Wireless Mobile Networking 7COM1076 - Ad-hoc Networks 1
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Questions and Answers

What is the main characteristic of proactive/table-driven routing protocols?

  • They require nodes to establish connections when paths are needed.
  • They rely solely on local node information.
  • They do not maintain topology information.
  • They necessitate periodic exchange of routing information. (correct)

    • Which approach do reactive/on-demand routing protocols use to obtain necessary paths?

  • By storing global topology information on each node.
  • Through constant node communication.
  • By using a connection establishment process. (correct)
  • Through periodic routing information exchanges.

    • In a proactive routing protocol, what information does every node maintain?

  • Only local connection requests and responses.
  • Temporary paths established with neighboring nodes.
  • Global topology information in the form of routing tables. (correct)
  • A log of user activity for performance analysis.

    • What could be a potential drawback of using table-driven routing protocols in ad hoc networks?

    <p>They lead to increased overhead due to regular information exchanges.</p> Signup and view all the answers

    What is a characteristic feature of reactive routing protocols compared to proactive ones?

    <p>They do not exchange routing information periodically.</p> Signup and view all the answers

    What does the term 'Ad hoc' imply in the context of networking?

    <p>A network specifically configured for a particular purpose</p> Signup and view all the answers

    Which of the following best describes the characteristic topology of Ad-hoc Networks?

    <p>Dynamic and unpredictable</p> Signup and view all the answers

    Which type of Ad-hoc Network is specifically for mobile nodes that can freely move?

    <p>Mobile Ad-hoc Network (MANET)</p> Signup and view all the answers

    Which of the following is NOT a type of Ad-hoc Network classification?

    <p>Fixed Infrastructure Network</p> Signup and view all the answers

    What challenge is commonly faced in Routing within Ad-hoc Networks?

    <p>Mobility and link breakage</p> Signup and view all the answers

    How does a Mobile Ad-hoc Network (MANET) primarily differ from Cellular Networks?

    <p>MANET consists of self-organizing nodes</p> Signup and view all the answers

    Which of the following network types is characterized by nodes that are typically part of a vehicular structure?

    <p>Vehicular Ad-hoc Network (VANET)</p> Signup and view all the answers

    In the context of wireless networking, what does 'mobility' impact the most?

    <p>Connection stability</p> Signup and view all the answers

    What characterizes a Mobile Ad-hoc Network (MANET)?

    <p>Is a collection of isolated mobile nodes connected dynamically</p> Signup and view all the answers

    Which of the following is NOT a feature of MANET?

    <p>Fixed network topology</p> Signup and view all the answers

    What role does a mobile node play in a MANET?

    <p>Functions as both an end system and a router</p> Signup and view all the answers

    Why are MANETs considered infrastructure-less?

    <p>They do not require existing physical infrastructure for deployment</p> Signup and view all the answers

    What is a key advantage of using MANETs?

    <p>Less dependence on infrastructure</p> Signup and view all the answers

    Which statement accurately describes the characteristics of Cognitive Radio (CR) technology?

    <p>Can learn and adapt to the environment in real time</p> Signup and view all the answers

    In what context are Vehicle Ad-hoc Networks (VANETs) categorized?

    <p>As a subset of Mobile Ad-hoc Networks</p> Signup and view all the answers

    What is a challenge associated with MANETs?

    <p>Limited physical security measures</p> Signup and view all the answers

    Study Notes

    Wireless Mobile & Multimedia Networking 7COM1076 - Ad-hoc Networks 1

    • This module covers Ad-hoc Networks, specifically mobile ad-hoc networks (MANETs).
    • Ad-hoc networks are special networks for specific applications.
    • "Ad hoc" means "for this" or "for this purpose only".
    • Nodes in ad-hoc networks can move randomly and organize themselves arbitrarily.
    • The wireless network topology changes rapidly and unpredictably.

    Ad-hoc Networks - Classification

    • Ad-hoc networks are classified into different types, including:
      • Wireless Mesh Networks (WMN)
      • Mobile Ad-hoc Networks (MANET)
      • Vehicular Ad-hoc Networks (VANET)
      • Intelligent Vehicle Ad-hoc Networks (In VANET)
      • Wireless Sensor Networks (WSN)
      • Cognitive Radio Wireless Sensor Networks (CR-WSN)

    Mobile Ad-hoc Networks (MANET)

    • MANETs are autonomous systems of mobile nodes that move freely.
    • They are wireless networks formed spontaneously without an infrastructure for deployment.
    • MANETs consist of isolated mobile nodes that are connected in a self-configurable, infrastructure-less, dynamic, and decentralized network.
    • Mobile nodes use wireless interfaces and radio channels to communicate with one another without a centralised management system.
    • In a MANET, each mobile node acts as both an end system (host) and a router, taking part in the routing within the network.

