Multiple Energy Detectors Research Articles

Adaptive Double Threshold with Multiple Energy Detection Technique in Cognitive Radio

The Cognitive Radio (CR) network is a system which lends help at the time of scarcity in spectrum. One of the process by which CR senses the spectrum is energy detection method with a fixed single threshold. When energy levels fall below the threshold, secondary user is permitted to use the spectrum of the primary user. It is shown by simulation results that having two levels of threshold i.e., double threshold improves performance by giving importance to one of the major aspects of CR, reducing the confliction of the primary and the secondary user. For enhanced performance under noise conditions, dynamic allocation or adaptive threshold is employed with the two levels of threshold. The system is made better by the use of multiple energy detectors on the reception end.

The Effect of Multiple Energy Detector on Evidence Theory Based Cooperative Spectrum Sensing Scheme for Cognitive Radio Networks

Spectrum sensing is an essential function that enables cognitive radio technology to explore spectral holes and resourcefully access them without any harmful interference to the licenses user. Spectrum sensing done by a single node is highly affected by fading and shadowing. Thus, to overcome this, cooperative spectrum sensing was introduced. Currently, the advancements in multiple antennas have given a new dimension to cognitive radio research. In this paper, we propose a multiple energy detector for cooperative spectrum sensing schemes based on the evidence theory. Also, we propose a reporting mechanism for multiple energy detectors. With our proposed system, we show that a multiple energy detector using a cooperative spectrum sensing scheme based on evidence theory increases the reliability of the system, which ultimately increases the spectrum sensing and reduces the reporting time. Also in simulation results, we show the probability of error for the proposed system. Our simulation results show that our proposed system outperforms the conventional energy detector system.

Cooperative Spectrum Sensing with Multiple Antennas Using Adaptive Double-Threshold Based Energy Detector in Cognitive Radio Networks

In Cognitive radio networks, spectrum sensing is used to sense the unused spectrum in an opportunistic manner. In this paper, multiple antennas based energy detector utilizing adaptive double-threshold for spectrum sensing is proposed, which enhances detection performance and overcomes sensing failure problem as well. The detection threshold is made adaptive to the fluctuation of the received signal power in each local detector of cognitive radio (CR) user. Numerical results show that by using multiple antennas at the CRs, it is possible to significantly improve detection performance at very low signal-to-noise ratio (SNR). Further, the scheme was analyzed in conjunction with cooperative spectrum sensing (CSS), where CRs utilize selection combining of the decision statistics obtained by an adaptive double-threshold energy detector for making a binary decision of the presence or absence of a primary user. The decision of each CR is forwarded over error free orthogonal channels to the fusion centre, which takes the final decision of a spectrum hole. It is further found that CSS with multiple antenna-based energy detector with adaptive double-threshold improves detection performance around 26.8 % as compared to hierarchical with quantization method at −12 dB SNR, under the condition that a small number of sensing nodes are used in spectrum sensing.

Multiple antennas-based cognitive radio networks using energy detector with adaptive double-threshold for spectrum sensing

In this paper, we propose multiple antennas-based energy detector utilising adaptive double-threshold for spectrum sensing, which enhances detection performance and overcomes sensing failure problem as well. The detection threshold is made adaptive to the fluctuation of the received signal power in each local detector of cognitive radio (CR) user. Numerical results show that by using multiple antennas at the CRs, it is possible to significantly improve detection performance at very low signal-to-noise ratio (SNR). It is also found that when the number of antennas (Nr) increase, the probability of detection increases. Proposed work having Nr = 3 outperforms Nr = 1, 2 by 30.6 % and 10.5% at –12 dB SNR and probability of false alarm 0.1, respectively.

Cooperative spectrum sensing in multiple energy detectors based cognitive radio networks using adaptive double-threshold scheme

Cognitive Radio (CR) is a regulated technique for opportunistic access of idle resources and it is expected that the golden service of spectrum sensing is to be achieved via the robust sensing technique to sense the unused spectrum in an opportunistic manner. In this paper, we propose multiple energy detectors (MED) utilising adaptive double-threshold (ADT) for spectrum sensing. In the present framework of CR networks, each CR node is equipped with MED and each energy detector with single antenna. Numerical results show that it improves detection performance at very low signal-to-noise ratio (SNR), and overcomes sensing failure problem. Further, the scheme was analysed in conjunction with cooperative spectrum sensing (CSS), where each CR users employ selection combining (SC) scheme to take global decision by MED with adaptive double-threshold (MED_ADT). It is further found that this arrangement improves detection performance around 6.3% as compared to hierarchical with quantisation method at –10 dB SNR, under the case when a small number of sensing nodes are used in spectrum sensing.

