Fiber to the X (FTTX) Networks

Optical fiber is essential to broadband networks as it is more efficient and offers higher bandwidth than copper over longer distances. FTTX networks are an increasingly popular network archetype that utilizes fiber deployments in the “last mile” portion of a network to optimize network performance.

Last mile challenges

In a typical network infrastructure, a central hub transports data downstream/upstream from the core network to the network subscribers via transmission lines. One of the core challenges in building a network is figuring out how to tackle the “last mile” portion of the network. The “last mile” in telecommunications refers to the final leg of the network in which the delivery system physically reaches end user premises.

The last mile of a network is often the most expensive and difficult to build given the high number of individual user lines in a network. To illustrate this in an analogy, a network is similar to a tree that has a few large “trunks” (central hub lines) with many different “twigs” (end user lines) branching off of them. Building the large “trunks” is less expensive because there are fewer of them, and they each have high capacity. In contrast, there are far more “twigs” than “trunks” in a network, so building numerous, individual “twigs” is significantly more expensive.

Furthermore, there are a many different types of end user equipment. Existing coaxial equipment may also lack compatibility with fiber equipment. Finding a way to interface user equipment with fiber deployments to accommodate end users adds greater complexity to the network architecture. Although service providers spend a great deal on reorganizing network topologies, the last mile continues to be a bottleneck for most traditional networks.

FTTX networks

As network demands are constantly evolving, the focus for service providers has shifted greatly to Next-Generation Access (NGA) networks. NGA networks emphasize incorporating more optical elements into the network to improve broadband performance and improve the quality of services available to the end user.

Although many modern networks have mostly swapped out copper for fiber throughout the bulk of the network, copper is still predominantly used for the last mile portion of the network. FTTX networks are networks that incorporate fiber into all or some of the last mile. The term FTTX (Fiber to the X) is an umbrella term in which the 'X' is used as a variable to describe the termination point for the fiber in the network. Examples include:

FTTP

FTTP (Fiber to the premises) networks are a general term for networks that connect directly to the premises. FTTP networks are generally considered the most efficient types of fiber networks because they bring fiber much closer to the end user and reduce the amount of copper in a network. The tradeoff is that FTTP networks are more expensive to build.

Subcategories of FTTP (Fiber to the premises) networks include:

FTTH

In a FTTH (Fiber to the home) network, the termination point for the fiber is the actual home as it reaches the boundary of the living space. The fiber connects directly to a box located inside or just outside the user’s office space or home, delivering low latency network performance to the end user.

FTTB

Similarly, a FTTB (Fiber to the building) network deploys fiber that terminates at the boundary of a building but does not directly connect to the living space. This kind of network is used for multi-dwelling units such as an apartment building or a gated community where the fiber connectivity is shared by multiple tenants.

FTTN

FTTN (Fiber to the node) networks are networks in which the fiber terminates at a node. The node is usually in the form of a street cabinet which can be placed several miles away from the home. Network connectivity is distributed from the node to the subscriber homes via coaxial or copper cables.

This type of network uses the least amount of fiber and the most amount of copper compared to other networks, so its signal is weaker than a FTTP network. The transmission speeds are also slower and less reliable, but it is seen as an interim step to FTTP networks due to its cheaper costs.

FTTC

FTTC (Fiber to the curb) networks are very similar to FTTN networks, but the nodes are placed much closer to the end users. The shorter distance between the node and the end users means less copper is used than a FTTN network, but they are still outperformed by FTTP networks.