A novel asynchronous channel hopping scheme for blind rendezvous in cognitive radio networks

In order for cognitive radio networks (CRNs) to exchange control information reliably and efficiently, this paper proposes a novel channel hopping (CH) scheme, namely DS-ACH, for cognitive users (CUs) without a synchronized time clock to achieve rendezvous in the blind fashion. Originating from the mathematical concept of relaxed cyclic difference set (DS), the proposed DS-ACH can guarantee any two CUs to always rendezvous in every timeslot and at an arbitrary number of channels without knowing their time clock offset and CH sequences. Moreover, we show that the DS-ACH constructed based on a special class of DSs can closely approach the theoretical lower bound on the number of radio transceivers for asynchronous CUs to rendezvous blindly in every timeslot and hence minimize their required hardware complexity for exchanging control information at the minimum time delay. Numerical simulation also shows that the proposed asynchronous CH scheme outperforms the existing ones in several key performance metrics of CRNs.