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In a communication system, the transmitter and the receiver are important. The function of the receiver is to recover the data being transmitted. Thus, the concentration is more on the receiver side. In this paper, the system performance of 2D ZCC/MD code has been evaluated in terms of received power, number of users and data rate using APD and PIN as photodetectors to suppress MAI and mitigate PIIN. The results demonstrate that the APD provides a preferable performance compared to PIN. The evaluation of the proposed code is done for the same code length of spectral encoding sequence and the same code length of the spatial spreading sequence (M = 21, N = 3) with the APD gain variation (1, 3 and 5) compared to PIN. The APD with G = 3 can accommodate 390 active users whereas, PIN can accommodate 322 active users at a lower bit rate and lower effective power (- 23dBm). The APD photo-detector is a feasible solution for a system to be used to provide excessive cardinality with a low bit rate in 2D ZCC/MD OCDMA system.

This paper proposes a new spectral/spatial code for Spectral Amplitude Coding in Optical Coding Division Multiple Access (SAC-OCDMA) called two-Dimensional hybrid ZCC/MD code. The new code combines two of the one –dimensional codes which are Zero Cross Correlation (1D ZCC) and Multi-Diagonal code (1D MD). Moreover, it produces a zero cross correlation property for each code. The main goal of this proposed code is to mitigate Phase Induced Intensity Noise and eliminate Multiple Access Interference (MAI). This proposed code can provide a better performance comparing to other codes as 2D FCC/MDW and 2D DPDC according to the obtained numerical analysis.

Due to the increasing numbers of vehicles in the world which results in a rise in traffic density, smart city is seeking to minimize transportation problems such as accidents. To solve this issue, VANET has been developed to improve vehicles’ mobility and provide a safe city. VANET is a type of wireless technology which provides vehicle-to-vehicle (V2V) and vehicle-to-infrastructures (V2I) communication system. Despite the advantages of VANET, it faces a lot of challenges; security and privacy, for instance, are the most critical ones. In this paper, we implement an approach used in Optical CDMA system given its success in optical domain. This technique is based on the 2D ZCC/MD code which is characterized by zero cross-correlation property. The transmission system is based on the VLC system, in which the information will circulate in optic domain using light in free space. The proposed system can provide the security and the privacy due to the 2D ZCC/MD code which assigns each user by a specific unique code.

We propose a modified OFDM modulation based on multiband scheme for visible light communications (VLC) system. The method called catenated-OFDM VLC system can efficiently boost the propagation distance and combat multipath induced the inter symbol interference and inter carrier interference. Design parameters such as number of optical bands, input power, distance and data rate are varied to see their effect on the system performances. Simulation analysis is done using Optisys software Ver. 11.0. The results show that the proposed system offers a good performance at longer transmission distance of 12 m for input power of 2 dBm in case of Band=3 with 10 Gbps data rate. BER curves also indicates that the proposed system can be operated at very high data rate of 15 Gbps. This exhibits the ability of the proposed system to be one of the candidate for future optical wireless communication system.

Bike Sharing System (BSS) has been on a rapid rise to provide healthy lifestyle and a sustainable environment to the world. However, the concept of BSS has a multiple flaws such as in managing of bike’s usage and maintenance. BSS that is currently used in Universiti Malaysia Perlis (UniMAP) is based on rental concept which reduces time efficiency and is inconvenient to users due to its lack of maintenance management. Thus, this work has been innovated to monitor the bike’s maintenance by designing the concept of dock free system and design of mobile application to monitor bike’s usage, payment and location of the bike based on Internet of Thing (IoT) platform. UniCycle provides services that are useful as neither there will be wastage nor shortage of parking dock. The dock free system provides a service where users need not worry about finding the parking dock and they can place the bicycle at anywhere and anytime within the campus’ compound. Therefore, UniCycle provides dock-free smart bike sharing services which is a more convenient alternative to students to navigate around the campus. Furthermore, the maintenance team can also monitor the condition of the bicycles.

