scholarly journals Resource Allocation in a Cognitive Radio System with Imperfect Channel State Estimation

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Tao Qin ◽  
Cyril Leung ◽  
Chunyan Miao ◽  
Zhiqi Shen
Keyword(s):  
Cognitive Radio ◽  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Negative Impact ◽  
Radio Spectrum ◽  
Estimation Errors ◽  
Radio System ◽  
Channel Estimation Errors ◽  
Channel State Estimation ◽  
Cr System

Cognitive radio (CR) is a promising concept for improving the utilization of scarce radio spectrum resources. Orthogonal frequency division multiplexing (OFDM) is regarded as a technology which is well matched for CR systems. It is shown that channel estimation errors can result in a severe performance degradation in a multiuser OFDM CR system. A simple back-off scheme is proposed, and simulation results are provided which show that the proposed scheme is very effective in mitigating the negative impact of channel estimation errors.

Improved MB Cognitive Radio Spectrum Sensing Using Wavelet Spectrum Filtering

2019 ◽  
Vol 28 (08) ◽  
pp. 1950136
Author(s):  
Ricardo Tadashi Kobayashi ◽  
Aislan Gabriel Hernandes ◽  
Mario Lemes Proença ◽  
Taufik Abrao
Keyword(s):  
Cognitive Radio ◽  
Spectrum Sensing ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Performance ◽  
Signal To Noise Ratio ◽  
Analytical Description ◽  
Radio Spectrum ◽  
Wavelet Spectrum ◽  
Edge Location ◽  
Cr System

In cognitive radio (CR), the sensed aggregate bandwidth could be as large as several GHz. This is especially challenging if the bandwidths and central frequencies of the sensed signals are unknown and need to be estimated. This work discusses a new improved method for MB spectrum sensing (iMB-SS) based on edge detection and using Wavelet Spectrum Filtering. The proposed iMB-SS method uses a Welch power spectrum density (PSD) estimate and a multi-scale Wavelet approach to reveal the spectrum transition (edges), which is deployed to characterize the spectrum occupancy in CR scenarios where the operation frequencies of the primary users (PUs) are unknown. The focus of this work lies in improving the performance of the MB spectrum sensor, particularly by refining the spectral edge location and reducing misleading detection. A comprehensive analytical description and numerical analysis have been carried out by focusing on orthogonal-frequency-division-multiplexing (OFDM) signal applications in CR networks. Numerical results corroborate the effectiveness of the proposed iMB-SS approach. The simulated results for the multiple-PU’s OFDM-based transmission CR system demonstrate that the proposed iMB-SS method can achieve high performance even under low signal-to-noise ratio (SNR) regime, turning it out as an attractive choice for SS in the MB CR systems.

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