A novel 2-D wavelength-time Optical Code Division Multiple Access (OCDMA) code for high-performance system

• Main Author: Amir Razif Arief, Jamil Abdullah
• Format: Thesis
• Language: English
• Published: Universiti Malaysia Perlis (UniMAP) 2014
• Subjects: Code length; Multiple access interference (MAI); Optical Code Division Multiple Access (OCDMA); OCDMA system; Wireless communication systems; Optical network
• Online Access: http://dspace.unimap.edu.my:80/dspace/handle/123456789/31214
• Institution: Universiti Malaysia Perlis

The explosive growth of bandwidth demand, together with advance in latest communication services and emerging applications has inspired huge interest in application of code division multiple access (CDMA) technique in optical network. The major interference factor in optical CDMA (OCDMA) is to overcome the multiple access interference (MAI) noise which induces the occurrence of bit error rate. Ideal code property with minimum cross-correlation will mitigate MAI, reduce phase induced intensity noise (PIIN) and expand code scalability. Part of the work devotes to analyzing how OCDMA can suit into the future generation of optical network. In this thesis the new incoherent two-dimensional (2-D) modified double weight (MDW) OCDMA wavelength-time is proposed and demonstrated. The thesis begins with an explicit construction of incoherent 2-D MDW OCDMA system with allocation of wavelength and time dimensions resources to aspire performance goals and designed parameters. A novel 2-D MDW OCDMA uses balance detection for mitigating MAI. The code is theoretically analyzed and simulated for the performance. The good property of cross-correlation results in optimum PIIN suppression in comparison to the other codes such as 2-D PDC and 2-D MQC. This is reflected through high SNR value or low bit error rate (BER) as the cardinality increases. The comparison outcome of the proposed 2-D MDW code with 2-D PDC, 2-D MQC and 1-D MDW code indicates substantial performance improvements in cardinality, BER, bit rate and distance. The proposed code achieves high scalability; below 10-9 BER error floor the code cardinality reaches 189 simultaneous numbers of users which is double the 2-D PDC performance. The lowest effective transmitted power (Psr) for minimum optical transmission requirement for smallest number of users is achieved at -22.5 dBm. The combination of wavelength and time-chip can be further enhanced the overall system performance. The proposed code has successfully mitigating MAI by the balance detection technique. The 2-D MDW OCDMA simulation model is developed to validate the realization of the code for BER, bit rate and distance performance. In short the 2-D MDW OCDMA code successfully suppresses PIIN and mitigating MAI which result in high cardinality, reduce Psr, high bit rate and distance.