Cognitive Radio Applications Research Articles

Spectrum occupancy prediction using LSTM models for cognitive radio applications

ABSTRACT In recent days, mobile traffic prediction has become a prominent solution for spectrum management-related operations for the next-generation cellular networks in Cognitive Radio (CR) applications. To achieve this, the binary dataset has been created from the captured data by monitoring the spectrum activities of nine different Long Term Evolution (LTE) frequency channels. We propose a Long Short Term Memory (LSTM) based Spectrum Occupancy Prediction (SOP) approach for modelling infrastructure-based cellular traffic systems. The different types of LSTM models, such as Convolutional, Convolutional Neural Network (CNN), Stacked, and Bidirectional have been generated via offline training and tested for the created binary datasets. Moreover, the prediction performance evaluation of the generated LSTM models has been calculated using Mean Absolute Error (MAE). The pro- posed LSTM-based SOP model has achieved 2.5% higher prediction accuracy than the Auto-Regressive Integrated Moving Average (ARIMA) statistical model, accurately aligning the traffic trend with the actual samples.

Dual Polarized Reconfigurable MIMO Antenna for Multi-Band Functioning

This work presents the development, fabrication, and measurements of a new Ultra-wideband sensing multi-band frequency reconfigurable MIMO Active Integrated Antenna (AIA). The proposed antenna has two frequency reconfigured (switching element PIN diodes) planar inverted F-shape antennas (PIFA) using meandered line (ML) structures and a Mirror-shape UWB sensing antenna. The Mirror-shape UWB sensing antenna is integrated with 2x2 MIMO Meandered line PIFA elements for spectrum sensing. PIN diodes (BAR 6402V) are used to provide all digital switching on/off combination modes to attain frequency reconfigurability. Varactor diodes are used for tuning over the wide band. The proposed antenna senses a wide frequency band from 0.5GHz-3GHz and provides frequency reconfigurability over the five bands based on BARP6402V switching modes (0.78GHz-1.01GHz, 1.34GHz-1.62GHz, 1.85GHz-2.18GHz, 2.44GHz-2.67GHz, and 2.76GHz-2.80GHz). All the measured resultant performance parameters are compared with simulation software results. The antenna system is fabricated on an FR4 substrate of size 120mmX65mmX1.6mm. The proposed method used to achieve frequency reconfigurable ultra-wideband MIMO provides a high gain 6.15dBi at a frequency of 1.75GHz. The research also analyzed and investigated all 2x2 MIMO resultant parameters like Total Active Reflection Coefficient (TARC), Isolation coefficient, Envelope correlation Coefficients (ECC), Diversity Gain (DG), Multiplexing efficiency, etc. The proposed antenna is applicable for sensing, communication, & UWB sensing, and cognitive radio (CR) applications since it exhibits stable excellent gain and Omni-directional radiation pattern over the desired bands. Because of its reconfigurable nature, the same antenna also supports use in multiple general-purpose applications like GPS tracing, LTE, UMTS, GSM1800, rescue operation, Wi-Fi/Bluetooth/ISM/WLAN, CDMA, etc applications.

Design on CPW Quasi Dipole Meandered Printed Antenna for Cognitive Radio Applications

In this proposed paper, CPW-fed meandered printed antenna is designed and investigated for cognitive radio application. The suggested antenna is developed using two different substrates for varying the electrical properties. The first design is developed using an FR4 substrate and the second design is developed using jean material. Investigations are done on the design for wide bandwidth response for effective cognitive radio communication. The antennas are made to resonate at 2.45 GHz. The main focus in the proposed design is to achieve compactness and wider bandwidth. The proposed antenna is excited using coplanar waveguide (CPW) structure to reduce the antenna size and spurious radiations near the feed line. Two quarter-wavelength resonators with two separate current routes are part of the proposed antenna’s structure. It may therefore function in the WiMAX and WLAN (wireless local area network) frequency ranges. By adjusting the length of the appropriate resonators, the operational bands’ center frequencies can be separately controlled. The proposed antennas are designed and simulated for its resonance condition. A parametric study is done to identify the arm length of the proposed antenna for its appropriate resonance. Based on the suitable arm length, the antenna is designed and optimized for effective size reduction. The fabricated antenna module is integrated in the software defined radio (SDR) device for the real-time measurements. The footprint of the antenna is 48.5 mm × 25 mm. Both the simulated and measured results are in good concurrence.

