Analysis of beat noise in coherent and incoherent time-spreading OCDMA

• Published in: Journal of lightwave technology Vol. 22; no. 10; pp. 2226 - 2235
• Main Authors: Xu Wang, Kitayama, K.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.10.2004; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Additive noise; Additives; All-optical networks; Applied sciences; Bandwidth; Chips; Coherence; Exact sciences and technology; Information systems; Light sources; Multiaccess communication; Networks; Next generation networking; Noise; Optical fiber networks; Optical noise; Passive optical networks; Quality of service; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Additive noise; Performance evaluation; Beat noise; communication systems; Bit error rate; Optical telecommunication; optical networks; Wireless telecommunication; code-division multiple access (CDMA); Time spreading; Optical fiber network; Telecommunication system; Code division multiple access; Coherence; Optical fiber communication
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2004.833267

The effect of beat noise and other types of additive noise in time-spreading optical-code-division multiple-access (TS-OCDMA) networks is analyzed in this paper. By defining the coherent ratio kt, the ratio of the chip duration to the coherence time of the light source, TS-OCDMA systems are classified into incoherent, partially coherent, and coherent systems. The noise distributions and the bit-error rates are derived, and system performance is discussed for different cases. The performance of coherent systems is limited by the beat noise. With increasing kt, the effect of beat noise decreases in incoherent systems, and they eventually become free of beat noise. Possible solutions to the beat noise problem in coherent and partially coherent systems are also proposed and discussed.