Fiber Access: RFoG and PON Cases

Deployment of FTTx technologies continues, even as RFoG and PON solutions evolve and economic uncertainties persist.

Fiber to the home or premise (FTTH or FTTP), it still seems like a new category.

Fiber itself — or the hybrid fiber/coaxial (HFC) architecture — was introduced more than two decades ago. The industry’s $65 billion investment from 1996 to 2002 was heavy on fiber and opto-electronics. This latest spurt of interest in and activity surrounding fiber-to-the-wherever (FTTx), however, is only several years old.

That means it roughly corresponds with both the economic downturn and the continuing rollout of FTTH from Verizon.

In a recession, businesses hunker down. They mind the store, but also respond to threats and pursue growth, wherever possible. For large MSOs especially, the business services market continues to beckon. For smaller or rural-based operators, one opportunity is residential areas that have been outside the reach of their HFC plant.

Fiber optics offer ways to address residential and business opportunities. But economic constraints — along with perennial sensitivities to Wall Street — place a premium on preserving capital and protecting investments. These limits are influencing the introduction and adoption of these technologies.

Time Warner message

Several of these trends aligned at a CT-hosted webcast on RF over Glass (RFoG) and passive optical networking (PON) in October 2008.

The top executive on the panel delivered the obligatory disclaimer that there was no need for another massive upgrade. "HFC is well-suited to serving the current and future needs for residential and related commercial apps for many years into the future," Time Warner Cable Vice President, Network Planning and Architecture, Bob Harris said.

Harris explained that Time Warner’s interest in FTTx is to "understand how these technologies could be exploited into an overall ‘long-term’ access network strategy." He called for solutions that are "complimentary to and synergistic with the longer term evolution of the access network."

The theme was less innovation than continuity. Leverage existing equipment and infrastructure, including the DOCSIS control plane, he said.

From Time Warner’s perspective, the primary driver of FTTx was not residential but business, namely: Ethernet, voice/telephony and video services. Underscoring Ethernet, he cited E-line services (private and virtual private line), E-LAN (multipoint to multipoint) and multi-megabit and GigE connections.

As for the residential side, Harris listed two opportunities: Greenfield developments where FTTx is being mandated (which had been more common before the housing market collapsed); and local deployments "where economically feasible."

Harris drew out several implications. First, he endorsed 10Gbps symmetrical Ethernet PON. Second, he called for an RF overlay (or RFoG). Linking the two meant that that EPON and RFoG must "coexist on the same fiber" and (again) that DOCSIS serve as the control plane.

WG5, Vendor progress

Subsequent to the October webcast, progress continued on creating wavelength compatibility for EPON and RFoG in working group 5 (WG5) of the SCTE Interface Practices Subcommittee, the custodian of the emerging RFoG standard.

Beyond the wavelength question, complications have arisen regarding RFoG upstream and DOCSIS 3.0 bonded channels. Once expecting earlier resolution, WG5 chairman Mark Conner now is looking to completing the standards work by the end of 2009.

In other areas, vendors have moved toward some of Harris’s objectives. Driving this activity may have been a Time Warner Cable request for information (RFI), reported on by Light Reading’s Jeff Baumgartner in early February, likely some two months after it had been issued.

In any case, the DOCSIS PON (D-PON) has indeed grown.

When CT published a table on RFoG/PON vendors last October, there was a single entry for EPON systems with DOCSIS control plane technology: Salira Systems (now Hitachi Telecom).

Since then, Allopic announced the availability of its DOCSIS PON controller. Aurora Networks also has announced similar functionality. And chip manufacturer Teknovus demonstrated DOCSIS Mediation Layer (DML) technology at the Cable Show in April.

Also, the RFoG category itself has expanded. ARRIS introduced an optical networking unit (ONU) aligned with RFoG in March. In April, it added an optical line terminal (OLT) that fits within its CHP Max 5000 headend chassis. Electroline has also added RFoG optics to its portfolio, as has the firm 4CableTV. (For more, see table, page 29.)

Apps, deployments

The trend continues for the business and residential FTTx applications indicated during the October 2008 webcast.

In his presentation, BrightHouse Networks Senior Director Network Strategy and Architecture John Dickinson had spoken of PON as a business services enabler. He emphasized the technology’s favorable costs and capabilities and its link with existing fiber infrastructure and basis in international standards.

The month before, in September 2008, T-Mobile had announced Bright House as a backhaul partner. EPON’s role as an "ideal" technology for this application was further spelled out in an article co-authored by Bright House engineer Edwin Mallette in the February issue of CT. Another EPON application for the MSO was a multi-site hospital deployment, discussed in a CT-hosted webcast on healthcare in December 2008.

"So far so good. If it stays that way, we’ll definitely not build any more HFC." Ken Jordan, Troy Cablevision

By way of background, Salira had announced that BrightHouse was adopting its IEEE-based Gigabit Ethernet (GE, or just E)PON solution two years ago, in June 2007.

Dickinson also spoke in October 2008 of EPON’s potential on the residential side — along with using RFoG for video overlay services to businesses. As for residential, it is certainly the case that another flavor of PON, the ITU-T’s GPON recommendation, is flourishing in Verizon’s rollout of FiOS across the U.S. Some smaller operators and telcos also have adopted GPON. (See page 10, for the case of Prime Time Communications.)

As for extending the residential reach of the conventional HFC plant, however, RFoG remains a likely and viable choice.

In the October webcast, engineers from both Bresnan Communications and Armstrong Cable both had spoken favorably of RFoG’s costs, reliability and flexibility.

