5G

[PeteMc]

51 minutes ago, GeeBee said:

Cell phone companies are businesses too, don't they have to "adapt"?

Well, yes I think they should adapt, if they need to.  But, in theory, if they do their installations correctly, they should not be affecting the adjacent frequencies.  If they do, then the FCC and other world agencies should be all over them to fix it.

And I'm not stating this as a fact, just as a discussion point....   But if the issue is that the current RA designs did not properly factor in someone using the adjacent band and did not properly filter it out , then it is on the Aviation industry to fix their problem. 

And it sounds like there is a pause in the C Band rollout here in the US for more studies (at least by VZW & ATT).  So we should hear what, if any, real issues there are and which side will need to adapt.  

Also, I just checked to see if a Guard Band was noted anywhere.  In one FCC doc it states that "...C-band (3.7-3.98 GHz) and make it available for flexible use, including 5G. The 20 megahertz above that (3.98-4 GHz) would serve as a guard band..." And the RAs are in the 4.2 to 4.4 range, which means 4 to 4.2 GHz is an additional Guard Band.  So I'm really questioning why there would be any interference if designed correctly.

[EricJ]

5 hours ago, GeeBee said:

Why is the onus on the airlines alone to solve a problem created by the cell phone companies. Cell phone companies are businesses too, don't they have to "adapt"?

 

 

How is the problem "created by the cell phone companies"?   Nobody has accused them of violating spectrum rules to my knowledge.

[GeeBee]

4 hours ago, PeteMc said:

Well, yes I think they should adapt, if they need to.  But, in theory, if they do their installations correctly, they should not be affecting the adjacent frequencies.  If they do, then the FCC and other world agencies should be all over them to fix it.

And I'm not stating this as a fact, just as a discussion point....   But if the issue is that the current RA designs did not properly factor in someone using the adjacent band and did not properly filter it out , then it is on the Aviation industry to fix their problem. 

And it sounds like there is a pause in the C Band rollout here in the US for more studies (at least by VZW & ATT).  So we should hear what, if any, real issues there are and which side will need to adapt.  

Also, I just checked to see if a Guard Band was noted anywhere.  In one FCC doc it states that "...C-band (3.7-3.98 GHz) and make it available for flexible use, including 5G. The 20 megahertz above that (3.98-4 GHz) would serve as a guard band..." And the RAs are in the 4.2 to 4.4 range, which means 4 to 4.2 GHz is an additional Guard Band.  So I'm really questioning why there would be any interference if designed correctly.

According to the RTCA document I posted above, it is not just frequency but the design of the transmitter and antenna that creates the real problems. Therefore, the telecoms are culpable here with their demands for the spectrum while creating dubious designs.

[jaylw314]

It's rare that risk of liability pushes corporations to do the right thing, but I suspect telecoms are painfully aware of the risk of being sued if they build anything that could be reasonably linked to a well-publicized plane crash (as they almost always are).

[EricJ]

1 hour ago, GeeBee said:

According to the RTCA document I posted above, it is not just frequency but the design of the transmitter and antenna that creates the real problems. Therefore, the telecoms are culpable here with their demands for the spectrum while creating dubious designs.

The RTCA works for the aviation industry and are not unbiased.   They've already created a big potential problem for the airlines by claiming that the interference will be dangerous, because in the areas of the world where 5G is deployed in that spectrum and in the US when it is deployed they will now by their own arguments assume liability if they continue to use the equipment, because they've stated it will be dangerous.   Anybody else who gets sued will point to that and say the airline's technical agency told them it would be dangerous, but they used it anyway.

These sorts of things are not decided in the dark and the FCC rulemaking process is collaborative and public.   This has been in process for years, and the arguments are not new.    The guard band between the proposed 5G service and RA in the US is 220 MHz  wide which is ENORMOUS for what is usually allocated to protect adjacent services.   Seriously, it takes pretty crappy equipment to be susceptible to energy at the proposed out-of-band emission limits with that much separation.   The AVSI study that was done and submitted during the process found that RA systems were mostly susceptible to interference from other RA systems (which makes sense because those are in-band interferers), and there are intra-aircraft links that operate in the same band.   They also found that interference susceptibility varied widely between equipment manufacturers, which supports the notion that it is mostly sloppy design (imho).

