From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp99.iad3a.emailsrvr.com (smtp99.iad3a.emailsrvr.com [173.203.187.99]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 6EEE63B2A4 for ; Sun, 12 Dec 2021 15:39:25 -0500 (EST) Received: from app10.wa-webapps.iad3a (relay-webapps.rsapps.net [172.27.255.140]) by smtp13.relay.iad3a.emailsrvr.com (SMTP Server) with ESMTP id F1A98192D for ; Sun, 12 Dec 2021 15:39:24 -0500 (EST) Received: from deepplum.com (localhost.localdomain [127.0.0.1]) by app10.wa-webapps.iad3a (Postfix) with ESMTP id DE1CA20A80 for ; Sun, 12 Dec 2021 15:39:24 -0500 (EST) Received: by apps.rackspace.com (Authenticated sender: dpreed@deepplum.com, from: dpreed@deepplum.com) with HTTP; Sun, 12 Dec 2021 15:39:24 -0500 (EST) X-Auth-ID: dpreed@deepplum.com Date: Sun, 12 Dec 2021 15:39:24 -0500 (EST) From: "David P. Reed" To: starlink@lists.bufferbloat.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_20211212153924000000_85691" Importance: Normal X-Priority: 3 (Normal) X-Type: html In-Reply-To: References: X-Client-IP: 209.6.168.128 Message-ID: <1639341564.906916211@apps.rackspace.com> X-Mailer: webmail/19.0.13-RC X-Classification-ID: 65a3b5c6-b2b2-47aa-a460-02c9e9b03de7-1-1 Subject: Re: [Starlink] =?utf-8?q?some_details_on_the_DTN=2C_bundle_protocol?= =?utf-8?q?=2C_and_a_capacity_____question?= X-BeenThere: starlink@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Starlink has bufferbloat. Bad." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 12 Dec 2021 20:39:25 -0000 ------=_20211212153924000000_85691 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable =0AIt's worth noting that the patents on Bill Luby's digital fountain codes= , etc. have pretty much inhibited one of the best solutions for DTN out the= re. There's one exception - RFC 6330, which has a very, very specific use o= f the RaptorQ code specified in it. Qualcomm apparently negotiated a licens= e for that very specific use in that specific protocol, as long as it is ne= ver used in "wide area wireless" (see the details of the narrow license her= e) networking. [ https://datatracker.ietf.org/ipr/2554/ ]( https://datatrac= ker.ietf.org/ipr/2554/ )=0A =0ARateless erasure codes of ANY kind appear to= be covered by the claims in the early Digital Fountain patents.=0A =0ANow = why are rateless erasure codes important for DTN? Well, essentially such co= des have a *unique* property that is pretty surprising:=0A =0AThe coded for= m of any N-bit message (composed of segments that can be lost, e.g. checksu= mmed frames that are deemed lost/erased if the checksum fails), is an infin= ite sequence of non-identical segments. If a receiver receives a subset of = distinct segments, totalling N or more bits, the entire N-bit message can b= e reconstructed.=0A =0AThat's what makes the code "rateless" - it works for= ANY error rate, and is optimal for that error rate.=0A =0ATo solve the DTN= problem, you simply send each message as a sequence of coded segments. No = windowing is required, no retransmission of packets that are lost on one ho= p is required. Eventually, the message gets delivered, and it will take no = more time than the error rate on the path requires.=0A =0AThat's remarkable= . =0A =0AThere are of course some issues to resolve - when should a message= source assume that its message has been reliably and completely received b= y the intended destination?=0AThis is the "end-to-end" problem. If there is= a reverse channel, once a message has been received, the receiver should, = at least each time it receives a segment of some already completed message,= send a single ACK for that message. =0A =0ANow this is great for talking t= o a spacecraft that has a very low speed and noisy reverse channel.=0A =0AA= ny number of messages can be concurrently sent from any number of sources (= the requirement is that each message has a global unique ID).=0A =0AFair sh= aring of a multiplexed deep-space network's resources among many concurrent= messages is a bit more tricky. That's where "early ACks" might be used in = an advanced erasure code (one I doubt has been patented fully, at least I'v= e never seen that).=0A-----------------------------------=0ANow, my persona= l view about *patents* on communications protocols is very severe: since in= teroperability is the *essence* of communications protocols, the idea of pa= tents is antithetical to the utiliity of protocols. Just as mathematical al= gorithms should not be patentable subject matter, neither should communicat= ions protocols (which are just algorithms on a different abstract machine).= =0A =0AUnfortunately, Luby, et al. have threatened litigation over and over= , stymieing attempts to get usage of their remarkable invention, outside a = few monopolistic or oligopolistic licensees.=0A =0AIt looks like, even thou= gh the original patents are due to expire soon, lots of effort is being mad= e to insure that all possible derivable techniques are being patented to ex= tend this monopoly.=0A =0AConsequently, I'd suggest that someone might find= a way to "buy out" the inventors of these patents and their assignees. It'= s a cancerous growth.=0A =0AImagine if we who built the Internet Protocols = had filed patents on all the techniques used in the Internet? Would Vint be= sitting there counting his royalties, and with a team of lawyers negotiati= ng license agreements? (I have an oar in this - I'd be there with Vint in t= he countinghouse, probably, as a coinventor).=0A =0ABill Luby, his advisors= , etc. did a remarkable thing here. And like other inventors, he ought to b= e rewarded for his invention. I have no problem with that. What I have a pr= oblem with is the structure of patent law as it exists today. It is sociall= y counterproductive, and economically counterproductive, when used in the w= ay it is being used here.=0A =0ABut that's just my opinion.=0A =0APS: I am = co-inventor of a fair number of patented inventions. I live in this broken = system. But, in the case of communications protocols specifically, I think = this stuff shouldn't be protected by patent rights.=0A =0A ------=_20211212153924000000_85691 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable

