WiFi Receiver sensitivity

[HIPAR]

I've noticed from its specs that my WiFi router receiver sensitivity varies with mode and data rate. Does that mean I will have to force my B/G router into B mode and limit its throughput to say, one megabits, to achieve maximum sensitivity? Or, will the system negotiate the data rate based upon signal strength to achieve maximum sensitivity?

--- CHAS

 

[thiggins]

In general, the client (STA) driver adjusts its data rate according to its RSSI (Received Strength Signal Indication).

Playing with settings on one end of the connection isn't much help. Unless you want only one-way communication, any improvement needs to be on both ends of the connection.

 

[HIPAR]

Optimizing for range

Thanks Tim.

I guess that begs the question: If I set both ends of the link for B mode and limit the data rate at each end to 1 megabits can I increase the range?

Of course, let's assume the antennas and transmit power remain constant.

If I'm working this out properly, 3db of receiver gain on each end will of the link should increase the range by about 1.5 X and 6 db will double it. So 'in theory' range should generally increase.

I don't need the speed because the link only carries Web data from my DSL modem and that never gets much better than 700 kilobits. So B mode should serve just fine and still leave margin for overhead data.

--- CHAS

 

[Steve]

802.11 wireless communication uses the lowest common denominator for negotiating speeds.

The receiver sensitivity/speed of the AP you are referring to indicate what speed the user will connect if the signal from the client (STA) is received at that level. Your wireless NIC will have similar sensitivity specifications. Therefore the reverse is also true. And therefore, the AP and client negotiate speed in their initial "conversation", along with security settings, etc.

If the AP sees client A at -90db, he will negotiate with that client to be 1Mbps, for example. Unfortunately, a single AP can only talk at one negotiated data rate for all users, therefore when client B attaches at -70db, client B's negotiated data rate will still be 1Mbps.

Nailing up the speed of the AP to 1Mbps will not increase the range, it's simply a function of the RSSI value (that db thing) with respect to both the client and AP.