Circularly polarized dielectric resonator based MIMO antenna for sub-6 GHz 5G cognitive radio applications

A 2-port wideband circular polarized (CP) multiple input multiple output (MIMO) dielectric resonator antenna (DRA) integrated with cognitive radio (CR) application is designed and investigated. This is a novel concept of integrating wideband CP-MIMO antenna based on dielectric resonator (DR), with CR concept. The multi-functional reconfigurable filter is designed within the feedline of the antenna making it applicable for both the operations of CR, namely, underlay and interweave. Rogers RT Duroid 5880 is used as the substrate for the designed CP-MIMO antenna. The antenna shows wide Axial Ratio (AR) bandwidth of 48.14% (2.2–3.50 GHz) and an overlapping bandwidth of 41.85% (2.37–3.50 GHz). The DR based MIMO antenna shows sensing range of 2.37–3.66 GHz. For the interweave operation, the designed CP-MIMO antenna shows narrowband frequency reconfigurability from 2.45–2.83 GHz. For the underlay case, the designed antenna shows band notch tunability between 3.23–3.62 GHz. The proposed antenna can be used effectively in sub-6 GHz band of the 5G communication systems.

A multi-radio antenna system for Cognitive Radio(CR), 5G, WLAN and UWB MIMO applications

This article presents a multi-radio antenna system for Cognitive Radio (CR), NB MIMO (5G, WLAN), and UWB MIMO applications by combining independent antennas into a single system. The proposed multi-radio antenna system comprises three independent antennas: the CR antenna system, which consists of a UWB sensing radiator and two narrow band communication antennas; the UWB MIMO antenna system, which comprises a two-element UWB MIMO antenna; and the NB (5G, WLAN) NB antenna system, which consists of a two-element NB antenna. The UWB radiator functions over a bandwidth of 3–12 GHz for CR sensing and UWB MIMO operations, while the NB antennas operate at 3.3, 3.5, 5, 5.5, and 8 GHz for CR communication and NB MIMO communication. Mutual coupling between MIMO radiators is achieved by placing the radiators orthogonal to each other and a parallel line stub. The reflection coefficient, gain, efficiency, and radiation pattern of an antenna were studied. Furthermore, the MIMO performance of UWB MIMO and NB MIMO antenna systems is evaluated using MIMO parameters such as mutual coupling, envelope correlation coefficient, Total active reflection coefficients (TARC), and channel capacity loss (CCL).

A Compact Isolated CR Antenna System for Application in C-Band

In this work, a dual-port antenna system is simulated and fabricated for cognitive radio (CR) application. The proposed system comprises a tapered-fed monopole ultra-wideband (UWB) sensing antenna and a dual-narrowband (NB) communicating antenna. For miniaturization, the UWB sensing antenna is placed on the front side of the communicating antenna. The sensing operation takes place over 2.1–12 GHz. The E-shaped dual-band antenna operates at 3.9 GHz and 6.04 GHz. The envelope correlation coefficient (ECC) and isolation are measured to be lower than 0.12 and greater than 18 dB, respectively, within the range of acceptable values for both parameters. The antenna prototype was fabricated and tested experimentally to confirm the simulation’s findings. The outcomes of both the simulation and the testing revealed a definite consistency. This work gives a miniaturized model and good isolation, which is appropriate for C-band applications.

