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876 posts

Ultimate Geek
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Topic # 111809 15-Nov-2012 14:30 Send private message

Anyone here had a play with 802.11ac devices yet ?  Any good ?




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337 posts

Ultimate Geek
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  Reply # 717750 15-Nov-2012 15:12 Send private message

If they have, they'll be draft devices since 802.11ac isn't finalised yet. Hopefully those draft devices don't end up like some of the draft-N gear that wasn't compatible with final-N.

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Ultimate Geek
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  Reply # 718319 16-Nov-2012 14:46 Send private message

Fence sitting at the moment. I use my router(s) to support many other services via third party firmware and would need that gap to be filled and native routers(consumer) firmware does not have that support. And the likes of TomatoUSB don't support 802.11ac yet.

Also the other things is .. the client. You have 802.11ac and no clients for it to play with.

Most laptop and mobile devices are two stream 2.4GHz at best and very few would have three stream Wireless 5GHz builtin.

That said, mobile devices with one stream will (supposedly) support 80MHz channels along with Bluetooth 4.0. AND this means by it's nature you'll have Miracast too. 

My Notebook has two antennas built in with the addition of 3G antennas too. So If I can find a mini-PCIe 802.11ac module I should be able to jury rig up something. :-)

Already laying siege to the low end of 5GHz frequency.. :-)

I see Netgear has a USB dongle to support 802.11ac... but USB 2.0 and 1.1???? really. Would have thought USB 3.0 would have been a better choice. But guessing/hoping it would utilise the resources of USB 3.0 if available.

Look I've got 802.11ac on my 1998 netbook using it's USB 1.1 interface.... 12Mbits interface.... [yep. I known. leaving the room now] :-)


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Ultimate Geek
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  Reply # 718328 16-Nov-2012 14:57 Send private message

I have been trialling Netgear's 802.11ac router for a few months - the wifi range and performance is excellent with existing 802.11n devices. I expect to be testing with an 802.11ac USB dongle in the next few days.




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Uber Geek
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  Reply # 718751 17-Nov-2012 13:38 Send private message

Paulspain - i am very interested to hear more about your expierence.

Rant begins

From a technical radio perspective. I hate the idea.

80mhz channels are a waste of bandwidth. I really believe these devices should be using no more than 20 or 40 mhz out of the box and be 'configurable' up to 80+ mhz.
Otherwise its just a waste of spectrum.

We have all noticed in urban areas, when ISP's started handing out free wifi routers, the range of everyones wifi suddenly dropped over a period of 12 months because of all the excess noise (interference) from neighbors.
An 80mhz wide channel is more susceptible to interference as it uses more of the spectrum. If two 20mhz wide transmitters start causing noise in that channel width, the AC device could be wiped out or loose alot of speed. It would probably perform better on a 40mhz channel where there is less chance of another transmitter occupying that space, and it could go at a faster speed.
Its a delicate balancing act.

Some may say that 5ghz will offer more channels than 2.4ghz which has three non overlapping from the total of (11)
This may be true, however there are still a limited number of channels, and i think it drops to two non-overlapping if operating at 80mhz wide. 

The benefit though of 5ghz is that the EIRP power level limits set by RSM are exactly the same, so for an access point transmitting on 5ghz vs 2.4, the range will be much less. 5ghz has a harder time penetrating walls and the free space path loss (direct line of sight, no obstacles) is slightly higher. This results in less interference from neighbors because of walls, trees etc creating little cells of coverage areas.

http://www.rsm.govt.nz/cms/licensees/types-of-licence/general-user-licences/short-range-devices/information-on-the-operation-of-wireless-lan-and-related-systems-in-the-2-ghz-and-5-ghz-bands/
The above link shows you the frequencies available for use in NZ for wireless LAN devices under our general user license (any nz citizen, non license see)

200mw eirp is not much - a typical home router will put out at least 22db to 23db of transmitter power, going into a 1dbi antenna = 250mw eirp
Even if it was only a 20db radio and connected to a slightly larger antenna (like a typical tp-link that comes with a 3 to 5dbi antenna out of the box) then we are looking at 400mw eirp

So in NZ, that means our egal bands to use are
2.4ghz to 2.483 = 80mhz (1 channel)
5.25ghz to 5.35ghz = 100mhz (1x 80 mhz channel)
5.725 to 5.825 = 100mhz (1x 80 mhz channel)

So three channels - even with the higher path loss of 5.8ghz, the average cul-de-sac will probably have issues with wifi coverage using the 802.11ac standard.
If everyone switched to 40mhz channels, range would be much better and speed probably would be also.

rant over





Ray Taylor
Taylor Broadband (rural hawkes bay)
www.ruralkiwi.com

There is no place like localhost
For my general guide to extending your wireless network Click Here




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Ultimate Geek
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  Reply # 718961 18-Nov-2012 03:03 Send private message

raytaylor:
Rant begins.... [See above for content]



raytaylor - Good informative rant. :-)

paulspain - Look forward to reading your thoughts on 802.11ac


One could throw Bluetooth and large Mirrors(degrades signal) into the 2.4GHz morass too.

Miracast with 2.4GHz connection setup and 5GHz data is going to impact if phones, TV and any other device all start playing that game.

Cisco Systems - 20 Myths of Wi-Fi Interference


Myth #8: "There is no interference at 5 GHz."

It is generally true that fewer devices currently operating at 5 GHz are causing interference as compared to 2.4-GHz devices. But this will change over time. Just as everyone moved from 900 MHz to 2.4 GHz to avoid interference, the "band jumping" effect will catch up with 5 GHz. Some devices that already exist at 5 GHz include cordless phones, radar, perimeter sensors, and digital satellite

.
Summary: You can run, but you can't hide.

My noise floor is ~ -85dBm and my 2.4GHz signal at -60dBm/15metres is pretty good.

At the same distance on 5GHz(802.11n) I'm only getting -70dBm and my dual band 2 stream 300Mbps Notebook always gives better data throughput on 2.4GHz.

That may be somewhat different at closer distances if I could use all my 450Mbps 5Ghz(802.11n) capacity.

Get ~64Mbps (+/- 20Mbps) data transfer on 40MHz to my NAS at 15m on 2.4GHz

I would suggest to get to know your WiFi network when it's running well, so that when it's not you have a point of reference. When one moves to 802.11ac one has a good indicator of data transmission improvements.

Fig 1-1 Orange line is 2.4Ghz at 15m and at -70dBm(yellow line) we see 5Ghz(802.11n) at the same distance.


Blue line is neighbours 802.11g router located at the other end of the 2.4GHz frequency range.

Interestedly, 802.11ac will only have real benefits for people with NAS or corporate networks with servers.

For those just wanting Internet access, a good 300Mbps 2.4GHz Wireless router/modem is still all you need.


368 posts

Ultimate Geek
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  Reply # 719848 19-Nov-2012 23:54 Send private message

Not quite in the 802.11ac game field, but it's just another thing to consider.

USB 3.0 Radio Frequency Interference Impact on 2.4 GHz Wireless Devices

368 posts

Ultimate Geek
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  Reply # 721607 22-Nov-2012 23:25 Send private message


Some light reading to pass the time while we await the arrival of 802.11ac routers :-)

Cisco Systems - 802.11ac: The Fifth Generation of WiFi Technical White Paper
. (PDF)






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