  The base station (BS) in a multi-channel cognitive radio (CR) network has to
broadcast to secondary (or unlicensed) receivers/users on more than one
broadcast channels via channel hopping (CH), because a single broadcast channel
can be reclaimed by the primary (or licensed) user, leading to broadcast
failures. Meanwhile, a secondary receiver needs to synchronize its clock with
the BS's clock to avoid broadcast failures caused by the possible clock drift
between the CH sequences of the secondary receiver and the BS. In this paper,
we propose a CH-based broadcast protocol called SASS, which enables a BS to
successfully broadcast to secondary receivers over multiple broadcast channels
via channel hopping. Specifically, the CH sequences are constructed on basis of
a mathematical construct---the Self-Adaptive Skolem sequence. Moreover, each
secondary receiver under SASS is able to adaptively synchronize its clock with
that of the BS without any information exchanges, regardless of any amount of
clock drift.
