Cell Carriers One Step Closer To "Sharing" Your 5 GHz Bandwidth

[thiggins]

Qualcomm today announced that its subsidiary, Qualcomm Technologies, has successfully made the world's first over-the-air connection via MulteFire using listen-before-talk (LBT).

The MulteFire Alliance trade group was formed last fall with founding members Nokia and Qualcomm, along with members Ericsson and Intel. The Alliance was formed in response to the backlash from the Wi-Fi Alliance, Google and other Wi-Fi industry stakeholders to its predecessor, LTE-U/LAA (LTE in Unlicensed Spectrum / Licensed-Assisted Access). These technologies are aimed at allowing cellular carriers to increase available bandwidth in their networks by using the unlicensed 5 GHz band used by Wi-Fi devices.

MulteFire uses a Listen Before Talk (LBT) protocol to address bandwidth-sharing concerns. It also differs from LTE-U/LAA in that it can operate entirely in unlicensed spectrum, requiring no LTE "anchor channel". Qualcomm's MultiFire white paper makes it clear that sharing 3.5 GHz GAA spectrum is also targeted. The FCC created established the new Citizens Broadband Radio Service (CBRS) in the 3550-3700 MHz band (3.5 GHz Band) in April 2015.

Today's Qualcomm announcement appears to be an announcement more of proof-of-concept and offers no details about the test itself.

 

[DNet]

So in other words, gobble up everything that's not already taken, and then charge you to use it!

What happens to the poor individuals who can no longer find any available channels in this previously free, public spectrum?

 

[thiggins]

MulteFire is just another thing competing for spectrum. Which is worse, this or a neighborhood of people running 160 MHz channel Wi-Fi?

 

[L&LD]

Both.

 

[sfx2000]

MulteFire is just another thing competing for spectrum. Which is worse, this or a neighborhood of people running 160 MHz channel Wi-Fi?

It's more than that - I've posted in the past here on the threat of LTE in unlicensed spectrum...

The challenge here is while LTE-U techniques listen for activity first, when they grab the channel, since they're scheduled, WiFi will suffer as it will not be aware that LTE is actually there (the WiFi radio sees LTE as noise only)...

It's a complicated situation, and a real problem for WiFi (which tends to be regular folks like us) vs. big Telco which sees this as a spectrum opportunity...

 

[sfx2000]

MulteFire is just another thing competing for spectrum. Which is worse, this or a neighborhood of people running 160 MHz channel Wi-Fi?

Well, most folks might not be able to use a contiguous 160MHz anyways (80+80 will likely be more common due to DFS restrictions).

The 3.5GHz band is greenfield (e.g. not much for incumbent users/technologies in place relative to what we see in the 5GHz bands) - 3.5GHz does come with some DFS like restrictions as well, as unlicensed use is permitted as a secondary use (it's shared with some military radars). The CBRS band does seem to be the better opportunity for LTE-U/LAA approaches due to it being greenfield - but nothing stops them from deploying in the UNII-1/2/2e/3 bands...

Ultimately though - this becomes a policy issue balancing unlicensed users vs. big license holder that might have spectrum already in other bands. It becomes something of a fairness issue balancing the public benefit of WiFi vs. the basic issue that unlicensed usage has few limits in the first place...

I would be more worried about upcoming tech like 11ax - that is the real threat to folks that currently have investment in 11a/n/ac - interesting times...

 

[thiggins]

It's more than that - I've posted in the past here on the threat of LTE in unlicensed spectrum...

Yes you have and thanks. But does MulteFire address any of the objections raised to LTE-U/LAA? It's being presented as though it does through its use of LBT.

 

[sfx2000]

Yes you have and thanks. But does MulteFire address any of the objections raised to LTE-U/LAA? It's being presented as though it does through its use of LBT.

The problem is not LTE-U/LAA stepping on WiFi - if WiFi is running, then multifire plays nice, as the channel is active - the challenge is when LTE-U/LAA has seized the channel for it's usage, and then WiFi can't get a word in edgewise...

In other words - LTE-U is WiFi aware, but WiFi is not LTE-U/LAA aware...

Google prepared a well thought out and reasoned objection - and it makes sense what they're saying...

http://www.slideshare.net/zahidtg/15-105-06112015-google-inc-60001078145

Problem here is that there's big players with lots of licensed spectrum that really would to use unlicensed spectrum as well.

 

[sfx2000]

It's not that much different than the Lightsquared Terrestrial LTE and GPS policy issue - and there, saner heads did finally make the right policy call there - it was technically possible, but the risks to GPS were too high... and GPS (along with other GNSS systems) likely provide more value overall than what Lightsquared offered...

Same goes with the UNII-1/2/3 bands - while unlicensed, and in UNII-2/3, WiFi, depending on region might be a secondary user, the public benefit here with WiFi is well above subsidizing the likes of the potential LTE-U/LAA players...

It's getting bad enough with WiFi services anyways - good example here is Comcast providing both public (XFinityWiFi) along with Private wifi for their customers...

WiFi in the 5GHz band provides a great benefit to the public - as such, the FCC (and other regulatory bodies) must consider the benefits here vs. essentially subsidizing existing license holders that do have spectrum in other bands.

