Cognitive Radio Concept and Challenges in Dynamic Spectrum Access for the Future Generation Wireless Communication Systems

2011 ◽  
Vol 59 (3) ◽  
pp. 525-535 ◽  
Author(s):  
Sanjay Kumar ◽  
Janardan Sahay ◽  
Gajendra Kant Mishra ◽  
Sanjeet Kumar
Keyword(s):  
Cognitive Radio ◽  
Wireless Communication ◽  
Communication Systems ◽  
Dynamic Spectrum Access ◽  
Future Generation ◽  
Dynamic Spectrum ◽  
Wireless Communication Systems ◽  
Spectrum Access ◽  
The Future

scholarly journals Architecture and Implementation of Fading Compensation for Dynamic Spectrum Access Wireless Communication Systems

VLSI Design ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-9
Author(s):  
Masahide Hatanaka ◽  
Toru Homemoto ◽  
Takao Onoye
Keyword(s):  
Wireless Communication ◽  
Communication Systems ◽  
Orthogonal Frequency Division Multiplexing ◽  
Dynamic Spectrum Access ◽  
Dynamic Spectrum ◽  
Wireless Communication Systems ◽  
Clock Frequency ◽  
Spectrum Access ◽  
Ofdm Symbol ◽  
Piecewise Linear Interpolation

This paper proposes an efficient architecture and implementation of fading compensation dedicated to dynamic spectrum access (DSA) wireless communication. Since pilot subcarrier arrangements are adaptively determined in wireless communication systems with DSA, the proposed architecture employs piecewise linear interpolation to the channel response estimation for data subcarriers in order to increase the channel estimation accuracy. The fading compensation for an orthogonal frequency-division multiplexing (OFDM) symbol is performed within the time for one OFDM symbol to make increase of latency smaller. The proposed architecture guarantees real-time processing with 76 MHz or higher clock frequency. The FPGA implementation of the proposed architecture occupies 1,577 slices and works up to 121 MHz.

scholarly journals Design of Wavelet-Encoded Symbol Constellations for Cyclostationary Spectrum Sensing

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Pedro Thiago Valério de Souza ◽  
Vinícius Samuel Valério de Souza ◽  
Luiz Felipe de Queiroz Silveira
Keyword(s):  
Cognitive Radio ◽  
Communication Systems ◽  
Dynamic Spectrum Access ◽  
Dynamic Spectrum ◽  
Optimization Approach ◽  
Time Varying ◽  
Spectrum Access ◽  
Wavelet Coding ◽  
Cognitive Radio Systems ◽  
Radio Systems

In mobile communication systems, the signals propagate through multipath over time-varying channels, which are subject to distortion caused by fading and Doppler shifts. In order to minimize such distortions, coding techniques and transmission diversity can be employed, e.g., wavelet coding. In this work, the wavelet coding is investigated in scenarios of cognitive radio systems with dynamic spectrum access. Cognitive radio systems with dynamic spectrum access should be able to sense unoccupied frequency bands for opportunistic transmissions, as well as detect the presence of primary users when they occupy their licensed spectrum. Therefore, an essential element for the accurate operation of cognitive radio systems encoded by wavelet coding is the ability to sense the signals encoded by this technique. It is effectively demonstrated that the possibility of sensing such signals is associated with a suitable design of the signal constellation used in the modulation of the coded symbols. The constellation design of these is performed via genetic algorithms using a multiobjective optimization approach. The developed system is evaluated according to the robustness to time-varying flat fading through a bit error probability (BER) versus Eb/N0 analysis. The spectral sensing ability is also addressed employing the cyclostationary analysis. The results denote the feasibility of using wavelet coding in radio scenarios with dynamic spectrum access, with good performance in terms of BER and signal detection rates.

