Rendezvous sequence construction in Cognitive Radio Ad-Hoc networks based on difference sets

Cognitive Radio networks have emerged as a promising paradigm to achieve dynamic spectrum access (DSA). However under DSA scene, the available channels of each user are usually different and change dynamically, which makes the rendezvous between radios sophisticated. This paper focuses on the channel hopping sequence designing problem for blind rendezvous using difference sets as a tool. I) First, we will show that any hopping sequence previously proposed under asymmetric asynchronous channel hopping (AACH) system is essentially difference set-based, if all users in system act as the same manner. II) Second, we will deduce a low boundary for the difference set-based sequences. ΙΠ) Third, using the properties of difference sets, we will propose an efficient and systematic method to find difference sets that can be used to construct channel hopping sequences. IV) Finally, a performance simulation is discussed, which shows that the difference sets generated sequences outperform other algorithms, both under low primary users activity case and high primary users activity case.