Constellation shaping

Constellation shaping is an energy efficiency enhancement method for digital signal modulation that improves upon amplitude and phase-shift keying (APSK) and conventional quadrature amplitude modulation (QAM)) modulation by transmitting low-energy signals more frequently than high-energy signals.

A constellation is a pattern of the possible signal combinations. In a static constellation, all of the combinations are used equally. In practice, however, the transmission media (channel) distorts the signal unevenly; some combinations require lower energy and resist channel noise more than others.

A shaped constellation transmission sends some signal combinations more often and others less frequently to optimize the signal quality at the destination, or to maintain the same quality using less transmission energy.

Probabilistic constellation shaping

Probabilistic (and adaptive) constellation shaping changes the shaping parameters based on predefined terms. This allows a significant capacity increase (e.g. 15–43% on 16-QAM channel). This technique gathered more interest in September 2016 when Nokia Bell Labs demonstrated working 1 Tbit/s data transmission channels between German cities.[1] In October 2016, Alcatel-Lucent and Bell Labs claimed to have achieved 65 Tbit/s transmission over a 6,600 km (4,100 mile) single mode fiber in laboratory trials.[2]

References

1. "Optical fiber transmits one terabit per second". Technical University of Munich. 2016-09-16. Retrieved 2016-09-23.
2. Jeffrey, Colin (October 13, 2016). "Nokia's super-fast subsea data cable torpedos [sic] the competition". newatlas.com. Retrieved 2016-10-14.

External links

• Fehenberger, Tobias; Alvarado, Alex; Böcherer, Georg; Hanik, Norbert (2016-06-13). "On Probabilistic Shaping of Quadrature Amplitude Modulation for the Nonlinear Fiber Channel". Journal of Lightwave Technology. 34 (21): 5063. arXiv:1606.04073. Bibcode:2016JLwT...34.5063F. doi:10.1109/JLT.2016.2594271.
• Buchali, Fred; Böcherer, Georg; Idler, Wilfried; Schmalen, Laurent; Schulte, Patrick; Steiner, Fabian (2015-09-29). "Experimental Demonstration of Capacity Increase and Rate-Adaptation by Probabilistically Shaped 64-QAM". arXiv:1509.08836 [cs.IT].
• Xiang, Xingyu; Valenti, Matthew C (2012-10-17). "Closing the Gap to the Capacity of APSK: Constellation Shaping and Degree Distributions". arXiv:1210.4831 [cs.IT].
• Häger, Christian; Alexandre Graell i Amat; Alvarado, Alex; Agrell, Erik (2012-09-24). "Design of APSK Constellations for Coherent Optical Channels with Nonlinear Phase Noise". IEEE Transactions on Communications. 61 (8): 3362–3373. arXiv:1209.5221. Bibcode:2012arXiv1209.5221H. doi:10.1109/TCOMM.2013.061913.120713.
• Simulation of optical coherent transmission using probabilistic shaping