Specifications

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Cisco ONS 15530 Planning Guide
OL-7708-01
Chapter 5 Amplified Network Planning
Amplified Network Planning Guidelines
Chromatic Dispersion
Chromatic dispersion occurs because different wavelengths propagate at different speeds.It can result in
signal power spread and can reduce receiver sensitivity.
Amplified Network Planning Guidelines
This section describes the guidelines for planning a Cisco ONS 15530 amplified network.
Receive Power Levels
Receiver power levels for individual transponder line cards and ITU trunk cards should be within the
power range defined by minimum receiver sensitivity and maximum receiver overload for each card.
Depending on network configuration characteristics, such as dispersion and OSNR, apply the proper
penalties to the minimum receiver sensitivity.
Optical Component Gain or Loss
Use the statistical gain or loss, determined by mean and variance values, for optical components in the
network, such as OADM modules, connectors, and EDFAs. The loss for OADM modules should be
based on measured data, and the gain should be based on the gain flatness specification (+/- 0.75 dB) of
the Cisco ONS 15501 EDFA. The gain or loss of optical components should be accumulated in a
statistical manner, such that the mean and variance of the total gains and losses is the sum of individual
means and variances. The maximum gain or loss of an aggregate of optical components is equal to the
mean plus three times the standard deviation (sigma), and the minimum gain or loss is equal to the mean
minus three times the standard deviation.
EDFA Input Power Limits
The maximum total input power to a Cisco ONS 15501 EDFA is 0 dBm and the minimum total input
power is –29 dBm.
OSNR
Use the following equation to compute the OSNR:
OSNRout = –10*log(10
–OSNRin/10
+ 6.33*10
–6
* 10
–Pin/10
)
where OSNRin and Pin are the OSNR and input power, respectively, of the signal at the input of the
EDFA, and OSNRout is the OSNR of the signal at the output of the EDFA.
The signal OSNR at the receiver should be higher than the minimum OSNR required for the particular
card type and the data bit rate, with the proper penalties for dispersion depending on network
configuration.
The above OSNR calculations can be carried out manually to verify the OSNR of individual optical
channels. However, we recommend that a network design tool, such as Metro Planner, be used to validate
all amplified network designs.