
Hurricane LTE-U: Don’t Let Wi-Fi Get Blown Away - DiabloD3
https://www.eff.org/deeplinks/2015/11/hurricane-lte-u-dont-let-wi-fi-get-blown-away
======
minimax
_Meanwhile, Qualcomm, which is developing the technology, plied journalists
with breakfast and lunch in an effort to convince them LTE-U was totally
benign._

As much as I like the idea of a bunch of scheming Qualcomm executives sitting
around a giant conference table plotting to ply journalists with breakfast and
lunch, maybe it's possible they were just being polite hosts?

~~~
snowwrestler
Being a polite host is part of convincing people to feel good about you and
what you're saying. That's why there is so much entertaining (dinner, drinks,
parties, etc.) in politics, sales, and international relations.

There is also at least one study[1] showing that people who have recently
eaten have a more positive impression of others.

[1] Mentioned last night on the show "The Brain" on PBS, which I highly
recommend.

[http://www.pbs.org/the-brain-with-david-
eagleman/home/](http://www.pbs.org/the-brain-with-david-eagleman/home/)

------
late2part
I can assure you that the "bellhead" v. "IP-Everywhere" battles still exist.

As recently as 2 years ago, international telecom exists were lamenting the
proliferation of wifi - arguing that local LTE is more efficient than wifi;
and handsets should use local LTE base stations instead of wifi.

Be very afraid of this - telcos will take action to make their delivery
mechanisms metered and rated.

~~~
asn0
"The Rise of the Stupid Network" (1997) is the quintessential essay on this
topic, and unfortunately still relevant today.
[http://www.isen.com/stupid.html](http://www.isen.com/stupid.html)

~~~
DarkLinkXXXX
In case anyone wants it, I created an epub of it.

[https://r.kyaa.sg/vknoez.epub](https://r.kyaa.sg/vknoez.epub)

------
Johnny555
If LTE-U can coexist so peacefully with other unlicensed devices, then maybe
all of the LTE bands should be opened to unlicensed devices and carriers can
use the same mitigation measures on all LTE bands to let everything coexist
happily.

There, problem solved, I'm sure the carriers will jump right on this.

~~~
ksml
Hm, this is actually a great response. I can't think of a good counter
argument. It would be interesting to see someone with more technical or legal
experience to comment on the implications of this

~~~
Johnny555
I think the counter argument is that the carriers must be automatically
cutting back their use of the spectrum when they detect other devices, so if
unlicensed devices were allowed on the carrier licensed bands, it would reduce
spectrum available to the carriers.

Though it seems fair, if they want to eat into the public unlicensed spectrum,
they ought to give the public access to their own spectrum.

------
DiabloD3
If this ever happens around here, I'm replacing my AP with an even louder one,
as loud and disruptive as I can go without violating FCC requirements. I will
drown out LTE-U in my area and do whatever it take to disable LTE-U detection
on the AP (such as buying out of date APs that don't recognize it).

Qualcomm, who is leading the effort behind LTE-U, belongs to the Wi-Fi
Alliance and submits things to the IEEE 802.11 Working Group, and its not like
they're not making money no matter what they sell.

Maybe Qualcomm should be removed from the Wi-Fi Alliance and banned from the
IEEE 802.11 Working Group if they continue to push for standards and
"features" (term used loosely) that damage Wi-Fi.

5.8 GHz isn't even good for long distance transmission, this is why it was
given away as an unlicensed block to begin with. So, what the hell?

Not only that, cell phone data already has tons of frequency space; they just
keep wasting it on 2G, 3G, non-LTE 3.9G, non-VoLTE voice. It is not my problem
that "oh, customers are still using hardware that doesn't support more
efficient use of the spectrum"; I own a reasonably up to date LTE phone that
can do VoLTE, I did not pay out my ass for one (its an original Nexus 5).

LTE is the first protocol that is meant to be fully backwards and forwards
compatible, all previous protocols just muck up perfectly good spectrum. You
know what happened when USB came out? Or HDMI and DisplayPort? Or PCI-E? Or
SATA and SAS? They all quickly replaced all legacy standards and became the
norm in short order. Their collective hallmark is easier and cheaper to
produce hardware that has a protocol that is forwards and backwards compatible
(something they all share with LTE).

LTE, however? In my town, about half the spectrum is dedicated to non-LTE
usage, yet most phones around here are LTE data, with or without VoLTE
capability, and the few dumb phones remaining are 3G voice.

You know what that means? 5 mbps or less is the norm for downstream data
unless you're right in front of the tower, then I've seen it go past 50 mbps.
If they shut off 2G completely, shut off 3G/3.9G data, moved all the VoLTE-
capable customers over to VoLTE, and shrank the 3G voice segment down to only
what we need to serve the area, we'd be getting 10 or 15 mbps instead of 5.

We don't need more cell phone spectrum, we just need to stop wasting it on
ancient inefficient protocols.

