Wireless ad hoc network
`
`From Wikipedia, the free encyclopedia
`A wireless ad hoc network (WANET) is a decentralized type of wireless network.[1][2] The network is ad hoc
`because it does not rely on a pre existing infrastructure, such as routers in wired networks or access points in
`managed (infrastructure) wireless networks. Instead, each node participates in routing by forwarding data for
`other nodes, so the determination of which nodes forward data is made dynamically on the basis of network
`connectivity. In addition to the classic routing, ad hoc networks can use flooding for forwarding data.
`An ad hoc network typically refers to any set of networks where all devices have equal status on a network and
`are free to associate with any other ad hoc network device in link range. Ad hoc network often refers to a mode
`of operation of IEEE 802.11 wireless networks.
`It also refers to a network device's ability to maintain link status information for any number of devices in a 1-
`link (aka "hop") range, and thus, this is most often a Layer 2 activity. Because this is only a Layer 2 activity, ad
`hoc networks alone may not support a routeable IP network environment without additional Layer 2 or Layer 3
`capabilities.
`The earliest wireless ad hoc networks were the "packet radio" (PRNETs) from the 1970s, sponsored by DARPA
`after the ALOHAnet project.
`
`Contents
`1 Application
`2 Technical requirements
`3 Medium-access control
`4 Mathematical models
`5 Security
`6 Simulation of wireless ad hoc networks
`7 See also
`8 References
`
`Application
`The decentralized nature of wireless ad-hoc networks makes them suitable for a variety of applications where
`central nodes can't be relied on and may improve the scalability of networks compared to wireless managed
`networks, though theoretical[3] and practical[4] limits to the overall capacity of such networks have been
`identified.
`
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`Minimal configuration and quick deployment make ad hoc networks suitable for emergency situations like
`natural disasters or military conflicts. The presence of dynamic and adaptive routing protocols enables ad hoc
`networks to be formed quickly.
`Wireless ad-hoc networks can be further classified by their application:
`mobile ad hoc networks (MANET)
`Technical requirements
`An ad hoc network is made up of multiple “nodes” connected by “links.”
`Links are influenced by the node's resources (e.g., transmitter power, computing power and memory) and
`behavioral properties (e.g., reliability), as well as link properties (e.g. length-of-link and signal loss, interference
`and noise). Since links can be connected or disconnected at any time, a functioning network must be able to
`cope with this dynamic restructuring, preferably in a way that is timely, efficient, reliable, robust, and scalable.
`The network must allow any two nodes to communicate by relaying the information via other nodes. A “path” is
`a series of links that connects two nodes. Various routing methods use one or two paths between any two nodes;
`flooding methods use all or most of the available paths.[5]
`Medium-access control
`In most wireless ad hoc networks, the nodes compete for access to shared wireless medium, often resulting in
`collisions (interference). Using cooperative wireless communications improves immunity to interference by
`having the destination node combine self-interference and other-node interference to improve decoding of the
`desired signal.
`Mathematical models
`The traditional model is the random geometric graph.
`These are graph structures consisting of a set of nodes placed according to a point process in some usually
`bounded subset of the n-dimensional plane, mutually coupled according to a boolean probability mass function
`of their spatial separation (which may be a step function, see unit disk graphs).
`They can be used to study mathematically the set of network observables, such as the probability there exists a
`path of links between every pair of nodes (connectivity),[6] the distribution of centralities [7] or the distribution
`of node degrees.
`Security
`Microsoft does not allow advanced encryption and security protocols for wireless Ad hoc networks on
`Windows. In fact, the security hole provided by Ad hoc networking is not only the Ad hoc network itself, but
`the bridge it provides into other networks (see Ad hoc networks in the article Wireless security).
`
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`A randomly constructed geometric
`graph drawn inside a square
`
`Simulation of wireless ad hoc networks
`One key problem in Wireless Ad Hoc networks is foreseeing the variety
`of possible situations that can occur. As a result, Modeling and
`Simulation using extensive parameter sweeping and what-if analysis
`becomes an extremely important paradigm for use in ad hoc networks.
`Traditional M&S tools include NS2,(and recently NS3), OPNET
`Modeler, and NetSim.
