Comcast Tests DOCSIS 4.0

Comcast recently conducted its first test of the DOCSIS 4.0 technology and achieved a symmetrical 4-gigabit connection. The test was enabled by a DOCSIS 4.0 chip from Broadcom. The DOCSIS 4.0 standard was released in March 2020 and this is the first test of the new standard. The DOCSIS 4.0 standard allows for a theoretical transmission of 10 Gbps downstream and 6 Gbps upstream – this first test achieved an impressive percentage of the capability of the standard.

Don’t expect this test to mean that cable companies will be offering fast symmetrical broadband any time soon. There is a long way to go from the first lab test to a product deployed in the field. Lab scientists will first work to perfect the DOCSIS 4.0 chip based upon whatever they found during the trial. It typically takes most of a year to create a new chip and it would not be surprising for Comcast to first spend several years and a few iterations to solidify the chip design. Assuming Comcast or some cable company is ready to buy a significant quantity of the new chips, it would be put into the product design cycle at a manufacturer to be integrated into the CMTS core and home cable modems.

That’s the point when cable companies will face to tough choice of pursuing the new standard. When the new technology was announced last year, most of the CTOs of the big cable companies were quoted that they didn’t foresee the implementation of the new standard for at least a decade. This is understandable since the cable companies recently made the expensive upgrade to DOCSIS 3.1.

An upgrade to DOCSIS 4.0 isn’t going to be cheap. It first means the replacement of all existing electronics in a rip-and-replace upgrade. That includes cable modems at every customer premise. DOCSIS 4.0 will require network capacity to be increased to at least 1.2 GHz. This likely means replacement of power taps and network amplifiers throughout the outside plant network.

There is also the bigger issue that the copper plant in cable networks is aging in the same manner as telco copper. There are already portions of many cable company networks that underperform today. Increasing the overall bandwidth of the network might result in the need for a lot of copper replacement. And that is going to create a pause for cable company management. While the upgrade to DOCSIS 3.1 was expensive, it’s going to cost more to upgrade again to DOCSIS 4.0. At what point does it make sense to upgrade instead to fiber rather than tackle another costly upgrade on an aging copper network?

There is then the market issue. The cable companies are enjoying an unprecedented monopoly position. Comcast and Charter together have over half of all broadband customers in the country. While there are households that are unhappy with Comcast or Charter broadband, most don’t have any competitive alternative. The FCC statistics and the screwball websites that claim that Americans have multiple broadband choices are all fiction. For the average urban or suburban family, the only option for functional broadband is the cable company.

This market power means that the cable companies are not going to rush into making upgrades to offer greater speeds just because the technology exists. Monopolists are always slow to introduce technology upgrades. Instead, the cable companies are likely to continue to increase customer speeds across the board. Both Charter and Comcast did this recently and increased download speeds (or at least the download speed they are marketing).

I expect that the early predictions that it would be a decade before we see widespread DOCSIS 4.0 were probably pretty prescient. However, a continued clamor for faster upload speeds or rapid deployment of fiber by competitors could always move up the time when the cable companies have to upgrade to DOCSIS 4.0 or fiber. But don’t let headlines like this make you think this is coming soon.

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