Infrastructure Networks

• Devices on the network all communicate through a single access point: a device that allows wireless devices to connect to a wired network using Wi-Fi

• Problem: the large overhead of maintaining the routing tables

• Ad-hoc means for this purpose'

Ad-Hoc Network

• Decentralized type of wireless network
• It is ad-hoc because it does not rely on preexisting infrastructure such as routers in wired networks ,access points in wireless networks

Mobile Ad-Hoc Network (MANET)

• It is a continuously self-configuring, infrastructure-less network of mobile devices connected without wires
• Each device is free to move independently in any direction, and will therefore change its links to other devices frequently

Challenges

• Mobility of nodes
• Error prone channel state
• Resource constraints
• Bandwidth constraints
• Hidden and Exposed station problem

MANET Design Issues

• Network size and node density.
  • Network size = coverage area of the network.
  • Network density= no of nodes presents in that geographical area.
  • Clustering requires to keep low on overheads in communications in a larger networks.
  • Clustering size depends on the density of the network.

• Connectivity

  • Connectivity refers number of neighbour nodes.
  • Link capacity is based on connectivity.
  • It keeps on changing.

• Network Topology

  • Connectivity among the nodes is also known as topology.
  • Mobility make topology more dynamic.
  • Node's can become inoperative due to discharge of batteries or hardware failures.
• User Traffic
• MANET Designing is carried based on,
  • Node density.
  • Average rate of node movements.
  • Expected Traffic.

• Types of Traffic

  • Bursty Traffic.
  • Large packets sent periodically.
  • Combination of Both.

• Operational Environment

  • Environment may differ,
    • Urban
    • Rural
    • Maritime.
  • Most of these requires the line of sight (LoS) communication system.
  • Node density differs all the time MANET may suit for this.
• Energy Constraints
  • No infrastructure so no reliable power source.
  • Extra roles like routers.
  • Routing workload drains the batteries quickly.
• Node must be kept in sleeping mode when the overhead occurs to save the batteries.