From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-x232.google.com (mail-wm0-x232.google.com [IPv6:2a00:1450:400c:c09::232]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 4FF973B29E for ; Sat, 4 Nov 2017 22:04:58 -0400 (EDT) Received: by mail-wm0-x232.google.com with SMTP id z3so7985245wme.5 for ; Sat, 04 Nov 2017 19:04:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=broadcom.com; s=google; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=ltjN+hHPYbKougktA8P5YaAajD0F3g+AhodyIB8/nvc=; b=DVvuIBTLwsl9MuSS/OvbMDbcbBM/Jbi3HlFPMUwlmIhx63frkpKe5aw2iX585E8FHQ XOc0/TG71y1kdeFeF99wDCXfzJn5qWpTt9bx+JKzoBJfdYNOk+GTUo0t6MBh4PV8R33a ColnTsz4nk6sYCf4YkNo4WdAF4OJvEgyo09V0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=ltjN+hHPYbKougktA8P5YaAajD0F3g+AhodyIB8/nvc=; b=qybpQ00Crct63ymVNKoWApqtkBGNr3MPZIrGOWNPmz0CJT/3zq41Vy/dPhk0hfgocw VTdgDNpuZXxuKVDY9c1RkRFloLSHsOApS1jcMc5Bq7qDHMSpYXMLdso9c9fUzneC76+O wCOJLIdVW4mGdwU2Uhc8D2YF9QcY5nvgWI8Fvsd2WFhSpGSn1KxQmGeIPrep4P9Untou cJDrrD7uPs4CLin9U2BkrDLKz3TcnuIXH6jfrLbiBmpeL7JTMQ5H/n6JSIr0997I+XLm aNpjPJyYIRBDYbwW6JTIB6j1mCU2PE/wzENUYQ8A5IRO9b6QNXV4nhu+Na6MX6ZmiuIv sZ+A== X-Gm-Message-State: AMCzsaW5VlTIW9m/4yDaHsqNub4hnsmFu4EvPqIgRF7Cwv3YIMed2S87 wH3v2pOx53uapP32hEVSZa/DnVzD3rA6aIOuVb8Jaw== X-Google-Smtp-Source: ABhQp+RHtklXv/KSpCGDqXUikQ4RsZsZ/cUgMjtQUevKWDmEo2eRyh3/YPisat/GU2WgoaI4Ug2XMD1POQs1bUgH4Zk= X-Received: by 10.80.182.116 with SMTP id c49mr14647684ede.124.1509847497237; Sat, 04 Nov 2017 19:04:57 -0700 (PDT) MIME-Version: 1.0 Received: by 10.80.186.35 with HTTP; Sat, 4 Nov 2017 19:04:56 -0700 (PDT) In-Reply-To: References: <87tvybm0x2.fsf@toke.dk> <87efpdn2at.fsf@toke.dk> From: Bob McMahon Date: Sat, 4 Nov 2017 19:04:56 -0700 Message-ID: To: =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= Cc: Aaron Wood , make-wifi-fast@lists.bufferbloat.net Content-Type: multipart/alternative; boundary="94eb2c0df8c4bd15c9055d32c3fe" Subject: Re: [Make-wifi-fast] Wiring up a wireless testbed X-BeenThere: make-wifi-fast@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 05 Nov 2017 02:04:58 -0000 --94eb2c0df8c4bd15c9055d32c3fe Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Also, the final piece of the puzzle is chip power consumption. Monsoon makes a current meter for a reasonable price. I realize the focus here is on low latency. The market is also driving power consumption, i.e. "energy consumed for useful information energy successfully delivered with the lowest latency possible." The chips themselves can give the RF energies (as well as dump h matrices) so having an expensive network analyzer for that isn't required beyond chip design. Bob On Sat, Nov 4, 2017 at 6:56 PM, Bob McMahon wrote: > Also, Ixia is selling a controllable RF system and it's in early stages. > Maybe contact them to see what the market is driving them to build? My > guess is their asking price will exceed $100K and has huge margins relati= ve > to bill of materials. > > One could probably work with telemakus and build a few using their parts > and sell it for cheaper than the IXIA chassis and still make a nice profi= t. > > Bob > > On Sat, Nov 4, 2017 at 6:50 PM, Bob McMahon > wrote: > >> Try telemakus for variable attenuators and >> variable phase shifters. Aeroflex works well to though are a bit more >> expensive, e.g. the 8331 >> is an >> example >> >> Power dividers, splitter/combiners and butler matrix devices are sold by >> multiple vendors. Prices will vary. Unfortunately, prices aren't super >> low. But usually it's worth the extra money to get a reliable and >> controllable test bed, particularly when one values their time into the >> equation. >> >> Bob >> >> On Sat, Nov 4, 2017 at 2:48 PM, Toke H=C3=B8iland-J=C3=B8rgensen >> wrote: >> >>> Bob McMahon writes: >>> >>> > A way I think about is to emulate the "system" in both range/power >>> > (attenuation) and in mixing (phase shifts) It's a diagonal matrix f= or >>> > range feeding into an h-matrix for the mixing. A butler matrix can b= e >>> used >>> > for the latter if variable phase control isn't required, e.g. you don= 't >>> > care about spatial stream relative powers. >>> > >>> > On adding energy for "random" noise, some knobs of concern are the >>> energy >>> > detect on the tx and signal floor for the rx. These sources can be >>> fed >>> > into the same h-matrix through their own d-matrices. This won't >>> replace >>> > field tests but helps get closer towards that while providing for >>> repeat >>> > ability. >>> >>> What equipment would it take to do something like that? >>> >>> > Also, equally important by my judgment, though not related to >>> wireless, is >>> > to synchronize the clocks on the PCs. An oven controlled oscillator >>> and >>> > PTP works well towards that goal. >>> >>> Yeah, already using PTP in my testbed; quite essential for measuring >>> one-way delay. >>> >>> -Toke >>> >> >> > --94eb2c0df8c4bd15c9055d32c3fe Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Also, the final piece of the puzzle is chip power consumpt= ion.=C2=A0 =C2=A0 Monsoon makes a current meter for a reasonable price.=C2= =A0=C2=A0

