Proposal of New Spreading Code Generation Method in Direct Optical Switching CDMA RoF System

摘要

Direct Optical Switching (DOS) CDMA system is proposed as a multiple access method for RF signals in RoF network. In this system, following two methods can improve received carrier-to-interference ratio (CIR): the increase of chip rate with its constant spreading code period, and the expansion of spreading code length in time domain with its constant chip rate. In the second method, CIR performance can be improved without using high speed photonic switch devices. However, the "aliasing canceller" whose signal processing is relatively complicated, must be used to eliminate aliasing distortions. This paper proposes a new spreading code generation method to suppress aliasing distortions without using any processing at the receiver in DOS CDMA RoF system and experimentally investigates the signal qualities.