Search

This paper considers the combination of two promising technologies: Spatial Modulation (SM) and Non-Orthogonal Multiple Access (NOMA). In contrast to the conventional Multi-Radio Frequency (M-RF) NOMA-SM model, we propose a generalized Single-Radio Frequency (S-RF) model. This model splits each NOMA user data between the spatial bits and modulation bits in a flexible manner. Hence, the S-RF models in the literature are special cases of our proposed model. Besides, our model preserves the energy efficiency property of SM and strikes a compromise between the M-RF and existing S-RF models in terms of Spectrum Efficiency (SE). The SE of the proposed model is evaluated through mutual information analysis with Monte Carlo integration. Moreover, we propose a fair power allocation algorithm based on Equal Signal to Interference plus Noise Ratio (ESINR) for the NOMA-SM users. Besides, we evaluate the Bit Error Rate (BER) performance of the M-RF and S-RF NOMA-SM models and show considerable advantages of the proposed S-RF system.

This article proposes an N-finite Radon transform (N-FRAT) and a discrete framelet transform (FT) for the design of a new orthogonal frequency division multiplexing (OFDM) system. In the proposed system, the inverse FT (IFT) and FT were used instead of the inverse fast Fourier transform (IFFT) and fast Fourier transform (FFT) to realize multicarrier modulation and demodulation techniques, respectively. Simultaneously, it was suggested that the N-FRAT technique operate as a data mapper instead of the conventional phase shift keying (PSK) and quadrature amplitude mapping (QAM), which are usually used with the traditional OFDM system. The usage of the N-FRAT and FT in the proposed system led to an increase in the orthogonality between the subcarriers due to the application of IFFT in the N-FRAT, which was added to improve the orthogonality and time–frequency localization properties of the FT. Furthermore the proposed structure improved the bandwidth efficiency through the elimination of the cyclic prefix compared to the traditional system. The proposed system was simulated and compared with other OFDM systems, such as FFT based OFDM using N-FRAT mapping (N-FRAT-FFT-OFDM), FT based OFDM using QAM mapping (QAM-FT-OFDM), and FFT based OFDM using QAM mapping (QAM-FFT-OFDM). The simulation was performed over frequency selective fading channel using MATLAB technical programming language. The results of simulations showed that the new structure outperformed the other three systems by reducing the inter-symbol interference (ISI) and inter-carrier interference (ICI), which then improved the bit error rate (BER) performance.

A hybrid technique, which is a combination of the Fast Fourier Transform (FFT) and Sliding Window (SW) technique, is proposed for the development of new structure for Discrete Multiwavelet Critical-Sampling Transform based Orthogonal Frequency Division Multiplexing (DMWCST-OFDM) system under multipath fading channels with the Doppler frequency effect. FFT is utilized to increase the orthogonality of subcarriers against the multipath frequency-selective fading channels. SW technique reduces the fluctuation of signal amplitude, thereby reducing the Doppler frequency effect. This hybrid technique offers a good tradeoff between performance and complexity, where this technique needs more computations. However, it performs better than the standard DMWCST-OFDM system. The performance of the proposed system, called SW-DMWCST-OFDM, was compared to that of the standard DMWCST-OFDM, SW-FFT-OFDM, and FFT-OFDM systems under three channels, namely, additive white Gaussian noise, flat fading, and frequency-selective fading. The simulation results show that the proposed model performs better than the three other models in all types of channels.

Framelet Transform-based OFDM (FT-OFDM) was proposed recently as an alternative to traditional Fast Fourier Transform-based OFDM (FFT-OFDM). By using the Framelet Transform, the spectral containment of the channels will be more efficient, since it does not use Cyclic Prefix (CP) that usually used in the traditional model. To improve the error rate performance of FT-OFDM, forward error correction coding is essential. This paper proposes Low-Density Parity-Check (LDPC) coded Framelet Transform-based OFDM (LDPC-FT-OFDM). The use of LDPC coding with FT-OFDM is useful in providing the desired performance at high data rates. The proposed system was tested according to two different coding rates and mapping techniques over Additive White Gaussian Noise (AWGN) and frequency-selective fading channels. The performance of the proposed system was compared to that of the uncoded FT-OFDM, LDPC-FFT-OFDM, and uncoded FFT-OFDM systems. The simulation results showed that the proposed model performs better than the three other models. Hence, the proposed LDPC-FT-OFDM system is a promising solution for high efficient data transmission over wireless channels.

