WARP Project Forums - Wireless Open-Access Research Platform

You are not logged in.

#1 2017-Aug-04 03:52:48

gmkim
Member
Registered: 2016-Jul-19
Posts: 27

.

.

Last edited by gmkim (2020-Aug-17 20:04:03)

Offline

 

#2 2017-Aug-04 09:29:44

chunter
Administrator
From: Mango Communications
Registered: 2006-Aug-24
Posts: 1212

Re: .

There is no SNR estimator in the 802.11 Reference Design. I'm not sure what threshold you were referring to in "wlan_mac_low.c".

In the absence of interference, receive power will be proportional to SNR. Depending on how accurate it needs to be for your purposes, this might be a decent first cut. This is a little hand wavy, but you could argue that the DCF is designed to try to access the medium when others aren't using it, so the Rx power of received frame that properly decodes with FCS good likely had zero or very little interference in it.

Otherwise, you'll have to modify the design to add an SNR estimator into the PHY. This is a challenge, but doable. The WARPLab OFDM example does the standard technique of converting an EVM measurement into SNR. However, that won't work directly int the real-time 802.11 Reference Design because of coding. Even with an FCS good packet, you don't know exactly what every decoded symbol was, so you can't compare it to anything to calculate a real EVM value. So, you'd have to either settle for a "pseudo" EVM where you calculate the value as compared to whatever it decoded as, or you limit your EVM measurements to known pilot symbols.

Offline

 

Board footer