Title :
A New Parallel Carrier Recovery Architecture for Intradyne Coherent Optical Receivers in the Presence of Laser Frequency Fluctuations
Author :
Gianni, Pablo ; Corral-Briones, Graciela ; Rodríguez, Carmen E. ; Carrer, Hugo S. ; Hueda, Mario R.
Author_Institution :
Lab. de Comun. Digitales, Univ. Nac. de Cordoba, Cordoba, Argentina
Abstract :
This paper introduces a new parallel carrier recovery architecture suitable for ultra- high speed intradyne coherent optical receivers (e.g., ≥40Gb/s). The proposed scheme combines a novel low-latency parallel digital phase locked loop (DPLL) with a feedforward carrier phase recovery (CPR) algorithm. The new low-latency parallel DPLL is designed to compensate not only frequency offset, but also frequency fluctuations such as those induced by mechanical vibrations. It is well-known that nonzero frequency offset leads to higher phase error variance in a feedforward CPR. Furthermore, it has been recently shown that laser frequency instability caused by mechanical vibrations significantly degrades the performance of CPR. Other effects such as power supply noise may also introduce laser frequency fluctuations. To avoid receiver performance degradations, both frequency offset and frequency fluctuations should be compensated before the feedforward CPR block. We show that this task can be achieved by using a typical decision-directed serial DPLL. Then, a new approximation to the DPLL computation is introduced to enable a parallel-processing implementation in multigigabit per second receivers. The proposed technique reduces the latency within the feedback loop of the DPLL introduced by parallel processing, while providing a bandwidth and capture range close to those achieved by a serial DPLL. Simulation results demonstrate that the effects caused by frequency deviations can be eliminated with the proposed parallel carrier recovery architecture.
Keywords :
digital phase locked loops; feedforward; laser frequency stability; optical phase locked loops; optical receivers; parallel algorithms; parallel architectures; decision-directed serial DPLL; feedback loop; feedforward CPR; feedforward carrier phase recovery algorithm; frequency offset compensation; laser frequency fluctuations; laser frequency instability; low-latency parallel DPLL algorithm; low-latency parallel digital phase locked loop; mechanical vibrations; nonzero frequency offset; parallel carrier recovery architecture; parallel processing; phase error variance; power supply noise; ultra-high speed intradyne coherent optical receivers; Feedforward neural networks; Frequency estimation; Frequency modulation; Optical receivers; Phase locked loops; Phase noise;
Conference_Titel :
Global Telecommunications Conference (GLOBECOM 2011), 2011 IEEE
Conference_Location :
Houston, TX, USA
Print_ISBN :
978-1-4244-9266-4
Electronic_ISBN :
1930-529X
DOI :
10.1109/GLOCOM.2011.6133717