Experiment on Optical Code-Division-Multiple-Access Switch System Using Spectral Amplitude Encoding of Light-Emitting Diodes
Significant research is directed toward developing fiber-optic local distribution networks providing high data rate transmission in the local end of the backbone network. Code-Division Multiple-Access (CDMA) technique is capable of utilizing the optical channel bandwidth to provide simultaneous asynchronous access. Time-encoded optical CDMA systems can be classified according to the type of encoding, coherent or incoherent. Incoherent time-domain CDMA has advantages of direct detection and low-cost low-coherence optical sources1–3. Coherent time-domain encoding is more difficult to implement4. Such systems with low-coherence sources have also been proposed5. For time-encoded CDMA, the code length increases with the number of users and spectrum broadening occurs. To overcome the drawbacks of time-encoded CDMA, frequency-encoded systems have emerged based on coherent phase coding of ultrashort pulses6. Users operate at data rates compatible with the electronics, but high-cost mode-locked lasers are required. An optical CDMA system based on incoherent amplitude encoding of low-cost light-emitting diodes (LEDs) and direct-detection receivers has been proposed by D. Zaccarin and M. Kavehrad7–8. A comprehensive overview of the optical CDMA systems has been introduced by K. Iversen9.
KeywordsCDMA System Optical Code Division Multiple Access Optical Transfer Function Spatial Frequency Domain High Data Rate Transmission
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