A New Frequency Switching/IM3 Reduction Method in Fiber-Optic Microcellular System

Toshiaki OKUNO  Hironori MIZUGUTI  Shozo KOMAKI  Norihiko MORINAGA  

Publication
IEICE TRANSACTIONS on Communications   Vol.E76-B   No.9   pp.1178-1185
Publication Date: 1993/09/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Fiber-optic Microcelluler Radio Communication System and Their Technologies)
Category: Propagation Matters
Keyword: 
microcell,  radio communication,  optical communication,  intermodulation,  frequency switching,  

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Summary: 
Fiber-optic microcellular system has been studied actively as an excellent system for solving the equipment cost problems in microcellular systems. However, the occurrence of intermodulation distortion (IMD) arising from the nonlinearity of the laser diode used for E/O conversion which degrades the transmission quality is a serious problem in this system. In this paper, we propose a new frequency switching/IM3 reduction method, which dynamically reassigns the carrier frequencies to minimize the carrier to IMD power ratio under the hostile environment with time-varying received carrier strength, and analyze the performance improvements by the proposed method. The improvements obtained both for the worst value of the overall CNR and for the overall CNR in a specific user are numerically made clear. It is also shown that if the interval between frequency reassignings is set less than one second, a sufficient improvement in the overall CNR is achievable.