Categories
Technology The Industry

DOCSIS 4.0 vs. Fiber

Comcast and Charter previously announced that they intend to upgrade cable networks to DOCSIS 4.0 to be able to better compete against fiber networks. The goal is to be able to offer faster download speeds and drastically improve upload speeds to level the playing field with fiber in terms of advertised speeds. It’s anybody’s guess if these upgrades will make cable broadband equivalent to fiber in consumers’ eyes.

From a marketing perspective, there are plenty of people who see no difference between symmetrical gigabit broadband offered by a cable company or a fiber overbuilder. However, a lot of the public has already become convinced that fiber is superior. AT&T and a few other big telcos say they quickly get a 30% market share when they bring fiber to a neighborhood, and telcos claim aspirations of reaching a 50% market share within 3-4 years.

At least a few big cable companies believe fiber is better. Cox is in the process of overbuilding fiber in some of its largest markets. Altice has built fiber in about a third of its markets. What’s not talked about much is that cable companies have the same ability to overlash fiber on existing coaxial cables in the same way that telcos can overlash onto copper cables. It costs Cox a lot less to bring fiber to a neighborhood than a fiber overbuilder that can’t overlash onto existing wires.

From a technical perspective, engineers and broadband purists will tell you that fiber delivers a better broadband signal. A few years back, I witnessed a side-by-side comparison of fiber and coaxial broadband delivered by ISPs. Although the subscribed download speeds being delivered were the same, the fiber connection felt cleaner and faster to the eye. There are several technical reasons for the difference.

  • The fiber signal has far less latency. Latency is a delay in getting bits delivered on a broadband signal. Higher latency means that a smaller percentage of bits get delivered on the first attempt. The impact of latency is most noticeable when viewing live sporting events where the signal is sent to be viewed without having received all of the transmitted bits – and this is seen to the eye as pixelation or less clarity of picture.
  • Fiber also has much less jitter. This is the variability of the signal from second to second. A fiber system generally delivers broadband signals on time, while the nuances of a copper network cause minor delay and glitches. As one example, a coaxial copper network acts like a giant radio antenna and as such, picks up stray signals that enter the network and can disrupt the broadband signal. Disruptions inside a fiber network are comparatively minor and usually come from small flaws in the fiber caused during installation or later damage.

The real question that will have to be answered in the marketplace is if cable companies can reverse years of public perception that fiber is better. They have their work cut out for them. Fiber overbuilders today tell me that they rarely lose a customer who returns to the cable company competitor. Even if the cable networks get much better, people are going to remember when they used to struggle on cable holding a zoom call.

Before the cable companies can make the upgrade to DOCSIS 4.0, which is still a few years away, the big cable companies are planning to upgrade upload speeds in some markets using a technology referred to as a mid-split. This will allocate more broadband to the upload path. It will be interesting to see if that is enough of an upgrade to stop people from leaving for fiber. I think cable companies are scared of seeing a mass migration to fiber in some neighborhoods because they understand how hard it will be to win people back. Faster upload speeds may fix the primary issue that people don’t like about cable broadband, but will it be enough to compete with fiber? It’s going to be an interesting marketing battle.

Categories
The Industry

Faster Speeds for Comcast

Comcast held a press release on September 8 that announced the introduction of a 2-gigabit download broadband product. The product is already available in Colorado Springs, CO, Augusta, GA, Panama City Beach, FL, and in the Comcast headquarters market of Philadelphia. I can’t find any mention yet of the price.

Along with the announcement of faster download speeds, the company is claiming new upload speeds of as much as 200 Mbps – at least for the 2 Gbps plan. The press release made it sound like all upload speeds would be increased by five to ten times the existing speeds, and today’s blog looks at what it would take for a cable company to increase upload speeds across the board.

Interestingly, the same press announcement said that Comcast would be introducing DOCSIS 4.0 in 2023, at least for some business customers. That’s an announcement that has me scratching my head. Comcast just announced a successful test for DOCSIS 4.0 in January of this year. To be able to go from a lab prototype to production units in less than two years would be extraordinary. The normal time to market for a major new technology is five or six years. I’m skeptical about the announcement and wonder if this is aimed at Wall Street more than any actual technology plan. The company has been asked non-stop about DOCSIS 4.0 for several years, and maybe this announcement is taking advantage of that hype. Comcast could hold a field trial of the new technology next year and still meet this promise.

But cable companies have another option to get faster upload speeds. A cable network is essentially a captive radio network inside of the coaxial cable. Cable networks don’t all have the same total bandwidth, and most of the big cable company networks have total bandwidth of either 1 GHz or 1.2 GHz. The total bandwidth has to be shared between video channels and broadband.

Most existing cable companies have allocated bandwidth between download and upload using something called the sub-split. This assigns a relatively small amount of frequency between 5 MHz and 42 MHz for upload. On top of being a small swath of throughput, this is also the part of the spectrum that suffers from external interference. This combination results in both relatively slow upload speeds and also variable speeds due to interference – something most cable customers are aware of.

There are two additional configurations for allocating upload speeds. A mid-split configuration uses the spectrum between 5 MHz to 85 MHz for upstream. In a high-split, the upload is enhanced by using the spectrum up to 204 MHz. DOCSIS 4.0 will provides multiple options for upload bandwidth with possible spits at 300 MHz, 396 MHz, 492 MHz, and 684 MHz.

If Comcast is going to improve bandwidth in the near future, it will have to implement one of the larger DOCSIS 3.1 splits. There is a cost for moving to a different split. There must first be enough room available for video channels and download bandwidth. It can be expensive if the entire bandwidth of the network must be increased. That can mean replacing amplifiers and other outside electronics, and even some coax. In most cases, the existing customer modems would need to be replaced unless already configured to accept the different split.

At the recent SCTE Cable-Tec Expo, CommScope, Vecima, and CableLabs said there are plans for a different upgrade path for the DOCSIS 3.1 higher splits. They are claiming new ‘turbocharged’ modems that will add more effective upload bandwidth capability. I’ve not heard of any field trials of the new modems, and perhaps this is what Comcast has in mind by the end of 2023.

Cable companies are sensitive about the marketing advantage that faster upload speeds give to fiber and even to slower technologies like FWA cellular wireless. It’s hard to know if the Comcast announcement foreshadows big improvements next year or was just a way to signal to Wall Street that cable companies are working towards improved bandwidth. It’s inevitable that faster upload bandwidth is coming – the big questions are when and how much faster.

Exit mobile version