Fog-Aided Cognitive Radio Networks With Guard Zone and Interference Cancellation Based Opportunistic Spectrum Access

We investigate the spatial spectrum sharing mechanism design in fog-aided cognitive radio (CR) networks with the methods of guard zone and interference cancellation. Particularly, it is assumed that the studied CR network is comprised of a library of multimedia files
$\mathcal {F}$
with size
$F$
and two types of users, namely the primary and secondary users, with fog computing capability. The primary users are authorized devices and have privilege to preferentially utilize the bandwidth resources. The secondary users, on the other hand, are unauthorized devices and can access the spectrum only if the primary transmissions are unaffected. To constrain the unintended secondary interference at the active primary receivers (PRs) while enhance the spectrum accessibility of the secondary users, the guard zone and interference cancellation-based opportunistic spectrum access (GZ-IC OSA) protocol is proposed and analyzed. Under the GZ-IC OSA protocol, by exploiting the cached content as side information, the
$f$
-th file sent by a secondary transmitter (ST) can be effectively cancelled at the unintended active PRs which cache the same file. As such, under the GZ-IC OSA protocol, a ST is allowed to transmit the
$f$
-th file in
$\mathcal {F}$
as long as it is outside the union of the guard zones of all active PRs which cache other files except the
$f$
-th file. Assuming decentralized probabilistic caching, under the GZ-IC OSA protocol, we derive the first-order moment measure of the access probabilities of primary transmitters (PTs) and STs, respectively. Further, we capture the conditional spatial distributions of active PTs and STs as piecewise functions with respect to the radius
$R_{d}$
of the guard zone. Finally, we evaluate the performance of the proposed GZ-IC OSA protocol in terms of coverage performance and spatial throughput based on the derived conditional spatial distributions.