Four-Dimensional Coded Modulation for Coherent Optical OFDM Systems


In Charge: Dipl.-Ing Ümit Abay
Project Funding: DFG
Duration: 04/2011 -- 02/2013
Keywords: Coded Modulation, CO-OFDM, coherent optical transmission, 4D signal constellation


In order to cope with the steadily growing demand for capacity in metro and core networks, an ongoing maximization of the utilization of fiber bandwidth is pursued. This led to the use of higher-order signal constellations, such as QPSK or 16QAM in combination with coherent receivers.

Besides the classical benefits of coherent systems, e.g., higher sensitivity (power efficiency), increased spectral efficiency and the potential for digital equalization, additionally also the use of both polarization components of the electromagnetic field is enabled. One opportunity to utilize this additional degree of freedom is to transmit conventional bi-dimensional signal constellations, e.g., M-QAM, or M-PSK, over both polarizations leading to polarization-division multiplexed (PDM) systems. On the contrary, one can consider the new multiplexing dimension as four-dimensional (4-D) signal space, in which modulation formats with improved performance can be designed.

Major Goals

  • Evaluation and Optimization of 4D Signal Constellations in Optical Coded Modulated Systems
  • Application-Oriented Evaluation of 4D Coded Modulation Strategies in Coherent Optical OFDM Systems

Persons Involved

Project Members

Alcatel-Lucent Stuttgart