If you are unfamiliar with the term “CoExistence Element,” you won’t be for long. It’s coming, and faster than you think.

Next-Generation PON2 (NGPON2) is a 40 Gb/s multi-wavelength system that can grow to 80 Gb/s. Time and Wavelength Division Multiplexed–Passive Optical Network (TWDM-PON) is the technology that will be used to implement NGPON2.

Although the current 2.5-GPON architecture is more than enough bandwidth for the average residential customer, the goal of NGPON2 is to merge Fiber-To-The Business, mobile backhaul/fronthaul networks and “cloud opportunities” onto that existing network.

The advantage of TWDM-PON is it can support different types of customers and applications by using various wavelengths and a variety of bitrates on those wavelengths. It has the ability to allocate a single wavelength to an individual subscriber like a business, or to a specific application, like mobile backhaul. Business and mobile services sometimes require symmetrical rates, often more than 1 Gb/s. Some larger enterprise customers demand dedicated wavelength, point-to-point services. Although Gfast MDU solutions use copper in the building, they require greater fiber backhaul speeds. For these reasons, NGPON2 will initially roll out to business class services, mobile networks and MDUs. SFU bandwidth needs will lag, but by 2020, they also will start to feel the “bandwidth burn.”

With the functionality of a CoExistence Element, TWDM-PON can serve these new potential services over the same optical network without disruption to the current GPON network, and preserve the legacy investment.

Although technology advances often surprise even the most technical of us in our industry, I have been told we are starting to reach the technological limit that Time Division Multiplexing (TDM) can achieve. It is getting increasingly hard to turn on and off that laser faster and faster and still recognize it at the other end as a 1 or a 0. And in its simplest form, that is what TDM is: the presence of light is a one, the absence of light is a zero. WDM is where our bandwidth growth will shine. Some of the leading scientists in our industry say theoretically there is NO limit to how many wavelengths we can make work. We just keep “halving” the wavelength spacing, which doubles the number of wavelengths, creating thousands of usable wavelengths, which should last us well into the future.

I have up close and personal experience with two CoExistence elements. Last November, I had open-heart surgery to replace a valve and reinforce a weakened aorta. The surgeon used a pig valve, and “tissue” from a calf. I am happy to report they are coexisting just fine. (No, I haven’t given up bacon or hamburgers.)

When it’s time to add an element to your network and you want to make sure it can coexist with current network elements, please contact us. Clearfield^® offers CoExistence Element WDM solutions that can be tailored to meet your needs. Below is a drawing that demonstrates where a CoExistence Element fits into a GPON and NGPON2 hybrid network with specific Clearfield part numbers.

I’m living proof that CoExistence Elements work. TDM and WDM are a winning combination, like peanut butter and jelly or bacon, lettuce and tomato.

It’s remarkable what the medical field can do to save lives these days. Just as remarkable are the technological advances our industry continues to make to keep up with the voracious appetites of our customers.

And remember…“He who has a why to live can bear almost any how.” – F. Nietzsche

By Jim Pilgrim

Jim Pilgrim has 40 years of experience in telecommunications with Northwestern Bell/US West, Fujitsu and Clearfield. His work experience includes Central Office switching, fiber optic transport, Fiber to the Home (FTTH) and engineering. Jim currently works as an application engineer at Clearfield, where he helps customers design Fiber to the Home networks across the country.