Two-Stage Detectors with Multiple Energy Detectors and Adaptive Double Threshold in Cognitive Radio Networks

Cognitive radio (CR) is a regulated technique for opportunistic access of idle resources. In CR, spectrum sensing is one of the key functionalities. It is used to sense the unused spectrum in an opportunistic manner. In this paper, we have proposed two-stage detectors for spectrum sensing in cognitive radio networks (CRN). The first stage consists of multiple energy detectors (MED), where each energy detector (ED) is having single antenna with fixed threshold (MED_FT) for making a local binary decision, and if required, the second stage comprised of ED with adaptive double threshold (ED_ADT) is invoked. The detection performance of the proposed scheme is compared with cyclostationary-based sensing method and adaptive spectrum sensing scheme. Numerical results show that the proposed scheme improves detection performance and outperforms the cyclostationary-based sensing method and adaptive spectrum sensing by 12.3% and 14.4% at signal to noise ratio (SNR) setting of as low as −8 dB, respectively. Performance was also measured in terms of sensing time. It is shown that the proposed scheme yields smaller sensing time than cyclostationary detection and adaptive spectrum sensing scheme in the order of 4.3 ms and 0.1 ms at −20 dB SNR, respectively.

Comments on “Detection of signals of unknown duration by multiple energy detectors”

In the 2010 paper entitled “Detection of signals of unknown duration by multiple energy detectors”, a procedure to detect signals of unknown duration under Gaussian noise has been proposed and probability of detection and probability of false alarm expressions have been derived. This note indicates an error made at the beginning of these derivations.

Multiple Energy Detectors based Spectrum Sensing for Cognitive Radio Networks

Cognitive radio is an enabling technology to solve the spectrum scarcity problem in wireless communication. This is based on the concept of opportunistic spectrum access. Spectrum sensing is one of the most important functions in cognitive radio (CR) implementation. In this paper, we propose a multiple energy detectors (MED) based scheme with improved detection performance at low SNR. We consider a framework of CR networks in which each CR node is equipped with MEDs and each energy detector with single antenna. An analytical model is developed for performance evaluation in terms of probability of false alarm Pf, and probability of detection Pd. Numerical results obtained in Rayleigh fading channel show that the proposed scheme performs better as compared to conventional energy detector (ED).

Cooperative Spectrum Sensing Based on Two-Stage Detectors With Multiple Energy Detectors and Adaptive Double Threshold in Cognitive Radio Networks

This paper presents two-stage detectors for spectrum sensing in cognitive radio networks. The first stage consists of multiple energy detectors, where each energy detector (ED) has a single antenna with fixed threshold for making a local binary decision. If required, the second stage comprised of ED with adaptive double threshold is invoked. The detection performance of the proposed scheme is compared with a cyclostationary-based sensing method and adaptive spectrum sensing scheme. The numerical results show that the proposed scheme improves detection performance and outperforms the cyclostationary-based sensing method and adaptive spectrum sensing by 12.3% and 14.4% at signal-to-noise ratio (SNR) setting of as low as -8 dB, respectively. Performance was also measured in terms of sensing time and scheme has smaller sensing time than cyclostationary detection and adaptive spectrum sensing scheme in the order of 4.3 and 0.1 ms at -20-dB SNR, respectively. Furthermore, the scheme was analyzed in conjunction with cooperative spectrum sensing (CSS), where each cognitive radio (CR) user used two-stage spectrum sensing detectors for local detection and sent detection decisions to the fusion center to give the final decision based on hard decision OR rule. It is further found that the proposed two-stage spectrum sensing scheme with CSS achieves spectrum detection performance in the order of 0.9 for an SNR value of as low as -19 dB as the number of CR users (K) is 10.

Improving Detection of Acoustic Signals by Means of a Time and Frequency Multiple Energy Detector

Standard energy detectors (ED) are optimum to detect unknown signals in presence of uncorrelated Gaussian noise. However, in real applications the signal duration and bandwidth are unpredictable and this fact can considerably degrade the detection performance if the appropriate observation vector length is not correctly selected. Therefore, a multiple energy detector (MED) structure is applied in the time as well as in the frequency domain and it is evaluated in real acoustic scenarios. The results obtained demonstrate the robustness of the MED structure and a performance improvement in comparison to the standard ED.

Detection of signals of unknown duration by multiple energy detectors

An extension of the classical energy detector is proposed to deal with the case of unknown signal duration. Multiple energy detectors are applied to partitions of the original observation interval; presence of signal is decided if at least one of the detectors is in favor of it. We have derived the corresponding probabilities of false alarm and detection for a particular strategy of successive segmentations of the original interval, thus obtaining a layered structure of energy detectors. One key problem is that individual decisions obtained from the multiple energy detectors are statistically dependent, thus complicating the derivation of the overall probabilities of detection and false alarm. ROC curves have been computed, showing significant improvements in detectability when there is a large mismatch between the duration of the observation interval and the actual duration of the signal. This can be especially interesting in the framework of novelty detection where specific parameters of the signal, like duration, are totally unknown.