In this paper, we propose an alleviation interference scheme (AIS) for spectral amplitude coding (SAC) – optical code division multiple access (OCDMA) coding system approaches. The AIS SAC-OCDMA systems is demonstrated by utilizing the new flexible cross correlation (FCC) code. The FCC code has advantages, such as flexibility in-phase cross-correlation at any given number of users and weights, as well as effectively reduces the impacts of phase-induced intensity noise (PIIN) and has the multiple-access interference (MAI) cancelation property. The results indicated good performance whereas the FCC (W = 4, K = 150) AIS SAC-OCDMA coding system offers 66%, 172%, 650% and 900% percentage of cardinality enrichments as a contrast to DCS (W = 4, K = 90), MDW (W = 4, K = 55), MFH (W = 4, K = 20) and Hadamard (W = 8, K = 15) codes, respectively. Finally, the FCC AIS SAC-OCDMA coding system has low effective receive power Psr = −21 dBm which is expected to be more significant for future SAC-OCDMA coding systems without requiring any amplification at the receiving plant.

A new two-dimensional (2-D) optical code division multiple access (OCDMA) scheme to increase the achievable system capacity is proposed. The code exhibits good cross-correlation property time and wavelength shift. Performances are analyzed on code size and correlation properties affecting two important system parameters, bit error rate (BER) as a function of cardinality generated and optical power transmission requirement. The proposed system can effectively suppress phase-induced intensity noise (PIIN) and has multi-access interference (MAI) cancellation property. Results in a good agreement indicate that 2-D modified double weight (MDW) offers 163.7% and 336.2% larger cardinality compare to 2-D perfect difference code (PDC) and 2-D modified quadratic congruence (MQC) code. By increasing spatial code (N) and keeps similar code length system performance can be further optimized. 2-D MDW (M = 45, N = 18) accommodates 252.2% and 18.3% cardinality increment and low effective transmitted power (Psr) at −17.9 dBm, compare to 2-D MDW (M = 247, N = 3) and (M = 84, N = 9) at 10−9 BER error floor. The architecture of the spectral/spatial MDW OCDMA system with property of MAI cancellation is presented.

A new code for Spectral Amplitude Coding - Optical Code Division Multiple Access (SAC-OCDMA) is proposed and is called Flexible Cross-correlation (FCC) code. The FCC code possesses various advantages; including easy code construction using Tridiagonal matrix compared to other SAC-OCDMA codes such as MDW, MQC and MFH, shorter code length and the important properties of this code is the flexible cross-correlation. Our results reveal that FCC code can effectively alleviated Phase Induced Intensity Noise (PIIN) and allows large cardinality and improve the bit error rate performance.

A new class of code called Flexible Cross-Correlation (FCC) for Spectral-Amplitude Coding Optical Code-Division Multiple-Access (SAC-OCDMA) systems has been de-veloped. The FCC code has advantages, such as flexible cross-correlation property at any given number of users and weights, as well as effectively reduces the impact of Phase-Induced Intensity Noise (PIIN) and Multiple-Access Interference (MAI) cancellation property. The results revealed that the FCC code can accommodate 150 users, where FCC code offers 66%, 172%, 650% and 900% improvement as a contrast to 90, 55, 20 and 15 numbers of users for Dynamic Cyclic Shift (DCS), Modified Double Weight (MDW), Modified Frequency Hoping (MFH) and Hadamard codes, respectively, for a permissible Bit Error Rate (BER) of 10−9 •

Various two-dimensional (2-D) OCDMA codes have been introduced in recent years due to their capabilities in enhancing cardinality, suppressing phase induced intensity noise (PIIN) and eliminates multiple access interference (MAI). This paper presents our new proposal of 2-D spectral/spatial Extended Enhanced Double Weight (2-D Extended-EDW) code. This code is designed to enhance cardinality and effective transmitted power. In other word, it effectively reduces noise and increasing simultaneous users. From our numerical analysis, we found that 2-D Extended-EDW code has a significantly better performance, in terms of the cardinality and effective transmitted power when compared with 2-D M-Matrices code.

A 2-Dimensional (2-D) Wavelength/Time (W/T) scheme is proposed for spectral amplitude coding OCDMA network system. The new hybrid codes are utilizing Flexible Cross Correlation (FCC) and Modified Double Weight (MDW) codes which both codes have good correlation properties and capable to suppress multiple access interference (MAI). From the numerical calculation, it has been shown that this new hybrid code effectively suppresses the phase Induced Intensity Noise (PIIN) and eliminates MAI. Furthermore, the cardinality of this proposed code accommodates 150% and 275% improvement compared to 2-D PD code and 2-D M-Matrices code respectively at the BER=10−9. As a result, the performance of the system can be improved as well as support much more simultaneous users compared to Perfect Difference (PD) and M-matrices codes.

