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Is Channel Fragmentation/bonding in IEEE 802.22 Networks Secure?

We address a unique security threat that arises due to channel fragmentation (or aggregation or bonding) in dynamic spectrum access (DSA) based IEEE 802.22 networks. Typically, channel fragmentation, aggregation and bonding have been studied in the literature as a means to enhance the spectrum utilization. However, the loss of orthogonality between the spectrum bands due to channel fragmentation, aggregation or bonding can be exploited by malicious attackers to cause a cognitive service disruption. We present an analysis of such a threat. We determine the optimal transmit powers a malicious attacker transmits on each fragment, so as to create maximum service disruption. Numerical results indicate that a malicious attacker can cause up to about 16% loss in the capacity of the system as a consequence of fragmentation. Detailed analysis is presented for channel fragmentation and can be easily applied to channel aggregation and bonding. To the best of our knowledge,this is the first analysis of such cognitive service disruption threats due to fragmentation.