Optical Distribution Network

FTTH - Optical Distribution Network

Comparison of ODN Class A, B, and C Optics

In this chapter, let us understand what Split Ratios, Maximum Reach and Traffic Management are in the Optical Distribution Network (ODN).

The maximum permissible optical power attenuation between OLT optical ports to ONT input is 28dB, which is by utilizing the so-called Class B optical network elements. ODN Class A, B, and C are differentiated mainly on the ‘optical transmitter power output’ and ‘bit-rate optical receiver sensitivity.’ Class A gives the least optical-budget and Class C gives the highest, while cost wise they are in the same order. For maximum 1:64 split ratio, Class B optics is commonly deployed on commercial basis.

The comparison of class A, B, and C ODN optics is shown in the table given below −

S.No.ParameterUnitClass AClass BClass CRemarks
1Attenuation range (ITU-T Rec. G.982)dB5 – 2010 – 2515 – 30
22488 Mbps downstream direction
2.1OLT Transmitter
2.1.1Mean launched power MINdBm0+5+3Single fiber
2.1.2Mean launched power MAXdBm+4+9+7Single fiber
2.1.3Mean launched power MINdBm0+5+3Dual fiber Mean launched power MAXdBm+4+9+7Dual fiber
2.2ONU Receiver
2.2.1Minimum sensitivitydBm-21-21-28Single fiber
2.2.2Minimum overloaddBm-1-1-8Single fiber
2.2.3Minimum sensitivitydBm-21-21-28Dual fiber
2.2.4Minimum overloaddBm-1-1-8Dual fiber
31244 Mbps upstream direction
3.1ONU Transmitter
3.1.1Mean launched power MINdBm-3-2+2Single fiber
3.1.2Mean launched power MAXdBm+2+3+7Single fiber
3.1.3Mean launched power MINdBm-3-2+2Dual fiber
3.1.4Mean launched power MAXdBm+2+3+7Dual fiber
3.2OLT Receiver
3.2.1Minimum sensitivitydBm-24-28-29Single fiber
3.2.2Minimum overloaddBm-3-7-8Single fiber
3.2.3Minimum sensitivitydBm-24-28-29Dual fiber
3.2.4Minimum overloaddBm-3-7-8Dual fiber