From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bosmailout06.eigbox.net (bosmailout06.eigbox.net [66.96.189.6]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 910F33B2A4; Sun, 8 Aug 2021 00:35:57 -0400 (EDT) Received: from bosmailscan07.eigbox.net ([10.20.15.7]) by bosmailout06.eigbox.net with esmtp (Exim) id 1mCaXV-0003i3-7D; Sun, 08 Aug 2021 00:35:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=alum.mit.edu; s=dkim; h=Sender:Content-Transfer-Encoding:Content-Type: MIME-Version:Message-ID:Date:Subject:In-Reply-To:References:Cc:To:From: Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender :Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=yvYIFYToAZM1xWjvK2wdA4YvUlOs7QaMQ1e1gxb0CZY=; b=ibDvwDXQ6MAv+TJC1S2Jx6OqJu cD+Bo0rTisA6PzGMVLDfLURCF7Xw2i3SRWQxAhdNHONUD4Fn88MiHRg0yM4ZbCdFqHu52YHLwH7vp 8W28+n3PW9B3N5ovD4a6PYZtE0EB5zgT5I6hw9i4MrWgpZMeDvbi7s9RphsRnV4WtnbRjC6ITwyob W+6QQX2PyoYQbhsN3HgW4T7Bpjvzag8ypaRnS1OG+kSQ7m+Pe7zH2TORL5a8al6g2lJHt78sf6mdV scCwEdg4QjoVajPFPo1s6ytCkaq0e0yQCVairhnfx55BaUCrUh4pYKd9N+WJ+lBQ8Ix/8b0EFpeTp uEinkA4Q==; Received: from [10.115.3.32] (helo=bosimpout12) by bosmailscan07.eigbox.net with esmtp (Exim) id 1mCaXU-0003DM-Ve; Sun, 08 Aug 2021 00:35:56 -0400 Received: from bosauthsmtp17.yourhostingaccount.com ([10.20.18.17]) by bosimpout12 with id esbt250010N5uqq01sbwq0; Sun, 08 Aug 2021 00:35:56 -0400 X-Authority-Analysis: v=2.3 cv=d4VuNSrE c=1 sm=1 tr=0 a=f4kFLigMKr8AH7rIJ//qJA==:117 a=x+7tlP9+fMpTIVJEmcsKvw==:17 a=kj9zAlcOel0A:10 a=MhDmnRu9jo8A:10 a=Wo7qeYC63mUA:10 a=kurRqvosAAAA:8 a=Q-fNiiVtAAAA:8 a=uYVGJH5IAAAA:8 a=o83nqyVRAAAA:8 a=s_HMJkiOXO9JVvx2e5sA:9 a=CjuIK1q_8ugA:10 a=kbxRQ_lfPIoQnHsAj2-A:22 a=Fp8MccfUoT0GBdDC_Lng:22 a=ZkEWZNUrOYKkpCLSUeX7:22 Received: from c-73-222-32-85.hsd1.ca.comcast.net ([73.222.32.85]:62483 helo=SRA6) by bosauthsmtp17.eigbox.net with esmtpa (Exim) id 1mCaXR-0006SG-G6; Sun, 08 Aug 2021 00:35:53 -0400 Reply-To: From: "Dick Roy" To: "'David Lang'" , "'Bob McMahon'" Cc: , "'Make-Wifi-fast'" , "'Cake List'" , , "'cerowrt-devel'" , "'bloat'" References: <1625188609.32718319@apps.rackspace.com> <989de0c1-e06c-cda9-ebe6-1f33df8a4c24@candelatech.com> <1625773080.94974089@apps.rackspace.com> In-Reply-To: Date: Sat, 7 Aug 2021 21:35:42 -0700 Organization: SRA Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook 11 Thread-Index: AdeLuSn3FAru8zxtRo2sd1864ZKtggAVNELg X-MimeOLE: Produced By Microsoft MimeOLE X-EN-UserInfo: f809475445fb8041985048e338e1a001:931c98230c6409dcc37fa7e93b490c27 X-EN-AuthUser: dickroy@intellicommunications.com Sender: "Dick Roy" X-EN-OrigIP: 73.222.32.85 X-EN-OrigHost: c-73-222-32-85.hsd1.ca.comcast.net X-Mailman-Approved-At: Mon, 09 Aug 2021 13:17:41 -0400 Subject: Re: [Cake] [Starlink] [Make-wifi-fast] [Cerowrt-devel] Due Aug 2: Internet Quality workshop CFP for the internet architecture board X-BeenThere: cake@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Cake - FQ_codel the next generation List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 08 Aug 2021 04:35:57 -0000 -----Original Message----- From: Starlink [mailto:starlink-bounces@lists.bufferbloat.net] On Behalf Of David Lang Sent: Monday, August 2, 2021 9:31 PM To: Bob McMahon Cc: starlink@lists.bufferbloat.net; Make-Wifi-fast; Cake List; codel@lists.bufferbloat.net; cerowrt-devel; bloat Subject: Re: [Starlink] [Cake] [Make-wifi-fast] [Cerowrt-devel] Due Aug 2: Internet Quality workshop CFP for the internet architecture board symmetry is not always (or usually) true. [RR] There is a big difference between "symmetric RF channels" and "balanced RF links". Be careful not to confuse the two. stations are commonly heard at much larger distances than they can talk, mobile devices have much less transmit power (becuase they are operating on batteries) than fixed stations, and when you adjust the transmit power on a station, you don't adjust it's receive sensitivity. [RR] Not quite true. Rx sensitivity is a function of MCS (the modulation and coding scheme) and those levels can be adjusted, both up and down, by changing the MCS. This is in fact one of the major tools that needs to be integrated into wireless systems today. It's generally overlooked, though not always! Starlink should be doing this if they are not already BTW! David Lang On Mon, 2 Aug 2021, Bob McMahon wrote: > Date: Mon, 2 Aug 2021 20:23:06 -0700 > From: Bob McMahon > To: David Lang > Cc: Ben Greear , > Luca Muscariello , > Cake List , > Make-Wifi-fast , > Leonard Kleinrock , starlink@lists.bufferbloat.net, > codel@lists.bufferbloat.net, > cerowrt-devel , > bloat > Subject: Re: [Cake] [Make-wifi-fast] [Starlink] [Cerowrt-devel] Due Aug 2: > Internet Quality workshop CFP for the internet architecture board > > The distance matrix defines signal attenuations/loss between pairs. It's > straightforward to create a distance matrix that has hidden nodes because > all "signal loss" between pairs is defined. Let's say a 120dB attenuation > path will cause a node to be hidden as an example. > > A B C D > A - 35 120 65 > B - 65 65 > C - 65 > D - > > So in the above, AC are hidden from each other but nobody else is. It does > assume symmetry between pairs but that's typically true. > > The RF device takes these distance matrices as settings and calculates the > five branch tree values (as demonstrated in the video). There are > limitations to solutions though but I've found those not to be an issue to > date. I've been able to produce hidden nodes quite readily. Add the phase > shifters and spatial stream powers can also be affected, but this isn't > shown in this simple example. > > Bob > > On Mon, Aug 2, 2021 at 8:12 PM David Lang wrote: > >> I guess it depends on what you are intending to test. If you are not going >> to >> tinker with any of the over-the-air settings (including the number of >> packets >> transmitted in one aggregate), the details of what happen over the air >> don't >> matter much. >> >> But if you are going to be doing any tinkering with what is getting sent, >> and >> you ignore the hidden transmitter type problems, you will create a >> solution that >> seems to work really well in the lab and falls on it's face out in the >> wild >> where spectrum overload and hidden transmitters are the norm (at least in >> urban >> areas), not rare corner cases. >> >> you don't need to include them in every test, but you need to have a way >> to >> configure your lab to include them before you consider any >> settings/algorithm >> ready to try in the wild. >> >> David Lang >> >> On Mon, 2 Aug 2021, Bob McMahon wrote: >> >>> We find four nodes, a primary BSS and an adjunct one quite good for lots >> of >>> testing. The six nodes allows for a primary BSS and two adjacent ones. >> We >>> want to minimize complexity to necessary and sufficient. >>> >>> The challenge we find is having variability (e.g. montecarlos) that's >>> reproducible and has relevant information. Basically, the distance >> matrices >>> have h-matrices as their elements. Our chips can provide these >> h-matrices. >>> >>> The parts for solid state programmable attenuators and phase shifters >>> aren't very expensive. A device that supports a five branch tree and 2x2 >>> MIMO seems a very good starting point. >>> >>> Bob >>> >>> On Mon, Aug 2, 2021 at 4:55 PM Ben Greear >> wrote: >>> >>>> On 8/2/21 4:16 PM, David Lang wrote: >>>>> If you are going to setup a test environment for wifi, you need to >>>> include the ability to make a fe cases that only happen with RF, not >> with >>>> wired networks and >>>>> are commonly overlooked >>>>> >>>>> 1. station A can hear station B and C but they cannot hear each other >>>>> 2. station A can hear station B but station B cannot hear station A 3. >>>> station A can hear that station B is transmitting, but not with a strong >>>> enough signal to >>>>> decode the signal (yes in theory you can work around interference, but >>>> in practice interference is still a real thing) >>>>> >>>>> David Lang >>>>> >>>> >>>> To add to this, I think you need lots of different station devices, >>>> different capabilities (/n, /ac, /ax, etc) >>>> different numbers of spatial streams, and different distances from the >>>> AP. From download queueing perspective, changing >>>> the capabilities may be sufficient while keeping all stations at same >>>> distance. This assumes you are not >>>> actually testing the wifi rate-ctrl alg. itself, so different throughput >>>> levels for different stations would be enough. >>>> >>>> So, a good station emulator setup (and/or pile of real stations) and a >> few >>>> RF chambers and >>>> programmable attenuators and you can test that setup... >>>> >>>> From upload perspective, I guess same setup would do the job. >>>> Queuing/fairness might depend a bit more on the >>>> station devices, emulated or otherwise, but I guess a clever AP could >>>> enforce fairness in upstream direction >>>> too by implementing per-sta queues. >>>> >>>> Thanks, >>>> Ben >>>> >>>> -- >>>> Ben Greear >>>> Candela Technologies Inc http://www.candelatech.com >>>> >>> >>> >> > > _______________________________________________ Starlink mailing list Starlink@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/starlink