Design Con 2015
Breaking News
Blog

802.11ac Test Challenges Take Off

NO RATINGS
View Comments: Threaded | Newest First | Oldest First
LarryM99
User Rank
CEO
Backhaul limitation
LarryM99   7/7/2014 4:33:16 PM
NO RATINGS
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
User Rank
CEO
Re: Backhaul limitation
Bert22306   7/7/2014 5:19:06 PM
NO RATINGS
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
User Rank
CEO
Re: Backhaul limitation
LarryM99   7/7/2014 8:03:38 PM
NO RATINGS
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
User Rank
CEO
Re: Backhaul limitation
Bert22306   7/7/2014 8:39:59 PM
NO RATINGS
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
User Rank
Blogger
Re: Backhaul limitation
MeasurementBlues   7/8/2014 1:27:45 PM
NO RATINGS
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
User Rank
CEO
Re: Backhaul limitation
LarryM99   7/8/2014 3:54:05 PM
NO RATINGS
@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
User Rank
Blogger
Re: Backhaul limitation
Olga Shapiro   7/10/2014 3:15:00 PM
NO RATINGS
Great point! I think its something to watch out for.

MeasurementBlues
User Rank
Blogger
Hesitation
MeasurementBlues   7/8/2014 1:23:53 PM
NO RATINGS
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

David Ashton
User Rank
Blogger
Re: Hesitation
David Ashton   7/10/2014 4:42:00 PM
NO RATINGS
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
User Rank
Blogger
Re: Hesitation
MeasurementBlues   7/10/2014 4:51:46 PM
NO RATINGS
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.

 

 

MeasurementBlues
User Rank
Blogger
Re: Hesitation
MeasurementBlues   7/10/2014 4:56:00 PM
NO RATINGS
For my father-in-law's birthday last week, my wife and I told him we're getting him 1 Mb/s DSL. He uses dialup because it's the least expensive internet available ($5/month for Juno). We're paying the $15/month for his DSL for the first year. I'll report back next year and see if he keeps it or goes back once he has to pay for it himself. At his birthday, we gave him a DSL filter and told him waht it comes with.

David Ashton
User Rank
Blogger
Re: Hesitation
David Ashton   7/10/2014 7:17:28 PM
NO RATINGS
@MB it will be interesting to see what he thinks.   I could never go back to dial up.  But then I look at YouTube, download data sheets and stuff, and get messages with huge attachments sometimes.   Even EETimes, whose home page is fairly big and complex, takes an annoyingly long time to load sometimes.  I have an ADSL1 line which gives me around 5 MB/s on a good day I think, but usually a bit slower.  ADSL2 (up to 20MB/s) is not available in my area yet.

When I had a 14.4K dial-up line in Zimbabwe, I sometimes had to contact my ISP and ask them to remove large email attachments that locked up the line.  And I had a signature on my emails which said "DON'T send attachments"!  Glad I'm past those days, but if you had a 56K dialup and you only wanted it for email I guess you would get by OK still....

Radio
LATEST ARCHIVED BROADCAST
EE Times Senior Technical Editor Martin Rowe will interview EMC engineer Kenneth Wyatt.
Top Comments of the Week
Like Us on Facebook

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
EE Times on Twitter
EE Times Twitter Feed
Flash Poll