This paper presents the simulative performance of optical CDMA system incorporated with subcarrier multiplexing (SCM) technique. The system is designed based on the Recursive Combinatorial (RC) code in the Spectral amplitude coding (SAC) - OCDMA. SAC-OCDMA approaches is capable to reduce the effect of Multiple Access Interference (MAI) using code sequences with fixed in-phase cross correlation. The performance of this hybrid system is shown through simulative experiment results of bit error rate (BER) and eye patterns for various numbers of subcarrier channels and frequencies. The simulation is done using Optisys version 7.0. The simulation results shows decreasing the number of weight will produce better performance compared to increasing the number of weight. Increasing the number of weight will increase the spectral chips and makes the system more sensitive to the noise. For the weight = 3, the transmission distance is up to 9.5 km.

Several two dimensional OCDMA have been developed in order to overcome many problems in optical network, enhancing cardinality, suppress Multiple Access Interference (MAI) and mitigate Phase Induced Intensity Noise (PIIN). This paper propose a new 2D hybrid ZCC/MD code combining between 1D ZCC spectral encoding where M is its code length and 1D MD spatial spreading where N is its code length. The spatial spreading (N) code length offers a good cardinality so it represents the main effect to enhance the performance of the system compared to the spectral (M) code length according to the numerical results.

Visible light communication (VLC) technology offers unregulated, unlicensed and huge bandwidth to meet the growing demand in future indoor communication system. One of the major challenge in VLC system is in improving transmission speed with optimize the bandwidth capacity. The method to improve spectral usage is using advanced modulation formats such as orthogonal frequency division multiplexing (OFDM). In this work, a new approach for modulation technique based on multiband OFDM has been developed which capable to improve the spectral efficiency and optimize the data rate. A proposed technique is then adapted in OCDMA-VLC environment to analyse the reliability of the proposed scheme in high capacity network. Different selection of parameter values such as bit rates, number of bands and effective received power will have different effect on the system performance. Numerical result shown that the catenated-OFDM outperforms conventional OFDM by five times spectral efficiency improvement and eight times spectral efficiency improvement at their five and eight number of bands respectively. It is also shown that the proposed catenated-OFDM design is working well even at very high bit rate of 15 Gbps. Moreover, there are enhancement in receiver sensitivity with 7.3 dB power penalty compared to previous work.

The combination of 1D zero cross correlation (ZCC) and 1D Multi Diagonal (MD) results a new two dimensional hybrid called 2D ZCC/MD code for spectral/spatial OCDMA system. The proposed code aims to enhance the functional qualities of Optical Code Division Multiple Access (OCDMA) and to overcome the limitations of one dimensional codes. In this paper, 2D ZCC/MD is evaluated at data rate; 622Mbps. A comparison of the proposed 2D ZCC/MD code to 1D Random Diagonal (RD) and 1D Modified Double Weight (MDW) highlight that 2D ZCC/MD can support a large number of active users even at the higher user bit rate. Furthermore, in term of effective power 2D ZCC/MD can achieve lower effective power.

Explosive growth of bandwidth demand together with advance in latest communication services and emerging applications have inspired interest in optical code division multiple access (OCDMA). The work focuses on analysis and demonstration of two-dimensional (2-D) modified double weight (MDW) OCDMA wavelength-time. The 2-D MDW uses balance-detection for mitigating multiple access interference. The property of cross-correlation results in optimum phase induces intensity noise suppression (PIIN). The proposed code achieves high scalability; below 10-9 BER error floor the code cardinality reaches 254 simultaneous numbers of users which is double the 2-D PDC performance. The lowest effective power (Psr) for minimum optical transmission requirement for smallest number of users is achieved at-17.5dBm. The 2-D MDW OCDMA simulation model is developed to validate the realization of the code for BER and distance performance. The 2-D MDW OCDMA code successfully suppresses PIIN and mitigating MAI which result in high cardinality, reduce Psr and improved distance.

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.

In this paper, we show details of zero cross correlation (ZCC) code development and investigate performance by measuring bit-error-rates compared to other optical code division multiple access (OCDMA) codes using Avalanche photodiode (APD) and PIN photodetector. We present a configuration to determine how optical OCDMA systems can be applied with PIN and APD photodetector. Analysis of Avalanche photodiode gain optimization is discussed in ZCC code system. We also present analytical and numerical theoretical results for data transmission of spectrally encoded incoherent OCDMA signal and how signal-noise is being affected by using these two photodetectors.