Dual-port circularly polarized dielectric resonator–based antenna with reconfigurable integrated multifunctional filter for 5G cognitive radio applications

Abstract In this paper, the design of a circularly polarized (CP) multiple-input–multiple-output (MIMO) antenna system is presented, utilizing a dielectric resonator (DR). This presented antenna system is subsequently integrated with a multifunctional filter, all meticulously structured on a single substrate. The multifunctional filter operates in three modes: reconfigurable band-pass and band-reject filter as well as all-pass filter. The overall structure works as a tunable filtenna. The designed filtenna is expanded into a two-port MIMO system on a unified substrate, providing strong port isolation below −28.5 dB. The overall dimension of proposed radiator is 180 × 180 × 1.6 mm3. The value of peak gain is 5.19 dBic. By switching the states of PIN diodes, the designed filtenna operates as a sensing and communicating antenna for interweave and underlay cognitive radios (CRs). The proposed antenna supports the CP waves within the working band, i.e., 3.6–4.5 GHz. The simulated results are validated by comparing them with the measured results showing less variation among them. MIMO parameters, including the envelope correlation coefficient and diversity gain, have been calculated for the proposed filtenna, representing its suitability for 5G-CR applications.

Three-Modes, Reconfigurable Filtenna System with UWB, WiMAX, and WLAN States for Cognitive Radio Applications

Three-Modes, Reconfigurable Filtenna System with UWB, WiMAX, and WLAN States for Cognitive Radio Applications

A miniaturized-slotted planar MIMO antenna with switchable configuration for dual-/triple-band notches

This paper outlines the design and validation of a four-port compact Multi-Input Multi-Output (MIMO) antenna engineered to provide reconfigurable band notches within the ultra-wideband spectrum. The antenna features a circular monopole engraved with split ring slots along its radiating section, while a U-shaped slot is etched onto the feed line to facilitate band notches at specific frequencies—4.3 GHz (corresponding to INSAT), 6.8 GHz (aligned with Wi-Fi-6E), and 8.3 GHz (pertaining to X-band satellite). To ensure proper isolation, the MIMO elements are arranged orthogonally, and a decoupling periodic structure is strategically interposed between these elements to enhance isolation further. The incorporation of a PIN diode within the U-shaped slot introduces reconfigurability into the band notching mechanism. The MIMO antenna operates in two distinct modes depending upon the state of the PIN diode, either activated (ON) or deactivated (OFF). In the former mode, the antenna offers switchable band notches across three frequencies, while in the latter mode, it offers band notches at two specific frequencies. The validity of the antenna’s performance is validated through real-time fabrication and measurement. Both simulated and measured results exhibit a notable correlation. The antenna stands as an appropriate candidate for future cognitive radio applications.

Dual band Orthogonal Polarized 2-port MIMO Antenna for Cognitive Radio Applications

An arrangement of orthogonally aligned antennas over two planes of a substrate is designed in this paper. The design is a novel miniaturized cognitive model operating at LTE, C-band and X-band with sufficient band stop notch. The antenna is etched over a 0.8 mm thick FR-4 Epoxy substrate of dimension 15 mm x 15 mm. On one side the antenna is a hexagonal slotted microstrip antenna and on the other side is a partial CPW type hexagonal patch antenna. The top hexagonal patch antenna is a wide band from 1800 MHz to 12000 MHz. With the use of a slot on the patch creates one notch from 2240 MHz to 5090 MHz and another notch is created at 6200 MHz to 8100 MHz. Thus, the working bands comprise of LTE 1900, Wi-Fi 5G and X-band under a single polarization. Similarly, the second antenna has its first resonance at LTE 1900 and the second resonance at X-band with a polarization orthogonal to the antenna at top. Being a miniaturized antenna, the cognitive radio provides gain ranging from 2.0 dB at lower frequency to 5.4 dB at higher frequency. The isolation over the operating bands suggests non-interference between the antennas.

