Open AccessClock recovering characteristics of adaptive finite-impulse-response filters in digital coherent optical receivers
Author(s) -
K. Kikuchi
Publication year - 2011
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.19.005611
Subject(s) - computer science , finite impulse response , asynchronous communication , electronic engineering , digital clock , digital filter , clock recovery , transmitter , block (permutation group theory) , clock drift , synchronous circuit , clock signal , algorithm , bandwidth (computing) , telecommunications , jitter , mathematics , engineering , channel (broadcasting) , geometry
We analyze the clock-recovery process based on adaptive finite-impulse-response (FIR) filtering in digital coherent optical receivers. When the clock frequency is synchronized between the transmitter and the receiver, only five taps in half-symbol-spaced FIR filters can adjust the sampling phase of analog-to-digital conversion optimally, enabling bit-error rate performance independent of the initial sampling phase. Even if the clock frequency is not synchronized between them, the clock-frequency misalignment can be adjusted within an appropriate block interval; thus, we can achieve an asynchronous clock mode of operation of digital coherent receivers with block processing of the symbol sequence.