mobile ad hoc networking: imperatives and challenges

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Mobile ad hoc networking: imperatives and challenges

Imrich Chlamtac, Marco Conti, Jennifer J.N. Liu

2005. 10. 10.MMLAB, Seongil Han

sihan@mmlab.snu.ac.kr

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Contents Introduction

Mobile ad hoc network research

Medium Access Control

Networking issues

Applications and middleware

Cross layers’ research issues

Discussion and conclusions

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Introduction Mobile Ad hoc Network (MANET)

Sensor network

An important part of the 4G architecture Non infrastructure based Spontaneous networking Can be connected to a backbone network Attractive technology

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MANET issues Traditional problems of wireless network

Channel characteristics Hidden and exposed terminal

MANET specifics Autonomous and infrastructure-less Multi-hop routing Dynamically changing network topology Variation in link and node capabilities Energy constrained operation Network scalability

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Research area 3 layers and cross layers issues

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Medium Access Control Bluetooth

De-facto standard For low-cost, short-range radio links Contention-free token-based multi-access Masters and slaves

Many applications is developed and being developed.

Mobile phone, headset, etc. The scatternet

Multi-hop Bluetooth networks, interconnecting several piconets

Various formation algorithm

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Medium Access Control (cont.)

IEEE 802.11 Infrastructure-based and infrastructure-less Little or no attention was given to Ad hoc mode With TCP, problems get large

HiperLAN ETSI has promoted “High Performance Radio Local Area Network” HiperLAN/2 is noticeable

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MAC research issues Random access

Used by most proposal Collision avoidance and utilization maximization Hidden-terminal and exposed-terminal problem

Controlled access More suitable for QoS Handling dynamic change of topology TDMA Time Spread Multiple Access (TSMA)

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Networking Considerations

Self-organizing, dynamic, energy-constrained

Location service Reactive and proactive

Routing and forwarding algorithms Unicast, geocast, multicast, broadcast

Redesign of Transport layer mechanisms Mainly TCP issues

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Routing Unicast

Proactive routing protocols Table-driven, periodic and event-driven updates DSDV, CGSR, WRP, OLSR, TBRPF, FSR

Reactive routing protocols On demand, route discovery DSR, AODV, TORA, ABR, SSR, ZRP

Multicast Tree based : AMRoute, MAODV, AMRIS Mesh based : CAMP, ODMRP

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Routing (cont.) Location aware routing

Greedy forwarding, directed flooding, hierarchical routing

Clustering Clusterhead Inter-cluster, intra-cluster communication Cluster bottleneck problem

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TCP issues Impact of mobility

Route failure Packet loss and increased delay

Exacerbate unfairness

Nodes’ interaction at MAC

Impact of TCP congestion window size Small congestion windows is good

New mechanisms Explicit Link Failure Notification (ELFN) Ad hoc TCP (ATCP) Link RED

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Applications and middleware Applications

Tactical, sensor, emergency service, commercial environment, home and enterprie networking, educational application, entertainment, location aware services

Middleware Provide service abstraction Efficiency is open issue Service discovery and location QoS-Aware resource discovery

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Cross layers’ research issues Energy conservation

Local strategy : power saving mode Global strategy : maximize the network

lifetime

Security Attacks and protections

Cooperation

Simulation and performance evaluation

Quality of Service

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Security Attacks

Passive attacks Eavesdropping

Active attacks Impersonation, Denial of Service, Disclosure

attack

Security mechanism Preventive and detective

Key-based, Intrusion detection Wired Equivalent Privacy

Secure routing Wormhole attack

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Discussion and conclusions The center of evolution

Toward 4G wireless technology Flexibility, easy maintenance, infrastructure-less, a

uto-configuration, self-administration capability, cost advantage

IETF MANET WG “killer application(s)” has yet emerged. Many open research issues