AFHO‐based link reliable routing and power‐assisted channel allocation protocol in cognitive radio networks for healthcare applications

AbstractIn the realm of cognitive networks, accommodating the increasing need for radio spectrum to facilitate both secondary and primary users stands as an intricate and demanding task. This study introduces a tailored framework for healthcare applications in Cognitive Radio (CR) networks for link reliable routing and power‐assisted channel allocation. Through the integration of Adaptive Fire Hawk Optimization for routing, the strategy addresses optimization complexities while prioritizing robust link quality via optimal hop selection for effective communication. A new routing optimization challenge is formulated, aiming to establish reliable communication pathways and extend link reliability. Moreover, the framework incorporates power‐assisted channel allocation to strategically enhance resource management and overall network performance. The rigorous evaluation demonstrates significant enhancements across key performance metrics, which showcase percentage improvements of 9.86%, 14.56%, 3.85%, 5.06%, 6.94%, and 17.80% for active nodes, delay, Packet Delivery Ratio (PDR), residual energy, and throughput, respectively. These advancements underscore the proposed approach's efficacy in enhancing CR network performance, particularly for healthcare applications.

Dynamic Tuning of Notch Bands in UWB Antenna Based on Liquid Metal for Cognitive Radio Applications

Dynamic Tuning of Notch Bands in UWB Antenna Based on Liquid Metal for Cognitive Radio Applications

Transfer Learning based Location-Aided Modulation Classification in Indoor Environments for Cognitive Radio Applications

Transfer Learning based Location-Aided Modulation Classification in Indoor Environments for Cognitive Radio Applications

Frequency reconfigurable two-element MIMO antenna for cognitive radio and 5G new radio sub-6 GHz applications

Abstract In this paper, a compact two-element reconfigurable multiple-input multiple-output (MIMO) antenna for 5G new radio sub-6 GHz is presented and discussed. The proposed MIMO antenna has four frequency operating modes: a wideband operating mode (2.41–6 GHz), a wideband operating mode with a notching band at 3.5 GHz (3.2–3.66 GHz), a low-pass filter mode that filters the higher frequencies with a wide operating band from 2.41 GHz to 4.7 GHz, and a dual-band mode with two operating narrow bands (2.41–3.16 GHz and 3.64–4.7 GHz). To improve the isolation over the entire operating band, a strip line connecting the two ground planes of the two antenna elements has been used. To validate the proposed approach, different prototypes have been fabricated and measured. The simulation results are in good agreement with the measurement results. The proposed antenna has good MIMO diversity performance with a maximum gain of 4.64 dBi. The minimum isolation is 18 dB for the four operating modes, while a measured envelope correlation coefficient of less than 0.008 is achieved. The diversity gain is near 10 dB for various operating modes. The antenna is suitable for cognitive radio and 5G sub-6 GHz applications.

Universal and complementary representation learning for automatic modulation recognition

AbstractAutomatic modulation recognition (AMR) is a fundamental research topic in the field of signal processing and wireless communication, which has widespread applications in cognitive radio, non‐collaborative communication etc. In this paper, the focus is on the multi‐modal utilization in AMR. Specifically, the universal and complementary characteristics of multiple modality data in the domain‐agnostic and domain‐specific aspects are mined, yielding the universal and complementary subspaces network accordingly (dubbed as UCNet). To facilitate the subspace construction, universal and complementary losses are proposed accordingly. The proposed UCNet has achieved the highest recognition accuracy of 93.2% at 10 dB on the RadioML2016.10A dataset, and the average accuracy is 92.6% at high SNR greater than zero.

Efficient design of a wideband tunable microstrip filtenna for spectrum sensing in cognitive radio systems

This paper presents a novel design of a compact, wideband tunable microstrip filtenna system for effective spectrum sensing in cognitive radio (CR) applications. The proposed filtenna structure has a total bandwidth of 1.63,text{GHz} and flexible frequency scanning design throughout the frequency range from 1.93,text{ to },3.56,text{ GHz} with high selectivity and narrow bandwidths ranging from 39.9,text{to}53,text{MHz}. Frequency tuning is accomplished electrically via integrating a varactor diode into the filtenna construction. The filtenna is realized on a Rogers TMM4 substrate with h=1.52,text{mm} thickness and relative dielectric constant of {varepsilon }_{r}=4.5 with dimensions of (25times 35), {text{mm}}^{2}. The obtained gain and efficiency of the filtenna ranged from 0.7 to 2.26,text{dBi} and 49% to 60%, respectively, within the tuning range. Simple biasing circuitry, wideband operation, and compact planar structure are distinctive and appealing aspects of the design. For the manufactured prototypes, a significant level of agreement is found between the simulated and measured results in terms of scattering parameter {text{S}}_{11} and radiation patterns at different operating frequencies.