This paper demonstrates the comparison between conventional OCDMA system and subcarrier multiplexing (SCM) SAC-OCDMA system by applying Recursive Combinatorial (RC) code based on single photodiode detection (SPD). SPD is used in the receiver part to reduce the effect of multiple access interference (MAI) which contributes as a dominant noise in incoherent SAC-OCDMA systems. From this analysis, the performance of SCM OCDMA network could be improved by using lower data rates and higher received power. The hybrid SCM OCDMA system shows better performance compare to conventional OCDMA system although the number of users involved is very high. This is because, for hybrid SCM OCDMA system, the number of users can be increased by increasing the number of subcarriers without affect the number of code length and optical codes. Increasing the number of subcarriers will enhance the power consumption by applying hybrid SCM system in OCDMA compared to the conventional OCDMA system. This is because increasing the number of users for hybrid SCM system does not affects the number of code length and the number of optical codes but only increase the number of subcarriers. Thus, hybrid SCM OCDMA system has to increase spectral efficiency and produce better performance compared to conventional of OCDMA system.

In this article, a subcarrier-multiplexed Optical CDMA system utilizing the direct and AND subtraction method in receiver's detection is explored. The OCDMA part exploits the Recursive Combinatorial (RC) code for its algorithm. The two different designs are then simulated and the performances are compared. Results indicate that the hybrid SCM/OCDMA system using direct detection technique could transmit to a longer distance of up to 50 km with better quality than that with AND subtraction detection for acceptable communication error rate of BER of 10−9.

This paper investigates the performance of hybrid scheme of subcarrier multiplexed spectral-amplitude-coding optical code division multiple access (SCM SAC-OCDMA) system based on AND Subtraction detection. In this system, Recursive Combinatorial (RC) code is used where it is a new code structure in SAC-OCDMA. The effects of noise such as phase-induced intensity (PIIN) noise, thermal noise and intermodulation distortion (IMD) are taken into consideration in order to analyze the system. The theoretical values are being compared based on some parameters. AND detection can discard the effects of multi access interference (MAI). As a result, the system performance are improved based on AND detection technique.

This paper analyses the spectral efficiency of hybrid subcarrier multiplexed (SCM) Optical Code Division Multiple Access (OCDMA) and conventional OCDMA based on AND Subtraction technique. We compared the spectral efficiency of SCM and the conventional OCDMA with respect the number of weights and number of users. Results indicate that the SCM OCDMA is more efficient compared to conventional 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 × 20 users) and 0.3 Tbps (15 Gbps × 20 users) data-rate transmission networks.

This paper presents a development of microstrip dual-band bandpass filter for Industrial, Scientific and Medical (ISM) band application. The proposed bandpass filter which can operate at 2.4 GHz and 5 GHz band is implemented based on parallel coupled line technique. The parallel coupled line filter allows tuning two bands at desired frequencies apart for minimizing the return losses within both dual passband. The Advanced Design System (ADS) simulator has been used during simulation and optimization. For the design verification, the prototype of the proposed microstrip filter has been fabricated and measured. The simulated return loss S11 and insertion loss S21 of the proposed microstrip filter are −25.092 dB and −0.013 dB at 2.4 GHz respectively, while −22.373 dB and −0.025 dB at 5 GHz respectively. For the design verification, the prototype of the proposed antenna was fabricated and measured. The result shows that the proposed design can be realized in any communication system applications.

A new dual-diffuser modulation (DDM) technique improve the performance of the conventional intensity modulation/direct detection (IM/DD) for On Off Keying (OOK) in term of data bit rate and propagation distance. This new modulation technique employs two transmitters and two receivers to create a robust modulation with optimizing the reduction scintillation index, enhance the power received and improve the threshold signal level. At the transmitters, the laser exits combine with low cost phase screen diffuser to create a ‘new’ superior laser beam characteristic in order to combat atmospheric turbulence effectively. Meanwhile at the receivers, the signal will be subtracted. The analysis result shows that in comparison various data bit rates at BER10−9, the DDM is capable to operate excellent under small power launched where the bit rate can achieved above 10Gbps at 5dBm power transmit. Meanwhile for phase screen diffuser effect, the DDM optimizes the performance of diffuser where the data bit rate can reached approximately 1.5Gbps and the conventional IM/DD-OOK only performed at 0.155Gbps.

