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