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Despite 5G’s Capabilities, Mobile Providers Can’t Connect With Airline Industry

I spoke with Hallie Cotnam on CBC Ottawa Morning on 19-Jan-2022 about this issue and how the US ended up in this situation.

5G is here. 5G is rolling out. Just wait for 5G.

What is going on?!?

For the last few years, the mobile industry has been a buzz with 5G this and 5G that…and for good reason. The fifth generation (5G) of mobile network technologies has a lot to be excited about.

Not Just One Thing

The first thing you need to understand about 5G is that it’s not just one thing. As a term, 5G covers a range of technologies that are all aimed to take better advantage of specific areas of radio frequency.

The early cellular networks were not very efficient. They had a limited capacity to connect customers. That was ok, not many of us had cell phones back in 1970’s and 80’s.

But now, everyone has a smartphone.

For most conversations, you can think of 5G as three distinct technologies; the low, mid, and high band.

Low band is slightly faster than what we have today in 4G/LTE networks. It’s got good range and reasonable speeds. This is great for general use cases.

Mid-band is the sweet spot for big cellular networks. It’s reasonable range and has great speeds. This will be the new normal in a few years.

High band doesn’t go very far but is crazy fast. This section of 5G is best used in high density location or small spaces. Think stadiums (lots of people) or hospitals (small spaces with high bandwidth needs for those surgery robots).

But I Have 5G, Right?

Part of the problem is that in depending on the cellular network or phone provider, you may have had a “5G” phone or connection in your hand for the past few years…even though you didn’t notice anything different.

You’re not imagining that. Way too many announcements have pumped up the 5G hype train.

Which brings us around to the current issue in the United States.

In 2019, AT&T and Verizon won the auction to license the mid-band (or C-band) of the 5G spectrum in the USA. The price tag? $67 billion.

December 2021 was when this part of their 5G networks were supposed to go live. That got delayed repeatedly, eventually ending up on a 19-Jan-2022 launch date.

Why?

Catastrophic Rollout

Despite the 3 year design and rollout post-auction, it took until just recently for the aviation industry to really grasp the importance a potential issue. An issue the CEOs of United, American Airlines, Southwest, and Delta called “potentially catastrophic.”

It turns out that the frequency used for mid-band 5G (3.7—3.98 GHz) is “next” to the frequencies used by radio altimeters (4.2—4.44 GHz).

A radio altimeter is a very important piece of equipment. It helps the airplane know what altitude it’s flying at…especially critical in adverse conditions.

The altimeter is critical to several systems onboard the aircraft, including the auto landing and other systems.

With the gap between the frequencies in use, why is there an issue?

Like most technology, radio altimeters aren’t perfect. Older models could be susceptible to interference from 5G signals given their strength of those signals at lower altitudes.

Is this a problem? No one is quite sure.

The FAA (Federal Aviation Administration) issued a regulatory assessment on 23-Dec-2021 advising everyone of the potential risk and calling for collaboration in order to research the issue.

But Why?

This issue really boils down to two things. One it much easier to solve than the other.

The easier problem mitigating the potential impact of the rollout.

This has been a known issue well before the spectrum auction was held in 2019. The last minute advisories, open letters, and hyperbole should not have been needed and have muddled a reasonably simple issue.

There have been multiple opportunities since the auction to address the issue on any number of fronts…that didn’t happen. The result is the battle in the media until a reasonable compromise was reached last minute.

AT&T and Verizon will go ahead with the rollout of this section of their 5G networks as planned but will not enable any towers near airports. Effectively creating little protective bubbles around the airports until this can all be sorted out.

Don’t worry! 4G / LTE will still be available in this 5G-less bubbles.

The harder problem is how to balance the pressure new technologies are putting on the spectrum and how they can co-exist with older technologies.

Newer technologies are digital and use protocols and filters that can ignore signals that aren’t intended for them. As long as something isn’t blasting so loud on frequencies they shouldn’t be that it drowns everything else out, the filtering built into new technology is sufficient to avoid problems like this.

That leaves the multitude of other technologies that are using spectrum with assumptions that no longer hold up.

This has been managed by licensing of the spectrum that included specific limits on broadcast power. That’s why you can listen to 91.5 MHz FM radio in one city and get a completely different station on 91.5 MHz in another city.

Their broadcast licenses limit the power of their signals and reduce the chances of interference.

That system works fine as long as things are stationary and everyone respects the rules. Newer technology is far more precise and spectrum is a finite resource.

We’ll see more demand for licenses that are closer and closer to each. There won’t be as much space between uses. This issue will pop up again and again until we phase out older technologies.

But those technologies are working just fine. It’s hard to justify the replacement of a technology used in one industry for the benefit of a completely different industry.

As usual, the technology side is pretty straight forward (if still challenging) but it’s the economics and motivation that are the roadblock.

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