scholarly journals THE STUDY OF BIT ERROR RATE EVOLUTION IN A MOBILE COMMUNICATIONS SYSTEM USING DS – CDMA TECHNOLOGY

2017 ◽  
Vol 18 (2) ◽  
Author(s):  
ION POPA
Keyword(s):  
Mobile Communications ◽  
Bit Error Rate ◽  
Error Rate ◽  
Code Division Multiple Access ◽  
Additive White Gaussian Noise ◽  
Direct Sequence ◽  
Access Technology ◽  
M Sequence ◽  
Code Division Multiple ◽  
Communications System

<p>This paper follows the study of bit error rate evolution in a mobile communications system using DS – CDMA (Direct Sequence – Code Division Multiple Access) technology. We have assessed the bit error rate (BER) based on the signal/noise ratio, Eb/N0, and the number of users in the system. For this purpose, we have used M sequence and Orthogonal Gold sequence and the AWGN (Additive white Gaussian noise) transmission medium<strong>.</strong></p>

scholarly journals Bit Error Rate Performance of Spread Spectrum Communication Systems for AWGN Channels

2020 ◽  
Vol 9 (3) ◽  
pp. 277-280
Keyword(s):  
Bit Error Rate ◽  
Error Rate ◽  
Spread Spectrum ◽  
Communication Systems ◽  
Digital Communication ◽  
Additive White Gaussian Noise ◽  
Direct Sequence Spread Spectrum ◽  
Rate Performance ◽  
Direct Sequence ◽  
Spread Spectrum Systems

The digital communication technologies have gained immense significance as it provides secure and error free services. One of the major advantages of digital communication is that they are much resistant to transmitted as well as interpreted errors. For ensuring the security of data, the most suitable method is to use spread spectrum technique. The spread spectrum technique has gained immense popularity for use in various systems as the spreading of the spectral bandwidth offer many advantages, including the establishment of secure communications, increasing resistance to interference, noise rejection, and so on. The signals which are modulated by using these techniques cannot be jammed and are very hard to interfere. This paper presents the results of investigation of BPSK based direct sequence spread spectrum systems for Additive White Gaussian Noise (AWGN) and undersea channels. The bit error rate performance of BPSK based direct sequence spread spectrum systems has been simulated for the AWGN channel and the results have been plotted.

Spectral Efficiency of Phase Encoding OCDMA Systems

2013 ◽  
Vol 760-762 ◽  
pp. 133-136
Author(s):  
Xiao Gang Chen ◽  
Chao Jiang ◽  
Zhao Xu Liu ◽  
De Xiu Huang
Keyword(s):  
Bit Error Rate ◽  
Error Rate ◽  
Spectral Efficiency ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Spectral Phase ◽  
Code Length ◽  
Phase Encoding ◽  
Bandwidth Limitation ◽  
Code Division Multiple

The spectral efficiency and bit-error-rate (BER) of phase encoding optical code division multiple access (OCDMA) systems is evaluated, coherent time-spreading (TS) and spectral phase encoding (SPE) OCDMA systems are considered. The results indicate that SPE-OCDMA has better tolerance to performance degradation due to receivers bandwidth limitation than TS-OCDMA system, while for the practical en/decoders with implementable longest code length, TS-OCDMA can yield a spectral efficiency advantage over SPE-OCDMA systems.

scholarly journals Generalized Receiver with Parallel Interference Cancellation for Multiuser Detection

2021 ◽  
Vol 16 ◽  
pp. 633-654
Author(s):  
Vyacheslav Tuzlukov
Keyword(s):  
Interference Cancellation ◽  
Code Division Multiple Access ◽  
Additive White Gaussian Noise ◽  
Direct Sequence ◽  
Parallel Interference Cancellation ◽  
Two Stage ◽  
Multiuser Detector ◽  
Complete Set ◽  
Optimal Values ◽  
Code Division Multiple

Parallel interference cancellation is considered as a simple yet effective multiuser detector for direct -sequence code-division multiple-access (DS-CDMA) systems. However, system performance be deteriorated due to unreliable interference cancellation in the early stages. Thus, a detector with the partial parallel interfere-nce cancellation in which the partial cancellation factors are introduced to control the interference cancellation level has been developed as a remedy. Although the partial cancellation factors are crucial, complete solutions for their optimal values are not available. In this paper, we consider a two-stage decoupled generalized receiver with the partial parallel interference cancellation. Using the minimum bit error rate (BER) criterion, we derive a complete set of optimal partial cancellation factors. This includes the optimal partial cancellation factors for pe-riodic and aperiodic spreading codes in channels with the additive white Gaussian noise and multipath chann-els. Simulation results demonstrate that the considered theoretical optimal partial cancellation factors agree clo-sely with empirical ones. The proposed two-stage generalized receiver with the partial parallel interference can-cellation using the derived optimal partial cancellation factors outperforms not only a two-stage, but also a three-stage conventional generalized receiver with the full parallel interference cancellation.

scholarly journals Design of Bipolar Optical Code-Division Multiple-Access Techniques Using Phase Modulator for Polarization Coding in Wireless Optical Communication

2021 ◽  
Vol 11 (13) ◽  
pp. 5955
Author(s):  
Eddy Wijanto ◽  
Chun-Ming Huang
Keyword(s):  
Code Division Multiple Access ◽  
Power Efficiency ◽  
Multiple Access ◽  
Additive White Gaussian Noise ◽  
Superior Performance ◽  
Phase Modulator ◽  
M Sequence ◽  
Polarization Coding ◽  
Code Division Multiple ◽  
Hadamard Code

In this study, a bipolar optical code-division multiple-access (Bi-OCDMA) technique based on spectral amplitude coding (SAC) was proposed by using a phase modulator to realize polarization coding through a free-space optical (FSO) channel. Various types of noise, such as amplified spontaneous emission (ASE) noise, thermal noise, and shot noise, were included in the simulation to approach the real application. The first simulation, utilizing a modified M-sequence as signature code, demonstrated that the proposed Bi-OCDMA system could be implemented in FSO communication. The proposed Bi-OCDMA scheme improves the transmission rate and power efficiency compared with the previous scheme. The structure of the proposed system alleviates multiple-access interference (MAI) with a simple and cost-effective design. The second simulation observed the performance of the proposed Bi-OCDMA for two users with several well-known SAC codes, i.e., multi-diagonal (MD) code, modified quadratic congruence (MQC) code, modified maximum length sequence (M-sequence) code, and Walsh–Hadamard code, in extreme weather conditions, both for additive white Gaussian noise (AWGN) and turbulence-induced fading channel. The simulation results indicated that the Walsh–Hadamard code has superior performance compared to other codes. The results show the MD code can be implemented in the proposed Bi-OCDMA scheme for a medium-distance FSO.

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