I realize the focus here is on low latency.=C2=A0 =C2=A0Th= e market is also driving power consumption, i.e. "energy consumed for = useful information energy successfully delivered with the lowest latency po= ssible."=C2=A0 The chips themselves can give the RF energies (as well = as dump h matrices) so having an expensive network analyzer for that isn= 9;t required beyond chip design.

Bob

On Sat, Nov 4, 2017 at 6:56 PM, Bob McMahon= <bob.mcmahon@broadcom.com> wrote:
Also, Ixia is selling a controllable RF = system and it's in early stages.=C2=A0 Maybe contact them to see what t= he market is driving them to build?=C2=A0 =C2=A0My guess is their asking pr= ice will exceed $100K and has huge margins relative to bill of materials.= =C2=A0

One could probably work with telemakus and build a few using= their parts and sell it for cheaper than the IXIA chassis and still make a= nice profit.=C2=A0

B= ob

On Sat, Nov 4, 2017 at 6:50 PM= , Bob McMahon <bob.mcmahon@broadcom.com> wrote:
Try telemakus for variable attenuators and v= ariable phase shifters.=C2=A0 =C2=A0 Aeroflex works well to though are a bi= t more expensive, e.g. the 8331 is an example

Pow= er dividers, splitter/combiners and butler matrix devices are sold by multi= ple vendors.=C2=A0 Prices will vary. Unfortunately, prices aren't super= low.=C2=A0 But usually it's worth the extra money to get a reliable an= d controllable test bed, particularly when one values their time into the e= quation.

Bob
=

On Sat, Nov 4, 2017 at 2:48 PM, Toke H=C3=B8iland-J= =C3=B8rgensen <toke@toke.dk> wrote:
Bob McMahon <bob.mcmahon@broadcom.com> writes:

> A way I think about is to emulate the "system" in both range= /power
> (attenuation) and in mixing (phase shifts)=C2=A0 =C2=A0It's a diag= onal matrix for
> range feeding into an h-matrix for the mixing.=C2=A0 A butler matrix c= an be used
> for the latter if variable phase control isn't required, e.g. you = don't
> care about spatial stream relative powers.
>
> On adding energy for "random" noise, some knobs of concern a= re the energy
> detect on the tx and signal floor for the rx.=C2=A0 =C2=A0These source= s can be fed
> into the same h-matrix through their own d-matrices.=C2=A0 This won= 9;t replace
> field tests but helps get closer towards that while providing for repe= at
> ability.

What equipment would it take to do something like that?

> Also, equally important by my judgment, though not related to wireless= , is
> to synchronize the clocks on the PCs.=C2=A0 An oven controlled oscilla= tor and
> PTP works well towards that goal.

Yeah, already using PTP in my testbed; quite essential for measuring=
one-way delay.

-Toke



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