Before revision:  The analytical framework models the following : number of sensing stages, physical layer sensing techniques  , single and parallel channel access, primary and secondary user traffic, as well as buffering of incoming secondary user traffic  .
After revision:  The contribution of our work lies in studying the effect of the following parameters on performance : number of sensing stages, physical layer sensing techniques , single and parallel channel access, primary and secondary user traffic, as well as buffering of incoming secondary user traffic .