scholarly journals WON-OCDMA System Based on MW-ZCC Codes for Applications in Optical Wireless Sensor Networks

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 539
Author(s):  
Saleh Seyedzadeh ◽  
Andrew Agapiou ◽  
Majid Moghaddasi ◽  
Milan Dado ◽  
Ivan Glesk
Keyword(s):  
Optical Networks ◽  
Video Surveillance ◽  
Multiple Access ◽  
Optical Sensing ◽  
Multiple Access Interference ◽  
Service Differentiation ◽  
Sensor Data ◽  
Variable Weight ◽  
Code Division Multiple ◽  
The Impact

The growing demand for extensive and reliable structural health monitoring resulted in the development of advanced optical sensing systems (OSS) that in conjunction with wireless optical networks (WON) are capable of extending the reach of optical sensing to places where fibre provision is not feasible. To support this effort, the paper proposes a new type of a variable weight code called multiweight zero cross-correlation (MW-ZCC) code for its application in wireless optical networks based optical code division multiple access (WON-OCDMA). The code provides improved quality of service (QoS) and better support for simultaneous transmission of video surveillance, comms and sensor data by reducing the impact of multiple access interference (MAI). The MW-ZCC code’s power of two code-weight properties provide enhanced support for the needed service differentiation provisioning. The performance of this novel code has been studied by simulations. This investigation revealed that for a minimum allowable bit error rate of 10−3, 10−9 and 10−12 when supporting triple-play services (sensing, datacomms and video surveillance, respectively), the proposed WON-OCDMA using MW-ZCC codes could support up to 32 simultaneous services over transmission distances up to 32 km in the presence of moderate atmospheric turbulence.

Blind Multiuser Receivers for Chaos Based Communications

2003 ◽  
Vol 13 (08) ◽  
pp. 2353-2359 ◽  
Author(s):  
Francisco Argüello ◽  
Manuel Bugallo ◽  
Juan López
Keyword(s):  
Communication Systems ◽  
Multiple Access ◽  
Good Deal ◽  
Multiple Access Interference ◽  
Detection Techniques ◽  
Multiuser Receivers ◽  
Cdma Systems ◽  
Blind Receivers ◽  
Code Division Multiple ◽  
The Impact

Recently, there has been a good deal of interest in the use of chaotic signals for direct sequence code division multiple access (DS-CDMA) communication systems. The capacity of DS-CDMA systems is interference-limited, and can therefore be increased by techniques that suppress interference. This letter is devoted to the evaluation of the impact of blind multiuser detection techniques on chaos based DS-CDMA systems. Blind receivers can suppress multiple access interference and do not require knowledge of the code sequences and propagation channels of the interference. We demonstrate that, for chaotic sequence-based communications, blind multiuser receivers significantly improve the BER with respect to single-user receivers, and that their use is practically essential with a high number of users.

A Review on Successive Interference Cancellation-Based Optical PPM-CDMA Signaling

2017 ◽  
Vol 38 (1) ◽  
Author(s):  
Naif Alsowaidi ◽  
Tawfig Eltaif ◽  
Mohd Ridzuan Mokhtar
Keyword(s):  
Interference Cancellation ◽  
Multiple Access ◽  
Multiple Access Interference ◽  
Successive Interference Cancellation ◽  
Optical Cdma ◽  
Quadratic Congruence ◽  
Random Location ◽  
High Intensity Signal ◽  
Code Division Multiple ◽  
The Impact

AbstractThis paper presents a comprehensive review of successive interference cancellation (SIC) scheme using pulse position modulation (PPM) for optical code division multiple access (OCDMA) systems. SIC scheme focuses on high-intensity signal, which will be selected after all users were detected, and then it will be subtracted from the overall received signal, hence, generating a new received signal. This process continues till all users eliminated one by one have been detected. It is shown that the random location of the sequences due to PPM encoding can reduce the probability of concentrated buildup of the pulse overlap in any one-slot time, and support SIC to easily remove the effect of the strongest signal at each stage of the cancellation process. The system bit error rate (BER) performance with modified quadratic congruence (MQC) codes used as signature sequence has been investigated. A detailed theoretical analysis of proposed system taking into account the impact of imperfect interference cancellation, the loss produced from the splitting during encoding and decoding, the channel loss and multiple access interference is presented. Results show that under average effective power constraint optical CDMA system using SIC scheme with

scholarly journals Computationally Efficient Chaotic Spreading Sequence Selection for Asynchronous DS-CDMA

2017 ◽  
Vol 13 (1) ◽  
pp. 75-80
Author(s):  
Anna Litviņenko ◽  
Artūrs Āboltiņš
Keyword(s):  
Multiple Access ◽  
Cross Correlation ◽  
Search Algorithm ◽  
Multiple Access Interference ◽  
Sequence Length ◽  
Spreading Sequence ◽  
Chaotic Sequences ◽  
Code Division Multiple ◽  
The Impact ◽  
Spreading Sequences

Abstract The choice of the spreading sequence for asynchronous direct-sequence code-division multiple-access (DS-CDMA) systems plays a crucial role for the mitigation of multiple-access interference. Considering the rich dynamics of chaotic sequences, their use for spreading allows overcoming the limitations of the classical spreading sequences. However, to ensure low cross-correlation between the sequences, careful selection must be performed. This paper presents a novel exhaustive search algorithm, which allows finding sets of chaotic spreading sequences of required length with a particularly low mutual cross-correlation. The efficiency of the search is verified by simulations, which show a significant advantage compared to non-selected chaotic sequences. Moreover, the impact of sequence length on the efficiency of the selection is studied.

