From owner-freebsd-wireless@FreeBSD.ORG Thu Feb 19 16:41:32 2015 Return-Path: Delivered-To: freebsd-wireless@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 83D2E771 for ; Thu, 19 Feb 2015 16:41:32 +0000 (UTC) Received: from mail-ig0-x229.google.com (mail-ig0-x229.google.com [IPv6:2607:f8b0:4001:c05::229]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4640EE13 for ; Thu, 19 Feb 2015 16:41:32 +0000 (UTC) Received: by mail-ig0-f169.google.com with SMTP id hl2so1477543igb.0 for ; Thu, 19 Feb 2015 08:41:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type:content-transfer-encoding; bh=WO9YM9cTCEWY8l2RHuuuzTGtlf1syQyRX5SL+/SK/aY=; b=NW5Vl+0gHxl9aq8URFJzU/1nPRt69Y6NxhkLgJZTtXh1ffUG0b54qhDt9YlfNwsjC+ cEOvIoQ6O7PvBJKi1Ru4q7KvFgSJfAeXyOjDU5MZhRE7xVawfj7Qtny6GAPtSIP+2swI NFJL/J/Wd1ES4vun72bDiswLxP7fykNG1WnxxP/7Plqu3vedeuzm2y8v6T49zIM9miWe 1LLakIrPVO8aVSJJJsvdNedbx+5rwx09VBGAyX2E5dJC97DG/9nf1g2vT/2nyJ+fawpz Ju4Bq6n5zPAL2z4nC3cvkX2Z5C2i8qhOLypq9ga6H0l9sq/frw09hZerY3zhLzvBB/c4 yLOg== MIME-Version: 1.0 X-Received: by 10.50.164.227 with SMTP id yt3mr8455582igb.32.1424364091691; Thu, 19 Feb 2015 08:41:31 -0800 (PST) Sender: adrian.chadd@gmail.com Received: by 10.36.17.66 with HTTP; Thu, 19 Feb 2015 08:41:31 -0800 (PST) In-Reply-To: <4e2942f9.fdd.14b9dd49b7e.Coremail.u8j9@163.com> References: <4e2942f9.fdd.14b9dd49b7e.Coremail.u8j9@163.com> Date: Thu, 19 Feb 2015 08:41:31 -0800 X-Google-Sender-Auth: igsV1k0XhX6qsT35QIUAwBhSeMc Message-ID: Subject: Re: TDMA slot(bh) From: Adrian Chadd To: =?UTF-8?B?5a2Q5paH?= Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Cc: "freebsd-wireless@freebsd.org" X-BeenThere: freebsd-wireless@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: "Discussions of 802.11 stack, tools device driver development." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 19 Feb 2015 16:41:32 -0000 The whole point here is that DBA is used to control the start of the slot times, and SWBA is used to only send out actual beacon frames in multiples of that. normally you'd have SWBA be just before DBA, and and they'd have the same interval. Here DBA is used primarily to gate the start of the slot time for that particular device, and it only bothers sending the beacon frame every 'tdmaswba' DBA intervals. The beacons are used to announce that the device is there and to update RTT estimates; it's not doing anything like gating broadcast traffic. -adrian On 18 February 2015 at 09:55, =E5=AD=90=E6=96=87 wrote: > Dear Adrian > In HAL_INT_SWBA handler of ath_intr funtion . What means tdmaswba? I f= ound the tdmaswba default is five and when it decrease to zero ,the ap wi= ll send out the beacon package. From here I fell every SWBA is the start of= the slot? > > > > > -- > =E5=8F=91=E8=87=AA=E6=88=91=E7=9A=84=E7=BD=91=E6=98=93=E9=82=AE=E7=AE=B1= =E6=89=8B=E6=9C=BA=E6=99=BA=E8=83=BD=E7=89=88 > > > =E5=9C=A8 2015-02-19 01:28:38=EF=BC=8C"Adrian Chadd" = =E5=86=99=E9=81=93=EF=BC=9A >>Yup. >> >>DBA gates the actual beacon transmit - if there's no beacon in the >>slot, then it's fine. >> >>SWBA is the software timer that fires just before DBA, so the software >>stack has a chance to program the hardware with a beacon and let the >>hardware get the packet DMA -> TX FIFO setup all correctly so that >>when it's DBA time (ie, time to /transmit/ the beacon), it's already >>ready to go. >> >> >>-adrian >> >> >>On 18 February 2015 at 09:09, bh wrote: >>> Dear Adrian >>> In ath_intr , there are a variable which decrease every swba, so = when the variable swbaintalval is zero, ap will send beacon .So I think th= e period of swba is slot time, ap will send beacon every five slot, the be= acon interval is five slottime? >>> >>> Adrian Chadd =E7=BC=96=E5=86=99=EF=BC=9A >>> >>>>On 18 February 2015 at 07:55, bh wrote: >>>>> Dear >>>>> The default slotcnt=3D2 , becntival=3D5.For ap it will generate = SWBA every slot,it will send beacon every five slots, beacause ap fire th= e DBA timer in every slot, so it will send data package in every slot. Is = my above understanding correct? >>>> >>>>It generates SWBA every beacon interval, which is calculated in >>>>ath_tdma_bintvalsetup(). >>>> >>>>Master stations beacon 20 times a second with the default config >>>>specified by the wiki. >>>> >>>> >>>>-adrian