It has been speculated for several years that 5G would represent an opportunity for the cable business, too, providing backhaul either for wireless companies or themselves.

Returning from Cable-Tec Expo in New Orleans last week, Gregory Williams, analyst for equity research company Cowen, said in a note to investors this morning that the opportunity is “moving from concept to reality.”

“Cable is the only one that could deploy at scale at a reasonable cost, and expeditiously,” Williams wrote. “Specifically, cable has the plant assets and unique footprint (reach) for small cell backhaul, mid-haul or fronthaul.”

Related: Expo News: Charter to Team with Plume for Managed WiFi

As the analyst noted, the cable industry, led by CableLabs, is currently working on “low-latency X-haul,” “a technology specifically designed to reduce the latency experienced by any mobile traffic while traversing the DOCSIS transport network on its way to the internet,” as CableLabs describes it.

Meanwhile, ahead of the conference, the NCTA published a white paper noting that, not only does hybrid fiber coax (HFC) have a much larger footprint than fiber (around 3.5x more), fiber lacks the power supply needed to make backhaul happen.

“Developing the backhaul and powering infrastructure will be a daunting task for any potential [fixed wireless access] operator [except cable]," the NCTA said.

Related: House Looks to Lock Up 5G Security

Cable operators, meanwhile, can deploy small cells throughout their networks and leverage the aerial amplifier nodes as the “ideal co-location opportunity with plenty of power in nearly all housing density scenarios.”

Also notable: As Williams pointed out, cable operators who are pushing fiber deep are freeing up network equipment, and thus, making more power available for small cells. 

Making an announcement that will certainly be heard by aspiring U.S. providers of fiber backhaul, Ericsson announced that it has teamed with Deutsche Telekom to produce 40 Gbps speeds data transmission speeds and sub 100-microsecond latency with wireless backhaul.

Ericsson said the test recently took place at the Deutsche Telekom Service Center in Athens. The test used millimeter wave transmission over a distance of 1.4 kilometers.

”While fiber is an important part of our portfolio, it is not the only option for backhaul,” said Alex Jinseng Choi, senior VP of strategy and technology innovation for Deutsche Telekom, in a statement.

“Together with our partners, we have demonstrated fiber-like performance is also possible with wireless backhauling/X-Haul solutions,” Choi added.

Noted Per Narvinger, head of product area networks for Ericsson: “Microwave continues to be a key technology for mobile transport by supporting the capacity and latency requirements of 4G and future 5G networks. Our joint innovation project shows that higher capacity microwave backhaul will be an important enabler of high-quality mobile broadband services when 5G becomes a commercial reality.”

Serving up a potential breakthrough that could factor heavily into cable’s future deployments of small cell networks, CableLabs and Cisco Systems said recent tests of a proposed technique called the “Bandwidth Report” (BWR) prove that super-low latencies can be achieved by extending a technical bridge between DOCSIS and LTE.

While the goal of the BWR test was to achieve upstream latencies of sub-5 milliseconds, the test, following some manual tuning of this “pipelining” of the DOCSIS and LTE schedulers, reduced latency to about 1.1 milliseconds.

“So, it worked,” John Chapman, a fellow at Cisco Systems who is also CTO of the company’s  Cable Access unit, proclaimed Thursday during a CableLabs-hosted webinar entitled Enabling Cable Networks for Mobile Backhaul.

The test, they said, shows that DOCSIS can become a viable backhaul for LTE and could play a major role as cable operators start to develop LTE-based small cell networks, and as they also look to complement their mobile and wireless strategies using the CBRS [Citizens Broadband Radio Service] 3.5 GHz band.

RELATED: Comcast Wants to Test CBRS in Philly

Notably, the BWR proposal is also extensible to future 5G networks, Chapman explained.

But the issue that’s being solved with BWR is to reduce inherent upstream latency in DOCSIS networks to a level that is required for 4G and 5G small cells – certainly beneath the 5 millisecond mark.

So, in order to play that key backhaul role, DOCSIS must provide a low latency path between neighboring small cells, Jennifer Andreoli-Fang, a distinguished technologist at CableLabs, said.

BWR, a method that was described in detail at last fall’s SCTE/ISBE Cable-Tec Expo in Denver, aims to overcome a mismatch between the schedulers for DOCSIS and LTE by having them work together and hit the latency goal.

And there’s quite a chasm to overcome.

For the DOCSIS upstream, 5 milliseconds has been the “minimum latency,” though it’s typical to see it at 11 milliseconds, and grow to 30 milliseconds or 50 milliseconds if there is contention in the upstream, Chapman said.

The goal with the BWR proposal is to shrink that number down 2 milliseconds or lower.

Fundamentally, BWR enables the DOCSIS and LTE schedulers to talk to each other through a technique called “pipelining,” with BWR serving as a request into the DOCSIS system.

“It’s fundamentally an API into the DOCSIS scheduler” that allows an external component, like a small cell, to ask for a certain number of bytes at some future point in time, Chapman explained.

While this allows the LTE and DOCSIS scheduling systems to communicate, the BWR method essentially “hides” the DOCSIS latency beneath LTE and reduces the latency by taking advantage of the predictive nature of the LTE scheduler, he said.

For the trial, CableLabs and Cisco set up a physical LTE and DOCSIS test bed that includes a commercial LTE user device talking to an open source LTE small cell that was being backhauled on a commercial DOCSIS 3.1 modem and a Cisco cBR-8 CCAP/CMTS.

A small amount of code was inserted into the LTE MAC layer, which didn’t change the scheduler, but instead sent out a scheduling decision that is put into the form of a BWR message, Andreoli-Fang explained.

That message was then sent out on the DOCSIS uplink and received by an API on the cBR-8. A series of packets were then sent from the LTE user device to the CMTS, and the results showed that the method provided a clear latency advantage.

The results showed that “DOCSIS is well positioned as a viable backhaul technology for LTE,” Chapman claimed. “The path to success is actually having mobile and DOCSIS technologies working together as one."

The proof-of-concept is now moving to the next phase, as CableLabs has kicked off a committee that will explore the possible specification of the BWR protocol and have it become part of the DOCSIS scheduling system, Andreoli-Fang said.

“It’s something we can define at CableLabs,” Chapman said, adding that LTE will also have the ability to write to that API.

What’s not known is when BWR might become a more formal piece of the puzzle.

Fellow webinar panelist, Craig Cowden, SVP of wireless technology at Charter Communications, stressed that there’s time for that to develop, noting that the FCC is still working out rules for the use of CBRS and that the broader product ecosystem still needs to come together.

RELATED: Charter Puts Wireless Broadband to the Test (subscription required)

“There is some time, for us anyway, to see this evolve,” he said.

But the underlying work is “incredibly important as we talk about how we could be able to enable our DOCSIS HFC networks for true fixed mobile convergence, particularly as we talk about 4G, and especially 5G, where those lower latency requirements are essential,” Cowden said earlier in the webinar.