scholarly journals Analysis of Multiuser Detectors and Performance improvement in DS-CDMA system using Multistage Multiuser Detection Techniques

2021 ◽  
Author(s):  
Ravindrababu Jaladanki ◽  
Krishnarao Ede ◽  
Raja Rao Yasoda
Keyword(s):  
Computational Complexity ◽  
Multiuser Detection ◽  
System Performance ◽  
Interference Cancellation ◽  
Multiple Access ◽  
Signal Amplitude ◽  
Cdma System ◽  
Parallel Interference Cancellation ◽  
Detection Techniques ◽  
Code Division Multiple

Abstract Among the various interferences, the Multiple Access Interference (MAI) is a significant issue in Direct Sequence Code Division Multiple Access (DS-CDMA) system due to its users. When the number of users is increasing the MAI is likewise increments, subsequently the system performance progressively diminishes particularly in fading environment. In this paper, the system performance is improved by the proposed multistage multiuser detection technique called Multistage Multiuser Differencing Partial Parallel Interference Cancellation (DPPIC). This is the combination of Partial Parallel Interference Cancellation (PPIC) and Differencing Parallel Interference Cancellation (DPIC). Multistage Multiuser Parallel Interference Cancellation (PIC) and Multistage Multiuser PPIC techniques that exist gave improved system performance meaning as the number of stages increases the MAI decreases but at the cost of increased computational complexity. The computational complexity was reduced by utilizing Multistage Difference PIC (DPIC) technique but with no improvement in the performance. To improve the system performance as well as reduce the computational complexity Multistage Multiuser Partial Differencing Parallel Interference Cancellation (PDPIC) method can be used. The simulation results show that the proposed DPPIC technique performs better than PIC, PPIC and PDPIC in terms of Bit Error Rate (BER) versus normalized signal amplitude ( i.e., E b / N 0 ), but computational complexity slightly more than PDPIC in fading environment.

2-Dimensional optical CDMA system performance with parallel interference cancellation

2007 ◽  
Vol 31 (4) ◽  
pp. 215-221 ◽  
Author(s):  
Mikaël Morelle ◽  
Claire Goursaud ◽  
Anne Julien-Vergonjanne ◽  
Christelle Aupetit-Berthelemot ◽  
Jean-Pierre Cances ◽  
...  
Keyword(s):  
System Performance ◽  
Interference Cancellation ◽  
Optical Cdma ◽  
Cdma System ◽  
Parallel Interference Cancellation

scholarly journals The Channel Shortening comparison between OFDM & MC-CDMA System over an ADSL Channel using a Water-filling

2019 ◽  
Vol 9 (5) ◽  
pp. 3695
Author(s):  
Bouasria Fatima
Keyword(s):  
System Performance ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Digital Transmission ◽  
Cdma System ◽  
Channel Shortening ◽  
Multiple Paths ◽  
Water Filling ◽  
Cdma Systems ◽  
Code Division Multiple

<p>In this paper our objective focuses on the development of digital transmission techniques in order to solve the problem of Inter-Symbol Interference (ISI) due to multiple paths and the improvement of Multi-Carrier Code Division Multiple Access (MC-CDMA) system performance. The both algorithm: MERRY algorithm (Multicarrier Equalization by Restoration of Redundancy) called TEQ (Time domain EQualizer) and the power allocation method to allocate appropriate power to each user (Water-filling technique (WF)) [1] is used. Finally, the numerical results show that combining Water Filling with TEQ technique allows to reduce the ISI for MC-CDMA systems.</p>

A Review on Successive Interference Cancellation Scheme Based on Optical CDMA Network

2014 ◽  
Vol 35 (4) ◽  
Author(s):  
N. Alsowaidi ◽  
T. Eltaif ◽  
M. R. Mokhtar
Keyword(s):  
Interference Cancellation ◽  
Multiple Access ◽  
Direct Detection ◽  
Multiple Access Interference ◽  
Successive Interference Cancellation ◽  
Optical Cdma ◽  
Spectral Amplitude ◽  
Cdma System ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

AbstractDue to various desirable features of optical code division multiple access (OCDMA), it is believed this technique once developed and commercially available will be an integral part of optical access networks. Optical CDMA system suffers from a problem called multiple access interference (MAI) which limits the number of active users, it occurs when number of active users share the same carriers. The aim of this paper is to review successive interference cancellation (SIC) scheme based on optical CDMA system. The paper also reviews the system performance in presence of shot noise, thermal noise, and phase–induced intensity noise (PIIN). A comprehensive review on the mathematical model of SIC scheme using direct detection (DS) and spectral amplitude coding (SAC) were presented in this article.

