wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

7
Ad Hoc Networks
Sajjad Ahmad
Madani
COMSATS Institute
of Information Technology
Shahid Khattak
COMSATS Institute
of Information Technology
Tariq Jadoon
Lahore University
of Management Sciences
Shahzad Sarwar
University of the Punjab
7.1 Introduction........................................................................................7-1
Principles and Benefits. •. Applications. •. Ad Hoc Network
Characteristic. •. Enabling Technologies
7.2 Protocol Stack.................................................................................... 7-4
Transport Layer. •. Network Layer. •. MAC Layer. •. Physical Layer
7.3 Performance Evaluation................................................................... 7-8
7.4 Challenges and Issues....................................................................... 7-9
Quality-of-Service. •. Energy Management. •. Topology
and Connectivity. •. Security
References.....................................................................................................7-11
7.1 Introduction
7.1.1 Principles and Benefits
Ad hoc network is a collection of mobile nodes that dynamically organize themselves to form arbitrary
and temporary networks. These mobile nodes can get connected without any preexisting infrastructure
or centralized administration where connection is facilitated through peer-to-peer (P2P) communication
which may involve multihop structures. The mobile nodes are free to move and organize
themselves in arbitrary fashion while communicating with each other. There can be multiple paths
employing heterogeneous radio between any pair of nodes. Ad hoc networks range from small singlehop
personal area networks (PANs) to large-scale multihop networks involving thousands of nodes.
Based on the coverage area, the ad hoc networks are classified into four main categories: body, personal,
local, and wide-area networks. These either connect to Internet through fixed infrastructure or may
operate as an isolated P2P network in a stand-alone fashion as shown in Figure 7.1a and b, respectively.
Although the idea of ad hoc network was first conceived in early 1970s, it did not generate wider interest
earlier as the original application scenarios were not directed to mass users. Recently, new concepts of
opportunistic ad hoc networks have emerged which have commercial applications as well. Here, ad hoc
network is used opportunistically to extend home or campus networks to previously inaccessible areas.
The development of sensor networks, which can be treated as specialized ad hoc networks, has also
contributed to an increased interest in this area.
Unlike the classical cellular network that requires prelocated cell sites and base stations, an ad hoc network
does not require any detailed infrastructure planning as it relies on highly dynamic network topologies
to deal with hostile environment and irregular connectivity. Since an ad hoc network automatically
establishes the communication channels (links) and adopts to change, the setup time is short and cost is
low. It can, therefore, be used to complement overloaded fixed wireless infrastructures (hot spots) and can
7-1
© 2011 by Taylor and Francis Group, LLC