Mesh Networks: Commodity Multihop Ad Hoc Networks

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Mesh Networks Commodity Multihop Ad Hoc Networks
Raffaele Bruno, Marco Conti, and Enrico Gregori,
in IEEE Communications Magazine, March 2005

• 2005.11.10
• Yusung Kim
• yskim_at_cosmos.kaist.ac.kr

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Abstract

• The low commercial penetration of products based
  on ad hoc networking technology.. Why?
• To turn mobile ad hoc networking into a
  commodity.. How?
• New class of networks is emerging from a view of
  mesh networks. What is its state of the art
  challenges?

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Contents

• Introduction
• Popular Commercial Applications for Wireless Mesh
  Networks
• System and Network Architectures for Wireless
  Mesh Networks
• Open Standards Implementing Wireless Mesh
  Networking Techniques
• Key Research Challenges
• Conclusion

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1. Introduction

• In the past decade the Ad hoc Networking
  paradigm absorbed a lot of research effort.
• Most of the ongoing researches are driven by
• Department of Defense (DoD) requirements(
  large-scale military applications )
• Specialized civilian application(disaster
  recovery, planetary exploration, etc)

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1. Introduction (cont.)

• Existing researches are far from real users
  requirements, they are focused on lack of
  infrastructure and instant deployment.
• From users standpoint, cost is an issue
  andInternet access is a must.
• A new class of networks is emerging from a view
  of Mesh Networks.

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1. Introduction (cont.)

• Mesh Networks
• Mix of fixed and mobile nodes interconnected via
  wireless links to form a multihop ad hoc
  networks

• Not isolated self-configured networks
• Flexible and low-cost extension of Wired
  infrastructure

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2. Popular Commercial Applications for
Wireless Mesh Networks

• 2.1 Intelligent Transportation System
• 2.2 Public Safety
• 2.3 Public Internet Access

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2.1 Intelligent Transportation System

• Portsmouth Real-Time Travel Information System
  (PORTAL)
• Providing real-time travel information to
  passengers
• 300 buses with Wi-Fi mesh technology by
  MeshNetworks Inc.
• Touch Screens at more than 40 locations in the
  city
• Passengers can know bus location, destination,
  schedule..
• The same system is also expected to be used to
  address and alleviate transportation congestion
  problems, control pollution, and improve
  transportation safety and security

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2.1 Intelligent Transportation System
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2.2 Public Safety

• After 9.11 events have dramatically increased
  interest in public safety.
• Started from cellular technologies
• Near ubiquitous coverage and allow high-mobility
  speedsbut data rate is limited and the network
  infrastructure is extremely costly
• Wireless mesh networks appear to be the solution
• San Matteo Police Department, San Francisco Bay
  Area
• Patrol cars with laptops PDAs employing
  Wi-Fiand mesh networking with 30 access points
  were installed throughout downtown by Tropos
  Networks.

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2.3 Public Internet Access

• The wireless mesh networks are the ideal solution
  to provide both indoor and outdoor broadband
  wireless connectivity in urban, suburban, and
  rural environments without extremely costly wired
  network infrastructure.
• City of Cerrito, California
• Tropos based mesh technology
• 8 square miles using more than 130 outdoor access
  points,less than 20 of them directly connected
  to Internet

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2.3 Public Internet Access
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3. System and Network Architectures for
Wireless Mesh Networks

• 3.1 Overview
• 3.2 Reduction of installation costs
• 3.3 Reliability
• 3.4 Self-management

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3.1 Overview

• Wireless mesh has been envisioned as the
  economically viable networking paradigm to build
  up broadband and large-scale wireless commodity
  networks.
• Different from flat ad hoc networks, a mesh
  network introduces a hierarchy in the network
  architecture with the implementation of dedicated
  nodes (called wireless routers)
• Data traveling from users to either other users
  or access points (access points are special
  wireless routers with a high-bandwidth wired
  connection to the Internet backbone)

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3.1 Overview
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3.2 Reduction of installation costs

• Wireless LAN hot spot
• where clients access the Internet through an
  access point.
• To ensure ubiquitous coverage in a metro-scale
  area, it is necessary to deploy a large number of
  access points.( limited coverage, cabling for
  every access point)
• gt costly, un-scalable, and slow to deploy
• Wireless mesh networks enormously reduces the
  infrastructural costs because they needs only a
  few points of connection to wired backbone.

