As high-bandwidth requirements continue to rise over the last few years, multiple system operators (MSOs) transform their hybrid fiber/coax (HFC) networks. Available architectures, such as DOCSIS 3.1 and Remote PHY, rely on fiber-based bandwidth deep into the cable television (CATV) network, which is why countless operators aim to create Node+0 architectures via “fiber deep” initiatives. 


Node+0 architectures imply that MSOs will strive to place fiber closer to customers to improve their service quality, which can be achieved through deploying fiber into more areas and resulting in the lack of need for amplifiers between the node and the subscriber. In the long run, the network architecture will look simpler, less expensive, and more reliable, which will benefit customers, business owners, and other shareholders.


However, this change results in field technicians within the cable industry needing to master the skill of installing and testing fiber further down the network. Although these technicians may have been experts in testing copper, they are now required to be proficient in handling fiber, which encompasses different processes and equipment, as fiber is more delicate than its copper counterparts.


In this article, we aim to provide an in-depth analysis of deep fiber architectures, including their features, methods, advantages, and challenges.


Network Architecture History

Traditionally, there are two primary technology types for wavelength division multiplexing (WDM) – coarse (CWDM) and dense (DWDM). These two technologies utilize multiple wavelengths of light within a single fiber, with the differences being the wavelength spacing, number of channels, and their abilities to amplify the multiplexed signals.


Since the mid-1990s, CATV operators have played an integral role in distributing radiofrequency (RF) signals from the node to the customers, which worked impeccably until the demand is too massive for this architecture to fulfill, as the fibers eventually run out. In light of the situation, operators commenced the deployment of CWDM to deliver wavelength services to businesses, which lightened the load of the CATV nodes. 


However, the fibers in the network’s feeder portion have again depleted, which led the operators to turn to DWDM to deliver fibers close to the customers. The DWDM wavelengths are delivered to a “parent” node, distributing the wavelengths to a “child” node. This shifts the focus from creating more “parent” nodes to adding new cables to the child nodes and reusing as much feeder fiber as possible. 


Understanding why this change is beneficial to the overall network architecture is crucial to note that DWDM can deliver around 40 wavelengths. Meanwhile, CWDM is only capable of delivering 16 to 18 wavelengths. With this increased capacity of DWDM, several challenges come as byproducts of change.  


Challenges and Benefits of Using More DWDM

Some of the challenges include:

  • The non-linear transmission nature of the optically amplified systems.
  • Increased requirements for high-performance lasers and optical equipment.
  • More power per wavelength


With that being said, multiple benefits come out of the DWDM, deep fiber implementation, such as the availability of complete capacity systems – up to 160 channels across C + L bands, the ability to reach maximum distances, and no optical-to-electrical-to-optical signal processing. All of which increase the overall throughput and efficiency of the network architecture. 


Aspects of Deep Fiber Implementation to Take Note Of 

As fiber is more costly to repair or replace, it is of the highest importance to handle them with care. Throughout the whole process, make sure to utilize the Optical Time Domain Reflectometer (OTDR) tool to test and characterize all properties of fiber installation. 


Another critical point is to ensure that the Lucent Connectors (LCs) on both ends of the fiber have been inspected. Keep in mind to only make the connection when both connectors are clean. To ensure connector quality and cleanliness, utilize a fiber inspection probe with integrated IEC61300-3-35 PASS/FAIL judgment.


In Conclusion

To ensure a successful implementation of deep fibers, it is imperative to understand the history, network architecture, and their challenges and benefits. Network operators and field technicians alike also need to grasp the basic knowledge on how to conduct fiber testing, fiber validation, and fiber verification. If you’re interested to learn more about Deep Fiber Node, please visit this VIAVI whitepaper.


VIAVI Solutions is the industry leader in network testing and measurement, wireless and avionics solutions, and security and authentication. Whether you’re looking to implement deep fibers, use more DWDM, or other networks, VIAVI can assist you with any 5G validation, 5G testing, and 5G visibility needs you may have. Our industry-leading offerings deliver end-to-end network solutions. Learn more by visiting our website or contacting us today.

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