Enhancing the Spectrum Sensing Performance of Cluster-Based Cooperative Cognitive Radio Networks via Sequential Multiple Reporting Channels

Abstract

In cluster-based cooperative cognitive radio networks (CCRNs), spectrum sensing and decision making processes to determine whether the primary user (PU) signal is present or absent in the network are very important and vital issues to the utilisation of the idle spectrum. The reporting time delay is a very important matter to make quick and effective global decisions for the fusion center (FC) in a cluster-based CCRNs. In this paper, we propose the concept of multiple reporting channels (MRC) for cluster-based CCRNs to better utilize the reporting time slot by extending the sensing time of secondary users (SUs). A multiple reporting channels concept is proposed based on frequency division multiple access to enhance the spectrum sensing performance and reduce the reporting time delay of all cluster heads (CHs). In this approach, we assign an individual reporting channel to each cluster for reporting purposes. All the SUs in each cluster sequentially pass their sensing results to the corresponding cluster head (CH) via the assigned single reporting channel, which extends the sensing time duration of SUs. Each CH uses the dedicated reporting channel to forward the cluster decision to the FC that makes a final decision by using the “K-out-of-N” rule to identify the presence of the PU signal. This approach significantly enhances the sensing time for all SUs than the non-sequential as well as minimize the reporting time delay of all CHs than sequential single channel reporting approach. These two features of our proposed approach increase the decision accuracy of the FC more than the conventional approach. Simulation results prove that our proposed approach significantly enhances the sensing accuracy and mitigate the reporting time delay of CH compared to the conventional approach.

Appendix

Proof of Proposition 1

The reporting time delay of CHs for single reporting channel sequential approach are given as follows:

The reporting time delay for first CH is:

$$\begin{aligned} \begin{aligned} T_{d, ch_1}&=MT_{r,SU}+T_{r,ch}\\&=(M+1)T_r\\ \end{aligned} \end{aligned}$$

(19)

where $T_{r,SU}=T_{r,ch}=T_r$ and M is the number of SUs in a every cluster.

The reporting time delay for second CH is:

$$\begin{aligned} \begin{aligned} T_{d, ch_1}&= T_{d, ch_1}+MT_{r,SU}+T_{r,ch}\\&=2(M+1)T_r\\ \end{aligned} \end{aligned}$$

(20)

Similarly, the reporting time delay for the Nth cluster is:

$$\begin{aligned} \begin{aligned} T_{d, ch_N}&= N(M+1)T_r \end{aligned} \end{aligned}$$

(21)

where N is a number of cluster in the network.

Proof of Proposition 2

The identical reporting time delay for every CHs in our proposed approach is given as follows:

$$\begin{aligned} \begin{aligned} T_{d, ch}&=MT_{r,SU}+T_{r,ch}\\&=(M+1)T_r\\ \end{aligned} \end{aligned}$$

(22)

where $T_{r,SU}=T_{r,ch}=T_r$ and M is a number of SUs in a every cluster.