From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-x236.google.com (mail-wm0-x236.google.com [IPv6:2a00:1450:400c:c09::236]) (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 1DA363B2A0 for ; Mon, 27 Jun 2016 16:05:57 -0400 (EDT) Received: by mail-wm0-x236.google.com with SMTP id f126so113962892wma.1 for ; Mon, 27 Jun 2016 13:05:56 -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=3tYID6cGTMJjrKcV8dOCLjsUwArzCO6AOqXXIyDNxFs=; b=c3pVCi0GFVS1rstW4pFVbF5elS33bcLkZtBxKRhuysKts4irUTuyKDXkyFDQubU6AR 7FSJBTaX61KJJmcudZ0ajuRCMLu77BaDv4mmq6FMX18n1iyC8NsIliLFC+0SrDtRv9PP jYbPER9HfaI6c0X7UOimQ6qBqnqQ2zLSxpr08= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=3tYID6cGTMJjrKcV8dOCLjsUwArzCO6AOqXXIyDNxFs=; b=cijxHQYdFfc24wptC5O6YsZ5HIakNC8KJ+o9tWeSJ1NGkccTl1k/va7oscGnjlWNEE r6VfxhUw1iabMljC5877vSfidBFWVu244KqVu5QXZ4O7Y3P1soGalxxAWIeorjLgwfMH jkM/u2jCXKjFnEuS0abgM8okHAZliyKOWGPYHvE/0ehCEiXDdkrhCXmIdfoiqnZq3SHT fj5cWLT4rSRk8hOqh4BuiOtASCZpL5Zbth4exJFRHyiGFO9cjlDnIXrCdTeKddmux6oL 9Qs+GzqTS1jGhpiWUI7Zoxz6Dxs38SAD2B6AwPEW9d8v3Wl3Fy7bXsAcy/e0X40sqoon HORw== X-Gm-Message-State: ALyK8tJ9UI60KssT+0A4BLgybibj4LL7rxAKLNw0nP9S4ZRaCqj/Alswumc+GfrdlTgV57ppRMLvhwUSWXu9L1Jm X-Received: by 10.194.179.131 with SMTP id dg3mr2640028wjc.143.1467057955841; Mon, 27 Jun 2016 13:05:55 -0700 (PDT) MIME-Version: 1.0 Received: by 10.194.239.202 with HTTP; Mon, 27 Jun 2016 13:05:54 -0700 (PDT) In-Reply-To: References: <1466803464.927322699@mobile.rackspace.com> From: Bob McMahon Message-ID: To: David Lang Cc: Dave Taht , make-wifi-fast@lists.bufferbloat.net, "cerowrt-devel@lists.bufferbloat.net" Content-Type: multipart/alternative; boundary=089e013d13aa5341a40536480c5b X-Mailman-Approved-At: Mon, 30 Mar 2020 07:21:14 -0400 Subject: Re: [Cerowrt-devel] [Make-wifi-fast] more well funded attempts showing market demandfor better wifi X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Date: Mon, 27 Jun 2016 20:05:57 -0000 X-Original-Date: Mon, 27 Jun 2016 13:05:54 -0700 X-List-Received-Date: Mon, 27 Jun 2016 20:05:57 -0000 --089e013d13aa5341a40536480c5b Content-Type: text/plain; charset=UTF-8 The ~10K is coming from empirical measurements where all aggregation technologies are disabled, i.e. only one small IP packet per medium arbitration/access and where there is only one transmitter and one receiver. 900Mb/sec is typically a peak-average throughput measurement where max (or near max) aggregation occurs, amortizing the access overhead across multiple packets. Yes, devices can be hidden from each other but not from the AP (hence the use of RTS/CTS per hidden node mitigation.) Isn't it the AP's view of the "carrier state" that matters (at least in infrastructure mode?) If that's the case, what about a different band (and different radio) such that the strong signal carrying the data could be separated from the the BSSID's "carrier/energy state" signal? Bob On Mon, Jun 27, 2016 at 12:40 PM, David Lang wrote: > On Mon, 27 Jun 2016, Bob McMahon wrote: > > Hi All, >> >> This is a very interesting thread - thanks to all for taking the time to >> respond. (Personally, I now have better understanding of the >> difficulties >> associated with a PHY subsystem that supports a wide 1GHz.) >> >> Not to derail the current discussion, but I am curious to ideas on >> addressing the overhead associated with media access per collision >> avoidance. This overhead seems to be limiting transmits to about 10K per >> second (even when a link has no competition for access.) >> > > I'm not sure where you're getting 10K/second from. We do need to limit the > amount of data transmitted in one session to give other stations a chance > to talk, but if the AP replies immediatly to ack the traffic, and the > airwaves are idle, you can transmit again pretty quickly. > > people using -ac equipment with a single station are getting 900Mb/sec > today. > > Is there a way, >> maybe using another dedicated radio, to achieve near instantaneous >> collision detect (where the CD is driven by the receiver state) such that >> mobile devices can sample RF energy to get theses states and state changes >> much more quickly? >> > > This gets back to the same problems (hidden transmitter , and the > simultanious reception of wildly different signal strengths) > > When you are sending, you will hear yourself as a VERY strong signal, > trying to hear if someone else is transmitting at the same time is almost > impossible (100 ft to 1 ft is 4 orders of magnatude, 1 ft to 1 inch is > another 2 orders of magnatude) > > And it's very possible that the station that you are colliding with isn't > one you can hear at all. > > Any AP is going to have a better antenna than any phone. (sometimes > several orders of magnatude better), so even if you were located at the > same place as the AP, the AP is going to hear signals that you don't. > > Then consider the case where you and the other station are on opposite > sides of the AP at max range. > > and then add cases where there is a wall between you and the other > station, but the AP can hear both of you. > > David Lang > --089e013d13aa5341a40536480c5b Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
The ~10K is coming from empirical measurements where all a= ggregation technologies are disabled, i.e. only one small IP packet per med= ium arbitration/access and where there is only one transmitter and one rece= iver. =C2=A0900Mb/sec is typically a peak-average throughput measurement wh= ere max (or near max) aggregation occurs, amortizing the access overhead ac= ross multiple packets.

