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Future wireless communication systems demand high data rates. It increasingly adopts an orthogonal frequency division multiplexing (OFDM) to consume the available spectrum efficiently. To obtain a good performance, such systems need to know the impact of channels to achieve the communication quality. It is a matter of how to extract transmitted data in an efficient way. The system employs pilot symbols...
This paper was executed in order to design side lobe suppression of Vivaldi antenna using shorting pin structure at S-band frequency. Nowadays, Vivaldi antenna has been used to satellite communications, remote sensing and radio telescope. There are a variety of designs such as tapered slot Vivaldi antenna, antipodal Vivaldi antenna and balanced antipodal Vivaldi antenna. Tapered slot Vivaldi antenna...
VANET is a field of technology through which road accidents can be reduced which leads to the reduction of the death rate. For this purpose, different protocols were proposed to improve the VANET network for safety messages, priority messages, and application based schemes, but MAC (Medium Access Control) is a branch where fewer researchers explored the literature. We proposed a VANET lane model for...
This paper presents a new methodology in inspection on laser scribe defect of PV thin film solar modules. The work focuses on the application of machine vision as an inspection tools which has successfully integrated in other manufacturing environment as pattern recognition utility. Compared to manual inspection by human, machine vision system could offer better measurement accuracy as scribe defects...
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...
This paper describes the design and implementation of the 4-stage Villard multiplier for RF energy harvesting. Each stage is a combination of two HSMS 2850 Schottky diodes and two capacitors for each stage. For ambient energy harvesting, the incident power is extremely small, thus an efficient rectifier is needed. The designed rectifier with the matching circuit is a good candidate since it is able...
Free Space Optical communication system is a technology that solves the problem of network connectivity. In this system, it contains a coding and technique to control the data that transferred using a laser beam from transmitter station through the atmosphere to receiver station. This technique is to optimize the error rate and improve the signal received. In this paper, the comparison between conventional...
This paper presents an improvement design of an Optical Code Division Multiple Access for Radio over Fiber (OCDMA-RoF) system. This improved system is divided into two main subsystems, Central Stations (CS) and Base Station (BS). Implement OCDMA code into RoF system promised a secure, cost-effective, and high-capacity mobile and multimedia wireless services. The analysis was made based on the relationship...
This paper contains a microstructure photonic optical fiber based on a circular cladding with asymmetric core for high birefringence. Simulation results show a high birefringence of 2.78×10−2 at 1550 nm operating wavelength. The proposed fiber also has dispersion compensation properties in a wide range of wavelengths covering S to L communication bands. The proposed design can obtain a negative dispersion...
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...
This paper organizes the performance of twodimensional (2-D) Modified Double Weight (MDW) code for Optical Code Division Multiple Access (OCDMA) system by employing Avalanche Photodiodes (APD) as a gain. To accomplish the perfection system capacity, their cardinality, bit error rates (BER) and noise interferences are analyzed. With 2-D MDW with APD able to recovered the cardinality at least 61%, which...
In this paper, we will focus on the modulation format used to produce the optical pulses, which are return to zero (RZ), and non-return to zero (NRZ). Bit error rate (BER) performance is assessed for OCDMA-RoF system. OCDMA-RoF system is viewed as a promising method for improving spectral efficiency and in the meantime diminish hardware equipment. The execution of RZ against NRZ is looked at through...
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.
Research in optical communications is always determined by fundamentals for high information rates and enhanced spectral efficiency. Also, the development of highrequest modulation formats is included a higher bit rates per channel, which requirement expanded signal-to-noise ratio considerably and high power per channel. Then again, higher spectral efficiency also needs closely spaced channels to...
In this paper, an indoor optical wireless CDMA system based on zero cross correlation (ZCC) code is investigated under the influence of ambient light noise. We consider line of sight communication links between multiple emitters and receivers. We first establish an analytical expression of bit error rate and then validate its estimations with the simulated results. The finding results show a great...
This paper develops new coding technique to generate multiplexed patterns for Duty-Cycle Division Multiplexing (DCDM) which allows users to share the single transmission medium by assigning different duty cycles for each user. This coding technique aims to reduce the amount of noise which is added due to multilevel signalling. Single channel back-to-back optical fibre system is designed based on the...
This article investigates the comparative between the Bit Error Rate (BER) performance of Phase Shift Keying (PSK) and quadrature amplitude modulation (QAM) based on Space Time Block Coded Orthogonal Frequency-Division Multiplexing based on Discrete Framelet transform (STBC-FT-OFDM) system. This comparison is accomplished through simulation programs for different constellation points numbers for M-PSK...
In this paper, different detection technique is presented through bit rate 1Gbps. Advanced modulation technique is used for enhancing the performance of optical access network. Differential phase shift keying (DPSK) has significant attention for the researcher during last two decades. Optisystem version 12 has been employ for investigate the transmission capability of the hybrid system. The comparison...
Over the years, different types of relay selection mechanism in wireless networks have been proposed for Cooperative Medium Access Control (MAC) protocols considering the metrics like — residual energy, delay, signal to noise ratio (SNR) etc. In recent days, distance metric is added to the list for optimal relay selection. However, protocols those use distance metric are found to be suffered from...
Optical splicing is regarded as the optical “welding” to combine two or more optical fiber to perform specific functions in modern optical telecommunication systems. In this paper, two crucial parameters in evaluating optical splicing; arc power and arc duration, are optimized for optical fiber splicing. Arc power of 32757 and arc duration of 12000 ms both yielded 0.01 dB splice loss while splicing...
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