SAC-OCDMA

In this paper, we present the impact of the multi-diagonal (MD) code for high data rate in spectral amplitude coding optical code division multiple-access (SAC-OCDMA) networks. An MD code structure for SAC-OCDMA system is presented. The MD code can be flexibly generated for any weight and number of users by using a combination of diagonal matrices. Several advantages of the MD code family are: the cross-correlation value remains zero even in case of an increased number of users for any weight value, supporting large number of users, and easy code construction. Thus, these features show the MD code family be a solution to enhance the data rate of SAC-OCDMA networks. Based on the theoretical and simulation evaluation, MD code is shown to provide a much better performance compared to existing SAC-OCDMA codes. The ability of MD code to support simultaneous transmissions at different high data rate has been successfully established through the simulated results of the 0.24 Tbps (12 Gbps ...

This study investigated end-users personalization potentials and factors contributing to efficient housing occupancy that are embedded in the Housing Occupancy Model (HOM). These factors were sourced through literature review, policy documents along with experts’ opinions till consensus was reached on five factors, which are: personalization, satisfaction, environmental condition, attitude towards occupancy and subjective norm to occupancy. Thereafter, an instrument based on Structural Equation Model (SEM) was designed and administered to a total of 247 respondents. Subsequently, the inter-relationships between and within these factors were tested and fully investigated towards developing a valid HOM. Therefore, the results obtained indicating that the probability (p-value) of Chi-square value is 0.011 for ‘satisfaction’ in the prediction of occupier intention is therefore supported. The value obtained for ‘environmental condition’ in the prediction of occupier intention is 0.242 wh...

In this paper we investigate the use of wavelength multiplexed spectral amplitude coding (WM SAC) codes in beat noise mitigation in coherent source SAC OCDMA systems. A WM SAC code is a low weight SAC code, where the whole code structure is repeated diagonally (once or more) in the wavelength domain to achieve the same cardinality as a higher weight SAC code. Results show that for highly populated networks, the WM SAC codes provide better performance than SAC codes. However, for small number of active users the situation is reversed. Apart from their promising improvement in performance, these codes are more flexible and impose less complexity on the system design than their SAC counterparts.

Smart and sustainable cities require a network that can ensure many exchanges of information. In this sense, the deployment of optical fiber seems essential in order to guarantee urban interconnection. In this work, a new algorithm for the right shift code to be used in optical fiber communication (OFC) is proposed. The algorithm was designed to support different quality of services (audio, video, and data) for smart cities. This algorithm was based on varying the code weight for a certain number of users and transmitting a service to them. This algorithm was used for a spectral amplitude-coding optical code division multiple-access (SAC-OCDMA) system. Two detection scheme approaches were used, which are the single photodiode (SPD) detection technique and the direct detection (DD) technique. The performance was analytically studied for the proposed system in terms of BER, SNR, and the maximum number of users. The obtained results, when our system used SPD, showed an improvement in t...

In this paper, we present a new code design for the Optical Code Division Multiple Access (OCDMA) system based on the Jacobi function. One of the major factors limiting the performance of OCDMA systems is known as Multiple Access Interference (MAI). A good code design provides a minimum cross-correlation, maximum number of users with minimum code length, and implementation flexibility to remove the MAI effectively. The use of finite field arithmetic’s in the construction of our proposed code yield a zero cross-correlation (ZCC) which is the least desired value. Theoretical analysis and simulation results show that the proposed code outperforms the previously reported codes with zero maximum cross-correlation. Thus, the Multiple Access Interference (MAI) and Phase-Induced intensity noise (PIIN) effects are eliminated, improving the system’s performance. The system can accommodate more simultaneous users than other codes at a standard acceptable bit error rate value (≤ 10). Furthermor...

We present the transmission of four users with 5 WDM × 4 TDM × 4 CODE channel at variable data rate for 3D OCDMA system based on Model A using GF (5) with varying receiver attenuation at the front end on OPTSIM simulation software using optical orthogonal codes and cubic congruent operator from algebraic coding theory. The performance of these coding sequences is judged in terms of BER, Signal Strength and Eye Diagrams.