Performance Analysis of SAC Optical PPM-CDMA System-Based Interference Rejection Technique

2016 ◽  
Vol 37 (1) ◽  
Author(s):  
N. Alsowaidi ◽  
Tawfig Eltaif ◽  
M. R. Mokhtar
Keyword(s):  
Interference Cancellation ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Multiple Access Interference ◽  
Spectral Amplitude ◽  
Cdma System ◽  
Pulse Position Modulation ◽  
Interference Rejection ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

AbstractIn this paper, we aim to theoretically analyse optical code division multiple access (OCDMA) system that based on successive interference cancellation (SIC) using pulse position modulation (PPM), considering the interference between the users, imperfection cancellation occurred during the cancellation process and receiver noises. Spectral amplitude coding (SAC) scheme is used to suppress the overlapping between the users and reduce the receiver noises effect. The theoretical analysis of the multiple access interference (MAI)-limited performance of this approach indicates the influence of the size of

scholarly journals FPGA Implementation of Block Parallel DF-MPIC Detectors for DS-CDMA Systems in Frequency-Nonselective Channels

2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
Adel Omar Dahmane ◽  
Lotfi Mejri
Keyword(s):  
Interference Cancellation ◽  
Multiple Access ◽  
Multiple Access Interference ◽  
Fpga Implementation ◽  
Decision Feedback ◽  
Practical Implementation ◽  
Parallel Interference Cancellation ◽  
Arithmetic Complexity ◽  
Cdma Systems ◽  
Code Division Multiple

Multistage parallel interference cancellation- (MPIC-) based detectors allow to mitigate multiple-access interference in direct-sequence code-division multiple-access (DS-CDMA) systems. They are considered serious candidates for practical implementation showing a good tradeoff between performance and complexity. Better performance is obtained when decision feedback (DF) is employed. Although MPIC and DF-MPIC have the same arithmetic complexity, DF-MPIC needs much more FPGA resources when compared to MPIC without decision feedback. In this letter, FPGA implementation of block parallel DF-MPIC (BP-DF-MPIC) is proposed allowing better tradeoff between performance and FPGA area occupancy. To reach an uncoded bit-error rate of10−3, BP-DF-MPIC shows a 1.5 dB improvement over the MPIC without decision feedback with only 8% increase in FPGA resources compared to 69% for DF-MPIC.

scholarly journals A Multistage Decision-Feedback Receiver Design for LTE Uplink in Mobile Time-Variant Environments

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Juinn-Horng Deng ◽  
Shu-Min Liao
Keyword(s):  
Frequency Domain ◽  
System Performance ◽  
Interference Cancellation ◽  
Multiple Access ◽  
Decision Feedback ◽  
Block Type ◽  
Frequency Division ◽  
Parallel Interference Cancellation ◽  
Group Frequency ◽  
Lte Uplink

Single-carrier-frequency division multiple access (SC-FDMA) has recently become the preferred uplink transmission scheme in long-term evolution (LTE) systems. Similar to orthogonal frequency division multiple access (OFDMA), SC-FDMA is highly sensitive to frequency offsets caused by oscillator inaccuracies and Doppler spread, which lead to intercarrier interference (ICI). This work proposes a multistage decision-feedback structure to mitigate the ICI effect and enhance system performance in time-variant environments. Based on the block-type pilot arrangement of the LTE uplink type 1 frame structure, the time-domain least squares (TDLS) method and polynomial-based curve-fitting algorithm are employed for channel estimation. Instead of using a conventional equalizer, this work uses a group frequency-domain equalizer (GFDE) to reduce computational complexity. Furthermore, this work utilizes a dual iterative structure of group parallel interference cancellation (GPIC) and frequency-domain group parallel interference cancellation (FPIC) to mitigate the ICI effect. Finally, to optimize system performance, this work applies a novel error-correction scheme. Simulation results demonstrate the bit error rate (BER) performance is markedly superior to that of the conventional full-size receiver based on minimum mean square error (MMSE). This structure performs well and is a flexible choice in mobile environments using the SC-FDMA scheme.

scholarly journals Multiuser Detection and Channel Estimation for CDMA System under Flat Fading Channels

2020 ◽  
Vol 9 (4) ◽  
pp. 2884-2888
Keyword(s):  
Channel Estimation ◽  
Fading Channels ◽  
Multiuser Detection ◽  
Speech Signal ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
State Condition ◽  
Cdma System ◽  
Flat Fading ◽  
Code Division Multiple

For a level blurring code-division multiple access (CDMA), the numerous entrance framework is done by speech signal, and it shows the real framework by different conditions like comprising of state condition, multiplicative commotion condition , the nonlinear estimation condition, and an ideal separating calculation and these are used for joint recursive channel estimation and multi users separation. It ought to be focused on that the new calculation is pertinent to issues with a similar sort of nonlinear framework which shows that related commotions. Recreations process demonstrates that the new calculation performs are superior to the expanded Kalman channel estimation in faster merging rate and lower in bit mistake rate.

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