MANET Evolution

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Historicly,mobile ad hoc networks primarily been used for tactical network related applications to improve battlefield communications/survivability. The dynamic nature of military operationsmeans that military cannot rely on access to a fixed pre-placed communication infrastructurein battlefield. Pure wireless communication alsohas limitation in that radio signals are subject tointerference and radio frequency higher than 100MHz rarely propagate beyond line of sight (LOS). Mobile ad hoc network creates a suitable framework to address these issues by providing a multi-hop wireless network without pre-placed infrastructure and connectivity beyond LOS.Early ad hoc networking applications can be traced back to the DARPA Packet Radio Network(PRNet) project in 1972 , which was primarily inspired by the efficiency of the packet switching technology, such as bandwidth sharing and storeand-forward routing, and its possible application in mobile wireless environment. PRNet features a distributed architecture consisting of network of broadcast radios with minimal central control; a combination of Aloha and CSMA channel access protocols are used to support the dynamic sharingof the broadcast radio channel.



Advantages

The following are the advantages of MANETs:
• They provide access to information and services regardless of geographic position.
• These networks can be set up at any place and time.
• These networks work without any pre-existing infrastructure.

Disadvantages

Some of the disadvantages of MANETs are:
• Limited resources. Limited physical security.
• Intrinsic mutual trust vulnerable to attacks. Lack of authorization facilities.
• Volatile network topology makes it hard to detect malicious nodes.
Security protocols for wired networks cannot work for ad hoc networks.


Ad hoc networking research
The specific MANET issues and constraints described above pose significant challenges in adhoc network design. A large body of research has been accumulated to address these specific issues,and constraints. In this paper, we describe the ongoing research activities and the challenges in some of the main research areas within the mobile ad hoc network domain.