PON architectures for next generation networks

As the Chief Technology Officer for Gigabit Fiber, I specialize in designing, permitting, and operating next-generation fiber and wireless networks. In this article, I will explore the different types of PON architecture(s) when designing and deploying future proof PON networks.

This is the first crucial step you need to decide on before anything else. Getting this wrong will result in a lot of wasted capital and time. With the following info, we will make sure that doesn't happen.

PON architecture types

In the world of PON, you primarily have three types of split setups:

● Centralized

● Distributed

● Indexing

We will go over each of the designs, and discuss the pros and cons of each, along with the architecture that I have chosen to go with for my deployments.

Centralized architecture

In a centralized splitter architecture, the entirety of the static split ratio is contained within the CO or ODN cabinet. In this configuration each customer usually gets their own dedicated fiber spliced in parallel from the cabinet to the customer premise.

This is the primary architecture I see the cable companies deploying (e.g. Spectrum, Cox). While this topology does allow for greater density, the drawback of this is the amount of fiber that is required, as each customer usually has a dedicated fiber (that needs to be spliced) back to the central splitter. This solution requires that you be fiber rich all the way to the customer premise.

Here are some advantages/disadvantages of using this architecture in your deployments:

Pros:

● Simplified network management due to centralized control

● Easier upgrade paths for network capacity enhancements

● Greater support for dense areas

Cons:

● Higher upfront infrastructure costs due to extensive fiber deployment requirements

● Potential for single points of failure, impacting large user groups

While this is a proven strategy, I steer away from this due to the amount of fiber/splicing required.

Distributed architecture

Unlike centralized architectures where the OLT/splitter devices are housed in a single central office or location, distributed architectures place remote OLTs and splitters in cabinet or underground enclosures closer to the customer. This approach is designed to reduce the length of the optical distribution network (ODN) from the central office to the subscriber, resulting in a reduction of fiber required for your PON solution.

This type of split architecture requires much less fiber compared to the centralized approach as splitters are distributed in handholes closer to the end user. This eliminates the need for each customer to have a dedicated fiber back to the ODN cabinet. Instead, dedicated fibers are only required for the splitters, which in turn connect to the end users using pre-terminated MST cables. This type of architecture allows for greater flexibility as you can distribute each splitter in various locations.

Pros:

● Enhanced network reliability and fault tolerance

● Reduced latency by bringing services closer to the user

Cons:

● Complexity in network management and maintenance

● Increased operational costs due to the distributed nature of equipment

Indexing architecture

Fiber indexing is the best of both worlds. It provides all the benefits of distributed splitters but with another major advantage. It uses a single fiber, which allows 12 terminals to be daisy chained in series. Instead of having to splice a dedicated fiber to each distributed splitter, indexing technology shifts the fiber position from one multifiber connector to another within each terminal. It also includes an integrated splitter within the terminal to feed users. This is truly a plug and play connectivity solution.

Fiber indexing deployments are quick and simple because the technology is based on fast and repeatable installation procedures. Unliked centralized deployments where you need to be fiber rich to every home, or distributed splitters where each splitter needs to be spliced back to the ODN, fiber indexing is very efficient as it achieves all the above across a single cable that is daisy chained down the line. You end up with a much more robust solution that requires less fiber, plus a lot less splices.

Advantages of indexing architecture:

● Saves as much as 70% of fiber cabling budget

● No splicing required in the terminal

● One of the best returns on investment in the industry

For these reasons I am choosing Fiber Indexing Architecture for all my FTTx rollouts. In my opinion, this is the key to the next evolution of FTTx networks.

It is crucial that you choose the right architecture for your deployment to achieve efficient, scalable, and cost-effective fiber rollouts. Let’s start building!

Alex Ochoa will be speaking at Light Reading Network X Americas. Join us in Texas from May 21-23, 2024, to learn more about XGS-PON progression, and the future of fiber and PON technologies.