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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">Hi All,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">I tend to agree with Jeremy, from a pure ARQ effectiveness view point, using ACK or NACK for signalling (or detecting) losses pretty much depends
on the channel model you are assuming underneath. I’m quite sure in the scientific literature you can find many papers about using either approach. For typical space links, probably using ACK or NAK does not bring significant differences from a performance
standpoint. As to the optical and Ka-band communication links, again, I’d say it depends on the channel model and more concretely on how packet losses are distributed after channel coding and CRC control at frame level. In particular, it may depend on the
specific reliability measures implemented at the physical layer (e.g., long interleavers, long codewords, etc…), hence possibly resulting in an almost error-free channel (with some sporadic erasures) or in a more correlated loss pattern. At the end, I don’t
think we can come up with an ideal ARQ solution that works at best for all possible channels…<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">My 0.02 cents,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">Tomaso<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> SIS-DTN <sis-dtn-bounces@mailman.ccsds.org>
<b>On Behalf Of </b>Jeremy Pierce-Mayer via SIS-DTN<br>
<b>Sent:</b> Montag, 4. April 2022 12:09<br>
<b>To:</b> Felix.Flentge@esa.int; chkoo@kari.re.kr<br>
<b>Cc:</b> sis-dtn@mailman.ccsds.org<br>
<b>Subject:</b> Re: [Sis-dtn] Positive reception claim vs. Negative reception claim in LTP Report Segment preparation and processing<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">Hi Cheol, Felix,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">The efficiency of positive vs. negative claims is
<b>highly</b> dependent upon the behaviour of the underlying link. If a link has long periods of successful communication punctuated by brief (complete) fading events, then NACK may be better. If a link is more erratic, then the calculations become a bit harder
and are highly dependent on the ratio and duration of successful vs lost packets/frames.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">In most “reliable” space links, fading is pretty intermittent (until your elevation reduces), so ACK/NACK should be pretty similar. I think Ka/optical might upset this balance though… We’ll
see.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif">Jeremy</span><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> SIS-DTN <<a href="mailto:sis-dtn-bounces@mailman.ccsds.org">sis-dtn-bounces@mailman.ccsds.org</a>>
<b>On Behalf Of </b>Felix Flentge via SIS-DTN<br>
<b>Sent:</b> Monday, April 4, 2022 12:08 PM<br>
<b>To:</b> </span><span lang="KO" style="font-size:11.0pt">구철회</span><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> <<a href="mailto:chkoo@kari.re.kr">chkoo@kari.re.kr</a>><br>
<b>Cc:</b> <a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a><br>
<b>Subject:</b> Re: [Sis-dtn] Positive reception claim vs. Negative reception claim in LTP Report Segment preparation and processing<o:p></o:p></span></p>
</div>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif">Ah, yes, of course you are right.</span><span lang="EN-US">
<br>
<br>
</span><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif">We will look into the negative ACK as part of our LTPv2 prototyping activity.</span><span lang="EN-US">
<br>
<br>
</span><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif">Regards,</span><span lang="EN-US">
<br>
</span><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif">Felix</span><span lang="EN-US">
<br>
<br>
<br>
<br>
</span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">From: </span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif">"</span><span lang="KO" style="font-size:9.0pt">구철회</span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif">"
<<a href="mailto:chkoo@kari.re.kr">chkoo@kari.re.kr</a>></span><span lang="EN-US">
<br>
</span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">To: </span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif"><<a href="mailto:Felix.Flentge@esa.int">Felix.Flentge@esa.int</a>></span><span lang="EN-US">
<br>
</span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">Cc: </span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif">"<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>"
<<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>></span><span lang="EN-US">
<br>
</span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">Date: </span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif">04/04/2022 11:58</span><span lang="EN-US">
<br>
</span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">Subject: </span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif">RE: Re: [Sis-dtn] Positive reception claim vs. Negative reception
claim in LTP Report Segment preparation and processing</span><span lang="EN-US">
<br>
</span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#5F5F5F">Sent by: </span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif"><a href="mailto:chkoo@kari.re.kr">chkoo@kari.re.kr</a></span><span lang="EN-US">
<o:p></o:p></span></p>
<div class="MsoNormal" align="center" style="text-align:center"><span lang="EN-US">
<hr size="2" width="100%" noshade="" style="color:#A0A0A0" align="center">
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<p class="MsoNormal"><span lang="EN-US"><br>
<br>
<br>
Hi Felix, <br>
<br>
I think current LTP spec quite works well with negative claim also. Consider below reception claim according to the LTP spec but negative claim.
<br>
<br>
lower bound = 0 <br>
upper bound = 7000 <br>
negative reception claim count = 1 <br>
offset = 1000 <br>
length = 2000 <br>
<br>
it means a receiver is requesting block of segements which starts at 1000 and length is 2000, i.e., 1000 ~ 2999, for retransmission.
<br>
A sender can safely remove 2 blocks, i.e., 0 - 999 and 3000 - 7000. I think it is simpler, lower overhead and *importantly* easier to calculate (acutally no painful for localizing the target segment position).
