Junita Mohd Nordin,Ts. Dr.
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/39951
2024-03-28T18:08:58ZNew catenated OFDM modulation scheme in zero cross correlation OCDMA at various number of user and effective power
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/69253
New catenated OFDM modulation scheme in zero cross correlation OCDMA at various number of user and effective power
Norizan Mohamed, Nawawi; Anuar, Mat Safar; Junita, Mohd Nordin; Mohd Rashidi, Che Beson
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.
Link to publisher's homepage at https://www.matec-conferences.org/
2017-01-01T00:00:00ZHarmonics suppression single-fed dual-circularly polarized microstrip patch antenna for future wireless power transmission
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/34953
Harmonics suppression single-fed dual-circularly polarized microstrip patch antenna for future wireless power transmission
Rosemizi, Abd. Rahim; Syed Idris, Syed Hassan, Prof. Dr.; Mohd Fareq, Abd. Malek, Dr.; Junita, Mohd Nordin; Haris Fazilah, Hassan
This paper presents a novel design of a harmonic suppression single-fed dual-circularly polarized microstrip patch antenna for a rectenna system in the future wireless power transmission application. The proposed antenna is capable of receiving both types of circular polarization signal; RHCP and LHCP simultaneously and at the same time it also able to filter the unwanted harmonic signals itself. These characteristics are achieved after introducing a circular slot defected ground structure to an array of nearly-square microstrip patch antenna with an offset inset microstrip feeding line and two open stubs on the feeding line. The proposed antenna is very simple on the single substrate only and this led to a reduction of errors that occurs during the fabrication process. However, the most importantly is the possibility of the polarization mismatch during transmission of signal can be minimized and the use of additional harmonic filter circuit can be eliminated. Thus the rectenna system becomes smaller, cheaper, less complexity and more efficient. The overall structure of the proposed antenna is designed on the top surface of the PCB only, thus it can be interfaced with other circuit such as rectifier or other circuit easily. The Computer Simulation Technology (CST) has been used in the simulation and optimization of the design. Finally, for the verification of the design, the prototype of the proposed antenna is fabricated and measured. From the simulation and measurement results, the proposed antenna can be a good choice in the rectenna system for future wireless power transmission application.
Link to publisher's homepage at http://www.enggjournals.com/
2013-10-01T00:00:00ZPerformance evaluation of Fi-Wi network based on SCM-optical code division multiple access architecture
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/34841
Performance evaluation of Fi-Wi network based on SCM-optical code division multiple access architecture
Junita, Mohd Nordin; Syed Alwee Aljunid, Syed Junid, Prof. Dr.; Rosemizi, Abd. Rahim; Anuar, Mat Safar, Ir. Dr.; Amir Razif Arief, Jamil Abdullah, Dr.; R. Badlishah, Ahmad, Prof. Dr.; Mohamad Naufal, Mohamad Saad
This paper investigates the performance of a spectral amplitude coding (SAC)-OCDMA system design utilizing subcarrier multiplexing techniques for use in the popular fiber-wireless (Fi-Wi) technology. Zero cross correlation code is employed because of its ability to eliminate phase induced intensity noise (PIIN) and the simplicity of using a direct detection technique at the receiving end. The performances are evaluated theoretically to derive the signal-to-noise ratio and results are presented in terms of bit error rates (BER). Results are analyzed to investigate the effect of code weight and variable data rates on the system performance. To validate the results, simulative analysis is also done using Optisys version 6.0. We demonstrated that the ZCC code performed better compared to other code for a BER floor of 10-9 with larger cardinality of subscribers. Results obviously indicate that system performance can be improved with larger code weight. In addition, the choice of lower bit rate is observed to perform better and more suitable for application in this hybrid Fi-Wi network.
Link to publisher's homepage at www.elsevier.com/
2013-10-01T00:00:00ZRealization of wavelength-time modified double weigs-button-field
http://dspace.unimap.edu.my:80/xmlui/handle/123456789/34377
Realization of wavelength-time modified double weigs-button-field
Amir Razif Arief, Jamil Abdullah, Dr.; Syed Alwee Aljunid, Syed Junid, Prof. Dr.; Anuar, Mat Safar, Ir. Dr.; R. Badlishah, Ahmad, Prof. Dr.; Junita, Mohd Nordin; Mohd Rashidi, Che Beson
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.
Link to publisher's homepage at http://www.ttp.net/
2014-01-01T00:00:00Z