Dense wavelength division multiplexing system is a system for coupling and transmitting the optical signals at different wavelength through the single fiber. Such technology is important in order to increase the capacity in optical communication system and to meet the growing demands of bandwidth. However, there are some limiting factors related to the data rate and capacity in this system. These limiting factors can be linear or nonlinear. Theoretically, the nonlinearities in fiber arise as the number of data channel, transmission length, data rate and input power level increase. In this project, the objective is focused towards analyzing on the nonlinearities effect by compensating the linear effect in the fiber. Dispersion Compensation Fiber (DCF) and linear loss EDFA compensation have been used in single mode fiber (SMF) channel to ensure the communication quality for the design. The proposed dispersion compensation DC-DWDM transmission system with 16 and 32 channels for 10Gbps with a channel spacing of 0.8nm was designed and simulated. The BER performance with various input power levels in the range of −10dBm up to 10dBm, and fiber length greater than 50km are analyzed. It has been shown that for fixed length of the fiber, the only variable that can be manipulated to lower the nonlinear contribution is the input power. The higher the input power the higher the nonlinear contribution. However, if the input power is low, the bit rate should be low to maintained transmission at the expected BER (BER < 10–12)

A detailed of code construction for an Optical Code Division Multiple Access (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 and DCS codes 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 DCS codes.

This paper proposed a new design of a 2.45 GHz harmonic suppression circularly polarized microstrip patch antenna. The purpose of harmonic suppression antenna is to eliminate the using of harmonic filter circuit in a rectenna system as well as for the others active integrated antenna (AIA) applications. By introducing a defected ground structure (DGS) technique with a back-to-back U shape slot, the magnitude of the return loss at the harmonic frequencies are suppressed successfully. The patch antenna is designed on an FR4 substrate with e r =4.7 and a thickness of 1.6 mm have −28dB return loss at 2.45GHz and suppress the second and third harmonic up to −0.8dB and −1.8dB respectively.

This paper presented a new design of harmonic suppression microstrip patch antenna with the circular polarization properties at frequency 900MHz for an RF ambient energy harvesting system. The purpose of harmonic suppression antenna is to eliminate the using of a harmonic filter circuit in filtering the unwanted signal at the harmonic frequencies in a rectenna system. By introducing a truncating to corner of the rectangular microstrip patch antenna to achieved the required axial ratio, an antenna with circular polarization property is presented. The dimension of patch is reduced by applying partially ground plane. Then an implementation of a defected ground structure (DGS) with a circular shape slot, the unwanted radiation at harmonic frequencies are successfully suppressed. The patch antenna is designed on an FR4 substrate with er=4.7 and a thickness of 1.6 mm has -20dB return loss at 900 MHz and suppress the second and third harmonic up to -2dB. The proposed circularly polarized harmonic suppression antenna is then fabricated and measured for the verification of the design.

This paper analyzes the performance of subcarrier multiplexing (SCM) of spectral amplitude coding optical code multiple access (SAC-OCDMA) by applying Recursive Combinatorial (RC) code based on single photodiode detection (SPD). SPD is used in the receiver part to reduce the effect of multiple access interference (MAI) which contributes as a dominant noise in incoherent SAC-OCDMA systems. Results indicate that the SCM OCDMA network performance could be improved by using lower data rates and higher number of weight. Total number of users can also be enhanced by adding lower data rates and higher number of subcarriers.

In this paper, we propose a novel 2D spectral/spatial hybrid code based on 1D ZCC and 1D MD where the both present a zero cross correlation property analyzed and the influence of the noise of optical as Phase Induced Intensity Noise (PIIN), shot and thermal noise. This new code is shown effectively to mitigate the PIIN and suppresses MAI. Using 2D ZCC/MD code the performance of the system can be improved in term of as well as to support more simultaneous users compared of the 2D FCC/MDW and 2D DPDC codes.

