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This paper presents a new Alleviation Interference Scheme (AIS) for Spectral Amplitude Coding (SAC) - Optical Code Division Multiple Access (OCDMA) coding approaches. The AIS SAC-OCDMA systems is demonstrated by utilizing the Flexible Cross Correlation (FCC) code. 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 impacts of phase induced intensity noise (PIIN) and multiple-access interference (MAI). The results indicated good performance whereas the FCC code offers 100%, 207% and 471% percentage larger number of active users compared to MDW W=4, Hadamard and MFH W=8 codes, respectively. Finally, the FCC code has low receive power Psr = -18 dBm which is expected to be more significant for future SAC-OCDMA coding systems.

This paper presented a new class of codes for Fiber-To-The-Home (FTTH) network design based on Spectral Amplitude Coding (SAC) - Optical Code Division Multiple Access (OCDMA) coding approaches. The FTTH SAC-OCDMA network is demonstrated by utilizing the Flexible Cross Correlation (FCC) code. The FCC code has an ability to suppress and cancels the effect of Multi Access Interference (MAI). The results indicated good performance whereas the FCC code offers 100%, 287% and 331% percentage larger cardinality compared to MDW W=4, MFH W=8 and Hadamard codes respectively. Finally, the FCC code accommodates low effective receive power Psr = -23dBm which is expected to be more significant for future FTTH network development for future usages.

In this paper, we present, several aspects of unipolar optical code-division multiple access (OCDMA) codes, focusing on the flexible in-phase cross-correlation code algorithm and its potential for future optical networks. We briefly present a new class of code namely Flexible Cross Correlation (FCC) code for Spectral-Amplitude Coding (SAC) OCDMA approaches. The main coding properties are reviewed. The FCC code provides simple tridiagonal matrix constructions compared to the other SAC-OCDMA codes such as MDW, MQC and MFH codes. This code possesses such a various advantages, including the easier code construction, less complexity of encoder/decoder design and flexible in-phase cross-correlation for uncomplicated to implement using Fiber Bragg Gratings (FBGs) for the OCDMA systems.

The paper presents a method for the development of a new class of zero cross correlation optical code for Optical Code Division Multiple Access (OCDMA) system using Spectral Amplitude Coding. The proposed code is called Modified Zero Cross Correlation Code (MZCC). The code has minimum length and can be constructed quite simply for any number of users and for any code weights. The code has better spectrum slicing properties and noise performance in term of Bit Error Rate. The Modified Zero Cross Correlation Code will be demonstrated in simulation using OptiSys. 6.0 to observe noise performance which is better as compared to the existing Zero Cross Correlation Code.

Block Data Transmission Systems (BDTS) are used in high-speed wireless communication systems with time dispersive channel characteristics. In such systems, blocks of data are separated by zeros to mitigate the effect of Inter-Symbol-Interference (ISI) between the blocks. An optimal detection process employs the Maximum Likelihood Block Detection (MLBD) technique on each block individually in the presence of ISI and Gaussian noise based on the Euclidean distance as an objective function. The detection process is computationally expensive therefore Genetic Algorithms have been used to reduce the overall design complexity. In this work, three types of Genetic Algorithms have been incorporated in the detection process i.e. the conventional GA, Micro GA(µGA), and Hybrid µGA to reduce computational load. In particular, a novel training method for Hybrid µGA has been proposed. Simulation results at 10dB channel SNR for the BDTS with Hybrid µGA executes as low as 3,750 number of objective functions evaluation for a block size of 20. The Bit Error Rate (BER) performance of this system is relatively good i.e. around 1dB inferior to the BDTS using the Exhaustive Search method that requires as many as 220 number of objective functions evaluation.

This paper presents a simulation study for code-division multiplex system over time varying channels. The scheme investigated here uses a precoding technique in the transmitter depending on the channel information, so that no need for any signal processing in the receiver rather than testing against a certain threshold. This coding technique minimizes the effect of intersymbol interference (ISI). The data itself is transmitted in the form of blocks of data symbols separated by blocks of no signal. The appropriate length of each data block depends on the channel parameters expected and the allowed complexity. The impulse response is required to be known at the transmitter which is the requirement for all systems that employ coding at the transmitter.

This paper considers the use of unequal error protection and median filtering for transmission of images over poor wireless channels usually encountered over cellular mobile networks. Hierarchical Quadrature Amplitude Modulation (HQAM) that provides Unequal Error Protection (UEP) to the transmitted image data is used at the transmitter. In HQAM, non-uniform signal constellation is used to provide different degrees of protection to the significant and non-significant bits in the image data at lower channel Signal to Noise Ratio (SNR). Median filter is employed at the receiver to remove the impulsive noise present in the received image. Simulation results show that the use of HQAM and median filtering provides a gain of PSNR over the more conventional Quadrature Amplitude Modulation (QAM).

