In MANETs (Mobile Ad-hoc Networks), an open wireless medium provides secure neighbor identification, especially defenseless to the jamming attack, where the adversary purposely conveys noise like signals in order to thwart neighboring nodes from transmitting messages and hence detecting each other. The ad-hoc nodes are devised with wireless senders or receivers through antennas that can be highly directional (point to point), Omni-directional (broadcast) or some amalgamation thereof. At a provided time, the network may be observed as a random graph because of the node movements, their sender or receiver coverage models, the level of co-channel interference and the level of transmission power. The network topology can vary with time as the nodes shift or modify their broadcast and reception parameters. The major challenge in designing these networks is their vulnerability to Jamming attacks (Zhang, and Huang, 2011).
Actually, the mobile hosts in MANETs share a wireless medium. Hence, a radio signal may be interfered or jammed that leads to the message to be lost or corrupted. If an attacker has powerful sender, then a signal may be created that will be very strong enough to overcome the aimed signals and interrupt communications. There have been various attack techniques in which a jammer may perform to obstruct with the other wireless communications. Some feasible techniques are as follows:
i. Constant or Continuous Jammer:
This jammer constantly gives out a radio signal, which indicates random bits. The signal creator doesn’t follow any MAC protocol.
ii. Deceptive Jammer:
It is distinct from constant jammer, because it doesn’t transmit random bits rather they broadcast semi-valid packets. This signifies that packet header is legal, but the payload is ineffective.
iii. Random jammer:
It represents alternates among sleeping as well as jamming the channel. The jammer stuffs for a random time period, in initial stage; and in next stage, the jammer twists its senders off for one more random time period (i.e. sleeping mode). The energy effectiveness is identified as the ratio of jamming period length over sleeping period length.
iv. Reactive jammer:
The reactive jammer attempts not to devastate resources through only jamming when it thinks that someone is sending.
Also, there are different metrics that may be employed to compare different jamming attacks. Some metrics are shown below: less possibility of detection, energy efficient, strong DoS, stealthy, maintain behavior close to or consistent with protocol standard, strength against error detection techniques and unauthorized or authorized users (Hamieh and Ben-Othman, 2009).