Internet Connection Stays at 3.2 Mbps

[wintersteele]

Hi Everyone,

Does anyone know what i might want to look at in my setup? I have a cable connection to my linksys WAP (with 4 port router) . I have WEP enabled using a 40 bit key. Id like a little security at least.

My sony vaio laptop has an internal orinoco wireless card and running windows xp pro.

Once my laptop picks up a signal it only connects at 3.2 mbps. Never less or more. I am usually only sitting 15 feet or less away. Huge downloads will knock out my connection. Web pages are slow or hang. Newsgroup reading is practically impossible. Frequenly my net connection disconnects for no reason at all even and I have to manually connect.

I got knocked offline 3 or 4 times while writing this post. What might be going wrong here?

Thanks in advance.

[oshea85]

Try upgrading all firmware, drivers, and utilities on both the AP and the client device.

If that doesn't do the trick, see what happens when you turn off WEP.

Also, how are you determining 3.2 Mbps? The media sense should only detect 1, 2, 5.5 and 11 Mbps, nothing in between. Are you measuring throughput instead of the data rate?

Most vendors do WEP encryption/decryption in software, reducing throughput by as much as 20%. Cisco is one exception to this that I'm aware of.

[jangeunjun]

Hi,
I think the data rate 3.2Mbps is pretty much reasonable.
I assume that you are using 802.11b, right?
And you wonder why you get only 3.2 Mbps and *not* 11 Mbps.

Ok, I think I have the answer.
It seems that it's natural. Typically there are a lot of overhead (especially protocol headers) in WLAN.

You said you are using WEP which may reduce the performance by %20. But why not 80% of 11 Mbps? (=8.8 Mbps)

If you are using 802.11b and RTS/CTS MAC scheme, you will never get that much bandwidth. The maximum is around 4.5 Mbps. And since you are using WEP, 80% of 4.5 Mbps is 3.6 Mbps. And unfortunately, the 3.6 Mbps is only the maximum throughput of the MAC SDU. Thus, the data rate that is experienced by the application is even worse than that. Think of LLC header, IP header, TCP/UDP header and application header. They are at least 40 bytes! No wonder why you get only 3.2 Mbps.

In order to find out the real throughput or the real maximum bandwidth of 802.11, 802.11a and 802.11b networks, try this url:
http://www4.ncsu.edu/~jjun/tmtcal.htm

The theory behind this tool is explained here:
http://www4.ncsu.edu:8030/~jjun/research.htm