This study utilized C-band carrier frequency to evaluate Spectral Amplitude Coding Optical Code Division Multiple Access (SAC-OCDMA) systems, employing Fiber Bragg Gratings (FBG) as encoders and decoders and implementing the AND subtraction detection technique. The system's performance is influenced by various factors, including optical transmission distance, optical power, channel bandwidth, data rate, and the number of channels. Extensive simulations were conducted to examine the impact of these parameters on system performance. The proposed SAC-OCDMA system was integrated with a Wavelength Division Multiplexing (WDM) system to increase the number of active channels. The network was designed and analyzed using commercially available Optisystem software. The proposed SAC-OCDMA system architecture with two channels maintained operational limits up to unrepeated transmission over 336 km at a data rate of 1.6 Gbit/s, achieving results within the pre-FEC threshold. Additionally, the SAC-OCDMA system was simulated with up to ten channels, considering the pre-FEC bit error rate threshold. The results were compared with recent technical articles and were found to be superior in terms of the number of channels and transmission distance. The proposed model achieved a superior data rate of 6.4 Gbps and a maximum transmission distance of 24 km for a 10-channel architecture.

We describe empirical study findings on the impact of throughput performance when transmission power is adjusted among access points in closed-proximity network devices. The experiment was conducted in an office environment to emulate such wireless LAN network. We introduce a potential energy efficient mechanism based on cognitively learning one of the attributes which then triggers the power selection. We show that similar throughput performance at the client can be obtained at reduced transmission power thus prevent an access point from maximizing power unnecessarily. We have also evaluated the impact of increasing and reducing power to other neighbouring access points. It was found that the improvement of throughput is increased to 44% maximum. Throughput performance alert is introduced in the mechanism to be aware of sudden throughput changes in the system.

The down Link signal travelling from satellite to the earth surface need to pass through the layers of the atmosphere situated at an altitude above the earth surface. While passing through these layers the radio wave undergoes some changes in its characteristics .These fluctuations are observed in the troposphere (0 to 12 km containing nitrogen (78 percent) and oxygen (21 percent), with the remaining 1- percent consisting of argon, (0.9 percent) and traces of hydrogen ozone (a form of oxygen)), very close to earth surface, so they are called as tropospheric scintillations. There are two types of scintillations called amplitude and phase scintillations. In this paper we are concentrating on estimation of trosposheric amplitude scintillation. While considering lower frequencies ( 10GHz) ionosphere acts as a transparent layer, so only tropospheric scintillations are taken into consideration. Tropospheric amplitude scintillation can be defined as rapid fluctuations in the amplitude of t...

This paper presents a design of compact Multiple Input Multiple Output (MIMO) of Planar Inverted F-Antenna (PIFA) involving parameters which may affect the characteristics of PIFA. The proposed antenna consists of two ports with one patches operates at GSM frequencies which is 0.9 GHz and 1.8 GHz. The single antenna is fabricated on an inexpensive FR4 a dielectric constant of ɛ = 4.3, with thickness of substrate that is 1.54 mm and the thickness of patch is 0.035 mm. The simulated result represents that the proposed antenna obtained the reflection coefficient as needed which is at least ≤ -6 dB for single antenna design and also for MIMO configuration of antenna. Simulation by using CST Microwave Studio program and measurement on the final prototype antenna were carried out and compared. A MIMO system characteristic of a two port MIMO antenna is performed.  A two port antenna for mobile applications is designed, the antenna shows good in frequency drop, radiation pattern and reflect...

A new detection technique named AND subtraction which is based on subtraction technique is proposed for a hybrid system of subcarrier multiplexed (SCM) spectral-amplitude-coding optical code division multiple access (SAC-OCDMA) of a point-to-point link. Spectral-amplitudecoding OCDMA is used because of its ability to cancel the multiple access interference (MAI) when code sequences with fixed in-phase cross correlation are used. On the other hand, the SCM scheme is able to enhance the channel data rate of OCDMA systems. This hybrid system is proposed for the purpose of combining the advantages of both techniques. As a result, the hybrid system is robust against interference and is much more spectrally efficient. A new code structure for spectral-amplitudecoding OCDMA system based on double weight (DW) code family is employed. The experimental simulation results of the hybrid system using the new proposed AND subtraction detection technique are compared to the hybrid system using complementary subtraction detection technique. The results show that the hybrid system using the proposed new AND subtraction detection technique improve the system performance significantly.

This paper presents the comparative performance of different detection and coding schemes for spectral-amplitude-coded optical code division multiple access (SAC-OCDMA) system. SAC-OCDMA systems are receiving more attention because of their ability to completely eliminate multiple access interference (MAI). Fiber Bragg grating (FBGs) are used as encoder/decoder. Experimental simulation was carried out using OptiSystem version 5.0 and performance of OCDMA network is characterized through bit error rate (BER) received power and no of filters required for a particular code.

