Return-path: Received: from mail-yh0-f41.google.com ([209.85.213.41]:38216 "EHLO mail-yh0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750840AbaFJIs2 (ORCPT ); Tue, 10 Jun 2014 04:48:28 -0400 Received: by mail-yh0-f41.google.com with SMTP id z6so90090yhz.28 for ; Tue, 10 Jun 2014 01:48:27 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <539030ED.4020006@globaledgesoft.com> References: <539030ED.4020006@globaledgesoft.com> From: Sergey Ryazanov Date: Tue, 10 Jun 2014 12:48:07 +0400 Message-ID: (sfid-20140610_104833_737485_15B2B08B) Subject: Re: Physical carrier sensing (CCA) To: Gaurav Kumar Chauhan Cc: "linux-wireless@vger.kernel.org" , ath9k-devel Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: Hi, 2014-06-05 12:57 GMT+04:00 Gaurav Kumar Chauhan : > I am working on measuring channel load which requires knowledge of carrier > sensing. > > I am comfortable with virtual carrier sensing but not with physical carrier > sensing. > I tried to google it but didn't get more than basics. I want to know about > physical carrier > sensing in detail and where code for physical sensing is present. > > Is it in driver or in firmware? > I am using atheros pci-express card and ath9k driver. Physical and virtual carrier sensing are both realized in hardware at least in AR9xxx chips. Chip provides some knobs to control both of them (on/off, setup levels, etc.) and allows retrieve some statistics (see channel survey code of ath9k driver for example). -- BR, Sergey