CableLabs Thinks Two Channels Are Better Than One

[thiggins]

CableLabs is pitching a Dual Channel Wi-Fi (DCW) specification that uses a hidden channel for downlink-only traffic and a second channel supporting normal bi-directional traffic.

This CableLabs test report describes a CableLabs experiment that used specially-prepared APs and Laptops to simultaneously send download FTP traffic over one 5 GHz channel and video streaming traffic over another 2.4 GHz channel. The report claims 7-12X improvement in download capacity using the technique.

CableLabs has also published "Integration and Operation Guides" to implement DCW on Open-WRT based routers and Linux clients.

In perhaps related news, Slashgear and Dignited have reported Chinese smartphone makers Oppo and Vivo have introduced smartphones capable of using two channels simultaneously. It's not clear whether the phones are using CableLabs' DCW spec.

(Via WiFi NOW)

 

[L&LD]

This seems more like marketing fluff right now but will be interesting to see it develop.

 

[RMerlin]

Considering a smart phone has very low bandwidth requirements, I fail to see the point in polluting the spectrum with more unneeded trafic.

If mobile manufacturers really want to upgrade throughput, then stop using single stream and go with double or triple streams. The Samsung Tab S5e I recently bought to replace my Asus Zenpad whose battery is starting to get weak in the knees is only single stream. For a 500$ mobile device, that is utterly retarded, if I may say. My Huawei smartphone is double stream AND 160 MHz (which I keep disabled, as I don't see the point in wasting an extra 80 MHz of spectrum just to download emails and application updates).

 

[thiggins]

The dual-channel is really currently a dual-band approach. The test white paper said 2.4 GHz was used for normal bi-directional traffic and 5 GHz for FTP downlink.

Consumer Wi-Fi is very wasteful of bandwidth. Campus/large venues usually run 20 MHz channels, 40 MHz maybe in 5 GHz.

 

[sfx2000]

CableLabs is pitching a Dual Channel Wi-Fi (DCW) specification that uses a hidden channel for downlink-only traffic and a second channel supporting normal bi-directional traffic.

Interesting idea, but it does beg the question as to why introduce complexity where it's not needed.

 

[mrc]

At least for mobile devices, a dual-band solution where both bands is in use at the same time, might have impact on batterytime. For for solutions where power usage is not that important, it can be quite interesting.

A "asymmetrisk" solution with use of different channels, where upstream had less bandwidth, also seem interesting taking into consideration that wifi is about sharing airtime.

 

[Razor512]

If they are using an additional channel that is dedicated to a single traffic direction, then why can't they make to dynamically switch?
For example, if the AP detects that tons of clients need upload throughput, then have that channel switch to upload to give it a little extra boost, but as soon as download on the main channel starts to saturate, then switch that extra channel over to download.

 

[Vexira]

Considering a smart phone has very low bandwidth requirements, I fail to see the point in polluting the spectrum with more unneeded trafic.

If mobile manufacturers really want to upgrade throughput, then stop using single stream and go with double or triple streams. The Samsung Tab S5e I recently bought to replace my Asus Zenpad whose battery is starting to get weak in the knees is only single stream. For a 500$ mobile device, that is utterly retarded, if I may say. My Huawei smartphone is double stream AND 160 MHz (which I keep disabled, as I don't see the point in wasting an extra 80 MHz of spectrum just to download emails and application updates).

The Samsung 5e is supposed to be a cut down device so I'm not entirely surprised, they probably reserved multi stream for the Samsung galaxy Tab S6 which is the premium model.

Also out of pure interest which tool did you use to determine the amount of streams if you don't mind me asking.

 

[Vexira]

I personally wouldn't mind using 160mhz bi directional aps to service my Xbox and a couple of connected PC's it's interesting the idea of using the 2.4 for downloading and or streaming and the the 5ghz for gaming or VoIP or high bandwidth streams it to me would be better used in on set top boxes or smart TVs for a 4k Netflix stream.

 

[thiggins]

If they are using an additional channel that is dedicated to a single traffic direction, then why can't they make to dynamically switch?

That's not their design approach. Did you read the white papers and other collateral I linked to?

 

[RMerlin]

The Samsung 5e is supposed to be a cut down device so I'm not entirely surprised, they probably reserved multi stream for the Samsung galaxy Tab S6 which is the premium model.

It's still a 550$ CAD "cut down device". Can't imagine they couldn't fit dual stream in that price budget - my Nexus 9 had it, years ago. I'd expect such a specs reduction to be part of the Tab A line, not of the Tab S line. The SDC670 supports two streams.

Also out of pure interest which tool did you use to determine the amount of streams if you don't mind me asking.

Asuswrt-Merlin. It reports both the link rate, the PHY type and number of streams of connected clients, as reported by the wifi driver.

 

[Razor512]

The main reason I was thinking that is since the paper listed that "all 802.11 response messages are allowed on the DC to ensure correct lower layer operations of the [802.11] protocols."

Thus at some hardware level it is physically capable of handling traffic in either direction, and any limitations to that will be purely at the firmware or driver level.

 

[Freedom39]

Here is much more from the subject. Dual Channel Wifi is software. MCSR (Multi Channel Single radio) is the hardware by Edgewater Wireless. The Third link is from Contention Window and the podcast on Dual Channel starts at about 13:10 into the podcast.

http://contentionwindow.libsyn.com/s1e11-wi-fi-mapping-dual-channel-wi-fi-space-supercomputing

My thoughts on this are Cable Labs wouldn't look at Edgewater Wireless unless they had technology that would be accepted by their member base like Cocmast Liberty ect. I think its big. I particularly liked the Podcast.

Still AX is single channel and its gimmick added to it really only allow for theoretical speeds they can put on their box. those speeds are only ever achieved in Greenfield.

 

[sfx2000]

Here is much more from the subject. Dual Channel Wifi is software. MCSR (Multi Channel Single radio) is the hardware by Edgewater Wireless. The Third link is from Contention Window and the podcast on Dual Channel starts at about 13:10 into the podcast.

Still - it introduces complexity, and needs client support - most clients are single radio/dual band, but they can only operate on a single band at a time.

Tech is what it is - and this is a good idea, but what problem are they trying to solve?