This work introduces a proficient method to build a newly proposed code, named diagonal permutation shifting (DPS) code for the spectral-amplitude-coding (SAC) optical code-division multiple-access (OCDMA) system. The DPS code is derived and constructed from well-known prime codes and certain matrix operations. This proposed code possesses numerous properties such as the cross-correlation (CC) between any two sequences is always equal to 1, short code length and proper design of the transmitterreceiver structure. In particular, the DPS is capable of removing the impact of multiple access interference (MAI) and further alleviate phase-induced intensity noise (PIIN). Numerical results demonstrate noticeable improvement for the DPS compared to the reported codes and can improve system performance considerably.

Due to the large bandwidth offered by the optical fiber, its implementation in local area network (LAN) where the traffic is typically bursty could be considered as the strongest candidates for the future high speed optical networks if coding technique is used. This paper presents a new code family named, diagonal permutation shifting (DPS) for spectral amplitude coding-optical code division multiple access (SAC-OCDMA) systems with fixed in-phase cross correlation (CC) and short code length. DPS code derived from well-known prime codes and some matrix operations. The results reveal that the DPS code acts effectively in removing multiple access interface (MAI) and mitigate phase induced intensity noise (PUN) impact with an adequate signal to interference plus-noise ratio (SINR) and low bit error rate (BER). It has been shown that the DPS code family can suppress intensity noise effectively and improve the system performance significantly.

This work introduces a proficient method to build a newly proposed code, named diagonal permutation shifting (DPS) code for the spectral-amplitude-coding (SAC) optical code-division multiple-access (OCDMA) system. The DPS code is derived and constructed from well-known prime codes and certain matrix operations. This proposed code possesses numerous properties such as the cross-correlation (CC) between any two sequences is always equal to 1, short code length and proper design of the transmitter - receiver structure. In particular, the DPS is capable of removing the impact of multiple access interference (MAI) and further alleviate phase-induced intensity noise (PIIN). Numerical results demonstrate noticeable improvement for the DPS compared to the reported codes and can improve system performance considerably.

We describe empirical study findings on the impact of throughput performance when transmission power is adjusted among access points in closed-proximity network devices. The experiment was conducted in an office environment to emulate such wireless LAN network. We introduce a potential energy efficient mechanism based on cognitively learning one of the attributes which then triggers the power selection. We show that similar throughput performance at the client can be obtained at reduced transmission power thus prevent an access point from maximizing power unnecessarily. We have also evaluated the impact of increasing and reducing power to other neighbouring access points. It was found that the improvement of throughput is increased to 44% maximum. Throughput performance alert is introduced in the mechanism to be aware of sudden throughput changes in the system.

In wireless communication system thermal noise is one of the noise that detected at the receiver. Thermal noise (Johnson Noise) exists in all resistors and results from the thermal agitation of free electrons therein by the temperature.This paper starts with an introduction onhow temperature appears on the receiver and thermal noise on thereceiver. The major contribution factor to thermal noise power and RMS voltage is also discussed analytically. The CDMA modem is used as a subject to study thermal noise in wireless communication system.

One dimensional (1D) spectral amplitude coding-optical code division multiple access (SAC-OCDMA) systems are generally known by a strict limitation in the number of users that can simultaneously connect. A main solution to overcome this drawback consists of constructing a two-dimensional (2D) structure using a new hybrid spectral/spatial code through combining a one dimensional new zero cross correlation code (NZCC) to a one dimensional multi-diagonal code (1D MD) to easily provide null cross-correlation properties and totally remove the multiple access interferences. Accordingly, this research paper describes an easy and fast technique to construct a hybrid two-dimensional NZCC-MD code based on a non diagonal matrix for SAC-OCDMA systems with direct spectral/spatial dimension (SDD) detection technique and water-filling (WF) optimization. The novel code presents many advantages such as less complex structure, acceptable code length as well as the possibility to construct it for any weight value. The proposed code demonstrates a very good performance for systems with high debit and high simultaneous user number keeps a less complex structure.

One dimensional (1D) spectral amplitude coding-optical code division multiple access (SAC-OCDMA) systems are generally known by a strict limitation in the number of users that can simultaneously connect. A main solution to overcome this drawback consists of constructing a two-dimensional (2D) structure using a new hybrid spectral/spatial code through combining a one dimensional new zero cross correlation code (NZCC) to a one dimensional multi-diagonal code (1D MD) to easily provide null cross-correlation properties and totally remove the multiple access interferences. Accordingly, this research paper describes an easy and fast technique to construct a hybrid two-dimensional NZCC-MD code based on a non diagonal matrix for SAC-OCDMA systems with direct spectral/spatial dimension (SDD) detection technique and water-filling (WF) optimization. The novel code presents many advantages such as less complex structure, acceptable code length as well as the possibility to construct it for any weight value. The proposed code demonstrates a very good performance for systems with high debit and high simultaneous user number keeps a less complex structure.