It's worth noting that= the patents on Bill Luby's digital fountain codes, etc. have pretty much i= nhibited one of the best solutions for DTN out there. There's one exception= - RFC 6330, which has a very, very specific use of the RaptorQ code specif= ied in it. Qualcomm apparently negotiated a license for that very specific = use in that specific protocol, as long as it is never used in "wide area wi= reless" (see the details of the narrow license here) networking. https://datatracker.ietf.org/= ipr/2554/

=0A

 

=0A

= Rateless erasure codes of ANY kind appear to be covered by the claims in th= e early Digital Fountain patents.

=0A

 

=0A<= p style=3D"margin:0;padding:0;font-family: arial; font-size: 10pt; overflow= -wrap: break-word;">Now why are rateless erasure codes important for DTN? W= ell, essentially such codes have a *unique* property that is pretty surpris= ing:

=0A

 

=0A

The coded= form of any N-bit message (composed of segments that can be lost, e.g. che= cksummed frames that are deemed lost/erased if the checksum fails), is an i= nfinite sequence of non-identical segments. If a receiver receives a subset= of distinct segments, totalling N or more bits, the entire N-bit message c= an be reconstructed.

=0A

 

=0A

That's what makes the code "rateless" - it works for ANY error rate,= and is optimal for that error rate.

=0A

 

= =0A

To solve the DTN problem, you simply send each mess= age as a sequence of coded segments. No windowing is required, no retransmi= ssion of packets that are lost on one hop is required. Eventually, the mess= age gets delivered, and it will take no more time than the error rate on th= e path requires.

=0A

 

=0A

That's remarkable. 

=0A

 

=0A

There are of course some issues to resolve - when should a me= ssage source assume that its message has been reliably and completely recei= ved by the intended destination?

=0A

This is the "en= d-to-end" problem. If there is a reverse channel, once a message has been r= eceived, the receiver should, at least each time it receives a segment of s= ome already completed message, send a single ACK for that message. =0A

 

=0A

Now this is grea= t for talking to a spacecraft that has a very low speed and noisy reverse c= hannel.

=0A

 

=0A

Any nu= mber of messages can be concurrently sent from any number of sources (the r= equirement is that each message has a global unique ID).

=0A

 

=0A

Fair sharing of a multiplexed de= ep-space network's resources among many concurrent messages is a bit more t= ricky. That's where "early ACks" might be used in an advanced erasure code = (one I doubt has been patented fully, at least I've never seen that).

= =0A

-----------------------------------

=0A

Now, my personal view about *patents* on communications protoc= ols is very severe: since interoperability is the *essence* of communicatio= ns protocols, the idea of patents is antithetical to the utiliity of protoc= ols. Just as mathematical algorithms should not be patentable subject matte= r, neither should communications protocols (which are just algorithms on a = different abstract machine).

=0A

 

=0A

Unfortunately, Luby, et al. have threatened litigation over = and over, stymieing attempts to get usage of their remarkable invention, ou= tside a few monopolistic or oligopolistic licensees.

=0A

 

=0A

It looks like, even though the origi= nal patents are due to expire soon, lots of effort is being made to insure = that all possible derivable techniques are being patented to extend this mo= nopoly.

=0A

 

=0A

Conseq= uently, I'd suggest that someone might find a way to "buy out" the inventor= s of these patents and their assignees. It's a cancerous growth.

=0A

 

=0A

Imagine if we who built = the Internet Protocols had filed patents on all the techniques used in the = Internet? Would Vint be sitting there counting his royalties, and with a te= am of lawyers negotiating license agreements? (I have an oar in this - I'd = be there with Vint in the countinghouse, probably, as a coinventor).

=0A=

 

=0A

Bill Luby, his advis= ors, etc. did a remarkable thing here. And like other inventors, he ought t= o be rewarded for his invention. I have no problem with that. What I have a= problem with is the structure of patent law as it exists today. It is soci= ally counterproductive, and economically counterproductive, when used in th= e way it is being used here.

=0A

 

=0A

But that's just my opinion.

=0A

 = ;

=0A

PS: I am co-inventor of a fair number of paten= ted inventions. I live in this broken system. But, in the case of communica= tions protocols specifically, I think this stuff shouldn't be protected by = patent rights.

=0A

 

=0A

 

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