In this attack, an attacker’s objective is to maximize its own spectrum usage. Depending on the motivation behind the attack, a PUE attack can be classified as either a selfish PUE attack or a malicious PUE attack: ■ Hence, the aim of the attackers is not to cause interference to primary users but to preempt spectrum resources that could have been used by legitimate secondary users. In PUE attacks, the adversary transmits only in fallow bands.