This paper introduces a differential phase shift keying (DPSK) modulation using different detection techniques to design a new hybrid system. The implementation of DPSK modulation technique is to find the optimal solution for optical access network. Modified double weight (MDW) code is proposed as a signature code. MDW code has a better technique to decrease multiple access interference (MAI). MAI is the main cause to degradation the performance of optical CDMA for large number of users. OptiSystem version 12 has been proposed and stimulated fibre length as single-mode fibre (SMF) wavelength of 1550 nm. This system can support large number of users with high bit rate 2.5Gbps where the targeted biterror-rate (BER) is ≤10 -10 .

In this paper, performance analysis of conventional spectral amplitude coding (CSAC) with hybrid (HSAC) for OCDMA system is investigated in local area network (LAN) environment. The CSAC is built based on arithmetic sequence with simple algebraic ways. The HSAC technique is used in which spectral amplitude coding (SAC) combined with wavelength division multiplexing (WDM) to effectively reduce multiple access interference (MAI) and mitigate the influence of phase induced intensity noise (PIIN) arising in photodetecting process. The main idea is to construct the code sequences in SAC domain then repeat it diagonally in the wavelength domain as groups which maintains the same cardinality of a given code weight. Results show that HSAC outperforms CSAC when the number of active users is high due to its better correlation properties. It has been shown that the HSAC can suppress intensity noise effectively and improve the bandwidth utilization significantly up to 4.2 nm.

An optical dynamic spectral encoding code division multiple access ͑CDMA͒ communication system is proposed. In this system, an electrically controlled tunable optical filter ͑TOF͒ is used to encode the modulated broadband light source. The code depends on the function set to the controller. Two-dimensional code, named functional code, is also proposed based on a shifted sine function. The function defines the dynamic coding pattern of the central wavelength of the transmitted narrowband optical signal. Thus, the system will allow for an easy reconfiguration of the transmitter without the need for a sophisticated encoder. At the receiver, a synchronized TOF with the same function is used as a decoder. The system is modeled and analyzed taking into account the multiple access interference, phase-induced intensity noise ͑PIIN͒, and thermal noise. The performance of this system is shown to be better compared with a fast frequency hopping ͑FFH͒ system and a spectral amplitude coding ͑SAC͒ system that uses either a Hadamard code, a modified quadratic congruence ͑MQC͒ code, or a modified frequency hopping ͑MFH͒ code.

The perfect difference codes minimize the Phase Induced Intensity Noise (PIIN) and cancel the multiple access interference. Earlier researchers analyze the performance of OCDMA systems considering three noises namely PIIN, shot and thermal noise for 3D Perfect Difference Codes (PDC) for OCDMA system. In this research paper we have considered two more noises i.e. 1/f and generation recombination noise for 3D PDC based OCDMA system. Mathematical analysis has been done and the performance of the system has been evaluated for higher data rates i.e. 1Gbps to 10Gbps for minimum BER −9 .

This paper presents the comparative performance of different detection and coding schemes for spectral-amplitude-coded optical code division multiple access (SAC-OCDMA) system. SAC-OCDMA systems are receiving more attention because of their ability to completely eliminate multiple access interference (MAI). Fiber Bragg grating (FBGs) are used as encoder/decoder. Experimental simulation was carried out using OptiSystem version 5.0 and performance of OCDMA network is characterized through bit error rate (BER) received power and no of filters required for a particular code.

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...

A new architecture for increasing the number of simultaneous users in a hybrid system and providing a solution for the channel bottleneck problem has been designed and simulated. The 10G-TDM-OCDMA-PON system combines optical code division multiple access (OCDMA) and time-division multiplexed passive optical network (TDM-PON) techniques. The high bit rate TDM-PON system is based on a bit interleaving that uses noncontiguous order for data arranging manner, this system used to obtain ultra-high-speed data rate of 40 Gbps based on four TDM channels of 10 Gbps. The OCDMA system is based on two-dimensional single weight zero cross-correlation (2D-SWZCC) employing polarization and wavelength scheme with two orthogonal polarization angles (vertical and horizontal states). The proposed hybrid system increases the scalability by multiplexing M OCDMA codes in the same time slot of the TDM system that has N time slots. The results show that the proposed system with 2D-SWZCC has better performance with a high number of users and higher scalability than the system with 1D-SWZCC.