Performance enhancement of multiple access 3D-OCDMA networks using a pascal triangle codes (original) (raw)
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2021
In this paper, a novel code named three dimensional single weight zero cross correlation (3D-SWZCC) code has been developed for spectral/time/spatial (S/T/S) encoding in non coherent optical code division multiple access (OCDMA) systems. This novel code is based on one dimensional (1D) and two dimensional (2D) SWZCC code already proposed. According to simulation results, it is really observed that 3D-OCDMA systems employing SWZCC code can resist against both thermal noise and phase induced intensity noise in other words; shot noise can be totally neglected. Mover, the proposed code can improve the system capacity up to 6, 8 and 2.98 times and save the receiver power level to reach − 8.39 dBm and − 1.5 dBm going by from (1D) to (2D) to (3D) respectively as well as this code has outperformed the already existing codes such 3D-perfect difference (3D-PD), 3D-perfect difference/multi diagonal (3D-PD/MD) and 3D-dynamic cyclic shift (3D-DCS/MD) and 3D-MD codes in terms of system's capacity 4.82, 4.13, 3.75 and 1.29 times respectively that satisfies the optical communication networks requirements. In accordance with simulation results, 3D-OCDMA system based on SWZCC code achieves good performance and meets optical communication requirements due to low BER and high Q-factor it provides, equal to 10 −27 and 10 dB respectively for 1 Gbps data rate and a distance of 50 km up to 70 km.
Photonics
In order to solve the problem of one-dimensional code length, two-dimensional code spatial length, phase induced intensity noise PIIN effect, improved system capacity, and increased the number of simultaneous users, a new three-dimensional spectral/time/spatial variable weight zero cross correlation code for non-coherent spectral amplitude coding-optical code division multiple access (3D-VWZCC-SAC-OCDMA) is proposed in this paper. Its construction is based on a one-dimensional (1D) spectral sequence and two-dimensional (2D) temporal/spatial sequences, which are characterized by the property of zero cross correlation ZCC. The simulation results demonstrate that our code proves high immunity against PIIN noise and shot noise, it increases multiplexing ability when the passage is from (1D) and (2D) to (3D) up to 5.112 and 2.248 times, and it saves −7.04 dBm and −5.9 dBm of the receiver power due to simple detection at the receiver; furthermore, the 3D-VWZCC system capacity has outperfo...
2018
This paper introduces a novel code called two dimensional Pascal's triangle zero cross correlation (2D-PTZCC) for spectral/spatial coding with its structure of the corresponding system to implement in spectral amplitude coding optical code division multiple access (SAC-OCDMA) systems The novel code is derived from a one dimensional zero cross correlation (1D-ZCC) code using Pascal's triangle rule. The analytical results prove that the proposed code has totally removed the multiple access interference (MAI), in addition the phase induced intensity noise (PIIN) influence is highly reduced due to the zero cross correlation (ZCC) property. Comparing with the recent developed two-dimensional codes like 2D multi diagonal (2D-MD), 2D dynamic cyclic shift (2D-DCS), 2D diluted perfect difference (2D-DPD) and 2D perfect difference (2D-PD) codes for the same code length. The results of simulation show that the suggested code improve the system capacity and increase the number of simultaneous users reaches 29 % and 64 % comparing to 2D-DPD and 2D-PD codes, respectively. As well, it supplies higher signal power and data bit rates whereas it saves effective source power around −0.81dBm for 2D-DCS and 2D-DPD codes and consumes minor light spectral width. The passage from 1D to 2D ameliorated 1.68 times the system capacity and saved around −4.27dBm the effective power for each user.
Design and analysis of three-dimensional OCDMA code families
Optical Switching and Networking, 2009
A new code design algorithm for application in three-dimensional (3D) optical code division multiple access (OCDMA) for asynchronous optical fiber communication is proposed. 3D refers to space-wavelength-time codes. The performance analysis of the proposed algorithm in 3D multiple pulses per plane (MPP) codes is shown. This design ensures a maximum cross-correlation of '1' between any two codes. The performance metrics that have been investigated are the bit error rate due to multiple access interference (MAI) for different values of the number of simultaneous users and, cardinality for different values of temporal length.