Yes, devices can be hidden from e= ach other but not from the AP (hence the use of RTS/CTS per hidden node mit= igation.) Isn't it the AP's view of the "carrier state" t= hat matters (at least in infrastructure mode?) =C2=A0If that's the case= , what about a different band (and different radio) such that the strong si= gnal carrying the data could be separated from the the BSSID's "ca= rrier/energy state" signal?

Bob =C2=A0 =C2=A0=

On Mo= n, Jun 27, 2016 at 12:40 PM, David Lang <david@lang.hm> wrote:
On Mon, 27 Jun 2016, Bob = McMahon wrote:

Hi All,

This is a very interesting thread - thanks to all for taking the time to respond.=C2=A0 =C2=A0(Personally, I now have better understanding of the di= fficulties
associated with a PHY subsystem that supports a wide 1GHz.)

Not to derail the current discussion, but I am curious to ideas on
addressing the overhead associated with media access per collision
avoidance.=C2=A0 This overhead seems to be limiting transmits to about 10K = per
second (even when a link has no competition for access.)

 I'm not sure where you're getting 10K/second from. We do need to li= mit the amount of data transmitted in one session to give other stations a = chance to talk, but if the AP replies immediatly to ack the traffic, and th= e airwaves are idle, you can transmit again pretty quickly.

people using -ac equipment with a single station are getting 900Mb/sec toda= y.

=C2=A0 Is there a way,
maybe using another dedicated radio, to achieve near instantaneous
collision detect (where the CD is driven by the receiver state) such that mobile devices can sample RF energy to get theses states and state changes<= br> much more quickly?

 This gets back to the same problems (hidden transmitter , and the simultani= ous reception of wildly different signal strengths)

When you are sending, you will hear yourself as a VERY strong signal, tryin= g to hear if someone else is transmitting at the same time is almost imposs= ible (100 ft to 1 ft is 4 orders of magnatude, 1 ft to 1 inch is another 2 = orders of magnatude)

And it's very possible that the station that you are colliding with isn= 't one you can hear at all.

Any AP is going to have a better antenna than any phone. (sometimes several= orders of magnatude better), so even if you were located at the same place= as the AP, the AP is going to hear signals that you don't.

Then consider the case where you and the other station are on opposite side= s of the AP at max range.

and then add cases where there is a wall between you and the other station,= but the AP can hear both of you.

David Lang

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