Generation Cognitive Radio Research Articles

Rate Splitting Multiple Access for Next Generation Cognitive Radio Enabled LEO Satellite Networks

Low Earth Orbit (LEO) satellite communication (SatCom) has drawn particular attention recently due to its high data rate services and low round-trip latency. It has low launching and manufacturing costs than Medium Earth Orbit (MEO) and Geostationary Earth Orbit (GEO) satellites. Moreover, LEO SatCom has the potential to provide global coverage with a high-speed data rate and low transmission latency. However, the spectrum scarcity might be one of the challenges in the growth of LEO satellites, impacting severe restrictions on developing ground-space integrated networks. To address this issue, cognitive radio and rate splitting multiple access (RSMA) are the two emerging technologies for high spectral efficiency and massive connectivity. This paper proposes a cognitive radio enabled LEO SatCom using RSMA radio access technique with the coexistence of GEO SatCom network. In particular, this work aims to maximize the sum rate of LEO SatCom by simultaneously optimizing the power budget over different beams, RSMA power allocation for users over each beam, and subcarrier user assignment while restricting the interference temperature to GEO SatCom. The problem of sum rate maximization is formulated as non-convex, where the global optimal solution is challenging to obtain. Thus, an efficient solution can be obtained in three steps: first we employ a successive convex approximation technique to reduce the complexity and make the problem more tractable. Second, for any given resource block user assignment, we adopt KarushKuhnTucker (KKT) conditions to calculate the transmit power over different beams and RSMA power allocation of users over each beam. Third, using the allocated power, we design an efficient algorithm based on the greedy approach for resource block user assignment. For comparison, we propose two suboptimal schemes with fixed power allocation over different beams and random resource block user assignment as the benchmark. Numerical results provided in this work are obtained based on the Monte Carlo simulations, which demonstrate the benefits of the proposed optimization scheme compared to the benchmark schemes.

Feature Extraction in Local Spectrum Sensing for Next Generation Cognitive Radios – A Review

In the context of the currently developed networks for the realization of future communications, the concept of Cognitive Radio (CR) has a significant place. Its implementation in modern ultra-dense networks (UDN) requires the development of novel and improved adaptive solutions for the main functionalities of a CR system. This technology has a great potential for solving the significant spectrum underutilization issue which has been established as characteristic for the traditional communication networks and hence, the continual and substantive research efforts in the recent years. The principal challenge for CRs is the optimization of spectrum utilization without creating unwanted interference for the incumbent (primary) users. Thus, a significant portion of the research is directed towards the vital spectrum sensing functionality. This paper reviews the potential uses of CR in UDN as well as the main approaches for modeling of spectrum sensing with respect to signal detection. The review focuses on local spectrum sensing techniques and presents the strengths and weaknesses of their mathematical definition. Specific attention is given to the channel models which are considered in the literature and to what kinds of features are extracted from the received signal to achieve accurate detection.

Feature Extraction in Local SpectrumSensing for Next Generation CognitiveRadios � A Review

In the context of the currently developed networks for the realization of future communications, the concept of Cognitive Radio (CR) has a significant place. Its implementation in modern ultra-dense networks (UDN) requires the development of novel and improved adaptive solutions for the main functionalities of a CR system. This technology has a great potential for solving the significant spectrum underutilization issue which has been established as characteristic for the traditional communication networks and hence, the continual and substantive research efforts in the recent years. The principal challenge for CRs is the optimization of spectrum utilization without creating unwanted interference for the incumbent (primary) users. Thus, a significant portion of the research is directed towards the vital spectrum sensing functionality. This paper reviews the potential uses of CR in UDN as well as the main approaches for modeling of spectrum sensing with respect to signal detection. The review focuses on local spectrum sensing techniques and presents the strengths and weaknesses of their mathematical definition. Specific attention is given to the channel models which are considered in the literature and to what kinds of features are extracted from the received signal to achieve accurate detection.

Spectrum Sensing using AMC and TFT

Spectrum Sensing (SS) is a foremost step to implement next generation Cognitive Radio (CR) systems. The primary goal of a SS technique is to examine whether the Primary User (PU) is in active state or not by analyzing the surrounding radio environment. Traditional methods such as energy detection and Matched Filter Detection (MFD) schemes along with decision making circuits are generally used in SS. However, these techniques are developed under cooperative scenarios and they are used to sense single PU (narrowband sensing). In non-cooperative scenarios and fading channel conditions, traditional techniques produce higher false alarm. If Secondary User (SU) is occupied in the channel then SS task is more difficult. In order to overcome these limitations, a narrowband and wideband SS algorithm using Automatic Modulation Classification (AMC) and Time-Frequency Transform (TFT) is developed in this paper. The performance analysis of proposed AMC and TFT based SS technique under various channel conditions which is also described in this paper.

