1 Current ITU-T recommendations for optical transmission systems
1.1 Recommendations for PON by ITU and IEEE

ITU (International Telecommunication Union) published recommendation for Passive Optical Networks (PON), including Reach Extended PON. There are a number of options in terms of attenuation classes, reach, wavelengths and bit rates.

PON - Passive Optical Networks (one of the main topics addressed in this teaching module) is a multipoint network that can be classified according to the functionality of components splitting optical signals. It uses passive components (of course besides lasers as sources of optical symbols), where power level decreases gradually with the distance from the laser sources.

Basic recommendation for current Passive Optical Networks - comparison of IEEE and ITU-T standards.
Recommendation | 10GEPON by IEEE 802.3av (2009) | EPON by IEEE 802.3ah (2004) | GPON by ITU-T G.984 (2003) | XG-PON by ITU-T G.987 (2010)
Transmission rate options | 10G/10G symmetric or asymmetric | 1G/1G symmetric | 1.25G/1.25G symmetric, 2.5G/1.25G asymmetric, 2.5G/2.5G symmetric | 10G/2.5G asymmetric
Transmission rate at the physical layer | 10.3125 Gbps, 1.25 Gbps | 1.25 Gbps | 1.24416 Gbps, 2.48832 Gbps | 9.95328 Gbps, 2.48832 Gbps
Attenuation classes | PR10, PRX10, PR20, PRX20, PR30, PRX30 | PX10, PX20 | Class A, B, B+,C | Class Nominal 1, 2, Class Extended 1, 2
Wavelengths [nm] | Downstream 1575-1580 Upstream 1260-1280 or 1260-1360 | Downstream 1480-1500 Upstream 1260-1360 | Downstream 1480-1500 Upstream originally 1260-1360, newly 1290-1330 | Downstream 1575-1580 Upstream 1260-1260
Physical reach [km] | ≤10, ≤20 | ≤10, ≤20 | ≤20 | ≤20 (future ≤40)
Max. splitting ratio | 1:16, 1:32 (future 1:64, 1:128) | 1:16, 1:32 | 1:64 (proprietary 1:128) | 1:256