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Energy efficient and reliable spectrum sensing become essential in cooperative cognitive radio networks. However, cooperation in spectrum sensing (SS) is often vulnerable to several security threats; one such operation is primary user emulation attack (PUEA). To address the issues, an optimization framework is developed in this work to minimize the energy consumption in cooperative spectrum sensing...
The effective capacity of the cognitive radio system is an important parameter to measure its performance. It is affected by the accuracy of spectrum sensing and spectrum management scheme. In this paper, we first design a multi-channel cognitive radio model in opportunistic spectrum access scenario. In this model, every channel has three different states. The transfer between the channel states is...
The cognitive radio is considered a best solution for the limited spectrum resources problem. The periodogram based energy detection can be used for spectrum estimation in cognitive radio. It does not need any prior information about the primary signal. This paper presents a new periodogram by using the Discrete Cosine Transform (DCT). In addition, it analyses and compares the performance with raw...
In cognitive radio spectrum sensing is a fundamental problem. Under the case of uncorrelated noise different methods are used for spectrum sensing. In this paper we compare the performance of MP and eigenvalue based methods. In eigenvalue based method we find the threshold using random matrix theory (RMT). Marchenko-Pastur (MP) method use standard condition number (SCN) to find the threshold. Here...
Spectrum sensing is important step for better utilization of unused frequency band in cognitive radio technology. In spectrum sensing, threshold determination plays the key role. In this paper, we analyze the performance metrics of cognitive radio network under conventional threshold and adaptive threshold. Conventional theory considers only one metric at a time i.e. either probability of false alarm...
Communication signal and noise's waveform can be described and distinguished by fractal theory with their irregular characteristics. In current cognitive radio system, single node spectrum sensing is susceptible to noise uncertainty and its detection accuracy in low SNR situation is poor. To solve these issues, a cooperative spectrum sensing algorithm based on Katz fractal dimension is proposed. It...
Selection of appropriate detection threshold (λ) is a very critical task in energy detection scheme based cognitive radio (CR) system. λ is mainly selected by using two principles called as constant detection rate (CDR) in which λ is calculated by taking fixed value of probability of detection (Pd) and constant false alarm rate (CFAR) in which λ is calculated by taking fixed value of probability of...
This paper presents a multichannel assignment problem in a centralized cognitive radio sensor network (CRSN). The basic aim of this problem is to maximize the overall system throughput and minimize the overall energy consumption of the CRSN. First, a weighted sum based optimization problem is formulated. Then the problem is represented using bipartite graph and solved using matching based hungarian...
Cognitive radio (CR) is an intelligent technique which is used to improve the spectrum utilization through four main functions: spectrum sensing, spectrum decision, spectrum sharing and spectrum mobility. In this paper, we focus on spectrum mobility (or called spectrum handoff) that occurs when the primary users (PUs) appear to occupy its licensed band that used by secondary users (SUs). We discuss...
Recently, the need to extra frequency bands is increasing significantly due to modern devices and applications. This problem can be addressed by exploiting the idle spectra. Thus, the spectrum exploiting is performed using the technique of spectrum sensing. In this paper, a new cooperative spectrum sensing scheme is proposed based on discrete cosine transform periodogram. This scheme is applied on...
Secondary users can utilize the spectrum in the absence of primary users (PU) in cognitive radio networks (CRN). Hence there is a need to sense the spectrum perfectly. Because of hidden node problem, the sensing information given by single SU may not be reliable information. In cooperative spectrum sensing, local sensing is performed by number of SUs and report their local decisions to fusion center...
In recent era of communication, limitation of the spectral resource has increased rapidly. Cognitive radio ad-hoc networks (CRAHNs) are an intelligent network which provides a good solution for effective utilization of the spectrum opportunities. In cognitive radios different research directions are identified like spectrum sensing, sharing, handover, and routing. This research directs the problems...
Wireless technology can eliminate dense wire ropes from hospitals and far access to medical devices. The bandwidth scarcity is the biggest issue in this technology. In order to overcome this issue, cognitive radio driven hospitals are introduced and devices are divided in two categories. Primary devices are the ones with very high priority and their communication is vital for the patients and hospital,...
This paper describes a joint detection and classification of OFDM/QAM, OFDM/OQAM and SC-FDMA signals, using their cyclic frequency domain profiles of spectral correlation density. Detection and classification are performed by introducing corresponding HMMs of these signals. Some performances of the considered joint detection and classification of these signals, obtained using software simulation models,...
Nowadays, Cognitive Radio (CR) is projected as the technology that will maximize the utilization of the spectrum resources in next generation wireless systems. Therefore, the Spectrum Sensing (SS) is the key function, which allows CR to know the available spectrum resources of an interest band. Nevertheless, one of the major problems in the SS is the big amount of samples that are processed in the...
Nowadays, Cognitive Radio (CR) is projected as the technology that will maximize the utilization of the spectrum resources in next generation wireless systems. Therefore, the Spectrum Sensing (SS) is the key function, which allows CR to know the available spectrum resources of an interest band. Nevertheless, one of the major problems in the SS is the big amount of samples that are processed in the...
In this paper, we present a multi-user resource allocation framework using fragmented-spectrum synchronous OFDM-CDMA modulation over a frequency-selective fading channel. In particular, given pre-existing communications in the spectrum where the system is operating, a channel sensing and estimation method is used to obtain information of subcarrier availability. Given this information, some real-valued...
In this work we investigate an auction mechanism for sharing available wireless bandwidth among competing cognitive radios. The bandwidth under consideration may be either in an unlicensed spectrum or in an unused licensed band. Spectrum sharing is achieved via a mechanism in which a cognitive radio acting as the auctioneer advertises spectrum availability to bidding cognitive radios and defines a...
With the increase in utilization of portable devices and ever-growing demand for greater data rates in wireless transmission, an increasing demand for spectrum channels was observed since last decade. Currently, radio spectrum channels are assigned for quite long time periods to licensed subscribers who may not constantly use these bands, which leads to an inefficient use of the radio spectrum. The...
In this paper, we consider a multi-level power allocation scheme for cognitive users in the cognitive radio networks. The proposed system uses a new frame structure to improve overall throughput of the cognitive radio systems. We propose a strategy in which, the licensed user can transmit with multiple levels of power which seems to be more realistic and practical. In this work, the proposed strategy...
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