Page 302 - Optical Communications Essentials

Optical Networks

292 Chapter Seventeen

TABLE 17.4. Source Output, Attenuation, and Receiver Ranges for Various Rates and
Distances up to 80km (See ITU-T G.957)
Parameter Intraoffice Short-haul (1) Short-haul (2) Long-haul (1) Long-haul (3)
Wavelength, nm 1310 1310 1550 1310 1550
Fiber SM SM SM SM
Distance, km 2 15 15 40 80
Designation I-1 S-1.1 S-1.2 L-1.1 L-1.3
Source
range, dBm
155Mbps 15 to 8 15 to 8 15 to 8 0 to 5 0 to 5
622Mbps 15 to 8 15 to 8 15 to 8 3 to 2 3 to 2
2.5Gbps 10 to 3 5 to 0 5 to 0 2 to 3 2 to 3
Attenuation
range, dB
155Mbps 0 to 7 0 to 12 0 to 12 10 to 28 10 to 28
622Mbps 0 to 7 0 to 12 0 to 12 10 to 24 10 to 24
2.5Gbps 0 to 7 0 to 12 0 to 12 10 to 24 10 to 24
Receiver
sensitivity, dBm
155Mbps 23 28 28 34 34
622Mbps 23 28 28 28 28
2.5Gbps 18 18 18 27 27

updated periodically, so the reader should refer to the latest version of the doc-
uments for specific details.
Longer transmission distances are possible by using higher-power lasers. To
comply with eye-safety standards, an upper limit is imposed on fiber-coupled
powers. If the maximum total output power (including ASE) is set at the Class-
3A laser limit of P 3A 17dBm, then for ITU-T G.655 fiber this allows trans-
mission distances of 160km for a single-channel link. Using this condition, for
M operational WDM channels the maximum nominal channel power P chmax
should be limited to
P chmax P 3A 10log M (17.1)

17.2.3. SONET/SDH rings
A key characteristic of SONET and SDH is that they usually are configured as
a ring architecture. This is done to create loop diversity for uninterrupted ser-
vice protection purposes in case of link or equipment failures. The SONET/SDH
rings commonly are called self-healing rings, since the traffic flowing along

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