    MANET - Features

    • MANETs have dynamic topologies and are infrastructure-less.
    • Bandwidth is constrained, and capacity of the links varies.
    • Energy consumption is a major concern in MANET operations.
    • Physical security is limited.
    • Network administration is distributed and self-organized in nature.
    • Multi-hop communications are used in MANETs.

    Why MANET?

    • MANETs are beneficial due to their ease and speed of deployment.
    • They are less dependent on pre-existing infrastructure.
    • They represent a significant advancement in wireless communications.

    Ad-hoc Networks

    • VANETS (Vehicle Ad-hoc Networks): A subset of MANETs with a unique characteristic of dynamic nature, real-time processing, self-organising and infrastructure less in nature.
      • Vehicles communicate with each other and/or roadside units (RSUs).
    • Cognitive Radio Sensor Networks (CR-WSN): Intelligent wireless radio devices that have the ability to sense, learn to adapt to the environment in real-time.
      • They can make decisions based on learned data, such as sensing the spectrum, altering operating parameters, and utilizing unoccupied frequency bands.

    Ad-hoc Networks Vs Cellular Networks

    • Cellular networks use fixed infrastructure whereas ad hoc networks are infrastructure-less.
    • Cellular networks use single hop links, while ad-hoc networks can use multi-hop links.
    • Cellular networks have centralised administration, while ad-hoc networks often have distributed administration.
    • Cellular networks offer guaranteed bandwidth, whereas ad hoc networks share radio channels.
    • Ad-hoc networks usually involve higher deployment costs and time.

    Ad-hoc Network Application

    • Military applications: Inhospitable terrain, quick and secure communication, secure multimedia, high-power transceivers
    • Emergency Operations: Self configuration, minimal overhead, freedom and flexibility of mobility, quick deployment, real-time communication capability, fault tolerant communication paths
    • Wireless Sensor Networks: Tiny sensor nodes sensing factors like temperature, humidity, and nuclear radiation, process data, and communicate to a monitoring station.
    • Collaborative and distributed computing: Temporary communication, Minimal configuration, Requires reliable multicast routing, High reliability of data transfer, Desired receivers must replicate transmitted file.

    Challenging Issues for Ad-hoc Networks

    • Medium access scheme: Hidden terminal problem, exposed terminal problem, throughput, fairness.
    • Routing: Dynamic topology, route breakage, transport layer protocol (poor TCP performance), quality of service provisioning, security, energy management.

    Routing Protocols-Challenges in Routing

    • Mobility: Frequent path breaks, packet collisions
    • Bandwidth constraint: Bit error rate (BER), location-dependent contention, and traffic-dependent contention.
    • Frequent path breaks and packet collisions due to mobility.

    Major Requirements of a Perfect Routing Protocol

    • Minimum route acquisition delay, quick route configuration/maintenance, loop-free routing, distributed routing approach, minimum control overhead, scalability, QoS support, secure communication.

    Classification of Routing Protocols

    • Broadly based on routing information update mechanism, routing topology, utilization of specific resources.
    • Further classified into proactive/table-driven and reactive/on-demand protocols.
    • Also classified by topology used (flat or hierarchical) and resources used (power, location, temporal information).

    Table Driven vs. On-demand Routing

    • Table-driven protocols maintain network topology information in tables and update periodically, using path finding algorithms.
    • On-demand protocols exchange topology information only when needed, establishing paths only as required.

    Table Driven Routing Protocols

    • Table Driven protocols are based on wired network principles.
    • It requires periodic exchange of information for nodes, thus maintaining overall information about topology.
    • It may not be ideal for ad-hoc networks given nodes need to have complete topology information at all times.

    References

    • Ad Hoc Wireless Networks, architectures and protocols, by C. Siva Ram Murthy and B. S. Manoj, 1st edition. (Sections 5.1, 5.2, etc.)
    • RFC 2501. (http://www.ietf.org/rfc/rfc2501.txt)

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    Ad-Hoc Networks Part 1 PDF

    Description

    Explore the fascinating world of Ad-hoc Networks in this quiz based on the 7COM1076 module. Learn about mobile ad-hoc networks (MANETs) and their unique characteristics, classifications, and applications. Test your understanding of how these networks function without infrastructure and adapt rapidly to changes in topology.

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