Amazon May Be Hiding Its Plans to Test New Wireless Tech | Hacker News Reader

Amazon May Be Hiding Its Plans to Test New Wireless Tech

spectrum.ieee.org

71 pointsamynordrum17 comments

Amazon is testing 5G.

The 3.5Ghz band has already been proposed by telcos in Australia. Will be implemented in the next year on certain towers.

[Reference: check ACMA tower database]

Do you mean the 3.6 GHz band? The auction commenced a week ago: https://acma.gov.au/Industry/Spectrum/Spectrum-projects/3-6-...

AFAIK the only reason WiFi sticks to 2.5/5 GHz is regulation. Same for microwaves and other appliances. Those are the only two “free use” bands in the spectrogram in most countries. Operating outside of them requires expensive fees and heavy scrutiny. It will be interesting to see how they sort that out...

The first step is probably building a HQ near Washington DC

There are a number of other "free use" bands (called ISM bands). See wikipedia[0] for more information. Some of the most interesting ones are at 433 MHz (Europe), 902 MHz (US only, often used for old cordless telephones), and 24 GHz (worldwide).

We have microwaves to thank for the 2.4 GHz band (and maybe 900 MHz as well)[1].

0: https://en.wikipedia.org/wiki/ISM_band

1: https://web.archive.org/web/20160304061338/https://www.itu.i... (see page 464)

For completeness: there is also a 900MHz band, and 24GHz and 60GHz bands.

Microwaves I assume refer to ovens, which use a frequency related to the nature of the water molecule.

The 2.4GHz ISM band supposedly exists because commercial and military users didn't want to deal with interference from ovens.

> Microwaves I assume refer to ovens, which use a frequency related to the nature of the water molecule.

They work using Dielectric Heating.

Water, fat, and other substances in the food absorb energy from the microwaves in a process called dielectric heating.

See: https://en.wikipedia.org/wiki/Microwave_oven#Principles

Also: https://en.wikipedia.org/wiki/Dielectric_heating

No, at the time the regulations were written, people were think terrestrial and Earth-to-space links, and the high absorption of 2.4G by atmospheric moisture and moisture in foliage makes it a poor choice for these kinds of paths.

Can anyone speculate on how this would be used by Amazon, if they are actually testing it?

It could be IoT. One of the biggest challenges of IoT is connectivity. It's pretty hard to build reliable IoT implementations with 99% uptime on top of WiFi or BLE (and even harder when relying on broadband cellular networks).

There are many critical systems that in order to take advantage of connected technologies require dedicated or special protocols that can provide speed, reliability, high security, low latency, low power consumption, low data rates.

Most unlicensed radio gear chooses between the 2.4GHz and 5GHz ISM bands. 2.4GHz offers longer range and better penetration of walls, but a lower available bandwidth (fewer/slower channels). 5GHz offers better bandwidth but lower range and less penetration. Perhaps 3.5GHz provides a happy middle ground for Amazon? Not to mention there is much less interference on that band because they don't have to put up with everyone's wifi, bluetooth, microwave ovens, etc etc.

Generally you use whatever spectrum you can get rather than having the luxury to strike beard and decide which spectrum you would prefer.

When available for non-military use, 3.5GHz will be attractive because it will be empty of encumbant users. Therefore far more usable than 2.4 and 5GHz, provided the cost is reasonable. Also likely much cheaper than the other available P2MP bands (principally allocated to LTE in the US).

If it's free for everyone to use (on the "lowest" tier) like 2.4 and 5GHz, won't it be quickly saturated as well?

Hopefully it'll be sliced into smaller channels than 2.4 was. Also, 3 frequencies gives more room than 2.

"strike beard"?

Maybe "Stroke beard" as in " rather than having the luxury to stroke your beard and decide which spectrum you would prefer.".

I'm imagining like a cartoon evil villain stroking their beard/chin.

In their application letter, they clearly say they are using it for LTE (specifically on 10 and 20 MHz channels): https://apps.fcc.gov/els/GetAtt.html?id=219961&x=.

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