`However, these tools focus primarily on the simulation of the entire
`protocol stack of the system. Although this can be important in the
`proof-of-concept implementations of systems, the need for a more
`advanced simulation methodology is always there. Agent-based
`modeling and simulation offers such a paradigm. Not to be confused
`with multi-agent systems and intelligent agents, agent-based modeling[8]
`originated from social sciences, where the goal was to evaluate and view large-scale systems with numerous
`interacting "AGENT" or components in a wide variety of random situations to observe global phenomena.
`Unlike traditional AI systems with Intelligent agents, agent-based modeling is similar to the real world. Agent-
`based models are thus effective in modeling bio-inspired and nature-inspired systems. In these systems, the
`basic interactions of the components of the system, also called Complex Adaptive System, are simple but result
`in advanced global phenomena such as emergence.
`See also
`802.11
`Independent Basic Service Set (IBSS)
`List of ad hoc routing protocols
`Mobile ad hoc network (MANET)
`Wi-Fi Direct
`References
`1. ^ Chai Keong Toh Ad Hoc Mobile Wireless Networks, Prentice Hall Publishers
`(http://www.informit.com/store/product.aspx?isbn=0130078174) , 2002.
`2. ^ C. Siva Ram Murthy and B. S. Manoj, Ad hoc Wireless Networks: Architectures and Protocols, Prentice Hall PTR,
`May 2004 [1] (http://www.amazon.com/Wireless-Networks-paperback-Architectures-
`Communications/dp/0133007065/ref=sr_1_2?ie=UTF8&qid=1388263042&sr=8-2&keywords=ad+hoc+wireless)
`3. ^ P. Gupta and P.R. Kumar. Capacity of wireless networks (http://ieeexplore.ieee.org/Xplore/login.jsp?
`url=/iel5/18/17872/00825799.pdf). IEEE Transactions on Information Theory, Volume 46, Issue 2, March 2000,
`doi:10.1109/18.825799 (http://dx.doi.org/10.1109%2F18.825799)
`4. ^ Jinyang Li, Charles Blake, Douglas S. J. De Couto, Hu Imm Lee, and Robert Morris, Capacity of Ad Hoc Wireless
`Networks (http://pdos.csail.mit.edu/papers/grid:mobicom01/paper.pdf), in the proceedings of the 7th ACM International
`Conference on Mobile Computing and Networking, Rome, Italy, July 2001
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`5. ^ Wu S.L., Tseng Y.C., "Wireless Ad Hoc Networking, Auerbach Publications", 2007 ISBN 978-0-8493-9254-2
`6. ^ J.P. Coon, C.P. Dettmann, O.Georgiou. "Full Connectivity: Corners, edges and faces" (http://arxiv.org/abs/1201.3123).
`7. ^ A.P. Giles, O. Georgiou, C.P. Dettmann. "Betweenness Centrality in Dense Random Geometric Networks"
`(http://arxiv.org/abs/1410.8521).
`8. ^ Muaz Niazi, Amir Hussain (March 2009). "Agent based Tools for Modeling and Simulation of Self-Organization in
`Peer-to-Peer, Ad Hoc and other Complex Networks, Feature Issue" (http://cs.stir.ac.uk/~man/papers/niaziCommmag.pdf)
`(PDF). IEEE Communications Magazine. 47 No.3. Cs.stir.ac.uk. pp. 163–173.
`
`Retrieved from "http://en.wikipedia.org/w/index.php?title=Wireless_ad_hoc_network&oldid=641936528"
`Categories: Wireless networking
`
`This page was last modified on 10 January 2015, at 23:21.
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`An 802.11 networking framework in which devices or
`stations communicate directly with each other, without
`the use of an access point (AP). Ad-hoc mode is also
`referred to as peer-to-peer mode or an Independent
`Basic Service Set (IBSS). Ad-hoc mode is useful for
`establishing a network where wireless infrastructure
`does not exist or where services are not required.
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`Related Terms
`ad hoc mode
`mode
`IAHC
`peer-to-peer mode
`infrastructure mode
`AODV
`PIO
`learn mode
`i-mode
`dual-mode device
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