scholarly journals Pseudorandom Sequences in Spread-Spectrum Communications Generated by Cellular Automata

2012 ◽  
Vol 10 (5) ◽  
Author(s):  
F.C. Ordaz-Salazar ◽  
J.S. González-Salas ◽  
E. Campos-Cantón ◽  
H.C. Rosu
Keyword(s):  
Cellular Automata ◽  
Spread Spectrum ◽  
Communication Systems ◽  
Signal To Noise Ratio ◽  
Pseudorandom Sequence ◽  
Pseudorandom Sequences ◽  
Information Signal ◽  
Shift Keying ◽  
Golden Code ◽  
Digital Communication Systems

Dynamical systems methods have been recently used in spread-spectrum digital communication systems. Theexpansion of the spectrum using a pseudorandom sequence with a higher frequency than the information signal is thekey feature for its robustness against the signal traveling interference through the channel. In this work, we propose togenerate pseudorandom sequences by employing cellular automata and we check these sequences have thenecessary properties which are required in modern communication systems. The computed sequences obtained bythe cellular automata are tested in a quadrature phase shift keying (QPSK) spread-spectrum communication system.The efficiency of the system is analyzed by computing the bit error rate under different signal to noise ratio conditions.These results are compared with systems that employ Golden code and other typical pseudorandom sequences.

scholarly journals An enhanced correlation identification algorithm and its application on spread spectrum induced polarization data

2021 ◽  
Vol 28 (2) ◽  
pp. 247-256
Author(s):  
Siming He ◽  
Jian Guan ◽  
Xiu Ji ◽  
Hang Xu ◽  
Yi Wang
Keyword(s):  
Data Processing ◽  
Spread Spectrum ◽  
Background Noise ◽  
Signal To Noise Ratio ◽  
Induced Polarization ◽  
High Resistivity ◽  
Observation System ◽  
Pseudorandom Sequence ◽  
Identification Algorithm ◽  
The Time Domain

Abstract. In spread spectrum induced polarization (SSIP) data processing, attenuation of background noise from the observed data is the essential step that improves the signal-to-noise ratio (SNR) of SSIP data. The time-domain spectral induced polarization based on pseudorandom sequence (TSIP) algorithm has been proposed to improve the SNR of these data. However, signal processing in background noise is still a challenging problem. We propose an enhanced correlation identification (ECI) algorithm to attenuate the background noise. In this algorithm, the cross-correlation matching method is helpful for the extraction of useful components of the raw SSIP data and suppression of background noise. Then the frequency-domain IP (FDIP) method is used for extracting the frequency response of the observation system. Experiments on both synthetic and real SSIP data show that the ECI algorithm will not only suppress the background noise but also better preserve the valid information of the raw SSIP data to display the actual location and shape of adjacent high-resistivity anomalies, which can improve subsequent steps in SSIP data processing and imaging.

A Beamformer Employing Pseudo-Interference Technique for Digital Communication Systems

2011 ◽  
Vol 403-408 ◽  
pp. 1214-1217
Author(s):  
Yi Chu ◽  
Wei Yau Horng
Keyword(s):  
Communication Systems ◽  
Superior Performance ◽  
Adaptive Array ◽  
Phase Shift Keying ◽  
Excellent Performance ◽  
Shift Keying ◽  
Gain Errors ◽  
Binary Phase Shift Keying ◽  
Digital Communication Systems ◽  
Array Gain

This paper presents a new receiver for antenna array to provide robustness against adaptive array imperfections. These imperfections include the array gain errors and the directional mismatch. The superior performance of the proposed receiver is primarily achieved by adding an injected pseudo-interference in the diagonally loaded Capon beamformer. Simulation results demonstrate that the proposed method has excellent performance for both binary phase shift keying (BPSK) and quadrature amplitude modulation (QAM) systems.

scholarly journals RESEARCH OF CHARACTERISTICS OF NOISE IMMUNITY WITH USE OF ORTHOGONAL CODING

2018 ◽  
pp. 80-85 ◽  
Author(s):  
A. V. Rabin ◽  
M. A. Dobroselskij ◽  
V. A. Lipatnikov
Keyword(s):  
Fading Channels ◽  
Communication Systems ◽  
Signal To Noise Ratio ◽  
Additive White Gaussian Noise ◽  
Digital Signals ◽  
Coding Gain ◽  
Convolutional Coding ◽  
Orthogonal Codes ◽  
Effective Use ◽  
Digital Communication Systems

In the digital communication systems for noise immunity's increase with the fixed code rate it is proposed to use an additional orthogonal coding developed by the authors. It is an analogue of convolutional coding over the rational numbers' field. Transmission of digital signals in Additive white Gaussian noise (AWGN) channel and fading channels is considered including a joint use of the orthogonal and correcting codes (block and convolutional). It is shown that losses in signal-to-noise ratio can be significantly reduced by use of orthogonal coding. By increase of matrices' order, on which basis orthogonal codes are constructed, the coding gain grows also. By use of the proposed by the authors orthogonal coding the required quality of communication is implemented with a smaller energy cost. The significant coding gain (up to 6,4 dB in the channels with the AWGN, up to 22,74 dB in the fading channels) provided by more effective use of energy of transmitted signals is reached without increase in complexity and cost of transmitting/receiving devices.

