Abstract:
In this paper, we investigate users’ performance under the hybrid spectrum access model
in the massive cognitive radio network (CRN), where multiple primary users (PUs) and secondary
users (SUs) transmit on the same channel simultaneously. SUs first detect the state of the channel via
channel sensing and select an appropriate channel access scheme (either underlay or overlay) for
their transmissions based on the outcome of the channel sensing. When at least one PU is active, SUs
transmit under the underlay channel access scheme by employing the power control technique to
ensure that the interference generated in the primary network is below the pre-defined interference
threshold. In the absence of PU, SUs transmit with full transmit power under the overlay channel
access scheme, thereby maximizing their throughput. Using the tool of stochastic geometry, we
obtained tractable analyses for important metrics such as success probability, throughput, and the
average age of information (AoI) in both primary and secondary networks, while capturing the
interference between the two networks. The obtained analyses offer an efficient way to understand
the metrics of AoI, throughput and success probability in the hybrid spectrum access-based CRN. We
further compared users’ performance under the hybrid spectrum access scheme with performances
under overlay and underlay spectrum access schemes. The outcome of the numerical simulations
shows that the hybrid spectrum access scheme can significantly improve the performance of users in
the network, while also capturing more key features of real-life systems.
