The Secrets of Delivering G.Fast to Large MDUs
As Bob Dylan sang, “The times they are a-changin’.” What has constituted a definition for broadband for some 15 years now has been a series of Mother-may-I steps from tens of kilobits/second speeds (aka dialup) to xDSL technologies where speeds moved to megabits and then tens of megabits per second, eventually achieving a thousandfold speed improvement.
And now broadband is on the cusp of making yet another order-of-magnitude speed leap. The new utopian speed tier has become gigabit, and activities in the marketplace have already begun to enable this new broadband service tier.
In the realm of gigabit services, fiber has justifiably staked its claim as the technology of choice for enabling these services. After all, fiber is fast, reliable, and speed-wise scalable. According to a recent The Wall Street Journal report (www.wsj.com), high-speed Internet speeds can increase the price of a $439,000 home by as much as $11,815. Multi-dwelling unit (MDU) owners are also intimately aware of the importance of broadband speeds in attracting potential renters with fast broadband, now one of the most important features when selecting a rental property.
But as any carrier who deploys it can tell you, it is challenging, expensive, and very time consuming to deploy — in some cases, prohibitively so, especially in MDU-oriented brownfield neighborhoods.
Provisioning MDUs is challenging because many property owners and/or tenants are reluctant to engage in the time-consuming, and (often) physically damaging process of installing fiber into individual living units. If not done right, the installation process can be ugly, vulnerable, or both. Regardless of the cosmetic result, installing fiber in MDUs is almost always a multi-technician, multi-day (or multi-week) exercise that adds substantially to the provider’s investments in both time and money.
There must be a better way, right? After all, both tenants and property owners want high-speed tiers. They are less concerned with the underlying technology used to achieve those speeds.
The New Addition: G.Fast
G.fast was conceived with the vision of addressing the projected long-term transition to fiber, while delivering next-generation broadband speeds in the most rapidly deployable, cost-effective way. G.fast allows carriers to quickly return capital to pay for the fiber rollouts, lowering the need for additional, expensive capital investment. Carriers can focus their efforts on the deployment of new backhaul fiber into neighborhoods rather than dwell on the time- and money-consuming task of trenching in fiber to every home.
Being able to achieve fiber-competitive speeds by reusing existing copper is one of the clear benefits of G.fast, and comes into glorious play when provisioning MDU facilities, since the need to conduct major construction operations is eliminated. G.fast has the potential to be deployed at a rate 10-20 times that of fiber in terms of living units per day, with a cost per living unit that is very low, and a return on investment (ROI) period that is very, very short compared to full fiber construction.
Carriers can get customers online with these new services very quickly, and reap the benefits of substantial revenue improvements. They can then choose, at their fiscal leisure, when the time-consuming task of full conversion to fiber is conducted since the core infrastructure (fiber backhaul) is already in place. The ROI period for G.fast was, by design, meant to be very short to accommodate this expedited deployment process.
The vision of being able to use/reuse either traditional twisted pair wiring or coax as a vehicle for provisioning service to allow use of bonding capabilities, noise mitigation, or extended reach features as needed by the carrier is perfect for MDUs.
What are the G.fast deployment scenarios for MDU environments? There are several emerging trends:
Typical MDU Environments
Roughly two thirds of MDUs in the US have 16 living units or fewer. For these environments, fiber is delivered to a single 16-port, compact G.fast distribution point unit (DPU), which can deliver tremendous performance to each residence at a very low implementation cost. These DPUs can exist on a pole, in the ground, in a pedestal, or in the basement of the building. In this example, a 16-port, passively cooled, reverse power fed outdoor DPU is designed to run off a pole, wall, manhole, or pedestal. All the outdoor equipment is industrial rated for protection against the harshest weather.
The secret to keeping the costs down is to leverage the pre-existing infrastructure and utilize built-in vectoring to run over that infrastructure. This approach simplifies the design and implementation while ensuring the highest overall throughput across copper bundles.
Larger MDU Environments
G.fast can also be deployed affordably in MDUs with larger footprints. There are several approaches:
Grow Port Count. One approach is to increase the port count of the G.fast DPUs. Today, the 16-port vectoring solutions are the most popular G.fast DPU designs. Yet, denser port count solutions (24-port or greater) are around the corner, and in 2016, solutions will scale to as many as 96 concurrent subscribers within a single DPU.
Spread DPUs to Each Floor. Another approach is to pull fiber to each floor (Fiber-to-the-Floor) to break up the MDU into smaller segments of 16-24 residences. This can be done with either separate GPON strands or via WDM-PON. In the case of WDM, each wavelength represents 10 Gbps of backhaul. The same optical line is then filtered for each DPU, allowing for up to 48 or 96 living units could be concurrently served with G.fast via this clever WDM-PON approach.
Use an ADF. Another add-on approach is to use an Automated Distribution Frame (ADF) to provision all the apartments initially by pre-wiring all the subscribers in the MDU to the available G.fast equipment. For example, with a take rate of 20%, an MDU with 80 apartments can effectively be served with one 16-port DPU and an ADF. Both the DPUs and ADFs can be remotely controlled with zero-touch provisioning once installed, and churn can also be managed this way. (See Figure 1.)
As service providers move fiber to the basement, coax is another medium available to service providers beyond twisted pair. Coax comes with many benefits including better shielding, less interference, and better range. For MDUs with a home-run topology instead of a tree topology, G.fast can be an excellent solution for service providers wishing to leverage this media. Carriers can use the same DPU for coax as they use for copper, lowering the operating costs by using a common DPU platform.
When the coax is a home run from the basement or floor closet, the G.fast solution is wired to a RG-59 Balun-panel, which matches the impedance of the RG-59 coax to the twisted pair. If the MDU has more than 16-24 subscribers, multiple DPUs can be deployed without worry because there is little to no crosstalk between the coax subscriber lines.
To summarize, G.fast is clearly the hot broadband access technology for 2016. The opportunity to deliver high performance broadband into MDU environments over existing copper or even coax cabling has never been larger or more feasible.