Hopefully the FCC makes the right call here - and provides the 3.5GHz band for LTE-U/LAA as there is very little utilization of that band at the moment... and this is a fair outcome for all, IMHO...

 

[thiggins]

Thanks for the commentary SFX. So MulteFire plays no nicer with WiFi than LTE-U/LAA. Its main advantage is that it doesn't need the LTE anchor channel, so can be used for 3.5 GHz.

 

[sfx2000]

It would be interesting to see the test results... I not hard against technologies like MultiFire and the like, but I think we've all seen what happens in dense WiFi environments, and having a time aggressive scheduled MAC like LTE or Wimax (yes, 802.16 looked at the same approach), it might not be as WiFi friendly as proponents would suggest.

And this might be why 3.5GHz is so interesting... and being unlicensed, this is something that anyone could deploy in that band - private citizens as well as providers...

 

[sfx2000]

When I was working on 802.16, there was much exploration of unlicensed band operation - and while co-existance was looked at, in the time domain, Wimax operation took the fore...

This paper is somewhat dated (see the ref to 801.11a), but it does present the challenge in the time-domain in a cogent way...

https://www.researchgate.net/public...istence_with_80211A_in_Shared_Frequency_Bands

So I would be very interested to see how MultiFire solves the problem of fairness when they have the channel - and without taking total control of the channel with incumbent 802.11 a/n/ac BSS's in the same channel...

 

[sfx2000]

I'll apologize a bit, as some of the concerns here are probably over the head of many..

 

[sfx2000]

Thanks for the commentary SFX. So MulteFire plays no nicer with WiFi than LTE-U/LAA. Its main advantage is that it doesn't need the LTE anchor channel, so can be used for 3.5 GHz.

The problem here is that LTE does use licensed spectrum - so there is a region/local aspect for the incumbent provider to anchor the LTE cells...

So take a Verizon or T-Mobile (which are on record for supporting this stuff), they still need to keep the mobile stations anchored/registered on the eUTRAN interface in any event - at least on one channel over in licensed spectrum...

This might be a bit odd for some - but basically doing LTE in unlicensed space for commercial benefit in the public/common grounds - well, this grinds on me in a big way...

Tragedy of the commons -- I fail to see how this benefits all...

This is a much bigger threat to the WiFi community than the recent FCC lockdown on 3rd party firmware...

 

[sfx2000]

Say goodbye to 5GHz....

T-Mobile is going to deploy LTE-U in 5GHz - it's only a matter of time before VZW/ATT/Sprint do as well...

https://arstechnica.com/information...es-big-lte-boost-from-5ghz-wi-fi-frequencies/

 

[sfx2000]

Google prepared a well thought out and reasoned objection - and it makes sense what they're saying...

Problem here is that there's big players with lots of licensed spectrum that really would to use unlicensed spectrum as well.

Somehow Slideshare has dropped the Google Whitepaper - updated link...

https://ecfsapi.fcc.gov/file/60001078145.pdf

 

[thiggins]

The game is basically over and the carriers have won, especially with the new FCC boss.

At any rate, does anyone know which DEVICES, i.e. phones, tablets support LTE-U?

 

[System Error Message]

this sucks, phone carriers using 5Ghz as their long range carrier when it is meant for unlicensed short range use and to deal with the growing wifi traffic density. This will definitely increase interference on the 5Ghz level as wifi AC is a different protocol altogether and will only see the carrier as interference (a strong source of interference) and the phone will see the wifi AC as interference and can cause issues when both the modem and wifi are used at the same time.

As you know in the US the communications company are a monopoly and one big happy company that have no qualms of making your lives miserable from internet use (imagine if google fiber and similar never happened) to phones and with very poor customer services and tricks to avoid you from quitting (like that one ISP that charges you thousands if you quit them).

The reason why we have licensed wifi in the first place is so that companies can claim their space, but since all the tele companies are 1 big happy company they arent going to fight over the spectrum.

 

[sfx2000]

The game is basically over and the carriers have won, especially with the new FCC boss.

Yep - and the Big 4 have been looking at unlicensed spectrum for some time now...

Time will tell - if we start seeing bad performance, perhaps cooler heads will prevail - 3.5GHz makes sense, not 5GHz, IMHO, as 3.5 is pretty much greenfield anyways - that along with WhiteSpace...

At any rate, does anyone know which DEVICES, i.e. phones, tablets support LTE-U?

Nothing at the moment, except for reference designs used for testing and development. I suspect that LTE-U devices will be primarily mobile - so yes, tablets and phones..

 

[Razor512]

That would suck for those of us in areas where 2.4GHz is not performing well. In my area, 5GHz offers better reliability over a longer range than the 2.4GHz on both of my routers. Over 250APs (most on 2.4GHz). It also gets lots of usage because with more and more desktop computers also using WiFi, many people are not connecting the Ethernet cable, even when they have the route on the same table, thus tons of access points, and tons of clients using WiFi, even when they do not need to. this all leads to a bad noise floor and just slow performance.

I wonder in the area of DFS, has there been any benchmarks measuring how much of an impact on throughput it has due to the frequent checks it has to do (especially if there is no dedicated radio to check for radar)?