In this paper, we have proposed a high performance network design, which is based on mixed optical Code Division Multiple Access (CDMA) system using Zero Cross Correlation (ZCC) code and multiband Orthogonal Frequency Division Multiplexing (OFDM) called catenated OFDM. In addition, we also investigate the related changing parameters such as; effective power, number of user, number of band, code length and code weight. Then we theoretically analyzed the system performance comprehensively while considering up to five OFDM bands. The feasibility of the proposed system architecture is verified via the numerical analysis. The research results demonstrated that our developed modulation solution can significantly enhanced the total number of user; improving up to 80% for five catenated bands compared to traditional optical CDMA system, with the code length equals to 80, transmitted at 622 Mbps. It is also demonstrated that the BER performance strongly depends on number of weight, especially with less number of users. As the number of weight increases, the BER performance is better.

This paper proposes an integration of optical Code Division Multiple Access (OCDMA) with new catenated Orthogonal Frequency Division Multiplexing (OFDM) modulation scheme. This effective combination based on Zero Cross Correlation (ZCC) code can enhanced the system capacity and increased spectral efficiency by fully utilizing the available electrical bandwidth. We investigate the performance of the proposed system for various number of user, number of weight and effective power. The performance assessment is carried out by means of the signal to noise ratio (SNR) and bit error rate (BER) for up to five catenated OFDM bands transmitted simultaneously through optical link at 622 Mbps. More specifically, mathematical expressions for SNR and BER performance are derived. The corresponding numerical results are presented and compared with traditional OCDMA-ZCC system to verified the feasibility of the proposed system. The results show that with OCDMA/catenated-OFDM based on ZCC code provides 86% more number of permissible user for SNR of 15 dB. In addition, this integration provides higher receiver sensitivity; an approximately –22.5 dBm for 20 number of user with 8 number of weight. It is also found that, to accommodate more user, the system requires higher effective power at the receiver.

This paper presented a new design of rectangular patch antenna which is able to suppress the harmonic frequencies. The techniques that are used in the suppression of harmonics are a notch-loaded and curvature slots at the antenna patch together with an open stub and inset feed transmission line. The partially ground with a circular slot at ground plane is also introduced to reduce the overall patch size. The patch antenna is designed on an FR4 substrate with e r =4.7 and a thickness of 1.6 mm give −40dB return loss at 2.45GHz and suppress all the harmonics up to −1dB. The proposed of harmonic suppression antenna can avoid by using harmonic filter circuit in the rectenna circuit and active integrated antenna (AIA) applications, thus the system becomes compact and cheaper.

This paper proposed a new circular patch antenna design with harmonics suppression capability. The purpose of harmonic suppression antenna is to eliminate the use of harmonic filter circuit in rectenna circuit. By introducing slits at the antenna patch and stub at the transmission line, unwanted harmonics frequencies are successfully suppressed. In addition, the size of proposed circular patch antenna is reduced by using partial ground and circular slot technique at the ground plane. The patch antenna is design on FR4 substrate with e r =4.7 and a thickness of 1.6 mm has −48dB return loss at 2.45GHz and suppress the second and third harmonic up to −3dB. The proposed harmonic suppression antenna can be applied in rectenna and active integrated antenna (AIA) applications, thus the circuit become compact, cheaper and more efficient.

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.

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.

In this paper, a feasibility study of the ambient radio frequency (RF) as an energy source to be harvested and converted into electrical energy is presented. This study is to investigate the ability to harvest the ambient RF power density produced by the GSM telecommunication tower for very low power device usage. To capture the RF signal, a normal mode helical rectenna is designed and fabricated. The reason of choosing the normal mode helical antenna in this study is to solve the major problem of a microstrip patch antenna array where the overall size is very large. Experimental results showed that with −10dBm input power, a voltage of 0.3V is generated at the distance 2.5 meters. Hence, this proved that the ambient RF energy can be a suitable candidate as an energy harvesting source.

This paper demonstrates a novel architecture of hybrid subcarrier multiplexing Wavelength Division Multiplexing network combining laser and light emitting diodes (LED) as the light sources. The performances are simulated using Optisys software and analyzed based on bit error rates (BER) and the eye pattern of the received signals. Results proved that the combination of the laser and LED light sources in one system can be considered an effective way to maximize system capacity and at the same time, reduce implementation cost of hybrid SCM WDM network architecture.

