On optimal number of cognitive radios considering co-site electromagnetic compatibility

With the development and wide applications of wireless communication technology, the limited spectrum resources and the fixed spectrum allocation policy could no longer satisfy the demand for wireless communication. Just for this reason, many spectrum resources become spectrum holes because they are allocated but not used. Cognitive radio is now becoming one of the most important techniques for high utility of these spectrum holes. If the holes available to cognitive users are abundant over a certain time, it is a worth consideration to increase network throughputs by orthogonal multiplexing as many as spectrum holes. A multi-transceiver configuration is one of the possible solutions for this purpose. With such a schema, all transceivers within a cognitive user work in a concurrent or parallel mode, by which the throughput of the network can be increased. However, co-site working cognitive radios may incur electromagnetic interference between each other. When more cognitive radios are equipped, much electromagnetic interference may be incurred. Many techniques are proposed to mitigate such so-siting interference; however, none of them have addressed the probability that the interference will happen. If the probability could be estimated in advance, the user will make a better planning on the configurations of the co-siting working radios. Based on an elaborated n-fold multiple integral model, we propose a novel method to decide how many cognitive radios can be installed for one cognitive user at most. This is our main contribution with this work, providing an enhanced ability to determine the optimal number of cognitive radios installed within each cognitive user. We make a strict deduction on electromagnetic compatibility probability with various parameters of cognitive radios. Simulations are performed and the results show that the electromagnetic compatibility of the simulated cognitive radio system meets the deducted probability by this method very well.

Relay Assisted Spectrum Sensing in Presence of IQ Imbalance in Multi-Channel System

The increasing demand of wireless technology leads to a need for dynamic spectrum access that is positively accomplished by cognitive radio (CR) technology. For its acceptable efficiency it needs a robust detection scheme which detect the spectrum holes. This paper investigates a cooperative spectrum sensing method for a relay-based cognitive radio network. In general relay is a low cost device and is more prone to hardware impairment such as In-phase and Quadrature-phase Imbalance (IQI), which can considerably limit the capabilities of sensing spectrum holes. This work studies the energy detection (ED) based spectrum sensing in multi-channel receiver scenarios that are affected by IQI. The detection and false alarm probabilities considering Gaussian primary user signal models are derived. Our results are simulation based and verified with theoretical findings.

A Review on Modern Spectrum Sensing and Assignment Techniques in CRN

Cognitive radio (CR) is ascending as an advanced technology with the aim of utilizing the unused spectrum bands in an opportunistic and dynamic way. Fixed spectrum allocation done by government based agencies leads to underutilization of resources. The segments of spectrum bands that are unused, are called “spectrum holes” or “white spaces”. The solution to this issue is provided by implementing CR technology. It allows users to determine the unused bands in spectrum, choose the suitable one (depending on availability and accessibility of the spectrum) and use them in the best way possible. Spectrum assignment plays a vital role in minimizing any possibility of interference between secondary and primary users. Because of the varying parameters of available spectrum along with the different QoS specifications of various networks, CR technology raise a range of challenges. Spectrum management functions should tackle these problems and ensure that the CR network runs smoothly. This article therefore presents a brief survey on CR networks, its architecture and other relevant functionalities like spectrum sensing, spectrum decision, spectrum sharing, and spectrum mobility.

An Energy-Efficient Spectrum Sensing in Cognitive Radio Network Using Fractional Optimization Model

In wireless communication, the main challenge is to use the radio spectrum efficiently. The spectrum used for wireless radio technology is a natural resource that is limited and expensive. The tremendous growth of the market for wireless communication has led to radio spectrum scarcity. The process for conventional spectrum sensing initiates by scanning the frequency spectra for finding the spectrum holes. On the basis of the availability of spectrum holes, Secondary User (SU) can transmit data and need to perform periodic sensing for a seamless connection. In this work, to detect spectrum holes with improved energy utilization, we have proposed the Fractional Optimization Model (FOM) which is the combination of Gray wolf optimization and Cuckoo search algorithm to detect the spectrum holes with improved energy utilization. In this paper, the model is made to obtain energy efficiency while considering different spectrum sensing states. The energy efficiency is improved by optimizing the parameters such as transmission power, sensing bandwidth, and power spectral density using the Fractional GWO-CS optimization algorithm. With the proposed novel FOM, the spectrum holes can be detected with the optimized transmission power, sensing bandwidth, and power spectral density values. The proposed model will be implemented in the working platform of Matlab by optimizing the energy efficiency of spectrum sensing in terms of transmission power, spectrum sensing bandwidth, and power spectral density compared which will be compared with existing optimization methods.

On Optimal Number of Cognitive Radios Considering Co-site Electromagnetic Compatibility

Cognitive radio is becoming one of the most important techniques for high utility of spectrum holes. If the holes available to cognitive users are abundant over a certain time, it is a worth consideration to increase network throughputs by orthogonal multiplexing as many as spectrum holes. A multi-transceiver configuration is one of the possible solutions for this purpose. With such a schema, all transceivers within a cognitive user work in a concurrent or parallel mode, by which the throughput of the network can be increased. However, co-site working cognitive radios may incur electromagnetic interference between each other. When more cognitive radios are equipped, much electromagnetic interference may be incurred. Based on an electromagnetic compatibility probability analysis, this paper proposes a novel method to decide how many cognitive radios can be installed for one cognitive user at most. We make a strict deduction on electromagnetic compatibility probability with various parameters of cognitive radios. Simulations are performed and the results show that the electromagnetic compatibility of the simulated cognitive radio system meet the deducted probability very well.

Deep Cooperative Spectrum Sensing Utilizing Recurrent Convolutional Neural Networks

Cognitive Radio (CR) network was introduced as a promising approach in utilizing spectrum holes. Spectrum sensing is the first stage of this utilization which could be improved using cooperation, namely Cooperative Spectrum Sensing (CSS), where some Secondary Users (SUs) collaborate to detect the existence of the Primary User (PU). In this paper, to improve the accuracy of detection Deep Learning (DL) is used. In order to make it more practical, Recurrent Neural Network (RNN) is used since there are some memory in the channel and the state of the PUs in the network. Hence, the proposed RNN is compared with the Convolutional Neural Network (CNN), and it represents useful advantages to the contrast one, which is demonstrated by simulation.

Cognitive Radio Techniques over Conventional Radio Systems

Cognitive Radio (CR) has advanced like a brilliant innovation for crossing over the divergence between the accessibility and assignment of the radio recurrence range among various clients. It can change its transmission parameters dependent on the apparent accessibility of the range groups in its working condition. Cognitive radio (CR) innovation vows to be one potential answer for take care of the issue of absence of recurrence range, by permitting access of unlicensed clients in authorized groups, in view of a shrewd methodology and without meddling with the authorized user(PU). Subjective Radio has developed as a savvy innovation in crossing over the divergence between the accessibility and distribution of the radio recurrence range among numerous clients. This paper shows an outline of the spectrum holes in the licensed bands, the concepts of CR, types, spectrum holes, its features and sensing methods the transceiver details and it compares with conventional radio in terms of performance parameters such as interference, operating frequency, security, spectrum utilization, reliability, efficiency and power consumption