[CESG] Results of CESG Polls closing 1 August 2017

Shames, Peter M (312B) peter.m.shames at jpl.nasa.gov
Thu Aug 3 18:27:16 UTC 2017

Ciao Massimo,

Like you I would very much like to see this document get sent out for agency review and eventually get published as a CCSDS standard.  I think it can serve a very useful purpose that will be valuable to multiple missions, particularly those that would benefit from more available link margin during a long pass. That said, as I understand it, the intended purpose of this book, as stated in 1.2  is this:

"The purpose of this Recommended Practice is to specify various combinations of coding and modulations in references TM S&CC [1], SCCC [2], ETSI DVB-S2 [4], and DVB [5], that can operate under the VCM protocol defined in references SCCC [2] and ETSI DVB-S2 [4]. "

As such the intent is to provide a spec that may optionally be used to provide a variable coding and modulation signaling approach that works with all of the available CCSDS specified codes and modulations, and, more importantly in my eyes, work with all of the available CCSDS space data link protocols.  I do not think that purpose is quite so clearly stated in the document, but I believe it is what is intended.

In a similar way to what you stated in your comment 2., this VCM concept is defined, and used, in SCCC and DVB-S2.  But that is not the point of this spec.  If that were the point then there would be no need for this, we could just say "if you want VCM features use SCCC and DVB-S2."  But the intent of this spec is somewhat different, it is to provide this capability so that it works with all of the CCSDS link protocols, codes, and modulations.  So I think it should be clear and unambiguous about that point.

Where I am having problems with the spec is that it is not really specific as to just what is being recommended.  As you point out, in Sec 3.1 it says:

"slicing the CADUs asynchronously into encoder-input-sized blocks, encoding them with a channel code as specified in references [1], [2], and [3], producing modulation symbols corresponding to the encoded block, prepending a Physical Layer (PL) frame (PLFRAME) header, and optionally inserting pilot symbols 1 within the modulations
symbols of the non-header part of the PLFRAME."

So far, so good, but then footnote 1 says:

1 For systems compliant with CCSDS 131.2-B-1 and CCSDS 131.3-B-1, see relevant standard. For systems compliant with CCSDS 131.0-B-2 further work is needed.

So it appears that for the very coding spec for which we really need an unambiguous specification, i.e. TM S&CC, this document is silent.   I think this is rather odd, since that should be the whole focus of this book.

In Annex B1, which is admittedly marked as Informative, it says:

Pilot Symbols        DVB-S2: 36 pilot syms, every 1440 syms                   SCCC: 16 pilot syms, every 540 syms

This table does not specify what the comparable CCSDS 431.1-R-0 recommendation is, nor does it say which of these two Pilot Symbol (really pilot frame structure) options are recommended.  And, as I recall, not only are the pilot symbol and physical frame sizes different in [2] and [4], as stated,, but the pilot symbols themselves are also different in some small way.   I may have mis-remembered this and did not take the time to dig out that detail.  It seems to me that there is not really a CCSDS 431.1-R-0 recommendation, at least not one stated in clear and unambiguous terms.

As a final note, and I don't know why I missed making this point explicitly on first reading, but this is cast as a Magenta Book, a recommended practice.  And yet it does not have a firm recommendation for exactly the topic where one is most needed, it says that "further work is needed".  Furthermore, if it really did have a firm and unambiguously stated recommendation it would then really be a Blue Book "complete, unambiguous and at a sufficient level of technical detail that they can be directly implemented and used for space-mission interoperability and cross support."  If it does less than this it really is not meeting its stated purpose.

So, to return to you comment 1., while adding those missing "security/SANA/patents" sections is necessary, it is not sufficient.  The SANA, by the way, is a perfect place to record those Sec 3.3 VCM Mode Tables so that they may be extended when needed.  And, in contrast to your comment 3., where you suggest that we leave this Magenta Book topic to the Agency Review, I think that this is a CCSDS procedural matter that the Agencies will not be sensitive to.   In fact, I would be willing to bet that if we sent this document out, in its present form, that there would not be one single RID from a "normal" agency reviewer that would even touch on these topics, but that they might well notice the ambiguities and the vagueness just discussed.  This matter of Blue and Magenta books, and what their proper contents is, just does not matter to them.  It does matter to us, or should.

I think if you look in the notes in the marked up review document that you will see that all of these topics were touched upon in the conditions already provided.  As much as I would like to see this document sent out for review I do not think it acceptable to do so until these conditions are addressed in some affirmative way.  I do not know if your WG can deal with these conditions in time to complete a review prior to the Fall Meeting, but I do believe that they must be addressed prior to the Agency Review.

