfor commercial deployment,

Widespread use in defense


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Major Applications

Military

Emergency Service

Collaborative and Distributed Computing

Wireless Mesh Network

Wireless Sensor Network

Telematics

Wireless Personal Area Network

Home Network

Ad Hoc Relay for Cellular Network

Networks for ubiquitous computing

Demands for

group

communications


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Emergency Service


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MANET Research Target

MANET

No infrastructure

Self organizing networks

Communications via mobilenodes

Dynamic topologyHeterogeneity bandwidth-

constrained variable-capacity links

Limited physical security

Nodes with limited batterylife and storage capabilities

Issues in MANET

Ad Hoc Unicast Routing

Ad Hoc Multicast/BroadcastRouting

Power Saving

Global Connectivity forMANET

Addressing & DNS Service

Automatic Support ofNetworking in MANET

MANET Autoconfiguration


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WMN Architecture

WMNs (Wireless Mesh Networks) consist of:

mesh routers and mesh clientsMesh routersConventional wireless AP (Access Point) functions

Additional mesh routing functions to support multi-hopcommunications

Usually multiple wireless interfaces built on either the same ordifferent radio technologies

Mesh clientsCan also work as a router for client WMN

Usually one wireless interface

Classification of WMN architecture Infrastructure/Backbone WMNs

Client WMNs

Hybrid WMNs


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Infrastructure/backbone WMNs

Internet

Wi-FiNetworks

CellularNetworks WiMAX

Networks

SensorNetworksBase Station

Sink node

Sensor

Wireless MeshBackbone

Wired ClientsMesh RouterMesh Router

with Gateway

Mesh Router

with Gateway

Mesh Routerwith Gateway/Bridge



Access Point

Base Station


Wireless Clients


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Client WMNs

Mesh Client

Mesh Client

Mesh Client


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Hybrid WMNs

Wi-Fi, Wi-MAX,

Sensor Networks,Cellular Networks, etc.

Internet

Wireless Mesh Clients

Wireless MeshBackbone

Conventional Clients

Mesh Router

Mesh Router

Mesh Routerwith Gateway

Mesh Routerwith Gateway


Mesh Router Mesh Router



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Sensor Network Model

SourceStimulus

Sink

Sink


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Wireless Sensor Networks

A sort of ad-hoc networks

A network of low cost,densely deployed,untethered sensor nodes

Application areas:heath, military, and home

Placed in inaccessible terrains or disaster areas It may be impossible to recharge batteries

Different Node Characteristics from Traditional nodes # of nodes in a sensor network can be several orders of magnitude

higher than the nodes in an Ad Hoc network (100s to 1000s nodes)

Densely deployed (20 nodes/m3)

Prone to failures

Topology changes very frequently

Mainly use a broadcast communication, whereas most Ad Hocnetworks are based on point-to-point

Limited in power, computing capacities, and memory

May not have global ID because of the large amount of overhead andlarge number of sensors

Ad Hoc Net

Wireless

Sensor

Network


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Existing Wireless Net vs. Sensor Net

Cellular system Bluetooth, MANET Sensor Network

Single Hop Multi-hop Multi-hop

High QOS

Bandwidth

efficiency

High QOS Power conservation

Limited bandwidth

Large number ofnode

Narrow radio range

Frequent topologychange

Station to Basestation

Peer to peer

Peer to multi node

Peer to multi node


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Sensor Networks Architecture

Sensor node

Made up of four basic components

Sensing unit, Processing unit, Transceiver unit, and Powerunit

Additional application-dependent components

Location finding system, power generator, and mobilizer

Scattered in a sensor field

Collect data and route data back to the sink

SinkCommunicate with the task manager node (user) via

Internet or satellite


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Challenges in Ad Hoc Networks

Limited wireless transmission range

Broadcast nature of the wireless medium

Packet losses due to transmission errors

Mobility-induced route changes

Mobility-induced packet losses

Battery constraints

Potentially frequent network partitions

Ease of snooping on wirelesstransmissions (security hazard)


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Issues in Ad Hoc Networks

Medium access scheme

Routing

Multicasting

Transport layer protocol

Pricing shcemeQoS provisioning

Security

Energy management

Addressing and service discovery

Scalability

Deployment considerations


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Medium Access Scheme

Distributed operation

Synchronization Hidden terminal problem Exposed terminal problem Throughput

Access delay Fairness: especially for relaying nodes Real-time traffic support Resource reservationAbility to measure resource availability

Capability for power controlAdaptive rate control Use of directional antennas


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Routing (1)

Challenges

Mobility

results in path breaks, packet collisions, transient loops, stalerouting information, and difficulty in resource reservation

BW constraints

Error-prone and shred channel

BER: 10-5 ~ 10-3 wireless vs. 10-12 ~ 10-9 wired

Location-dependent contention

Distribute load uniformly


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Routing (2)

Requirements

Minimum route acquisition delay

Quick route reconfiguration

Loop-free routing

Distributed routing approachMinimum control overhead

Scalability

QoS provisioning

Support for time-sensitive traffic

Security and privacy


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Multicasting

Robusteness

recover and reconfigure quickly from potentialmobility-induced link breaks

Efficiency

Min control overhead

QoS support

Efficient group management

Scalability

security


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Energy Management

Tx power mgmt

MAC: sleep mode

Routing: consider battery life time: load balancing

Transport: reduce ReTx

AppBattery energy mgmt

Extend battery life by taking adv of chemicalproperties, discharge patterns, and by the selection of

a battery from a set of batteriesProcessor power mgmt

Device power mgmt


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Deployment Consideration (1)

Adv. in ad hoc net

Low cont of deployment

Incremental deplyment

Short deplyment time

ReconfigurablityScenario of deployment

Military deployment: data-centric or user-centric

Emergency operation deployment: hend-held,

voice/data, < 100 nodesCommercial wide-area deployment: e.g. WMN

Home network deplyment


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Deployment Consideration (2)

Required longevity of network

Area of coverage

Service availability: redundancy

Operational integration with other infrastructure

Satellite network, UAV(unmanned aerial vehicles), GPS

Cellular network

Choice of protocols

TDMA or CSMA-based MAC?

Geographical routing (using GPS)

Power-saving routing ?

TCP extension ?

01 adhocnet overview

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