Hello,
I want to find out Throughput of an Optical Interconnection Network by with the help of a simulator like Booksim2 / Sniper.
By definition, throughput is no. of bits ( or bytes) per second that can flow through a link.
In case of an optical fiber, if the modulation rate is 10 GHz and it is carrying 64 wavelengths, the total throughput is 640 bits/second.
In many Optical Interconnect papers, I am seeing losses are considered like bending loss,insertion loss etc. How losses can impact throughput of an optical fiber ? What is the mathematics behind that ? If somebody can suggest any material about this, that will be great help.
There is a minimum optical power required to receive a bit (Sorry, I do not have a reference at hand. But this is a fact.) Use the search engine of your choice...
Thus, given a 'link budget', losses reduce the power at the receiving end. Up to the point where the signal can no longer be received due to the lack of power.
Ho0e this helps to proceed.
Thank you Dreher.
But does Power Loss affects the Throughput in case where the Optical Power Level is still good for Transmission ?
Any optical receiver will add some noise to the recovered signal. If the signal is too small compared with the noise, the decision circuit will make errors in identifying the state of some input symbols. For binary modulation, a proportion of ones will be recovered as zeros, and vice-versa.
Propagation, bending and insertion losses all reduce the signal power at the receiver. If the signal is too low, the bit error rate (BER) will rise. In amplified systems, each optical amplifier will add noise.
A convenient assumption is that the noise follows Gaussian statistics, in which case there are are closed form expressions for BER. Often the noise is not strictly Gaussian - for example amplified spontaneous emission noise in optically amplified systems with square-law detection, or non-linear distortion and crosstalk in optical fibres - but a Gaussian approximation is a good starting point.
Communications links commonly use forward error correction to reduce BER. Additional symbols are transmitted using a redundant coding scheme. Data integrity is improved at the expense of a reduction in payload throughput, additional signal processing and an increase in latency.
https://en.wikipedia.org/wiki/Bit_error_rate
https://en.wikipedia.org/wiki/Forward_error_correction
https://fenix.tecnico.ulisboa.pt/downloadFile/3779572211086/Fiber-Optic%20Communication%20Systems%20(3rd%20ed%2C%202002).pdf
http://eu.wiley.com/WileyCDA/WileyTitle/productCd-0470505117.html
640 bits/second is the data rate . Throughput is less because of errors . . .
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