The wavelength-time modified double weight (MDW) optical division multiple access (OCDMA) scheme to reduce multiple access interference (MAI) and compensate bit error rate (BER) and phase-induced intensity noise (PIIN) in incoherent OCDMA systems is proposed. The analysis permits thorough understanding of PIIN, shot and thermal noises effect on 2-Dimensional (2-D) MDW OCDMA system performance. PIIN is the dominant noise factor in the OCDMA time-spreading scheme. The 2-D MDW code shows better tolerance to PIIN in comparison to others with enhanced system performance. We prove by numerical analysis that the PIIN is maximally suppressed by the proposed code through minimizing property of cross-correlation in comparison to the 2-D PDC and 2-D MQC OCDMA code.

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.

This chapter presents an adaptive Multicarrier Frequency Hopping Spread Spectrum (MCFH-SS) system employing proposed Quasi Cyclic Low Density Parity Check (QC-LDPC) codes instead of the conventional LDPC codes. A new technique for constructing the QC-LDPC codes based on row division method is proposed. The new codes offer more flexibility in terms of girth, code rates and codeword length. Moreover, a new scheme for channel prediction in MCFH-SS system is also proposed. The technique adaptively estimates the channel conditions and eliminates the need for the system to transmit a request message prior to transmitting the packet data. The proposed adaptive MCFH-SS system uses PN sequences to spread out frequency spectrum, reduce the power spectral density and minimize the jammer effects.

This work presents a new scheme for channel prediction in multicarrier frequency hopping spread spectrum (MCFH-SS) system. The technique adaptively estimates the channel conditions and eliminates the need for the system to transmit a request message prior to transmit the packet data. The new adaptive MCFH-SS system employs the Quasi-Cyclic low density parity check (QC-LDPC) codes instead of the regular conventional LDPC codes. In this work performance of the proposed MCFH-SS system with adaptive channel prediction scheme is compared with the fast frequency hopping spread spectrum (FFH-SS) system. The proposed system has full control of that spectrum; it plans for the system to keep off unacceptable adjacent channel interference. When an interferer suddenly changes its carrier, the set of appropriate channels has a large return and resultantly the adjacent channel interference between the systems is reduced. It has been shown from results that the signal power in FFH system exceeds the average by at least 6.54 dB while in the proposed MCFH-SS system signal power exceeds the average only 0.84 dB for 1% (correct use) of the time. The proposed MCFH-SS system is more robust to narrow band interference and multipath fading than the FFH-SS system, because such system requires more perfect autocorrelation function.

When the cyclic prefix is less than channel memory or under clipping noise in Orthogonal Frequency Division Multiplexing (OFDM) detection, a good Bit Error Rate (BER) performance is achieved using the Maximum Likelihood Block Detector (MLBD). However, the computational load at the receiver is high under this condition. It is well known that conventional GA based approach offers less computation for MLBD. In this paper, a Hybrid µGA based MLBD for IEEE 802.11a Wireless Local Area Network (LAN) modem is proposed. The new system offers reduction in computational load as compared to the conventional GA based approach without any performance deviation. This will enable consumers to use high data rate receiver by choosing a higher modulation scheme at low Signal-To-Noise-Ratio (SNR) under the above mentioned severe conditions. Simulation results show that the BER performance is the same as the conventional GA based system. Complexity analysis reveals that at 20dB channel SNR, the scheme executes five thousand functions evaluation only. Whereas, the GA based approach executes 50 thousand objective functions evaluation.

This paper presents a simulation study for a new block transmission system that depends on sharing the equalization process between the receiver and the transmitter. The transmitter share will be 75% of the signal processing, while the rest will be done at the receiver. A real time simulation is performed using Simulink to prove the mathematical model. Detailed block diagrams are introduced with description of the system behavior, with a comparison of the performance with the mathematical model for different signal to noise ratios.

Block transmission systems are used in inter symbol interference (ISI) channels for high data rate communication. In this system, messages are sent as blocks separated by known symbols. Detectors employing block-by-block detection basis is the optimum system and it can be implemented with global search techniques. The performance of such system is found better than block linear equalizers, block decision feedback equalizer. This paper presents the practical difficulty of such system and proposes usage of micro genetic algorithms as an alternative. The performance in terms of bit error rate is evaluated for channels with spectral nulls and hardware complexity is compared with present systems.

This paper presents a simulation study for code-division multiplex system, over time varying channels. The scheme investigated here uses a sharing technique for the signal processing unit between the transmitter and the receiver to improve the performance of the system. This technique minimizes the effect of inter-symbol interference (ISI). The data itself is transmitted in the form of blocks of data symbols separated by blocks of no signal. The appropriate length of each data block depends on the channel parameters expected and the allowed complexity. The impulse response is required to be known at the transmitter which is the requirement for all systems that employ coding at the transmitter.