"Service-uniform" ONU Based on Low Cost Audio AD/DA Converters and CDM with Novel Code Word Sets

Tetsuya ONODA  Tetsuo TSUJIOKA  Ryuma KAKINUMA  Seiichi YAMANO  

IEICE TRANSACTIONS on Communications   Vol.E82-B   No.9   pp.1446-1458
Publication Date: 1999/09/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Optical Communication
optical access network,  line card,  ISDN basic rate access,  A/D converter,  CDM,  

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This paper proposes a novel universal line termination scheme for the ONUs (optical network units) of fiber-optic local access systems. Its main feature is that only low cost AD/DA converters for Hi-Fi audio are needed. Because audio AD/DA converters are insufficient for ISDN basic rate access (● 320kbaud) and cause waveform distortion, we develop a simple detection algorithm that does not use any equalizing filter. The algorithm can handle plural channels with one general purpose MPU (micro-processing unit). Based on this, a novel architecture for a fiber-optic local access system is presented that removes the MPUs from each optical network unit (ONU) and places them in the central office (CO). The proposed system yields a small, service-uniform ONU that supports a wide range of narrow-band services (POTS & ISDN) with no distinction. To realize this system at the lowest possible cost, a high-speed code division multiplexing (CDM) scheme with novel code word sets is developed.