Best regards, Peter

From: "Massimo.Bertinelli at esa.int" <Massimo.Bertinelli at esa.int>
Date: Thursday, August 3, 2017 at 1:44 AM
To: Peter Shames <peter.m.shames at jpl.nasa.gov>
Cc: Gian Paolo Calzolari <Gian.Paolo.Calzolari at esa.int>, Tom Gannett <thomas.gannett at tgannett.net>, "Enrico.Vassallo at esa.int" <Enrico.Vassallo at esa.int>
Subject: Re: Fwd: Results of CESG Polls closing 1 August 2017

Dear Peter,

thank you for the comments you provided for the "Variable coding protocol" book.
Coming to your main points:

1. I suppose Tom could include the generic annexes (for security/SANA/patents) even though I don't expect this will add anything (the book simply refers to other
   books where these aspects have been already treated).

2. In our opinion, the definition of pilots is quite clear. For SCCC and DVB-S2 pilots are clearly defined in the relevant standard as explained in 3.1 and recapped
   in Annex B. For the other codes, it is under study as stated in 3.1.

3. I'm afraid this comment is not understood, I suggest that a discussion on this point (relationship between the Magenta and the other standards) is deferred to the
   Agency Review, where reviewers will have the chance to formulate their RIDs on this (and other) points

4. CSS service management is not mentioned in any other Book of the SLS area, to the best of my knowledge, so I don't see why it should be done for this one.
    Beside, as far as I know, the relative Blue Book has been retired and only a Green Book is currently available.
    Finally, please consider that the Managed Parameters section is always valid, in any configuration, even when cross-support is not required. As such, I disagree
    about the need to reference CSS service management.

Finally, I assume it is in the interested of everybody to have the Review closed in time for the Fall meeting, to avoid delaying the Book till next year. It is my understanding
that this will require a close-out of the poll in the next couple of weeks. I hope our replies can satisfy enough to proceed with this.

Best regards,

Massimo Bertinelli
Communication Systems Engineer

Tel. +31 (0)71 5653435

From:        Thomas Gannett <thomas.gannett at tgannett.net>
To:        Massimo.Bertinelli at esa.int
Cc:        Gian.Paolo.Calzolari at esa.int, andrews at shannon.jpl.nasa.gov, dennis.k.lee at jpl.nasa.gov, Enrico.Vassallo at esa.int, Gilles.Moury at cnes.fr
Date:        08/02/2017 10:45 PM
Subject:        Fwd: Results of CESG Polls closing 1 August 2017

Dear Massimo:

The CESG approval poll to release CCSDS 431.1-R-1, Variable Coded
Modulation Protocol (Red Book, Issue 1) for CCSDS Agency review
concluded with conditions. The conditions are stated in the poll results below.

Please respond directly to the ADs who voted to approve with
conditions--and CC the Secretariat--with proposed dispositions for
the conditions.

Attached to this message are relevant poll attachments as well as the
Word file used to generate the CESG approval copy. Please use the
Word file to make changes in response to the conditions.

Best regards,

>CESG E-Poll Identifier: CESG-P-2017-07-001 Approval to release CCSDS
>431.1-R-1, Variable Coded Modulation Protocol (Red Book, Issue 1)
>for CCSDS Agency review
>Results of CESG poll beginning 18 July 2017 and ending 1 August 2017:
>                  Abstain:  0 (0%)
>  Approve Unconditionally:  6 (85.71%) (Barkley, Merri, Burleigh,
> Cola, Calzolari, He)
>  Approve with Conditions:  1 (14.29%) (Shames)
>  Disapprove with Comment:  0 (0%)
>Peter Shames (Approve with Conditions): See attached PID form and
>marked up document. There are a few items that should be cleaned up
>before this is sent out for agency review.
>Here is a high level summary:
>1) The SANA, Security, and Patent Annexes are missing.
>2) The explicit definitions of pilots appears ambiguous (pg 3-1)
>3) Some of the explanations of the relationships among this doc, and
>[2] and [4] could be clearer. See pos 1-1, 3-1, 3-2, and Annex B.
>4) Sec 4 could reference, even if in passing, that these "Managed
>Parameters", in a compliant CCSDS cross support deployment, would be
>handled by CCSDS Service Management.
>Scott Burleigh (Approve Unconditionally): No conditions, but three
>comments. (1) On page 1-2, I think it would be good to define "ASM".
>(2) On page 2-1, I would have liked to have seen a note on why this
>protocol is not applicable to uplink. (3) On page 4-1: a personal
>preference, I think "static" would be better than "permanent".
>Total Respondents: 7
>No response was received from the following Area(s):
>PROPOSED SECRETARIAT ACTION:            Generate CMC poll after
>conditions have been addressed

Thomas Gannett
thomas.gannett at tgannett.net
+1 443 472 0805 [attachment "431x1r0_CESG_Approval-SEA.pdf" deleted by Massimo Bertinelli/estec/ESA] [attachment "CESG-P-2017-07-001_PID_form 431x1-SEA.txt" deleted by Massimo Bertinelli/estec/ESA] [attachment "431x1r0_CESG_Approval.doc" deleted by Massimo Bertinelli/estec/ESA]

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