From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johannes Berg Subject: multi-antenna handling Date: Mon, 20 Aug 2012 18:50:25 +0200 Message-ID: <1345481425.4459.46.camel@jlt3.sipsolutions.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Sender: radiotap-owner-sUITvd46vNxg9hUCZPvPmw@public.gmane.org To: "radiotap-sUITvd46vNxg9hUCZPvPmw@public.gmane.org" List-Id: radiotap@radiotap.org Hi, This isn't really a proposal for a field definition, but more a usage clarification that I'm seeking. When we have multiple RX chains, it is often useful to know how much power was received by each chain, and which chain(s) a frame was received on. Today, many drivers give the maximum power over all chains as a single value, and some drivers give no antenna information while other drivers (ab)use the (unitless) antenna index field (bit 11) as an antenna bitmap. I'm planning to modify this (in Linux) to include, where available, antenna index & per-antenna signal information by duplicating the radiotap namespace for each antenna, so that the header would, for example, read as follows for a 3x3 devices: * ... TSF, Flags, Rate, Channel, ... * antenna signal: -40 dBm * antenna: 0 * ... MCS, A-MPDU status, ... * antenna signal: -45 dBm * antenna: 1 * antenna signal: -43 dBm * antenna: 2 Does this seem like sane behaviour? If so, do you think it would be worthwhile describing it somewhere on the wiki? johannes