Hello, everyone!
For some time now, I wanted better WiFi performance in my home network, and, since I already own AirPort Express (draft 802.11n version) and iMac (Snow Leopard, 802.11n too), I went out and bought Linksys WUSB300N WiFi adapter for my PC (Windows XP), hoping for improvement. Unfortunately, to my great dissapointment, network went from sluggish to... er, a
little less sluggish
Now, I know those numbers like 300Mbit/s don't resemble reality (especially since you have to divide it by 2 in the first place), but what I got was more like I had to have in my 802.11g in the first place.
iperf confirms my observation. On its best run, it shows only 24.5Mbit/s between iMac and PC (peak: 3.2MB/s). I don't have enough experience, nor the reference rates to compare with, but to me, this sounds very bad for n. For testing purposes, i put back my 802.11g, and iperf shows me about 12Mbit/s. This sounds low for g too (54/2 = 27), doesn't it?
I live in a small apartment, and router, iMac, and PC are all within a reach of few meters. That's why I find it odd that it takes a while finding the perfect location for Linksys adapter, where it "connects at" maximum speed (144.5Mbit/s according to Windows network status) and stays like that. iMac's link speed is 130Mbit/s. Router is set to 802.11n only, with WPA2, but i observe identical behaviour with no encryption and compatibility with b/g turned on. By using AirPort utility, I can confirm that iMac and PC are the only clients connected to router. I tried automatic channel selection, and manual (where I live, only channel 1 is occupied, according to Network Stumbler, so I picked channel 7). I'd like to try with 5GHz, but Linksys doesn't support that (should have looked better before buying). I turned off every other device during testing, so that I can confirm that there is no interference (at least not from something in my apartment). I used latest drivers, and I tried adapter on PC and on my laptop, where I was free to move it around. Nothing helps. 24.5Mbit/s top.
Now, there is another interesting thing. I tried to find out where the bottleneck is, so I did this:
- Connected my PC with AirPort via WAN port (AirPort is in bridge mode anyway), connected wirelessly from iMac, and iperf-ed between iMac and PC -- it shows 80-90Mbit/s
- Connected my iMac with AirPort via WAN port, connected wirelessly from PC and iperf between iMac and PC shows 60-70Mbit/s at best. Obviously, Linksys has poor performance compared to iMac's wireless, but shouldn't I get at least 40Mbit/s when router is working in duplex (since it's obviously capable of sending out 90Mbit/s in one direction only)? Or am I missing something important here?
Can anyone tell me if this is normal? 25Mbit/s for n network? 12Mbit/s for g network? And if it isn't, what more can I do? Thanks in advance!
Igor
Slow 802.11n 
Linear Mode