In this paper, we present an effective encoder-decoder design utilizing Flexible Cross Correlation (FCC) code for Spectral Amplitude Coding-Optical Code Division Multiple Access (SAC-OCDMA) systems. The FCC code has advantages, such as flexibility cross-correlation property for any given number of users and weights, as well as effectively reduces the impacts of Multiple-Access Interference (MAI). The proposed FCC SAC-OCDMA encoder-decoder had shown superior performance indicated FCC SAC-OCDMA encoder-decoder offers 100%,287% and 331% much larger number of active users compared to MDW K=60, MFH K=31 and Hadamard K=29, respectively.

The analysis realization performance of 2-dimensional (2-D) code OCDMA system with the AND Detection technique was investigated. Two codes of 2-D has been employed in this project for OCDMA system; the 2-D M-Matrices code and 2-D Hybrid code. The performance was analyzing using Opti-Sys software. During simulation process, various parameters varied such as distance of the fiber, bit rate, and number of users. The result indicates that 2-D Hybrid code system modulated at 155 mbps has produced lower bit error rate (BER) of 8.31×10-9 at 65 km for 9 users in comparison to 2-D M-Matrices code system which can only achieve the maximum transmission distance at 25 km with BER of 1.16×10-9. It shows that the 2-D Hybrid code has better phase induced intensity noise suppression in comparison to the 2-D M-Matrices code.

Previously, various type of codes has been proposed for the Spectral Amplitude Coding (SAC) - Optical Code Division Multiple Access (OCDMA) with variable weights smaller than two which referring to Dynamic Cyclic, Random Diagonal, and Modified Quadratic Convergence codes. A minimum cross correlation of one can only be achieved by the best cross correlation property of the codes. In this research, Zero Cross Correlation (ZCC) code has been evaluated and compared with other codes in performing the result of effective power required. The OCDMA system using ZCC was constructed by using OptiSystem. The parameters are closely set to the theoretical parameters and 5 numbers of users are included in block diagram designation. Photodetector required low power efficient by using ZCC code. There is only small difference between the simulation estimations and theoretical result of ZCC with various effective powers. Multiple Access Interference effect can be minimized by developing new SAC-OCDMA code with ZCC property.

Optical Code Division Multiple Access (OCDMA) system are limited by the interference between users as well code length due to the code developments. A detailed of code construction for a OCDMA system with flexible cross correlation is presented to reduce the effect of interference thus optimizing the code length. In this paper, the proposed code called Flexible Cross Correlation (FCC) code. The FCC code can be constructed using a simple tridiagonal matrix compared to other OCDMA codes such as MDW, MQC and MFH, thus the FCC code possesses various advantages including easy code construction and less complexity of encoder/decoder design. As a result, OCDMA system performance significantly improved by using FCC code with flexible cross correlation instead of fixed cross correlation such as MDW, MFH and MQC codes.

In this paper, we demonstrate a novel architecture of variable weight Zero Cross Correlation code in the family of Spectral Amplitude Coding(SAC) Optical Code Division Multiple Access (OCDMA) to be utilized in the triple play services of OCDMA applications based on the end users demand and requirements. This is achieved by adapting multiple weights of Zero Cross Correlation (ZCC) code onto one system to accommodate different Quality of Service (QoS) requirements. The results are characterized by bit error rate (BER) and eye pattern simulated using OptiSystem software. Results proved a successful transmission of this scheme over 20km distance thus offering flexibility of independent QoS. It is also revealed that the performance is always better for users with larger number of code weight compared to those assigned with smaller code weight.

In this paper, an improvement of achievable system capacity Avalanche photodiode (APD) performance of spatial/spectral modified double weight (MDW) code for cardinality, bit error rates (BER) and noise interference is analyzed. The results in very good agreement indicate that 61% cardinality improvements compare to 2-D MDW code with PIN. The effective transmitted power (P sr ) for 2-D MDW-APD (M=135, N=3) improves by 8.5dBm at 10−9 error floor. At low gain BER value is mitigated through suppressing PIIN. Apparently, performance of the proposed system improves substantially with APD.

This paper presented a code with non-zero in-phase cross- correlation Spectral Amplitude Coding Optical Code Division Multiple Access (OCDMA) system. The proposed code called Modified Non Zero Cross Correlation (MNZCC) code. The MNZCC code can be constructed easily for any given number of users, weights and cross correlation (λmax) using tridiagonal matrix properties. MNZCC code will be demonstrated in simulation using OptiSys.6.0. The results indicated that MNZCC code is truly performed better with the presence of noise. We find that the performance of MNZCC code is better than OCDMA codes such as MDW and MFH. Finally, in term of systems complexity, MNZCC code introduced cost effectiveness due to less number of filter with direct detection scheme.