<br>
<br>
Cheol <o:p></o:p></span></p>
<p style="margin-top:22.5pt"><b><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#0062E1">---------
</span></b><b><span lang="KO" style="font-size:9.0pt;color:#0062E1">원본</span></b><b><span lang="KO" style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#0062E1">
</span></b><b><span lang="KO" style="font-size:9.0pt;color:#0062E1">메일</span></b><b><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#0062E1"> ---------</span></b><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><br>
</span><b><span lang="KO" style="font-size:9.0pt">보낸사람</span></b><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif"> : <<a href="mailto:Felix.Flentge@esa.int">Felix.Flentge@esa.int</a>><b><br>
</b></span><b><span lang="KO" style="font-size:9.0pt">받는사람</span></b><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif"> : "</span><span lang="KO" style="font-size:9.0pt">구철회</span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif">"
<<a href="mailto:chkoo@kari.re.kr">chkoo@kari.re.kr</a>><b><br>
</b></span><b><span lang="KO" style="font-size:9.0pt">참조</span></b><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif"> : "<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>" <<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>><b><br>
</b></span><b><span lang="KO" style="font-size:9.0pt">받은날짜</span></b><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif"> : 2022-04-04 (</span><span lang="KO" style="font-size:9.0pt">월</span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif">)
17:40:24<b><br>
</b></span><b><span lang="KO" style="font-size:9.0pt">제목</span></b><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif"> : Re: [Sis-dtn] Positive reception claim vs. Negative reception claim in LTP Report Segment preparation and processing</span><span lang="EN-US">
<br>
</span><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif">Hi Cheol,</span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif">
<br>
</span><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif"><br>
interesting question. One thing I can think of is that the positive claims would allow you to free memory earlier while for negative claims you need to wait until the end of a session.</span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif">
<br>
</span><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif"><br>
Regards,</span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif">
</span><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif"><br>
Felix</span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif">
<br>
<br>
<br>
<span style="color:#5F5F5F"><br>
From: </span>"</span><span lang="KO" style="font-size:9.0pt">구철회</span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif"> via SIS-DTN" <<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>>
<span style="color:#5F5F5F"><br>
To: </span>"<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>" <<a href="mailto:sis-dtn@mailman.ccsds.org">sis-dtn@mailman.ccsds.org</a>>
<span style="color:#5F5F5F"><br>
Date: </span>04/04/2022 10:15 <span style="color:#5F5F5F"><br>
Subject: </span>[Sis-dtn] Positive reception claim vs. Negative reception claim in LTP Report Segment preparation and processing
<span style="color:#5F5F5F"><br>
Sent by: </span>"SIS-DTN" <<a href="mailto:sis-dtn-bounces@mailman.ccsds.org">sis-dtn-bounces@mailman.ccsds.org</a>>
</span><span lang="EN-US"><o:p></o:p></span></p>
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<hr size="2" width="100%" noshade="" style="color:#A0A0A0" align="center">
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<p class="MsoNormal"><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif"><br>
</span><span lang="EN-US"><br>
</span><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif">Greetings,</span><span lang="EN-US" style="font-size:9.0pt;font-family:"Arial",sans-serif">
</span><span lang="EN-US"><o:p></o:p></span></p>
<p style="margin:0cm;margin-bottom:.0001pt"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif"> </span><span lang="EN-US"><o:p></o:p></span></p>
<p style="margin:0cm;margin-bottom:.0001pt"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif">This is Cheol. I am developing an LTP reference implementation. During reading the LTP specification (RFC-5326), the preparation of reception
claim in Report Segment makes me confusing about why it is positive claim not negative claim for segments that were not received successfully (i.e., NAK).</span><span lang="EN-US"><o:p></o:p></span></p>
<p style="margin:0cm;margin-bottom:.0001pt"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif"> </span><span lang="EN-US"><o:p></o:p></span></p>
<p style="margin:0cm;margin-bottom:.0001pt"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif">For reference, CFDP’s NAK PDU has the negative claim structure when it is requested to report missing PDUs. Does anyone know about the background
of choosing the positive claim for NAK operation in LTP?</span><span lang="EN-US"><o:p></o:p></span></p>
<p style="margin:0cm;margin-bottom:.0001pt"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif">I think negative claim is simpler and more efficient in terms of overhead for sender and receiver both.</span><span lang="EN-US"><o:p></o:p></span></p>
<p style="margin:0cm;margin-bottom:.0001pt"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif">I like to listen experts’ opinion on LTP operation and honestly hope it to be changed in newly coming LTP spec.</span><span lang="EN-US"><o:p></o:p></span></p>
<p style="margin:0cm;margin-bottom:.0001pt"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif"> </span><span lang="EN-US"><o:p></o:p></span></p>
<p style="margin:0cm;margin-bottom:.0001pt"><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif">Cheol</span><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span lang="EN-US"><br>
</span><span lang="EN-US" style="font-size:10.0pt;font-family:"Arial",sans-serif"><br>
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