Armstrong Cable Senior Engineer Roger Hughes told of opting in 2006 for a solution using the strand-mountable "virtual hub" (V-Hub) from Aurora Networks and "micronodes" from Alloptic (now aligned with Motorola.) By last October, Armstrong had built 225-plus miles of RFoG-based FTTH plant.

Reached in July 2009 for an update, Hughes said the light is still green. "We continue to build and rebuild areas with RFoG fiber to the home — no slowing down on that concept," he said.

Two additional examples of how various types of FTTx technologies are working out in the field come from Alabama and Michigan.

FTTx in Alabama

In a presentation at the NCTC Winter Educational Conference in February 2009, Ken Jordan, chief engineer of South Alabama-based Troy Cablevision, discussed how rising competition had led his company to review its options and then to test Commscope’s BrightPath FTTH solution.

The test proved cost claims and yielded 1 GHz of available spectrum, or an additional 300 MHz. It also showed increased drop distances — meaning more potential customers — and other operational benefits, such as high reliability, zero non-responders and the elimination of noise and ingress.

Troy expanded the hub-based test and pulled fiber to 1000 homes, with success measured in February at 56 percent HSD and 71 percent voice penetration. In a June 2009 update, Troy Chief Engineer Ken Jordan said he had expanded to passing around 1600 homes, "with an additional 12,000 on the drawing board."

Troy has continued to evaluate and adjust technologies. Jordan said that while they’re "sticking with BrightPath," he bought another vendor’s network interface units (NIUs) for testing. Installing a new 4-input return receiver from Motorola resulted in reducing space requirements by half, but to remain compatible with Motorola, he has turned to 4CableTV for an RF extender node.

Troy also has also moved away from fusion pigtails, adopting mechanical connectors instead. That adds about $20 of materials cost, but simplifies operations and training.

"We continue to build and rebuild areas with RFoG fiber to the home — no slowing down on that concept." Roger Hughes, Armstrong Cable.

And in an interesting twist, Jordan said they have used some "non standards design" in a non-residential move. To serve a cluster of businesses along the highway between Troy and Brundidge, Jordan did some unorthodox splicing off the trunk fiber and dropped in some BrightPath feeder taps and NIUs.

As for challenges, Jordan said documentation has been an ankle-biter, and the limit on 2dB of loss is non-negotiable. But the technology itself works. "So far so good. If it stays that way, we’ll definitely not build any more HFC," he said.

Others have taken note of Troy’s success, with several outside visitors this summer. "There seems to be a little more interest, maybe because of the (Broadband) Stimulus talk," Jordan said.

PON in Michigan

In Michigan, broadband services provider Broadstripe has worked with Aurora Networks on several applications, including commercial services delivery using the company’s GePON product.

Aurora has long been in the business of extending fiber deeper into the HFC plant. Aurora’s 5-year long project with Suddenlink in Arkansas, reviewed in an October 2008 CT article, is one example. In June 2008, the company announced that Videotron had selected its fiber deep products for a network upgrade passing some 1.8 million homes.

As noted earlier, Aurora’s V-Hub has played a role in some residential FTTx deployments. The environmentally hardened V-Hub, along with the more recent Node PON and media converter products, also enabled Broadstripe to reach a business park in Marshall, MI.

Prior to Broadstripe’s deployment this summer, which included laying fiber to the streetside curb at the Brooks Industrial Park, the 22 businesses occupying that space received their high-speed data from competitors — primarily AT&T, the incumbent LEC in the area.

Configured with Aurora’s GE4132M PON module, introduced in 2007, the V-Hub enabled Broadstripe to deliver 10-100 Mbps of dedicated, symmetrical fiber services to a media converters installed on business premises in the park.

The business customer can select from a choice of speeds.

"We got four customers in the first couple of weeks," Broadstripe Regional VP and GM Dave Harwood said. "Two dropped their T-1 line."

Broadstripe, which has reorganized under Chapter 11 bankruptcy protection, serves about 100,000 customers in four states. In Michigan, it is looking for additional commercial opportunities.

"Beyond that business park, there’s the city of Marshall, population of 8,000," Broadstripe Regional Engineering Manager Al Humphrey said. "If there is a business in that 6-mile radius that wants an Ethernet connection, we can sell that."

Aurora’s technology can actually reach up to 100 kilometers, according to John Dahlquist, Aurora VP Marketing.

The backdrop of Broadstripe’s GEPON deployment in Marshall is node segmentation across its 2,000 miles of fiber. "We are deploying Aurora nodes in many of our communities this summer on the residential side, as well," Humphrey said.

More questions

Broadstripe’s use of related technologies to drive fiber closer to the home on the one side and and to target it to businesses on the other sounds familiar. It is roughly similar to how Troy Cablevision has used RFoG primarily for deploying FTTH, but opportunistically for picking up business cusotomers.

In economically constrained times, piecemeal deployments of FTTx are likely to continue. The larger question is which applications can generate the largest returns, scale to the highest use and incur the lowest production and operational costs.

Given Time Warner Cable’s message from last October, business Ethernet services that leverage EPON standards look like the answer to that question. (For an update from Time Warner, check out the July 31 webcast; see sidebar, page 27.)

The Broadband Stimulus package, as Troy’s Ken Jordan surmised, may be a new factor.

Another question: Is Comcast more than an interested bystander? Comcast’s ongoing reclamation of analog spectrum and deployment of both additional digital video and bonded data channels may undercut its interest in (and need for) FTTH. But more serious attention to optical Ethernet business services — following the lead of Cox and Cablevision — is likely to follow.

Granted, the flexible HFC architecture is good for "many years in the future," as Harris put it. Yet as that future unfolds, it will be tempting to keep track of these currently limited but likely accelerating deployments of FTTx.