Cognitive Radio Networks

2016 ◽  
pp. 131-159 ◽  
Author(s):  
Deepti Singhal ◽  
Chandan Pradhan ◽  
Kunal Sankhe ◽  
Rama Murthy Garimella
Keyword(s):  
Cognitive Radio ◽  
Cognitive Radio Networks ◽  
Communication Systems ◽  
Dynamic Spectrum Access ◽  
Radio Networks ◽  
Dynamic Spectrum ◽  
Point Of View ◽  
Spectrum Access ◽  
Radio Communication ◽  
Increasing Demand

The ever increasing demand for communication bandwidth has led to spectrum scarcity. We need to manage spectrum as a scare resource. Better utilization of spectrum is the key requirement for the radio communication systems. The inefficient usage of the existing spectrum can be improved through opportunistic access to the licensed bands without interfering with the primary users. This introduces the concept of dynamic spectrum access. Cognitive radio is must for providing quality of service in dynamic spectrum access. To deal with the cognition at physical layer, upper layers are also modified to support cognition and adaptation which make a network cognitive network. This book chapter describes the technical challenges and approaches for cognitive radio networks. Spectrum access models from regulatory point of view are presented. It also explains the challenges and solutions from literature for physical, MAC and network layer of cognitive networks. In the end of the chapter, real hope for designing protocols for such networks, i.e. cross layer protocol design is discussed.

Orthogonal codes-based dynamic spectrum access in cognitive radio networks

2019 ◽  
Vol 16 (12) ◽  
pp. 34-46
Author(s):  
Ehab F. Badran ◽  
Amr A. Bashir ◽  
Amira I. Zaki ◽  
Waleed K. Badawi
Keyword(s):  
Cognitive Radio ◽  
Cognitive Radio Networks ◽  
Dynamic Spectrum Access ◽  
Radio Networks ◽  
Dynamic Spectrum ◽  
Spectrum Access ◽  
Orthogonal Codes

Geometric water-filling and radio resource management

2021 ◽  
Author(s):  
Zhiming He
Keyword(s):  
Cognitive Radio ◽  
Resource Management ◽  
Wireless Communication ◽  
Communication Systems ◽  
Optimization Problems ◽  
Radio Resource Management ◽  
Throughput Maximization ◽  
Wireless Communication Systems ◽  
Radio Resource ◽  
Water Filling

This thesis considers the radio resource management (RRM) of advanced wireless communication systems. With the emerging of more advanced and more complicated systems, such as cognitive radio, nodes with energy harvesting capacities (green communications), and the application of Multiple-Input Multiple-Output (MIMO) technology, RRM problems introduce more difficulties and challenges to optimize system performances. Due to specific structure of communication systems, water-filling (WF) plays an important role in RRM. This thesis introduces the fundamental theory and development of WF algorithm. The proposed Geometric Water-Filling (GWF) is presented and compared with the conventional WF algorithms. It can break through the limitations of the conventional WF to solve the more complicated optimization problems in the advanced wireless communication systems. For the application of the proposed GWF to solve the RRM problems in the advanced MIMO communication systems, cognitive radio communication systems, green communication systems and the “dual problems”, which are the sum power minimization problems, of the throughput maximization problems is investigated in this thesis. Efficient algorithms are presented to achieve the optimal resource allocation.

scholarly journals Spectrum Sensing Based on Nonparametric Autocorrelation in Wireless Communication Systems under Alpha Stable Noise

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Riqing Chen ◽  
Jun Wang ◽  
Ruiquan Lin ◽  
Xiangning Zhao
Keyword(s):  
Information Systems ◽  
Cognitive Radio ◽  
Wireless Communication ◽  
Spectrum Sensing ◽  
Communication Systems ◽  
Impulsive Noise ◽  
Wireless Communication Systems ◽  
Core Technology ◽  
Key Steps ◽  
Stable Noise

Cognitive radio is regarded as a core technology to support wireless information systems. Spectrum sensing is one of the key steps to achieve cognitive radio technology. To address this problem in the presence of Alpha stable noise in wireless communication systems, we propose a nonparametric autocorrelation method, which takes advantages of the characteristics of signal autocorrelation and noise nonstationarity. The autocorrelated signal is distinguished from Alpha stable noise. As a result, the proposed method is immune from noise uncertainty. Simulation results show the validity of the proposed method under Alpha stable noise, for example, impulsive noise in wireless information systems.

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