Three Most Common Fiber-to-the-Business Architectures You Must Know

Deploying fiber to the business creates a faster, more reliable connection, thus allowing businesses to store and access data quickly, streamlining their communication and business practices. This article explores three of the most common fiber-to-the-business architectures and discusses their pros and cons.

Fiber-to-the-Business Home Run Architecture

The first fiber-to-the-business architecture we will explore is home run architecture, which uses spare or dark fibers to feed every individual business. In a fiber-to-the-business home run architecture, an existing fiber trunk can usually feed a residential node and multiple individual businesses. Each business is supported by fibers that have to be tapped from the existing fiber trunk. The following figure shows a scenario where an existing fiber trunk feeds a residential node and two businesses. Four fibers are tapped from the existing fibers that feed a residential node, and the downstream fibers from tapped fibers cannot be reused unless a new cable is spliced into the trunk cable.

The following figure shows a more complex fiber-to-the-business home run architecture scenario. There are eight potential business customers as well as a new residential area that requires a fiber node. To deliver service to the businesses and homes, 18 dark fibers in an existing trunk cable have to be spliced in the existing splice closure.

Pros and Cons

From a technical standpoint, the pros and cons of fiber-to-the-business home run architecture include:

Pros

• Excellent long-haul network reach ( up to 60km) with low link budget

• Purely passive system that requires no protocol

Cons

• Low utilization of downstream fibers from tapped fibers

• More dark fibers required for multiple businesses and a node

Fiber-to-the-Business PON Architecture

In a fiber-to-the-business passive optical network (PON) architecture, only one or two dark fibers are needed to feed up to 16 or 32 businesses. The figure below shows how an existing fiber trunk feeds two businesses as well as a residential node using a PON. In this scenario, only one fiber is tapped from the existing fiber trunk to support services for business customers. It is realized by an optical power splitter that can split a broadcast signal to multiple businesses. Downstream fibers from the tapped fibers can be reused if there is enough optical power.

Now let's go back to the same complex scenario used in the home run architecture to see how a fiber-to-the-business PON architecture can support up to eight new business customers and a new residential node. In this scenario, only three dark fibers in the existing trunk are required. A field-hardened, passive 1x8 splitter is then deployed in an outside plant terminal from which drop cables run to business customers.

Pros and Cons

The pros and cons of the fiber-to-the-business PON architecture include:

Pros

• Good utilization of existing fiber plant with 1 or 2 fibers per PON

• Requiring less dark fibers to support multiple business

• Purely passive system

Cons

• Bandwidth has to be shared among multiple businesses

• Distance limited by optical loss and protocol

Fiber-to-the-Business WDM Architecture

The fiber-to-the-business wavelength division multiplexing (WDM) architecture is the last fiber-to-the-business architecture we will look into. Traditionally applied in the long-haul and metro networks for large amounts of data transmission, WDM offers an effective way to deliver fiber to the business. In a fiber-to-the-business WDM architecture, an operator can use 1 or 2 fibers from an existing trunk to deliver individual wavelengths to multiple businesses.

The following figure shows a detailed picture. Through a passive WDM mux device in the headend or hub, individual wavelengths are aggregated onto a single fiber. Then a passive WDM demux device, located in an outside plant terminal, drops the appropriate wavelength to the subscriber over the same pair of fibers.

Again, we will examine the same scenario mentioned above. There are the same eight new businesses and the new node, but only 2 dark fibers in the existing trunk are required. WDM mux terminals play a key role as they allow operators to easily install, maintain, add, and test WDM mux devices in the field.

Pros and Cons

The pros and cons of the fiber-to-the-business WDM architecture include:

Pros

• High utilization of existing fiber plant

• Requiring only 2 fibers for data and residential CATV node

• Purely passive system that requires no protocol

• Virtually unlimited bandwidth

Cons

• Distance limited by optical loss

Conclusion

Now that we know more about the three most common fiber-to-the-business architectures, it is obvious each of them has its own benefits and limitations. The home run architecture has a long reach but requires more dark fibers. The PON architecture needs fewer dark fibers but transmission distance is limited by protocols. The WDM architecture has the lowest requirement for the amount of dark fibers but transmission distance is most limited by optical loss. Thus businesses have to weigh the benefits they offer against their limits to make an informed decision.