In this paper, the implementation of subcarrier multiplexing technique in spectral amplitude coding (SAC) optical code division multiple access (OCDMA) network using Zero Cross Correlation code is developed and investigated. Theoretical analysis is done to determine the signal-to-noise ratio of such network and analysis of the performances in term of bit error rates are presented. Simulations are done using Optisys software version 6.0. Motivation to this research is driven to take advantage of both the low implementation cost of the SCM technology which uses the existing RF/microwave devices; and the attractive SAC which reduce the Multiple Access Interference (MAI) in OCDMA system. The use of ZCC code can eradicate phase induced intensity noise (PUN) which will contribute to better BER. For typical error rate of optical communication system of 10e-9, it has been observed fro theoretical results that the new hybrid SCM/OCDMA system provide better spectral efficiency and accommodate more users simultaneously with less code length and thus lower cost of implementations than the traditional OCDMA network utilizing the ZCC code. Thus this system could be one promising solution to the symmetric high capacity access network with high spectral efficiency, cost effective, good flexibility and enhanced security, which makes an attractive candidate for next generation broadband access network

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.

This paper examine about the selecting of wavelength in effecting the laser transmission over the free space spatial under the rain circumstances. The wavelengths used in these computation experiment theory are 780 nm, 850 nm, 1550 nm and 10000 nm. Comparison of the experiment result is measured in various types of rain such as drizzle, light rain, medium rain, heavy rain, cloudburst, extreme rain and very extreme rain. Visual range and scattering coefficient of rain is depending on wavelength utilize. This observation is based on an extensive literature search and from Mie scattering calculation.

This paper is to provide the preliminary result and activities of a research program at UNIMAP on rain attenuation in the Perlis region. The project uses the LaserBit product; model LB-2500 and LB-5000 which can maximum reach 2500 m and 5000 m with wavelength 785 nm and laser power 70 mW. The result will utilize four existing model rain attenuation and measured data will compared to calculated result to determine the validity of precipitation model and deepen the consequence of rain intensity. As additional to unwavering the measurement. Optisys software has been used to simulate the data to predict the possibility of result.

MIMO technology has attracted a lot of attention in the area of wireless communications such as radar applications, in term of increasing the spectral efficiency. This research paper will present the model of Simulated Radar Emission Environment for RWR testing using MATLAB. For the first phase of the research, the radar emission environment is modeled by modeling four directions of signals as continuous wave with different amplitude to represent their emission of power. These four directions are a distribution of 360 degrees from the aircraft. These signals are propagated through their own transmission channel, showing that they are coming from four different propagation transmissions. A LMS equalizer has been adopted to equalize and analyze the incoming signal. The main purpose of this research is to find an alternative way of testing the radar warning receiver in an indoor approach rather than taking a costly outdoor testing session from the aircraft.

A new detection scheme, namely AND subtraction technique is proposed and presented in this paper. The theory is being elaborated and experimental results have been done by comparing Double-Weight (DW) code against the existing code, Hadamard. In this paper we have proved that AND subtraction technique gives better Bit Error Rates (BER) performance than Complementary subtraction technique against the received power level. The overall system cost and complexity can be reduced by using less number of filters in this technique. At the same time, the performance of the OCDMA system is improved significantly because with less number of filters in the decoder, the total power loss can be reduced and this can be clearly seen in the result.

A hybrid subcarrier multiplexing (SCM) technique incorporating spectral amplitude coding and optical code division multiple access (SAC-OCDMA) technologies is investigated using both numerical and simulation methods. The hybrid SCM/SAC-OCDMA system combines the two above schemes in such a way that it is robust to multiple access interference and reveals much enhanced channel data rate. We improve the overall performance of the hybrid SCM/SAC-OCDMA system based on spectral amplitude coding to suppress a number of impairments and improve its sensitivity at a bit error rate of 10 -9 . As a result, the system suggested by us, which is based on a dynamic cyclic shift code, shows better performance when compared with the standard SAC-OCDMA systems employing the conventional code.