How coherent technology decisions that start in the lab impact your network
What is the difference between 400G, 600G and 800G coherent solutions? It seems to be obvious, but is it just about maximum wavelength capacity? Why are different baud, modulations or DSP implementations used, and more importantly, what are the networking implications associated with each?
By Helen Xenos – 32QAM, 64QAM, and hybrid modulation….32, 56, 64, now 95Gbaud? Are they really any different? Fixed grid, flex grid, what’s 75GHz? Is your head spinning yet?
Coherent optical technology is a critical element that drives the amount of capacity and high-speed services that can be carried across networks and is a critical element in controlling their cost. But with multiple generations of coherent solutions available and more coming soon, navigating the different choices can be difficult. Unless you are immersed in the details and relationships between bits and symbols, constellations and baud in your everyday life, it can be confusing to understand how the technology choices made in each solution influence overall system performance and network cost.
To clarify these relationships, here is an analogy that helps provide a more intuitive understanding: consider performance-optimized coherent optical transport as analogous to freight transport.
The goal of network providers using coherent is to transport as much capacity as they can, in the most cost-efficient manner that they can, using wavelengths across their installed fiber. This is similar to wanting to be as efficient as possible in freight transport, carrying as much payload as you can using available truck and road resources. more>
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