Censor-Based Cooperative Multi-Antenna Spectrum Sensing with Imperfect Reporting Channels

Abstract

The present contribution proposes a spectrally efficient censor-based cooperative spectrum sensing (C-CSS) approach in a sustainable cognitive radio network that consists of multiple antenna nodes and experiences imperfect sensing and reporting channels. In this context, exact analytic expressions are first derived for the corresponding probability of detection, probability of false alarm and secondary throughput, assuming that each secondary user (SU) sends its detection outcome to a fusion center only when it has detected a primary signal. Capitalizing on the findings of the analysis, the effects of critical measures, such as the detection threshold, the number of SUs and the number of employed antennas, on the overall system performance are also quantified. In addition, the optimal detection threshold for each antenna based on the Neyman-Pearson criterion is derived and useful insights are developed on how to maximize the system throughput with a reduced number of SUs. It is shown that the C-CSS approach provides two distinct benefits compared with the conventional sensing approach, i.e., without censoring: i) the sensing tail problem, which exists in imperfect sensing environments, can be mitigated; ii) less SUs are ultimately required to obtain higher secondary throughput, rendering the system more sustainable.

Optimisation of censoring‐based cooperative spectrum sensing approach with multiple antennas and imperfect reporting channel scenarios for cognitive radio network

“…Recently, Li et al [27] have analysed the effect of multiple antennas, reporting error probability and number of CUs on the probability of false‐alarm () and the probability of detection () individually at high SNR with OR cooperative rule for the predefined value of threshold ( λ ). However, the analysis in the context of total sensing error was missing in [27]. Further, Nallagonda et al [13] have employed threshold‐based censoring and analysed the performance of CSS under the fading channel.…”

“…It is reported in the available literature [25, 27, 44] that the multiple antennas are employed at CU for receiver diversity in order to get a detection performance improvement. Atapattu et al in [25] have employed square‐law combining (SLC) and square law selection (SLS) receiver diversity techniques for SS in CRN.…”

“… where denotes the number of antennae at each CU. Therefore, the false‐alarm probability and detection probability at each CU under SLS can be computed with the help of (8) and are given as [27] Further, (9) and (10) can also be written as where and are the false‐alarm and detection probabilities, respectively, of CU when CU employed single antenna.…”

“…Therefore, the SS results of those CUs are transmitted only, whose collected energy does not lie between the two threshold values. However, the researchers in [27] have considered the censoring scheme where the CU's claims the sensing decision in favour of hypothesis , forwards their SS result to the FC. In the proposed analysis, we have also employed censoring scheme of [27] by assuming that the CUs detecting the busy state of PU channel, only send their sensing results to FC.…”

“…The reason for selecting this approach of censoring is due to its simple implementation in our proposed model. Therefore, firstly we compute the number of cooperative CUs () sending the sensing results to FC with the help of Table 3 as given below [27]: where indicates the ceiling function and With the help of value, FC will know about number of CUs reporting in a sensing period. In addition, the received false‐alarm and detection probabilities at FC while considering the imperfect reporting channels can be determined from Table 3 and is given as Moreover, the false‐alarm (), detection () and error probability (…”