2006
A new code structure for Spectral-Amplitude Coding Optical Code Division Multiple Access (OCDMA) system with zero cross-correlation is been proposed in this paper. In contrary to the existing code, Zero Cross-correlation (ZCC) code provides much better performance of Bit Error Rate (BER) due to non-existence of Phase Induced Intensity (PIIN) noise. The newly proposed code can adapt to any variable number of weight and user without any constraint by using transformation and mapping technique respectively. Thus, we demonstrate in theoretically to compare the performance of ZCC code with the existing codes such as Hadamard, Modified Frequency Hopping (MFH) and Modified Double-Weight (MDW) codes. For typical error rate of optical communication system, 10-9 , it can accommodate 84 users simultaneously. The results indicate that our code is truly performs better than obtained OCDMA codes and applicable to OCDMA network.
Enhanced 3-D OCDMA Code Family using Asymmetric Run Length Constraints
2019 IEEE AFRICON, 2019
This paper suggests an enhanced performance of the 3-D optical code division multiple access (OCDMA) codes, a space/wavelength/time spreading family of codes. The initial codes are in the format wavelength hopping/time sequence (WH/TS), selected according to their performance requirements and the TS sequence is constructed to achieve a linear spacetime complexity. The asymmetric run length constraints are introduced in that regard, such that the positive bit positions align with the encoder/decoder frequency spacing pattern, yielding a 3-D WH/WS/TS. The selected 2-D OCDMA codes are onecoincidence frequency hopping codes (OCFHC) and optical orthogonal codes (OOC). As a time sequence code, the OOC code length is extended with a code rate of 0.04. The complexity and the bit error rate (BER) are herein given and compared with previous work. The results of the performance show not only an improvement in the number of simultaneous users due to the code length extension, but better correlation properties and hence a better signal-to-noise ratio. Index Terms-Optical orthogonal code (OOC), optical code division multiple access (OCDMA), difference of position (DoP), neighbor difference, asymmetric run length constraints.
Performance improvement of multi access OCDMA system based on a new zero cross correlation code
Performance improvement of multi access OCDMA system based on a new zero cross correlation code , 2020
In this paper, a novel zero cross correlation (ZCC) code is proposed for spectral amplitude coding-optical code division multiple access (SAC-OCDMA) systems. The code construction method starts from the identity matrix and has several benefits summarized in both the code simplicity and flexibility. The proposed code presents also an adapted (or accepted) code length for SAC-OCDMA systems and a high SNR value that reaches respectively 3.18 and 1.84 times of the system capacity comparing to other existed codes such as modified quadratic congruence (MQC) and modified double weight (MDW) codes.
Design and performance analysis of code families for multi-dimensional optical CDMA
IET Communications, 2009
A code design algorithm for application in Multi-Dimensional Optical Code Division Multiple Access (MD-OCDMA) for asynchronous optical fibre communication is proposed. Two-dimensional (2-D) wavelength-time or space-time OCDMA and three-dimensional (3-D) space-wavelength-time OCDMA are subsets of MD-OCDMA. Some applications and the performance analysis of the algorithm in 2-D multipulse per row codes and 3-D multipulse per plane codes are shown. In the applications discussed, this design ensures a maximum crosscorrelation of '1' between any two codes. The performance metrics studied are the probability of error due to multiple access interference for different numbers of 1 active users and optimum temporal length for different values of cardinality. The performance analysis shows that the proposed 2-D design offers very low probability of error due to multiple access interference at lower cardinality when compared with other 2-D designs using equivalent code dimension. A comparison of the proposed 3-D design with an existing 3-D design shows better performance at lower cardinality. The 3-D designs show better performance when compared with the 2-D designs. 1 Introduction Optical Code Division Multiple Access (OCDMA) is one of the competing technologies for future multiple access networks along with Wavelength Division Multiple Access and Optical Time Division Multiple Access. The concept of assigning spreading codes to each user in a fibre optic communication network is used in OCDMA. A user transmits an assigned code whenever a '1' is to be transmitted and does not transmit anything whenever a '0' is to be transmitted. The major advantage of OCDMA is asynchronous communication, which considerably reduces optical resources required for timing recovery. Codes for OCDMA systems employing intensity detection have to be unipolar, orthogonal (minimum cross-correlation) and constant weight to obtain low values of probability of error due to Multiple Access Interference (MAI). Hence, a family of codes called Optical Orthogonal Codes (OOCs) [1-3] have been designed. An OOC code family is represented as (T, K, λ a , λ c), where T is the temporal length of the code family, K is the weight of the code family, i.e., the number of ones in each code, λ a is