Date: Mon, 26 Mar 2007 11:59:08 -0500 From: David Young To: "Luis R. Rodriguez" Cc: Pavel Roskin , linux-wireless-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Scott Raynel , radiotap-rN9S6JXhQ+WXmMXjJBpWqg@public.gmane.org Subject: Re: RFC: radiotap discrepancy in Linux vs OpenBSD Message-ID: <20070326165908.GK31621-eZ+MEZF6i8Dc+919tysfdA@public.gmane.org> References: <20070325232416.64xwkc0kw04oosg0-2RFepEojUI3Rd1RZctBqVdHuzzzSOjJt@public.gmane.org> <20070326033839.GA24097-eZ+MEZF6i8Dc+919tysfdA@public.gmane.org> <43e72e890703260841v56047559y90b7c25c9c458564-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <43e72e890703260841v56047559y90b7c25c9c458564-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> User-Agent: Mutt/1.4.1i On Mon, Mar 26, 2007 at 11:41:38AM -0400, Luis R. Rodriguez wrote: > CC'ing radiotap list, this time with your comments inline. > > On 3/25/07, David Young wrote: > >On Sun, Mar 25, 2007 at 11:24:16PM -0400, Pavel Roskin wrote: > >> Hello! > > > >(Oops, this time cc'd radiotap.) > > > >The place to discuss this is the mailing list > >radiotap-eZodSLrBbDpBDgjK7y7TUQ@public.gmane.org, which I have cc'd. Subscribe at > >. Please feel free > >to circulate the URL. > > > >> I have noticed two different incompatible changes to enum > >> ieee80211_radiotap_type in ieee80211_radiotap.h. > >> > >> One is found in the current wireless-2.6.git: > >> > >> IEEE80211_RADIOTAP_RX_FLAGS = 14, > >> IEEE80211_RADIOTAP_TX_FLAGS = 15, > >> IEEE80211_RADIOTAP_RTS_RETRIES = 16, > >> IEEE80211_RADIOTAP_DATA_RETRIES = 17, > > > >These fields are slated to become part of the standard, I just haven't got > >around to updating the manual page, yet. I have time to do that tonight. > > > >> It was added together with Marvell Libertas USB driver. > > > >> Another set of the flags can be found in CVS OpenBSD: > >> > >> IEEE80211_RADIOTAP_FCS = 14, > >> IEEE80211_RADIOTAP_HWQUEUE = 15, > >> IEEE80211_RADIOTAP_RSSI = 16, > > > >These fields are not part of the standard, and they will not become part > >of the standard with these numbers. This is the first time I have ever > >heard of HWQUEUE and RSSI, actually. What are they for? > > RSSI is Received Signal Strength Indication. Its a measurement of the > received radio signal strength. Unfortunately though RSSI units used > are arbitrary and the maximum value differs amongst chipsets. From > wikipedia: > > -- > RSSI measurements will vary from 0 to 255 depending on the vendor. It > consists of a one byte integer value. A value of 1 will indicate the > minimum signal strength detectable by the wireless card, while 0 > indicates no signal. The value has a maximum of RSSI_Max. For example, > Cisco Systems cards will return a RSSI of 0 to 100. In this case, the > RSSI_Max is 100. The Cisco card can report 101 distinct power levels. > Another popular Wi-Fi chipset is made by Atheros. An Atheros based > card will return a RSSI value of 0 to 60. > -- > > As Samuel Barber had recommended before, we should probably instead > adopt RCPI. Quoting from his e-mail: RCPI sounds desirable. Let us avoid labeling a field RCPI if it isn't. We may need both fields, RSSI (defined: uncalibrated, unsigned, unitless signal strength, greater numbers -> greater strength) and RCPI (defined per 802.11k draft 5.0). Is 802.11k changing very rapidly, esp. the RCPI definition? Dave -- David Young OJC Technologies dyoung-eZodSLrBbDpBDgjK7y7TUQ@public.gmane.org Urbana, IL * (217) 278-3933