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LarryM99
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Backhaul limitation
LarryM99   7/7/2014 4:33:16 PM
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I have been tracking 802.11ac for a while now, and have even upgraded my home router to the standard. I haven't run real-world throughput tests on it, but it seems like it is getting close to the Gigabit Ethernet speed that is used as the backhaul for it in most cases. This, if nothing else, would seem to be a real limitation on further development (not to mention a little embarassing). Even some lucky cable customers with 1 Gb fiber could potentially be in the situation of having that be the bandwidth limitation.

Do you think that 802.11ac could shame the wired Ethernet guys into upping their game?

Larry M.

Bert22306
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Re: Backhaul limitation
Bert22306   7/7/2014 5:19:06 PM
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I don't know if "shame" is the right term. I assume you're talking about the service providers here, who have been steadily updating their core networks and last mile connections, over the years. It's labor-intensive, and therefore expensive work. But for example, DOCSIS 3.1 theroretically can deliver 10 Gb/s downstream and 1 Gb/s upstream, and it was approved as a standard earlier this year.

I am curious to see 802.11ac in the real world. I have 802.11n at home, and find that in the 5 GHz band, the bit rate will vary from the high 100 Mb/s or low 200 Mb/s ranges, to the AP's maximum of 270 Mb/s. My assumption is that the 2 X 2 or 4 X 4 MIMO used is not all that dependable, maybe even affected by people walking around the house. A system that depends on 8 X 8 MIMO will most likely exhibit this same behavior.

LarryM99
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Re: Backhaul limitation
LarryM99   7/7/2014 8:03:38 PM
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I see the shame as being directed more towards the Ethernet standard people rather than the ISP's, although there is certainly a portion to go in that direction as well. While 802.11 has gone through several upgrades Ethernet has remained stuck at GigE for quite a while now. There are standards for faster Ethernet, but they are nowhere near mainstream. It's pretty bad when wireless throughput starts to pass wired.

The marketing material around 802.11ac is starting to talk about 1300 Mbps. Yes, I know that that number is heavily asterisked, but so is wired Ethernet. Even if you allow for the larger fudge factor common in wireless, it is still starting to look like wired Ethernet is about due for an upgrade.

Actually, better antenna diversity should significantly increase throughput in the conditions that you describe.

Larry M.

Bert22306
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Re: Backhaul limitation
Bert22306   7/7/2014 8:39:59 PM
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IEEE 802.3-2012 includes 40G and 100Gb/s versions, in Section 6. These aren't commonly available in home or even office PCs, but I don't think that's what they are aimed at. These higher rates are primarily used in telco trunks, replacing SONET links, for instance.

Why, are you feeling limited by the 1000BASE-T commonly available in PC motherboards these days? I don't see that as any problem, for some time to come.

As to antenna diversity, that was my point. MIMO only works as well as the lack of correlation between the different propagation paths. That lack of correlation is not guaranteed, by any means. It all depends on conditions at the time. So if people walk about, or if your AP and your STA are not positioned just right, there's no guarantee you can make effective use of 4 X 4, much less 8 X 8.

At home, from an upstairs AP to a downstairs STA, the correlation between the propagation paths seems to vary constantly for me, with 802.11n. So I was only saying that I wouldn't be a bit surprised if the same occurs with 802.11ac.

MeasurementBlues
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Hesitation
MeasurementBlues   7/8/2014 1:23:53 PM
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Another reason for the hesitation is that not everyone needs 802.11ac speeds, at least not yet. So, many businesses will put off the expense as long as the can.

hesitation on when to schedule 802.11ac deployments

MeasurementBlues
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Re: Backhaul limitation
MeasurementBlues   7/8/2014 1:27:45 PM
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LarryM,

Why did you upgrade to ac? Did it give you a boost in performance? I just upgraded from 802.11g to 802.11n, but only because the g router needed a power cycle once a week. The n router has better range, the ability ot add guest networks, and USB sockets where I keep some network storage.

The Linksys g router that I replaced is still in production and is fine for many homes.

LarryM99
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CEO
Re: Backhaul limitation
LarryM99   7/8/2014 3:54:05 PM
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@MeasurementBlues, my previous router went to a relative whose router died on them. I ended up getting a Netgear Nighthawk. I have not done performance testing on it, but it does seem to perform nicely. I have not seen any reduction in range, and it might be a bit better. I also liked the USB ports on this device and the more-comprehensive setup options.

Larry M.

Olga Shapiro
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Re: Backhaul limitation
Olga Shapiro   7/10/2014 3:15:00 PM
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Great point! I think its something to watch out for.

David Ashton
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Re: Hesitation
David Ashton   7/10/2014 4:42:00 PM
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For home use. the high speeds of 802.11ac - 500 MB/s or  more - are not going to help you if your incoming DSL line is only around 20 MB/s.  In a corporate environment where there is more data shunted around internally there is more benefit to it.  Ditto if you have a fibre incoming line.

I had an 802.11g router (11 MB/s) and when it failed upgraded to an 802.11n (54 MB/s) and did notice a very slight difference, but probably most noticeable on printing speed - which of course is internal.

MeasurementBlues
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Re: Hesitation
MeasurementBlues   7/10/2014 4:51:46 PM
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if your incoming DSL line is only around 20 MB/s

My home DSL is 3 Mb/s and  we can run two video streams and a audio stream at the same time. I've considered upgrading to 7 Mb/s, but don;t think I'll need it for the extra $20/month.

 

 

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