Integrated compact UWB and frequency reconfigurable antenna with high isolation for cognitive radio

This paper presents the design of a compact ultra-wideband (UWB) antenna and a frequency reconfigurable antenna with high isolation for cognitive radio (CR) applications. The antenna prototype comprises a UWB antenna for sensing UWB spectrum and a frequency reconfigurable antenna for communication purposes. The proposed antenna has been designed on FR-4 substrate with a compact size of 25 × 36 × 1.6 mm3 (0.22λ0 × 0.32 λ0 × 0.014λ0), where λ0 is free space wavelength at 2.7 GHz. The −10 dB impedance bandwidth is realized for UWB antenna ranges from 2.7 GHz to 10 GHz and for frequency reconfigurable antenna in two frequency bands from 4.3 GHz to 5.5 GHz and 5.1 GHz to 6.8 GHz. A T-shaped stub is integrated into the ground plane to achieve high isolation between antenna element ports and the impedance bandwidth improvement. The proposed design attains high isolation of −21 dB over communication frequency range of frequency reconfigurable antenna and most of the UWB spectrum. The prototype has been fabricated and measured. The measurement results are in good agreement with the simulated results.

A Review of Wireless Sensor Networks with Cognitive Radio Techniques and Applications

The advent of Wireless Sensor Networks (WSNs) has inspired various sciences and telecommunication with its applications, there is a growing demand for robust methodologies that can ensure extended lifetime. Sensor nodes are small equipment which may hold less electrical energy and preserve it until they reach the destination of the network. The main concern is supposed to carry out sensor routing process along with transferring information. Choosing the best route for transmission in a sensor node is necessary to reach the destination and conserve energy. Clustering in the network is considered to be an effective method for gathering of data and routing through the nodes in wireless sensor networks. The primary requirement is to extend network lifetime by minimizing the consumption of energy. Further integrating cognitive radio technique into sensor networks, that can make smart choices based on knowledge acquisition, reasoning, and information sharing may support the network's complete purposes amid the presence of several limitations and optimal targets. This examination focuses on routing and clustering using metaheuristic techniques and machine learning because these characteristics have a detrimental impact on cognitive radio wireless sensor node lifetime.

A New Approach for the Design of Frequency Reconfigurable Antenna for Cognitive Radio Applications

A New Approach for the Design of Frequency Reconfigurable Antenna for Cognitive Radio Applications

Reconfigurable Compact Quad-port MIMO Antennas for sub-6 GHz Applications

This paper presents compact quad-port frequency reconfigurable multi-input multi-output (MIMO) antennas for 5 G applications that operate at sub-6 GHz. The proposed design provides more isolation (>13 dB) and pattern diversity using four orthogonal radiating elements. C-shaped metal is used to extend the antenna's radiating elements by inserting one positive intrinsic negative diode (PIN) in the metal. The C-shaped metal and matching stub achieve frequency reconfigurability with a consistent radiation pattern. The PIN diode's switching characteristics allow the frequency to be shifted between two communication bands. One mode (diode ON) covers 2.5 and 5 GHz, while the second mode (diode OFF) covers another dual band of 3.5 and 5.7 GHz. Substrate dimensions are only 50 x 50 x1.6 mm3, making the proposed design compact. Antenna peaks at a gain of 4.18 dB and radiation efficiencies of 80 and 94% in the four frequency bands. The antenna design is appropriate for multi-functional wireless systems and cognitive radio applications since it spans frequency bands below 6 GHz and can be reconfigurable between wide and narrow bands.