A Novel Technique to Detect Code for SAC-OCDMA System

2018 ◽  
Vol 39 (2) ◽  
pp. 215-221 ◽  
Author(s):  
Manisha Bharti ◽  
Manoj Kumar ◽  
Ajay K. Sharma
Keyword(s):  
Multiple Access ◽  
Optical Power ◽  
Multiple Access Interference ◽  
Spectral Amplitude ◽  
Main Task ◽  
Received Power ◽  
Performance Deterioration ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple ◽  
Detection Schemes

AbstractThe main task of optical code division multiple access (OCDMA) system is the detection of code used by a user in presence of multiple access interference (MAI). In this paper, new method of detection known as XOR subtraction detection for spectral amplitude coding OCDMA (SAC-OCDMA) based on double weight codes has been proposed and presented. As MAI is the main source of performance deterioration in OCDMA system, therefore, SAC technique is used in this paper to eliminate the effect of MAI up to a large extent. A comparative analysis is then made between the proposed scheme and other conventional detection schemes used like complimentary subtraction detection, AND subtraction detection and NAND subtraction detection. The system performance is characterized by Q-factor, BER and received optical power (ROP) with respect to input laser power and fiber length. The theoretical and simulation investigations reveal that the proposed detection technique provides better quality factor, security and received power in comparison to other conventional techniques. The wide opening of eye in case of proposed technique also proves its robustness.

Performance Analysis of Spectral Amplitude Coding Optical Code Division Multiple Access System using Modified Double Weight Codes with Adomian Decomposition Method

2018 ◽  
Vol 39 (4) ◽  
pp. 459-462 ◽  
Author(s):  
Monika Rani ◽  
Harbax Singh Bhatti ◽  
Vikramjeet Singh
Keyword(s):  
Code Division Multiple Access ◽  
Multiple Access ◽  
Decomposition Method ◽  
Adomian Decomposition Method ◽  
Multiple Access Interference ◽  
Spectral Amplitude ◽  
Adomian Decomposition ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple ◽  
Multiple Access System

Abstract In this manuscript, we have analyzed a Spectral Amplitude Coding-Optical Code Division Multiple Access (SAC-OCDMA) System. The system performance is enhanced by reducing the effect of Multiple Access Interference (MAI) using uniform Fiber Bragg Gratings (FBGs) encoders and decoders at central office and subscriber’s end. The results are verified through a mathematical model and Modified Double Weight (MDW) codes for the proposed system using Adomian Decomposition Method (ADM). Further, we have demonstrated SAC-OCDMA system for transmission of 40 Gbps data rate up to a distance of 80 km by increasing the number of FBGs. The proposed system has been analyzed in terms of distance, bit error rate (BER) and Quality Factor.

scholarly journals Incremental gradient algorithm for multiuser detection in multi-carrier DS-CDMA system under modulation schemes

2018 ◽  
Vol 7 (2.6) ◽  
pp. 311
Author(s):  
Sumitra N. Motade ◽  
Anju V. Kulkarni
Keyword(s):  
Spread Spectrum ◽  
Multiple Access ◽  
Minimum Mean Square Error ◽  
Multiple Access Interference ◽  
Gradient Algorithm ◽  
Channel Noise ◽  
Cdma System ◽  
Communication Performance ◽  
Optimum Performance ◽  
Code Division Multiple

Nowadays, Multicarrier Direct sequence code division multiple access (MC DS-CDMA) systems are used in mobile communication. Performance of these systems are limited by multiple access interference (MAI) created by spread-spectrum users in the channel as well as background channel noise. This paper proposes an incremental gradient descent (IGD) multi-user detection (MUD) for MC DS-CDMA system that can achieve near-optimum performance while the number of users is linear in its implementation complexity.  The IGD algorithm make an effort to perform optimum MUD by updating one user's bit decision each iteration in the best way. This algorithm accelerates the gradient algorithm convergence by averaging. When a minimum mean square error (MMSE) MUD is employed to initialize the proposed algorithm, in all cases tested the gradient search converges to a solution with optimum performance. Further, the iterative tests denote that the proposed IGD algorithm provides significant performance for cases where other suboptimum algorithms perform poorly. Simulation compares the proposed IGD algorithm with the conventional detectors. 

Performance Analysis of 2-D Prime Codes Encoded Optical CDMA System

2019 ◽  
Vol 40 (4) ◽  
pp. 463-472
Author(s):  
Ankita Rani ◽  
Deepak Kedia
Keyword(s):  
Multiple Access ◽  
Electrical Power ◽  
Multiple Access Interference ◽  
Optical Cdma ◽  
Wavelength Division ◽  
High Data ◽  
Construction Methods ◽  
Data Rates ◽  
Improved Performance ◽  
Code Division Multiple

Abstract Optical code division multiple access (OCDMA) system provides highly secured transmission in addition to its capabilities to support asynchronous transmission and soft blocking. Two-dimensional OCDMA codes are chosen in this paper due to their high cardinality, good spectral efficiency and flexibility in their construction methods against direct sequence codes. This paper focuses on study of impact of multiple access interference (MAI) at high data rates for 2-D prime codesbased OCDMA system. It is shown that how the change in number of simultaneous users affects the transmission quality. Further, performance of the system is analysed in terms of bit error rate, received electrical power and eye openings. In addition, this paper also shows a comparative analysis of 2-D codes-based OCDMA system and wavelength division multiple access (WDMA) system in order to justify the improved performance of the proposed system. It is observed that the performance of 2-D OCDMA system is much better than WDMA system in terms of quality as well as security.

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