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3.3 Reliability

• The wireless backbone of mesh networks provides
  redundant paths between each pair of endpoints,
  significantly increasing communications
  reliability eliminating
• Single points of failures (node or path failure)
• Potential bottleneck links

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3.4 Self-management

• Provides self-configuration and self-healingness
  as the advantages of ad hoc networking.
• Network setup is automatic and transparent to
  users
• When adding additional nodes in the mesh, these
  nodes automatically discover other wireless
  routers paths to the wired network.The
  existing wireless routes also reorganize as
  taking into account the new available routes.
• gt Network can easily be expanded.

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4. Open Standards Implementing Wireless Mesh
Networking Techniques

• Some task groups in IEEE have been established to
  define the requirements for mesh networking
• IEEE 802.15.5 (WPAN)
• Using shorter links increases the throughput
  implementation of mesh networking should be
  lightweight.
• IEEE 802.11s (WLAN)
• Self-configuring multihop topology end of 2006
• IEEE 802.16A (WMAN)
• WiMAX
• IEEE 802.20
• Mobile Broadband Wireless Access

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Integration of WiMAX and Wi-Fi technologies in
large scale wireless mesh networks
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5. Key Research Challenges

• 5.1 High-Capacity and Reliable Radio Interfaces
  for the wireless backbone
• 5.2 Designing Scalable and Opportunistic
  Networking Functions
• 5.3 System-Wide Resource Management

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5.1 High-Capacity and Reliable Radio Interfaces
for the wireless backbone

• To improve the capacity of wireless mesh networks
• Multiple channels and/or radio interfaces
• Spatial multiplexing divides the channel into
  multiple spatial channels
• gt Nevertheless strong interference is problem.
  The exploitation of directional transmissions
  could suffice to ensure a wireless backbone with
  high speed and a high degree of spatial reuse.

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5.2 Designing Scalable and Opportunistic
Networking Functions

• As the number of users increases, random MAC
  protocols suffer from increased contention in the
  network. Path capacity and channel bandwidth
  could be highly variable.
• New scalable and distributed scheduling, MAC, and
  routing protocol have to be designed to
  efficiently manage data traffic.
• Algorithms must be aware of the characteristics
  of the physical channel(cross-layer design among
  physical and networking functions)
• Scheduling process for multi-channel / multi-hop
  needs to be distributed where the coordination
  among wireless routers.
• Routing protocols need path diversity

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5.3 System-Wide Resource Management

• Coordinated multihop resource management
  algorithm must be developed to achieve high
  performance while preserving a system-wide
  fairness.
• Aimed at eliminating the spatial bias by ensuring
  that each user receives the same fair share of
  resources independent of how far it is from the
  Internet access point.
• Be careful with the additional overhead of
  increased protocol information to perform more
  precise control.

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6. Conclusion

• Turning ad-hoc networks into a commodity
• Make multihop flexible low cost last mile
  extensions of wired infrastructure Mesh Networks
• Presents the overview case studies of wireless
  mesh networks.
• Finally shows the research challenges of
  designing a high-performance, scalable, and
  cost-effective wireless mesh network.

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Issues Wireless Mesh Network compared to
Wired Network

• Is Wireless Mesh Network possible to support
  dynamically bandwidth provisioning ? or QoS ?
• Does Wireless Mesh Network have a benefic to
  deploy multicast mechanism?( In wired networks,
  the deployment of multicast is difficult due
  to a requirement of support in all routers )

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What is the cost of Tropos Wi-Fi cells?

• .Generally, installations will cost users
  20,000 to 50,000 per square mile. The exact
  price depends on a number of factors including
  topography, denseness of foliage, availability of
  mounting locations, interference sources and the
  level of network management desired.