Manet

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Overview

A mobile ad-hoc network (MANet) is a kind of wireless ad-hoc network, and is a self-configuring network of mobile routers (and associated hosts) connected by wireless links – the union of which form an arbitrary topology.

Mobile ad hoc networks (MANET) and peer-to-peer (P2P) file sharing systems lack of fixed infrastructure and do not have a-priori knowledge of arriving and departing peers. Thus, the task of deploying a P2P system in a MANET needs to consider that the application layer connections among peers are static and that the MANET topology can change frequently due to node mobility.

The routers are free to move randomly and organize themselves arbitrarily; thus, the network's wireless topology may change rapidly and unpredictably. Such a network may operate in a standalone fashion, or may be connected to the larger Internet.

Mobile ad hoc networks became a popular subject for research as laptops and IEEE 802.11 wireless networking became widespread in the mid to late 1990s. Many of the academic papers evaluate protocols and abilities assuming varying degrees of mobility within a bounded space, usually with all nodes within a few hops of each other, and usually with nodes sending data at a constant rate. Different protocols are then evaluated based on the packet drop rate, the overhead introduced by the routing protocol, and other measures.

Vehicular Ad Hoc Networks (VANET) are a form of MANets used for communication among vehicles and between vehicles and roadside equipment.

Intelligent Vehicular AdHoc Network (InVANET) is a kind of Intelligence in Vehicle(s) which provide multiple autonomic intelligent solutions to make automotive vehicles to behave in intelligent manner during vehicle-to-vehicle collisions, accidents, drunken driving etc. InVANET uses WiFi IEEE 802.11 b/802.11g/802.11p and WiMAX IEEE 802.16 for providing easy, accurate, effective communication between multiple vehicles on dynamic mobility. Effective measures to track the automotive vehicles, media download /upload, conference between vehicles are also preferred. InVANET can also be applied for artillery vehicles during warfare / Battlefield / Peace operations.

p2p over MANETs

Mobile Peer-to-Peer networks are formed by humans carrying mobile devices, like PDAs or mobile phones, with ad hoc communication capabilities. These applications exploit the physical presence of a user to support digital or real-life collaboration among them. The integration of wireless communication technologies like Bluetooth or IEEE 802.11b WiFi into mobile devices makes this kind of mobile Peer-tpPeer networks feasible. The key issue of user contribution prevails in mobile p2p networks, where in general, anonymous users form the network with their personal devices. Resources on the device are typically limited. Especially battery power can be a problem. A user risks draining his battery by contributin its resources to other users. the device may also become uavailable for personal tasks, like accessing the calendar or making phone calls.

The emergence of mobile peer-to-peer networks is motivated by the fact that, often, people in close proximity share a common goal or have a related motivation. Some of them may have valuable information relevant but unknown to others. The common goal of these applications is to make this oinformation available to other interested parties.


MANETs and P2P networks share a good number of key characteristics, such as the lack of a central infrastructure, a highly dynamic network topology, and the need for self-organization. Hence, when designing distributed network applications for MANETs, it would be intuitive to consider the building blocks that have proven themselves appropriate in P2P systems. However, conventional DHTs are ill-suited for a simple deployment on top of MANETs for the following three reasons:

