Communication
Bushra T. Hashim; Hadi T. Ziboon; Sinan M. Abdulsatar
Abstract
A new technique called cognitive radio seeks to utilize the available spectrum.. Spectrum sensing is the fundamental cognitive radio component. There are many types of sensing spectrums, one of which is The Two Thresholds Based on Covariance Absolute Values (TTCAV) method. This method's confused region, ...
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A new technique called cognitive radio seeks to utilize the available spectrum.. Spectrum sensing is the fundamental cognitive radio component. There are many types of sensing spectrums, one of which is The Two Thresholds Based on Covariance Absolute Values (TTCAV) method. This method's confused region, which is unsure whether it is a signal or noise, is one of its drawbacks. To solve this problem proposed two techniques, a 2-bit quantization technique and a 3-bit quantization technique. Both techniques use an adaptive threshold. The experimental results conducted using python version 3.7 and Jetson Nano kit show an improvement in the detection probability values after using the techniques. where the value of 𝑷𝒅= 80.2% for a 2-bit technique, 𝑷𝒅=90.3% for a 3-bit quantization technique,at SNR=-20 under smoothing factor L=3. The Monte Carlo was used to determine the effectiveness of the proposed techniques, and Binary Phase Shift Keying modulation BPSK. According to the experiment, the results after using the proposed techniques are better than before.
Communication
Samir M. Hameed; Sinan M. Abdulsatar; Atheer Alaa Sabri
Abstract
Researchers have extensively utilized optical orthogonal frequency division multiplexing (O-OFDM) in visible light communication (VLC) to achieve high data rate transmission for free spectrum bandwidth. The peak-to-average power ratio (PAPR) is the critical challenge for VLC systems-based O-OFDM that ...
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Researchers have extensively utilized optical orthogonal frequency division multiplexing (O-OFDM) in visible light communication (VLC) to achieve high data rate transmission for free spectrum bandwidth. The peak-to-average power ratio (PAPR) is the critical challenge for VLC systems-based O-OFDM that produces non-linearity and degrades performance. In this paper, a proposed model for PAPR reduction can be applied with different O-OFDM technologies. This model considered using -law companding with O-OFDM transmitter to compress high amplitude peaks and restore the signals using de-companding in the receiver. The obtained simulation results show an efficient achievement of about 75% PAPR reduction compared with the original O- OFDM for different techniques. Furthermore, The convolutional encoder with Viterbi decoder is used with our proposed model for improvement BER performance and tradeoff with PAPR. The BER performance for different coding schemes, O-OFDM technologies, and modulation orders has been graphed and compared. It can notice the convolutional encoder/Viterbi satisfies better BER than Hamming coding/decoding. However, the number of memory cells of the convolutional encoder plays an essential role in BER improvement.
