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With C-RAN deployments gaining momentum and 5G on the horizon, fiber is being recognized as a strategic asset to support wireless cell densification. Large incumbent service providers have both wireline and wireless operations, so converging the traffic onto a single access network and maximizing asset utilization makes excellent business sense. For smaller operators, addressing multiple market segments with multi-use fiber-to-the-home (FTTH) networks limits their risks and maximizes the return on investment.

Converged Network Challenges

In C-RAN networks, operators centralize baseband units and run fiber out to small cells or remote radio heads. Many small cells will require 10Gbps of fronthaul bandwidth in a fiber connection, and since there can be two to three small cells at each site, the wireless side of the business needs a lot of fiber bandwidth. Wireline operators want to maximize their investments in fiber infrastructure, so they are looking at converged FTTH, fiber-to-the-business (FTTB), and wireless connectivity in one network.

The challenge is that most large carriers have very different organizations running wireless and wireline networks. Each organization has different viewpoints on time, scale, cost, reliability, and what’s needed for deployment. For example, the wireline side of the house is responsible for bringing fiber from centralized locations out to neighborhood nodes near the cell site locations, while the wireless organization must connect that fiber to its cell sites. Wireless teams use terms like fronthaul or backhaul, where fiber teams don’t. When wireless teams ask for fiber, they’re typically asking for pairs of fiber, and they need push-on connectors at the fiber termination point to simplify deployment by installation teams that may not be skilled at fiber splicing. The wireless side thinks in terms of an end-to-end connection, while the fiber side thinks in terms of accessibility to the fiber to provide access for several different types of customers. This last difference is critical, because the converged network team needs to decide which parts of the network need to be connectorized and which need to be spliced.

These are all issues that need to be addressed as operators look at converging their wireless and wireline networks. The main thing is for these different entities to get into the same room and talk about their objectives – they need to spend sufficient time within the organization getting on the same page about terminology, how they look at their needs in servicing the network, and what the needs are for fiber in different areas. Ideally, the relationship with the operators should be that of a customer and partner, rather than a vendor.

Convergence Strategies

Solutions to convergence lie in making sure the network is built in such a way that any of the fibers can be used for whatever service makes sense. Network architects must make sure there are points on either end where they can add in devices, and that the network allows for expansion of fiber capacity, whether that’s via wavelength division multiplexing (WDM), coarse wavelength division multiplexing (CWDM), or other technologies.

It’s not just a matter of throwing a ton of fiber into the network. Rather, it means taking a broader look at the available fiber maximization technologies and how they might be used. Many people think fiber is cheap, and it is when it’s a matter of adding extra fibers to a large backbone cable. However, fiber becomes expensive in the access layer when technicians are working on it – too much fiber becomes unruly and teams must spend time figuring out the location of a particular fiber. So, it’s important to be intelligent about how much and where fiber is needed.

It’s equally imperative that the wireless and wireline teams sit down together and discuss the financial side of dedicated fiber pairs to all of the potential 5G and densification sites. This happens even before the wireline side takes on the cost of deploying extra fiber or predetermining the use of WDMs. The wireless side needs to be comfortable.

Stretching Fiber Capacity

There are a lot of technologies that can help maximize the use of existing fiber in the outside plant. For example, operators can change the way they manage a FTTH network, going from a centralized to a distributed split strategy that would allow them to service additional small cells by freeing up fibers in the access networks. They can also look at riding wavelengths across a passive optical network, using the extra wavelengths to serve small cells.

Using WDM and CWDM gives operators more leverage from the fiber distribution hubs that are already in the network. It may be a matter of upgrading those cabinets for additional fibers or increasing the split capacity – this can be done without laying new cables in the access network, which can be one of the most expensive options.

The bottom line is this: when wireless and wireline operators share their respective goals and plans for converged networks, it becomes a win-win for both teams. The future of fiber infrastructure is always changing and growing, and it’s best to leave the planning to the experts. It’s their job to know the strategies and architectures to make it work.

 

Mike Wolfe is the North American director of technical sales, Wireless, for CommScope, where he is responsible for troubleshooting and solving customers’ most challenging technical problems. Wolfe previously worked for CommScope as a regional sales manager and has served as director of operations for IDSI, LLC, general manager for General Dynamics Satcom Technologies, Inc, product line manager for Andrew Corporation and group head for Electrospace Systems, Inc.

Erik Gronvall is VP of Service Provider Strategy & Network Architect Americas for CommScope. He leads product strategy, design and development for inside and outside plant connectivity solutions.

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