Power Budget Improvement in Passive Optical Networks Using PAM4 Hierarchical Modulation

Hierarchical PAM4 modulation in passive optical network downstream channels is experimentally demonstrated as a way to redistribute power margin between users with different path losses due to unequal fiber distribution and split losses. Using hierarchical PAM4 modulation the most-significant bit (M...

Full description

Saved in:
Bibliographic Details
Published in:IEEE photonics technology letters 2017-10, Vol.29 (20), p.1747-1750
Main Authors: Dalla Santa, Marco, Antony, Cleitus, Talli, Giuseppe, Townsend, Paul D.
Format: Article
Language:English
Subjects:
Bandwidths
Budgeting
Budgets
Dispersion
Fiber optic communications
Fiber optic networks
hierarchical modulation
Modulation
Optical communication
Optical network units
Optical receivers
PAM4
Passive optical networks
power budget
Sensitivity
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Hierarchical PAM4 modulation in passive optical network downstream channels is experimentally demonstrated as a way to redistribute power margin between users with different path losses due to unequal fiber distribution and split losses. Using hierarchical PAM4 modulation the most-significant bit (MSB) and less-significant bit (LSB) can be assigned to two different optical network units (ONU) groups, whose receiver sensitivity can be optimized to increase the power budget of the ONUs with higher path losses, effectively redistributing power margin of the ONUs with lower losses. A single-threshold receiver is sufficient for the MSB ONU type and a dual-threshold receiver coupled with an and logic gate for the LSB ONU type, both of which are simpler than a full PAM4 receiver with three thresholds. Sensitivity improvement in a 25 Gb/s system is achieved using unequal signal level spacing and separate detection of the binary tributary streams of the PAM4 channel. Power budget increase of up to 3.5 dB is reported with respect to a standard PAM4 transmission. Higher chromatic dispersion tolerance is also measured for the higher sensitivity ONU group, enabling transmission over up to 40 km of single-mode fiber for the MSB ONUs with no chromatic dispersion compensation.
ISSN:1041-1135
1941-0174
DOI:10.1109/LPT.2017.2752283