~~~
makomk
This is a game you can't win, unfortunately. If the interference gets too much
LTE-U phones can just fall back to their parallel LTE connection on licensed
spectrum, but your wifi has nowhere to go that LTE can't follow you to.

------
ck2
Single sentence summary for any "authority" doing review on this to make a
decision:

 _" Wi-Fi devices aren’t equipped to recognize the presence of an LTE-U device
and don’t know that they should only transmit when the LTE-U device has
scheduled itself to remain silent."_

and that's why LTE-U cannot be allowed to exist

unless they are just looking for a reason to sell everyone new devices, again

~~~
kec
Unfortunately that's not a very good argument on its own. Wifi exists in the
unlicensed bands in the US and is thus subject to FCC title 47, part 15 rules.
This includes the provision that the onus is on the unlicensed transmitter (in
this case your wifi device) to gracefully deal with any interference it might
encounter.

~~~
granos
At the same time (from the article):

47 U.S. Code § 333 - Willful or malicious interference

No person shall willfully or maliciously interfere with or cause interference
to any radio communications of any station licensed or authorized by or under
this chapter or operated by the United States Government.

This puts some responsibility on the LTE operator to not stomp on WiFi.

~~~
scintill76
Also, "The FCC has already said that Section 333 applies to unlicensed
spectrum by prohibiting Wi-Fi jamming." [http://www.wetmachine.com/tales-of-
the-sausage-factory/my-in...](http://www.wetmachine.com/tales-of-the-sausage-
factory/my-insanely-long-field-guide-to-the-lteu-dust-up-part-ii-a-storm-of-
spectrum-swords/)

------
aidenn0
Here's my conspiracy theory for the day:

1) In the long-term, regulation is to the benefit of the incumbents.

2) Most in technology prefer light regulation

3) If you act as a "bad citizen" in such a way to piss off people you can
change #2.

Thus the result of acting out is more regulation, which increases your costs,
but also acts as a significant barrier to entry for future competitors.

------
benmorris
Our city and parts of the county have 5.8ghz Ubiquiti equipment serving
internet for thousands of residents provided by our local WISP. I also rely on
this service myself since I'm just outside of city limits, this would surely
be a big problem for everyone. I get a solid 10mbps connection, much better
than our only other option 1.5mb DSL.

------
sherifhanna
This is Sherif from Qualcomm. I know LTE-U is a new concept so there's a lot
misconceptions around it. I'll be happy to answer your questions.

~~~
KingMob
OK. Will LTE-U devices transmit at the same time as Wi-Fi devices and impair
their bandwidth?

~~~
sherifhanna
LTE-U will first seek out channels with no incumbent Wi-Fi (or LTE-U) access
points. If no clear channel is found, it'll seek the least occupied one, then
evaluate how many other transmitters are using it. It'll then use the channel
for a an amount of time proportional to that total number of transmitters. So
if sharing with 2 other Wi-Fi access points, it'll take one third of the time.
The result is that the impact of LTE-U on Wi-Fi is no more than the impact of
Wi-Fi on Wi-Fi.

~~~
oakwhiz
I would argue that the impact of LTE-U on Wi-Fi is actually greater than that
of Wi-Fi on Wi-Fi, despite what you have pointed out. It is true that LTE-U
operates on a fair time-share basis (TDMA [1]), however the problem here is
that LTE-U unfairly transmits while Wi-Fi stations are transmitting, giving
absolutely no regard to the actual channel usage by Wi-Fi stations. Wi-Fi does
not work on a time-share basis, it operates on a "don't talk while I'm
talking" basis, and since TDMA is a different way of communicating, Wi-Fi
stations don't know how to avoid collisions with LTE-U stations. From the
perspective of a Wi-Fi station, an LTE-U station is just like a leaky
microwave oven, there is no way to avoid radio collisions with it.

There isn't a way for Wi-Fi stations to know what TDMA time slots are "free,"
how long those time slots are, and there isn't a way for Wi-Fi networks to
"sign up" for a time slot with the TDMA networks. The TDMA networks just
decide to talk at some predefined interval without consulting the Wi-Fi
networks to see when they would like to talk. This does not sound fair to me -
it's kind of like saying "I'm going to yell very loudly once every minute. If
it interrupts the conversation that you are trying to have then too bad for
you. But I'm not going to yell when my friends are yelling, because we have an
agreement in place."

Normally, Wi-Fi stations use CSMA/CA [2] to avoid transmitting when other Wi-
Fi stations are transmitting, which overall reduces the number of lost Wi-Fi
frames for everybody. This is what I mean by "don't talk while I'm talking."
So the impact of Wi-Fi on Wi-Fi is materially lower than the impact of LTE-U
on Wi-Fi simply from a statistical standpoint.

