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criggs

join:2000-07-14
New York, NY
Reviews:
·Millenicom

Is WiMax One-Lane or Two-Lane?

Suppose that on a given afternoon, let's say today, my download speed is running at 10 mbps, as measured on Speedtest or Speakeasy or whatever.

Let's say that my upload speed is running at 1 mbps as measured on Speedtest or Speakeasy or whatever, the Sprint-capped maximum upload speed for its WiMax service.

Let's say I'm watching a high-speed video stream that runs at 2 mbps.

In addition, let's say that, at the same time, I'm uploading a file, and my upload speed is running at a minimum average speed spec provided by Sprint for WiMax, 500 kbps.

Now if WiMax is a one-lane highway, then I now have a total of remaining speed left of 7.5 mbps.

However, if WiMax is a two-lane highway, then I now have a total of remaining speed left of 8 mbps on the download lane and a total of remaining speed left on the upload lane of 500 kbps.

So here's my question: Which is it, a one-lane or two-lane highway?

Thanks.


cellguru

join:2008-09-22
Pleasant Grove, UT

I believe it is basically two lanes, having done my fair share of simultaneous up and down, I don't believe one significantly effects the other.

Not sure how exactly you would measure it though.


criggs

join:2000-07-14
New York, NY
Reviews:
·Millenicom

It would take a little doing, but how about this?

Ascertain what your download speed is, with one of the standard speed tests.

Let's say the download speed tests say that the connection is running at 10 mbps.

Now open up multiple browser windows with a broadband stream. The Indiana University opera streaming page at »music.indiana.edu/iumusiclive/streaming/ will do nicely, since their HD streams run at 3 mbps. So open three of those windows, and you will have used up 9 mbps of your available bandwidth, and you will only have 1 mbps of bandwidth left.

Now pull up one of those live TV streams which WWI TV offers at »wwitv.com/menu_left.htm . Pick one that runs almost 1 mbps. There's a good Czech video stream that runs almost .9 mbps at »mms://netshow7.play.cz/noetv .

Okay, now that you've got your download path completely clogged, see what happens with your upload. If you seem to have the full 1mbps available to you, then there are really two lanes. If the upload has been impacted by the maxing out of the download, then there's really only one lane.

And that's exactly what I just did.

And there are definitely two lanes, because, even as the stream playback began to falter and buffer because of the congestion, the upload speed just kept on sailing away at a constant 900 kbps.

So you are right; thank you!



dib22

join:2002-01-27
Kansas City, MO

remember that no mater the Duplex, once either side or both sides are saturated (download and/or upload) things will generally slow down anyway since the ACKnowldement packets will have to get in line to be sent and/or received.



espaeth
Digital Plumber
Premium,MVM
join:2001-04-21
Minneapolis, MN
kudos:2
Reviews:
·Vitelity VOIP
reply to criggs

said by criggs:

And there are definitely two lanes, because, even as the stream playback began to falter and buffer because of the congestion, the upload speed just kept on sailing away at a constant 900 kbps.

That could happen even on a single frequency TDD system. The timeslot allocation is controlled by the tower radio for both the upstream and downstream.

criggs

join:2000-07-14
New York, NY
Reviews:
·Millenicom

Interesting. Then that could mean that the download speed I'm getting on most speed tests might include whatever room I have for uploads as well.

I started experiencing congestion and buffering on the download side once I opened that third high-speed stream, BEFORE I started my upload. And yet then, when I subsequently started the upload, the upload was still smooth. If I had reached max capacity, and this was a single frequency system, how was the system able to make room for my upload?



espaeth
Digital Plumber
Premium,MVM
join:2001-04-21
Minneapolis, MN
kudos:2
Reviews:
·Vitelity VOIP

said by criggs:

If I had reached max capacity, and this was a single frequency system, how was the system able to make room for my upload?

The shared channel bandwidth is somewhere around 40mbps, no single end-point is allowed to run the table on utilization, and some percentage of the capacity is always reserved for upstream use. (ie, upstream timeslot reservations)

criggs

join:2000-07-14
New York, NY

Thank you for explaining that. It actually made sense even to me!