Design and Analysis of a Miniaturized Meandered Slot-Line-Based Quad-Band Frequency Agile MIMO Antenna

In this work, a novel miniaturized meandered slot-line-based quad-band multiple-input-multiple-output (MIMO) antenna system is presented. The proposed design consists of two-antenna elements meandered in an H-shaped configurations. The miniaturization techniques of meandered slot-line and reactive loading are implemented to operate the antenna in sub-1 GHz bands with compact structure which results in an antenna size of $0.08\lambda _{o}$ corresponding to its lowest operating band. The frequency reconfigurability in the design is achieved by reactively loading the slots using varactor diodes. Covering most of the modern communication standards, the antenna operates in 0.665–1.13 GHz, 1.415–2.005 GHz, 2.42–3.09 GHz, and 3.18–3.89 GHz bands. Furthermore, complete analysis of frequency reconfigurability and design procedure is provided as a guideline for designing such an antenna system for any desired band of operation. The proposed two-element design is realized on a board dimensions of $60\times 120\times0.76$ mm3 using an RO4350 substrate. The proposed design is well-suited for wireless terminals with second generation cognitive radio (CR) capabilities for radio-frequency (RF) front-end applications.

Split‐ring‐resonator‐loaded multiband frequency agile slot‐based MIMO antenna system

In this work, a compact quad-element multiple-input-multiple-output (MIMO) antenna system is proposed. The design consists of four annular slot-line based MIMO elements, printed on a commercially available RO4350 substrate with a total size of 60 × 120 × 0.76 m m 3 . Each annular slot has a rectangular slot inside it to increase its electrical length to further bring down the resonance frequency. Furthermore, a T-shaped defected ground structure is utilised to increase the isolation between the closely spaced antenna elements. Each element is loaded with a unique split ring resonator (SRR), which results in size reduction as well as multi-band operation covering 1.7–2.28, 2.35–2.85 and 2.9–3.1 GHz. Moreover, by using only a single varactor diode per element, fine frequency tuning over these bands is achieved. A wide frequency sweep over multi-band and a peak gain of 2.95 dBi with 82% maximum radiation efficiency is achieved. Low envelope correlation coefficient values are observed throughout the operating band, thus offering good MIMO performance. The overall planar antenna design is compact, low-profile and can easily be integrated with radio frequency front ends in second generation cognitive radios among many other applications.

Impact of Next Generation Cognitive Radio Network on the Wireless Green Eco system through Signal and Interference Level based K Coverage Probability

Land mobile communication is burdened with typical propagation constraints due to the channel characteristics in radio systems.Also,the propagation characteristics vary form place to place and also as the mobile unit moves,from time to time.Hence,the tramsmission path between transmitter and receiver varies from simple direct LOS to the one which is severely obstructed by buildings, foliage and terrain. Multipath propagation and shadow fading effects affect the signal strength of an arbitrary Transmitter-Receiver due to the rapid fluctuations in the phase and amplitude of signal which also determines the average power over an area of tens or hundreds of meters. Shadowing introduces additional fluctuations, so the received local mean power varies around the area –mean. The present paper deals with the performance analysis of impact of next generation wireless cognitive radio network on wireless green eco system through signal and interference level based k coverage probability under the shadow fading effects.

Impact of Next Generation Cognitive Radio Network on the Wireless Green Eco system through Signal and Interference Level based K Coverage Probability

Land mobile communication is burdened with typical propagation constraints due to the channel characteristics in radio systems.Also,the propagation characteristics vary form place to place and also as the mobile unit moves,from time to time.Hence,the tramsmission path between transmitter and receiver varies from simple direct LOS to the one which is severely obstructed by buildings, foliage and terrain. Multipath propagation and shadow fading effects affect the signal strength of an arbitrary Transmitter-Receiver due to the rapid fluctuations in the phase and amplitude of signal which also determines the average power over an area of tens or hundreds of meters. Shadowing introduces additional fluctuations, so the received local mean power varies around the area –mean. The present paper deals with the performance analysis of impact of next generation wireless cognitive radio network on wireless green eco system through signal and interference level based k coverage probability under the shadow fading effects.

Cognitive Radio: A New Standard in Wireless Communication Technology

The future of Wireless Communication Technology is going to be basically based on Cognitive Radio (CR) or Intelligent Radio (IR). At present the Spectrum allocation governed by the government agencies or the service providers who are in need of more spectrums, to manage the increasing frequency demands from the end users as the technological improvement increases exponentially. Efficient utilization of this scared Electromagnetic Radio Spectrum is the basis for the Cognitive Radio (CR). Spectrum Sensing being the fundamental issue of the Cognitive Radio i.e., detecting the underutilized spectrum of Primary User (PU) or Licensed User that can be efficiently utilized by the Secondary User (SU) or Unlicensed User. The spectrum is a scared natural resource, so it becomes essential to detect the unused spectrum of the PU to utilize it by other Users. The unused spectrums that are identified idle can be efficiently managed by spectrum management techniques. The managed spectrum should be mobilized for efficient utilization by the SUs. The spectrum mobilized can be shared properly by the SUs for proper usage which all governed by the physical layer operations of the Cognitive Radio. In this review paper, the fundamental issues of physical layer functions i.e., Spectrum Sensing, Spectrum Sharing, Spectrum Management and the NeXt generation Cognitive Radio functions have been analyzed and as a future work the higher layer issues of Cognitive Radio are considered to be the Link Layer, Network layer operations.