This paper presented a new class of code called Modified Non-Zero Cross Correlation (MNZCC) Code for Spectral-Amplitude Coding Optical Code Division Multiple Access. The MNZCC code can be constructed easily for any given number of users, weights and cross correlation (λmax) with tridiagonal matrix properties. We find that the performance of MNZCC code is better than OCDMA codes such as MDW and MFH. In term of performance, systems with MNZCC code had shown superior performance, where the Bit Error Rate (BER) of MNZCC code is significantly better than OCDMA codes such as MDW and MFH. Fiber Brag Grating filter has been used for the implementing SAC-OCDMA systems. Finally, in term of systems complexity system with MNZCC code with direct detection scheme introduced cost effectiveness due to less number of filter in decoder as well encoder.

This paper presented the novel of a new class of code with Non-Zero Cross-Correlation for Spectral-Amplitude Coding in Optical Code Division Multiple Access (OCDMA) systems. A new code namely Modified Non-Zero Cross Correlation Code (MNZCC). MNZCC code can be constructed easily for a given number of users K, weights and for a given cross correlation (λmax). The proposed code was demonstrated in simulation using OptiSys. 6.0 to observe the system performance. The results shown, that, the proposed code has superior performance in term of spectrum efficiency and reducing the effect of MAI and suppressing the effects of PIIN, with better bit error probability. The results are obtained for the MNZCC were compared with others existing optical codes such as DW code.

This paper presented the novel of optical code for Optical Code Division Multiple Access (OCDMA) system using Spectral Amplitude Coding. A new class of code, called Modified Non-Zero Cross Correlation Code (MNZCC). MNZCC code has minimum length, can be constructed easily for a given number of users, weights and any desired cross correlation (λmax). The MNZCC code was observed by OptiSys. 6.0 software. The MNZCC code has shown superior performance in term reducing the effect of MAI, with better bit error probability. The results obtain for the MNZCC were compared with others existing optical codes such as DW code.

A new family of spectral/spatial spectral amplitude-coding (SAC) optical code division multiple access (OCDMA) scheme using Modified Double Weight (MDW) code is developed. The new codes are derived from Modified Double Weight codes with good cross correlation. This proposed system can suppress the phase-induced intensity noise (PIIN) by using multiuser interference (MUI) cancellation property. The proposed 2-D OCDMA MDW can offer a much larger capacity compare to the 1-D OCDMA MDW Code.

A new design code structure for Spectral Amplitude Coding with zero cross- correlation in Optical Code Division Multiple Access (OCDMA) has been proposed in this paper. The proposed code called Modified Zero Cross Correlation Code (MZCC). MZCC code provides much easier code construction, given any number of users K and weights to have minimum code length. MZCC code will be demonstrated using OptiSys 6.0. The results indicated that MZCC code is truly performs better in term of noise performance compared with existing Optical CDMA codes.

A new class code structure for Spectral Amplitude Coding Optical Code Division Multiple Access (OCDMA) with zero cross-correlation is been proposed in this paper. The proposed code called Modified Zero Cross Correlation Code (MZCC) which evaluation from the existing Zero Cross Correlation Code. MZCC code provides much easier code construction, minimum code length with K number of users given any weight. MZCC code will be demonstrated in simulation using OptiSys. version 7.0. The results indicated that MZCC code is truly performs better in term of performance Bit Error Rate (BER) due to non-existence of Phase Induced Intensity (PIIN).

This paper the construction of the double weight (D\V) code family, one the recent codes for spectral amplitude coding (SAC) is studied. The DW code family is constructed using a matrix construction technique and a mapping scheme to increase the number of users. To obtain a single user's codeword the whole matrix must be constructed. In this paper a simplified equation based construction technique for the DW code family is proposed. This new simplified construction scheme depends on the three basic building blocks for the DW code family. General equations for the codeword construction and code length are given.

To increase the number of users in the double weight (DW) code family, a mapping technique is applied. This mapping technique increases the number of users but at a cost of unfixed cross-correlation property. The complementary detection technique used in spectral amplitude coding (SAC) systems, can completely cancel the multiple access interference (MAI) only if there is a fixed cross-correlation between different code sequences. In this paper we study the performance of the DW code family a alternative detection scheme that can support balance detection for unfixed cross-correlation property. Also a mathematical approach is proposed to reduce the number of fiber Bragg gratings and minimize the phase induced intensity noise.

This paper concentrates on double weight code family as a proposed code for the optical spectrum code division multiple access (OSCDMA) which has one cross correlation value. By eliminating the intersection columns of this code, the cross correlation value will be zero instead of one. This new derived code is called zero cross-correlation code (ZCC) (S. Amar et al., 2006). In ZCC code, the performance is expected to be better than MDW code because it offers low cross correlation value. It is easy to distinguish the desired signal from the interfering signal if the cross correlation value is low. Besides, a general new equation is obtained for code which has zero cross correlation value instead of basic matrix and mapping technique which are used in modified double weight code to obtain a specific code word.