In addition, LTE-U only transmits when it detects other Wi-Fi transmitters.
However, due to the hidden node problem [3], not all Wi-Fi stations that are
using the channel can necessarily be detected by an LTE-U station, but the
LTE-U station is still able to interfere with them. So there will be some
quiet Wi-Fi stations that the LTE-U station can't see at all, and when the
LTE-U station decides the channel is mostly empty and blasts its signal there,
the quiet Wi-Fi station will be disproportionately overcome with interference.
Again, the interference would be TDMA interference, but the Wi-Fi access
points would not know how or when to avoid TDMA collisions, so the
interference would be worse than Wi-Fi interference.

Normally, with Wi-Fi and CSMA/CA, the gaps in the louder station's
transmissions would be good opportunities for the quieter station to start
transmitting, allowing them to sometimes take turns even though the louder
station cannot hear the quieter station, and the hidden node problem would be
mitigated as best as CSMA/CA is capable of doing so. But with TDMA
interference, there isn't any cue that Wi-Fi can take which indicates that now
is a good time to transmit without interference.

This could all be avoided if LTE-U didn't solely operate on a TDMA basis, but
also ceased transmitting (or skipped time slots) while Wi-Fi networks are
transmitting.

LTE-U risks starting or worsening a "loudness war" where other unlicensed
spectrum users decide to buy louder and louder unlicensed equipment up to (and
possibly past) the legal limit, because their networks are unusable with too
much interference otherwise.

Combine this design decision with the interest that wireless
telecommunications companies have preferring their LTE networks over the well-
being of Wi-Fi networks, and it starts to paint a sinister picture - that
telecommunications companies might be attempting to deliberately interfere
with unlicensed Wi-Fi networks in order to promote their own networks and
equipment as being superior.

[1]:
[https://en.wikipedia.org/wiki/Time_division_multiple_access](https://en.wikipedia.org/wiki/Time_division_multiple_access)
[2]:
[https://en.wikipedia.org/wiki/Carrier_sense_multiple_access_...](https://en.wikipedia.org/wiki/Carrier_sense_multiple_access_with_collision_avoidance)
[3]:
[https://en.wikipedia.org/wiki/Hidden_node_problem](https://en.wikipedia.org/wiki/Hidden_node_problem)

------
swolchok
Sounds bad, but I would like to know if there is a technical benefit excluding
Listen Before Talk in some countries. Why would an engineer possibly want to
turn it off, given that the support has to be developed for those countries
that require Listen Before Talk anyway? (The evil megacorp financial reasons
are obvious, but let's pretend for the sake of discussion that they are not
stupid enough to think that breaking Wi-Fi networks across the country/world
will have no PR repercussions -- it will cause massive hassle for everyone.)

~~~
TorKlingberg
The throughput and latency are probably better if you can just go ahead and
transmit when you have something to send.

------
rsync
Right now, HAMs in the US can run personal/private GSM as long as they do it
in that little overlapping part of 900mhz band that euro GSM shares with an
amateur band...

Do I understand that one could also run a personal/private LTE in this 5.8ghz
band ?

~~~
makomk
Pretty sure the answer is no, because all the signalling to negotiate the use
of LTE-U happens over licensed LTE frequencies - so unless you're a ham that
happens to be able to transmit in one of those bands, no dice.

------
JustSomeNobody
Why can't they produce some samples and let the FCC and an independent body of
engineers determine if there really is going to be an issue?

Sending out letters with promises doesn't mean squat.

------
CuriousSkeptic
Why not just make it all licensed? I imagine we could solve the coordinatin
problem in some fair manner potentially even letting people get payed for not
using spectrum.

Establish some kind of protocol for negotiating where in devices acting on
behalf of interested parties (you, your neighbors, the local telco)
continuously negotiate for spectrum and power. The winner for a slot pay the
other parties for their slot.

It's not like violators can hide, so it should be pretty easy to enforce
compliance.

~~~
jschwartzi
This already exists. The modern unlicensed wireless protocols all play nice
with each other using some form of carrier-sense.

The problem is that LTE-U is going to use a TDMA scheme, and, according to the
article, will not include any collision avoidance. This means that it may
start transmitting at the same time your wifi is transmitting.

~~~
CuriousSkeptic
My point being that a little conflict with my wifi might be ok as long as it's
a fair transaction. If I'm freeing the spot for sale and get payed. It would
also replace bureaucracy with economics instead, which should be good for
optimizing utilization.

The main difference compared to carrier sense is that I'm suggesting a
competition based negotiation, not cooperation based. Instead of waiting for a
free spot, you buy the spot.

If the unlicensed spectrum is a commons, the problem with uncooperative
commoners like this LTE-U thing looks an instance of the tragedy of the
commons. In a sense I'm suggesting a form privatization.

------
swalsh
I wonder how much it'll be used once this tech start's growing:

[http://www.fiercewireless.com/tech/story/fcc-votes-adopt-
new...](http://www.fiercewireless.com/tech/story/fcc-votes-adopt-new-35-ghz-
spectrum-sharing-plan-innovation-band/2015-04-17)

------
azinman2
So if towers start broadcasting on 5.8, won't they have so many more devices
to talk to no wifi stands a chance?

