Date Added: Jan 2011
Cognitive radios operate in a particularly challenging wireless environment. In such an environment, besides the strict requirements imposed by the opportunistic co-existence with licensed users, cognitive radios may have to deal with other concurrent (either malicious or selfish) cognitive radios which aim at gaining access to most of the available spectrum resources with no regard to fairness or other behavioral etiquettes. By taking advantage of their highly flexible RF front-ends, they are able to mimic a licensed user's behavior or simply to jam a given channel with high power. This way these concurrent users (jammers) are capable of interrupting or delaying the neighbor discovery process initiated by a cognitive radio, which is interested in using a portion of the available spectrum for its own data communications.