WiMax + WiFi = slow?

DulacLancelot · 4G Newbie Joined: 24 Jun 2009 Posts: 7

i have the Sprint Xohm home modem.
i also have 2 wireless routers.
i've been using SpeedTest.net to test my internet speeds.

connecting the modem directly to my computer results in speeds around 8Mbps/1.4Mbps (down/up). routing that connection through one or both of my routers via ethernet cables results in the same speed results. however, if i connect to the routers wirelessly at any stage, the speed cuts down to 3/1.4Mbps.

i've heard Xohm is Wimax at around 2.5GHz. one of the routers is capable of 802.11a (5.5ish GHz), but even with that Wireless A connection, the speed is still slow.

there is certainly a lot of other wifi networks in the area, so i tried to measure the capacity of the wifi connection itself. i downloaded some point-to-point network performance measuring software (pcattcp.exe). a wired connection through my router LAN between my laptop and my desktop showed throughput at 88Mbps. when i used my laptop's wifi connection instead that dropped to about 20Mbps, but still plenty to handle my internet connection without slowing it down i would think.

i have the modem on the second floor, and have brought the connection through wires down to the first floor so as to keep the wireless routers far away from the modem but this did not have any effect.

someone else seems to have noticed this as well:
dslreports.com/comment/3365/72014
(search for "Speeds for wireless" on that page)
his comments say the wifi link about halves the internet connection speed. for me it seems more like it caps it at around 3Mbps.

any ideas on why the slowdown?

wakeman91 · Posted: Thu Jun 25, 2009 9:24 am Post subject:

I don't have the slightest idea as to how wi-fi anything works. But my experiences putting any connection through wi-fi significantly reduces the speed when compared to a straight connection to whatever is supplying the wi-fi. DSL, Xohm, even a brand-spanking new 100ish person college dorm backed with T1 and Gigabit ethernet to the wall connected to a cat 6 cable into a gigabit/wi-fi router (blazing fast connection between rooms when using wires, but standard crap wifi speeds). I'd be interested to know what the reasoning is.

DulacLancelot · 4G Newbie Joined: 24 Jun 2009 Posts: 7

first, i want to point out the experiment in my previous post where i measured the WiFi throughput speed to be 20Mbps. a little poor, but given the tons of other WiFi networks around, not unexpected. still, it is more than 8Mbps.

but i guess you are implying that whatever the measured throughput of the WiFi connection, the WiFi connection slows down any data going over it not by capping the speed at a certain limit, but by multiplying the speed by a certain amount, say 50%.

so here is another thing i did for the control part of the experiment. i brought one of my WiFi routers over to a 10Mbps non-WiMAX internet connection. the speed tested to be 10Mbps wired. and it tested to be 10Mbps over WiFi, too.

wakeman91 · Posted: Thu Jun 25, 2009 10:28 am Post subject:

As you correctly understood, I had been implying that it was a percentage drop but like I said I really know little about wi-fi and would be surprised if my issue wasn't just that something was incorrectly set up or needed some settings tweaked.

Interesting though that Wimax would experience a drop in speed different from other sources though. Was your test of the wifi router in the same room with all the other signals bouncing around that you mentioned....could that be what's causing a percentage drop?

DulacLancelot · 4G Newbie Joined: 24 Jun 2009 Posts: 7

are you still having your WiFi issue? i'm no WiFi expert either, but i could suggest some very basic things to check, since in the process of trying to solve the problem i am posting about i did a bit of reading about it.

that was actually what my comment about Xohm being at 2.5GHz and 802.11a being at 5.5ish GHz was about... most common WiFi is at 2.4GHz and although i wouldn't think it wouldn't matter, i tried the 5.5ish GHz option just in case, since it was much further away from the 2.5GHz of Xohm. that also probably why i even got the fairly decent 20Mbps throughput that i did... i was pretty much alone at that WiFi frequency band.

no, my test with the alternate 10mbps internet connection was not in the same environment. i had not really considered the WiFi-dminished-your-speed-by-a-factor idea, so my 20Mbps WiFi throughput test that was in the same environment satisfied me.

also, notice that the downstream 8Mbps dropped to 3, but the upstream 1.4Mbps stayed the same. since it is WiMAX, i can also easily adjust what internet connection speed i'm getting by moving the modem around. if i adjust it such that i get speeds like 2/0.5Mbps over a wired connection, measuring the speed over a WiFi connection does not change anything -- still 2/0.5Mbps.