During the collaborative rulemaking process the FCC published this:

"We agree with T-Mobile and Alion that the AVSI study does not demonstrate that
harmful interference would likely result under reasonable scenarios (or even reasonably “foreseeable”
scenarios to use the parlance of AVSI). We find the limits we set for the 3.7 GHz Service are sufficient to
protect aeronautical services in the 4.2-4.4 GHz band. Specifically, the technical rules on power and
emission limits we set for the 3.7 GHz Service and the spectral separation of 220 megahertz should offer
all due protection to services in the 4.2-4.4 GHz band. We nonetheless agree with AVSI that further
analysis is warranted on why there may even be a potential for some interference given that well-designed
equipment should not ordinarily receive any significant interference (let alone harmful interference) given
these circumstances. As such, we encourage AVSI and others to participate in the multi-stakeholder
group that we expect industry will set up—and as requested by AVSI itself. We expect the aviation
industry to take account of the RF environment that is evolving below the 3980 MHz band edge and take
appropriate action, if necessary, to ensure protection of such devices."

From: https://www.fcc.gov/document/fcc-expands-flexible-use-c-band-5g-0

Note that that was from February, 2020, and a lot of discussion followed before the final rulemaking.   I've seen nothing so far that indicates that the aviation industry has much of an argument here other than "some of our equipment is really bad and performs poorly and if we continue to use it it might cause problems."   The out-of-band emission limits proposed are quite reasonable, especially with the enormous guard band allocated, and the discussions note that the limits are consistent with other bands consistent with efforts to simplify and harmonize the rules...in other words, everything else in the rf spectrum is living with these rules just fine.

The FCC, as always, also notes that the "FCC may, in its discretion, require greater attenuation than specified in the rules if an emission outside of the authorized bandwidth causes harmful interference."   But from the discussions so far I think the FCC and the majority of collaborators feel that the existing limits and enormous guard band should be sufficient for any reasonable system to reject such interference even if it is a safety-of-life system.

It is not unusual and even expected that lobbying would be done even after the process is finished and the rules are written, because that's how lobbyists make their living.  As mentioned previously, I think the writing is on the wall here.  It's an opportunity for the airlines to replace crappy equipment with stuff that works and is tested to practical conditions rather than just complain about the neighbors when the neighbors are being reasonable.

 

[Brandt]

By Alan Levin / December 7, 2021 10:10AM ET / Bloomberg Government

A coalition of aviation groups has called a proposal by AT&T Inc. and Verizon Communications Inc. to limit the strength of 5G signals “inadequate,” adding a new level of controversy over the service set to start next month. The Aerospace Industries Association in a letter to the Federal Communications Commission called for additional restrictions on 5G mobile-phone towers near airport approaches and landing pads for helicopters. Bloomberg News reviewed the letter, which was dated Monday but hasn’t yet been posted to the FCC’s website.  “Our proposal also aims to minimize the impact on both the telecom operations and our national aviation system,” the trade group said in the letter.  The two wireless companies have said that the new 5G service in the so-called C-band poses no risk to aviation and on Nov. 24 offered to limit intensity of the signals, but aviation groups remain concerned that the radio waves are too close to those used by a critical safety device known as a radar altimeter and could cause interference.  The AIA letter was earlier reported by Reuters.  AT&T and Verizon pledged in the Nov. 24 letter to operate the new 5G service at reduced power everywhere for six months, with even lower power levels and limited antenna heights near airports and along landing paths. Transmissions would also be limited for antennas pointed skyward and at locations near “public helipads,” the companies said. AT&T and Verizon also opened the door to extending the restrictions beyond six months if “credible evidence emerges that real-world interference would occur if the measures were relaxed,” they said in the letter. The U.S. Federal Aviation Administration is expected as soon as Tuesday to issue possible flight restrictions once the 5G service becomes active starting on Jan. 5.

 

[GeeBee]

Boing and Airbus thinks there is a problem

 

https://finance.yahoo.com/news/boeing-airbus-executives-urge-delay-003001197.html

[carusoam]

All quiet on the western front…?

Any ongoing issues…?

Best regards,

-a-

[GeeBee]

I know there have been diversions of aircraft unable to execute low vis approaches.

 

[PT20J]

Latest info regularly updated by FAA https://www.faa.gov/5g

[EricJ]

Mostly it clutters the NOTAMs when I get a web briefing.