Reduction of multiple-access interference for optical CDMA systems

Abstract Optical code division multiple access (OCDMA) system provides highly secured transmission in addition to its capabilities to support asynchronous transmission and soft blocking. Two-dimensional OCDMA codes are chosen in this paper due to their high cardinality, good spectral efficiency and flexibility in their construction methods against direct sequence codes. This paper focuses on study of impact of multiple access interference (MAI) at high data rates for 2-D prime codesbased OCDMA system. It is shown that how the change in number of simultaneous users affects the transmission quality. Further, performance of the system is analysed in terms of bit error rate, received electrical power and eye openings. In addition, this paper also shows a comparative analysis of 2-D codes-based OCDMA system and wavelength division multiple access (WDMA) system in order to justify the improved performance of the proposed system. It is observed that the performance of 2-D OCDMA system is much better than WDMA system in terms of quality as well as security.

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Unified KS-Code

Encyclopedia of Multimedia Technology and Networking, Second Edition ◽

10.4018/978-1-60566-014-1.ch198 ◽

2009 ◽

pp. 1473-1479 ◽

Cited By ~ 1

Author(s):

M. K.A. Abdullah ◽

S. A. Aljunid ◽

M. D.A. Samad ◽

S. B.A. Anas ◽

R. K.Z. Sahbudin

Keyword(s):

Multiple Access ◽

Direct Detection ◽

Multiple Access Interference ◽

Optical Cdma ◽

Spectral Amplitude ◽

Service Guarantees ◽

Narrow Bandwidth ◽

Network Topologies ◽

Spectral Amplitude Coding ◽

Code Division Multiple

Many codes have been proposed for optical CDMA system as discussed in Svetislav, Mari, Zoran, Kosti, and Titlebaum (1993), Salehi (1989), Liu and Tsao (2002), Maric, Moreno, and Corrada (1996), Wei and Ghafouri-Shiraz (2002), and Prucnal, Santoro, and Ting (1986). Optical code division multiple access (OCDMA) has been recognized as one of the most important technologies for supporting many users in shared media simultaneous, and in some cases can increase the transmission capacity of an optical fiber. OCDMA is an exciting developments in short haul optical networking because it can support both wide and narrow bandwidth applications on the same network, it connects large number of asynchronous users with low latency and jitter, and permits quality of service guarantees to be managed at the physical layer, offers robust signal security and has simplified network topologies. However, for improperly designed codes, the maximum number of simultaneous users and the performance of the system can be seriously limited by the multiple access interference (MAI) or crosstalk from other users. Another issue in OCDMA is how the coding is implemented. The beginning idea of OCDMA was restricted in time domain, in which the encoding/decoding could not been fully utilized in optical domain. Therefore a new coding in OCDMA has been introduced based on spectral encoding (Kavehrad & Zaccarin, 1995; Pearce & Aazhang, 1994; Smith, Blaikie, & Taylor, 1998; Wei & Ghafouri-Shiraz, 2002). The system, called Optical Spectrum CDMA, or OS-CDMA, has the advantage of using inexpensive optical sources, and simple direct detection receivers. In this article with an emphasis on the Spectral Amplitude Coding scheme, a new code known as Khazani-Syed (KS) code is introduced.

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Comparison of multiple access interference in asynchronous MC-CDMA and DS-CDMA systems

Seventh International Symposium on Signal Processing and Its Applications, 2003. Proceedings. ◽

10.1109/isspa.2003.1224886 ◽

2003 ◽

Cited By ~ 2

Author(s):

D. Carey ◽

D. Roviras ◽

B. Senadji

Keyword(s):

Multiple Access ◽

Multiple Access Interference ◽

Cdma Systems

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