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One of the key problems in cognitive radio (CR) is the detection of primary activity in order to determine which parts of the spectrum are available for opportunistic access. In this work, we present a new multiantenna detector which fully exploits the spatial and temporal structure of the signals. In particular, we derive the generalized likelihood ratio test (GLRT) for the problem of detecting a...
Spectrum sensing is a key technology of cognitive radio (CR). In CR systems, the main requirement of spectrum sensing is the ability of rapid and accurate detection of the presence of the primary user. In this paper, we propose a spectrum sensing method using artificial neural network (ANN). Detailed analysis shows that the proposed scheme is appropriate to detect the signals under considerably low...
Cognitive radios (CR) are regarded as a viable solution to enabling flexible use of the frequency spectrum in future generations of wireless networks. An important aspect of spectrum management in CR systems is adaptation of the spectrum sensing methods employed by CRs in order to accurately detect the changing patterns of spectrum use and to update the spectrum and interference constraints under...
Cooperative spectrum sensing, a key technology in cognitive radio, has to summarize all the detection information from cognitive terminals without licensed band. In order to employ both reliable and efficient transmission of overhead, this paper seeks a way of quantifying the detection information with variable length to save the spectrum resource as much as possible. Analysis and simulation show...
Cognitive radio (CR) technology is a promising way to improve the bandwidth efficiency of underutilized radio spectra. For practical CR systems with limited a priori knowledge of the primary users' signal characteristics, spectrum sensing is mainly based on energy detection and cyclostationary feature detection. Energy detection is simple and practical but becomes ineffective at a low signal-to-interference-and-noise...
In this work, we investigate the performance of cooperative spectral sensing, where each OFDM-based CR is equipped with multiple-antennas and uses SLC based energy detector to detect the presence of PU signal within its communication range. Using this approach, the CR can detect the spectrum hole with subcarrier resolution. The simulation results suggest that a trade-off is necessary between detection...
In this paper we consider the spectrum sensing performance and requirements for detecting legacy users (LU) in cognitive radios (CR) with periodic scanning. The performance and requirements are studied based on the temporal spectral occupancy statistics of the LU and the sensing signal to noise ratio levels in order to achieve a certain level of detection probability. We model the temporal statistics...
In this paper, a spectrum sensing approach based on stochastic resonance (SR) technique is proposed. According to the theorem of the improvability of detection via SR and the spectral power amplification (SPA) promotion of the SR system, the property of the primary users (PUs) in cognitive radio (CR) networks can be detected easier when the SR phenomenon is realized. Performance analyses and computer...
According to dramatic increase of wireless communication demand, more spectrum resources are needed to support considerable and various wireless services. However, limited spectrum resources are regulatory assigned to licensed user and no interference needs to occur from unlicensed user to licensed user. In this paper, we propose efficient decision rule in order to get better chance to detect the...
In cognitive radios, the first and crucial task is to detect the spectrum holes or the presence of primary user by employing spectrum sensing. However, there exist two kinds of detection errors (i.e., miss-detection error and false-alarm error), which degrade the sensing performance severely. Aiming at minimizing the probability of total detection errors, based on the law of total probability we propose...
In this paper we present some experimental results on the cyclostationarity properties of the IEEE802.11n Wi-Fi transmissions, and the usage of the cyclostationarity features to detect IEEE802.11n radios in the context of ultra wide band (UWB) based cognitive radios (CR). The IEEE 802.11n lies in the UWB frequency range, at 5.2GHz, and the CR needs to successfully detect the legacy user to avoid interference...
In this paper we investigate spectrum sensing for cognitive radio (CR) by using multiple spectrum sensors. We explore sensing schemes based on soft information combining, hard information combining and a two-stage detection scheme that uses both soft information combining and hard information combining. The two-stage detection scheme is shown to provide improved performance compared to sensing based...
In this paper we describe a new cooperating sensing method using double threshold energy detection technique for cognitive radio. Each secondary cognitive user takes a local decision on spectrum occupancy based on two threshold energy detection and uses 1 bit information to convey its decision to the fusion center that collects decisions from all cooperating users who are able to detect presence or...
The energy based test is a popular detection scheme for cognitive radio (CR). However, it is infeasible or confronted with difficulty in threshold determination when a reference noise power level is unavailable or inaccurate. In fact, the presence of a primary signal not only changes the received signal energy, but also its correlation structure. In this paper, we show how to exploit information in...
The present wireless communication system under coal mines is characterized by single pattern, fixed communication frequency, incapability of adaptive to various tunnel environments. To solve the above problems, cognitive radio (CR) is applied to the system. With the energy detection algorithms used in the spectrum sensing of various tunnels under mines, the spectrum sensing method adaptive to tunnel...
Compressed sensing and the related recently introduced smashed filter are novel signal processing methods, which allow for low-complexity parameter estimation by projecting the signal under analysis on a random subspace. In this paper the smashed filter of Davenport et al. is applied to a principal problem of digital communications: pilot-based time offset and frequency offset estimation. An application,...
As an enabling functionality of overlay cognitive radio networks, spectrum sensing needs to reliably detect licensed signal in the band of interest. To achieve reliable sensing, we propose a linear fusion scheme for distributed spectrum sensing to combine the sensing results from multiple spatially distributed cognitive radios. The optimal linear fusion design is formulated into a nonconvex optimization...
One of the unique feature of cognitive radio systems is they can make use of temporarily idle spectral bands in an opportunistic manner. To achieve this however, robust sensing algorithm is required which otherwise incumbent services could suffer from interference. In this paper sensing algorithms based on energy detection and self-correlation detection are presented and compared. The self-correlation...
In a wireless regional area network (WRAN), the presence of wireless microphone (WM) signals must be detected as primary users. However, very narrow bandwidth and low power makes it difficult to sense WM signals especially when these WM signals are distributed in a wideband spectrum. In this paper, a singular value decomposition (SVD)-based approach is presented to sense and estimate multiple WM signals...
In cognitive radio (CR) networks, cognitive users need to continuously monitor spectrum to detect the presence of primary users, yet attain a reasonable throughput. In this paper, we exploit a scheme to detect the primary transmitting signal as quickly as possible using energy detection, besides a necessary transmission rate of CR networks is sustained. Also the relationship between time and frequency...
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