Improved Whale Optimized MLP Neural Network-Based Learning Mechanism for Multiuser Detection in MIMO Communication System

2020 ◽  
Vol 29 (15) ◽  
pp. 2050239
Author(s):  
R. Umamaheswari ◽  
M. Ramya Princess ◽  
P. Nirmal Kumar
Keyword(s):  
Neural Network ◽  
Spread Spectrum ◽  
Signal To Noise Ratio ◽  
Signal Transmission ◽  
Digital Signal ◽  
Learning Mechanism ◽  
Whale Optimization ◽  
Shift Keying ◽  
User Data ◽  
Code Division Multiple

Direct-Sequence Code Division Multiple Access (DS-CDMA) is a digital method to spread spectrum modulation for digital signal transmission. We propose to detect signal in DS-CDMA communication using the learning mechanism. Initially, the user signals are spread using the respective pseudo-noise (PN) code where the input signal is multiplied with the code which is then modulated using the quadrature phase shift keying (QPSK) modulator. The modulated signal is then transmitted in a 3G/4G channel considering all types of fading. The transmitted signal is received by the antenna array which is performed by demodulation. We propose to adaptively assign the weights by employing Improved Whale Optimized Multi-Layer Perceptron Neural Network (IWMLP-NN)-based learning mechanism. To design IWMLP-NN, Improved Whale Optimization Algorithm is combined with multilayer perceptron neural network. This is used instead of the normal Multiple Signal Classification (MUSIC) and least mean squares (LMS)/root-mean-square (RMS) algorithms used in beam-forming networks. After assigning weight through IWMLP-NN-based learning mechanism, we de-spread to get the original user data. We have compared our proposed technique with the normal techniques with the help of plots of Bit Error Rate (BER) versus Signal-to-Noise Ratio (SNR). We use both the AWGN channel and fading channel for analysis. Experimental results prove that our proposed method achieves better BER performance results even with deep fading.

Orthogonal Complex Quadrature Phase Shift Keying (OCQPSK) Spreading for 3G W-CDMA Systems

2011 ◽  
pp. 158-172
Author(s):  
S. Mishra
Keyword(s):  
Phase Shift ◽  
Spread Spectrum ◽  
Communication Systems ◽  
Multiple Channels ◽  
Phase Shift Keying ◽  
Reverse Link ◽  
Quadrature Phase Shift Keying ◽  
Quadrature Phase ◽  
Shift Keying ◽  
Spread Spectrum Systems

A variety of digital modulation techniques are currently being used in wireless communication systems. In 3G (third generation) spread-spectrum systems, such as W-CDMA (3GPP) and cdma2000 (3GPP2), the handset can transmit multiple channels at different amplitude levels. Modulation schemes such as OQPSK or GMSK do not prevent zero-crossings for multiple channels and are no longer suitable. There is a need for a modulation format or a spreading technique that can accommodate multiple channels at different power levels while producing signals with low peak-to-average power ratios. OCQPSK (Orthogonal Complex Quadrature Phase Shift Keying) has been proposed as the spreading technique for W-CDMA and cdma2000. OCQPSK is a complex spreading scheme that is very different from the modulation formats commonly used until now. The objective of this Chapter is to provide an overview of OCQPSK and explain how to start making modulation quality measurements on the reverse link (uplink) of 3G spread-spectrum systems. This chapter starts with the basic structure of the reverse link (uplink) for W-CDMA and cdma2000 with no scrambling, and explains the transition through complex scrambling to OCQPSK. The block diagrams shown are generic block diagrams for OCQPSK that are not particular to either W-CDMA or cdma2000. The chapter then describes: (1) why complex scrambling is used and how it works, and (2) why OCQPSK is used and how it works. Finally, this chapter provides how to measure modulation quality on the reverse link of 3G systems and a complete downlink physical layer model showing various results of BER and BLER calculation and also various time scopes and power spectrums.

Digital Bandpass Modulation Methods

2021 ◽  
pp. 215-304
Author(s):  
Stevan Berber
Keyword(s):  
Communication Systems ◽  
Orthonormal Basis ◽  
System Structure ◽  
Special Cases ◽  
Frequency Domains ◽  
Shift Keying ◽  
Modulation Methods ◽  
Power And Energy ◽  
Digital Communication Systems ◽  
Generic System

This chapter presents mathematical models of baseband and bandpass digital communication systems based on binary and quaternary phase-shift keying, frequency-shift keying, and quadrature amplitude modulation. The systems are deduced as special cases from the general generic system structure and the related theory of orthonormal basis functions. The systems are uniquely presented using mathematical operators and detailed derivatives for signals in time and frequency domains at the system’s vital points, that is, the transmitter, the receiver, and the noise generator, using the concepts of both stochastic (continuous and discrete) and deterministic (continuous and discrete) signal processing. The vital characteristics of the system and its blocks are expressed in terms of amplitude spectral density, autocorrelation functions, power and energy spectral densities, and bit error probability.

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