  • It is important to realize that overlay traffic as such does not exist physically. What does exist, though, is the physical traffic incurred by the overlay network. Furthermore, DHTs were designed as application-level overlay networks for the (wired) Internet. By abstracting away the underlying physical network, standard DHTs generally do not consider the physical topology in the construction of their overlay topology. In other words, by no means do two overlay neighbor nodes also have to be physical neighbors. This usually leads to the situation that overlay hops can incur unnecessarily long physical routes. Although a number of approaches have been proposed recently to alleviate this problem, standard DHTs are not primarily concerned with physical locality. While this might be tolerable on the wired Internet with its high bandwidth, it is obviously not feasible for MANETs. Here, the delivery probability of a packet quickly decreases with each physical hop due to factors such as low bandwidth, low computation power (of a node), packet collisions or transmission errors.
  • As nodes move around incessantly, routes in MANETs are usually quite volatile and break quickly. For this reason, ad-hoc routing protocols have to (re-) establish routes frequently. Due to the lack of a central infrastructure, the majority of ad-hoc routing protocols, have to at one point or another resort to flooding the network or regions thereof. This, of course, renders the overlay routing superfluous. There is no point in maintaining an application-level DHT when the physical route to carry out an overlay hop has to be (frequently re-) established through broadcasting. In that case, one would have been better off broadcasting the key lookup itself in the first place. In fact, it is easy to imagine a situation where a key lookup requires two overlay hops, both of which have to have their physical routes discovered through broadcasting. In that case, the key lookup would cause the network to be flooded twice, which is clearly suboptimal.
  • In order to guarantee routing convergence and consistency, DHTs have to periodically maintain their routing tables. Depending on the size and structure of a DHT's routing table and the lookup traffic pattern, the maintenance traffic can constitute a significant portion of the overall traffic. Given the limited bandwidth in MANETs, conventional DHT maintenance can be prohibitively heavy-weight and overwhelm the network.


Implementations of mobile peer to peer networks

  • Shark [1]
  • Mobitip [2]
  • SpotMe [3]
  • Socialight [4]
  • AdPass [5]


External links

References

  • [1] T. Schwotzer and K. Geihs, "Shark - a System for Management, Synchronization and Exchange of Knowledge in Mobile User Groups", Journal of Universal Computer Science, 8(6):644-651,2002.
  • [2] S. Rudström, M. Svensson, R. Cöster, and K. Höök, "MobiTip: Using Bluetooth as a Mediator of Social Context", UbiComp 2004: Ubiquitous Computing: 6th Interntional Conference.
  • [3] Shockfish SA Switzerland, Spotme website.
  • [4] Kamida IncNew York, Social light website.
  • [5] T. Straub and A. Heinemann, "An Anonymous Bonus Point System For Mobile Commerce Based On Word-Of-Mouth Recommendation" Proceedings of the 2004 ACM Symposium on Applied Computing, New York, 2004.
  • Rheingold, Macquarie University, Smart Mobs: The Next Social Revolution, 2002.
  • Royer, E., Toh, C. A Review of Current Routing Protocols for Ad Hoc Mobile Wireless Networks, IEEE Personal Communications, 1999.
  • Mauve, M., Widmer, J., Hartenstein, H. A Survey on Position-Based Routing in Mobile Ad Hoc Networks, 2001.
  • Maihöfer, C. A Survey on Geocast Routing Protocols, IEEE Communications Surveys and Tutorials, 2004.
  • Ozan, K. Tonguz, Gianluigi Ferrari, Ad Hoc Wireless Networks: A Communication-Theoreteic Perspective, 2006.
  • Arunkumar Thangavelu, Sivanandam S.N Location Identification and Vehicular Tracking for Vehicular Ad Hoc Wireless Networks, IEEE Explorer February 2007 pages 112-116.
  • Alexander Klemm, Christoph Lindemann, and Oliver P. Waldhorst. A Special-Purpose Peer-to-Peer File Sharing System for Mobile ad Hoc Networks orion University of Dortmund Vehicular Technology Conference 2003. IEEE.
  • Thomas Zahn Jochen Schiller. MADPastry: A DHT Substrate for Practicably Sized MANETs.

MadPastry. Institute of Computer Science Freie Universität Berlin, Germany.

  • Cecilia Mascolo, Licia Capra, Stefanos Zachariadis and Wolfgang Emmerich. xmiddle: A Data-Sharing Middleware for Mobile Computing. xMiddle. Dept. of Computer Science University College London.
  • Himabindu Pucha, Saumitra Das, Y. Charlie Hu. Ekta: An Efficient DHT Substrate for Distributed Applications in Mobile Ad Hoc Networks.

Ekta. Distributed Systems and Networking Lab, School of ECE, Purdue University.

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