[CESG] [EXTERNAL] Re: Comments (and only comments) on space link directionality discussion yesterday

Tue Jun 9 10:49:29 UTC 2020

Peter,
        frankly speaking, whatever happened in 2003 (and before) the timer 
was reset in Fall 2017 when the problem was reported and recovery actions 
were agreed in the WG.

However, since you look very interested in the forensic analysis about how 
some details were lost, I think I  can help you.
In fact I retrieved evidence of a number of events from that period 
spanning between the old P1A (chaired by Merv till spring 2000) and the 
eventual splitting (P1A chaired by Greg, P1B chaired by me, and P1C 
chaired by Pen-Shu).

Takahiro triggered a very huge work and - in that time frame - all 
meetings included a dedicated session chaired by him to deal with the 
complete bunch of restructured documents.
P1A used to report about those dedicated sessions both under Merv and 
under Greg.

1) Since the earliest draft - after starting the work in 1999 - the TM 
Coding book contained a mistake that mentioned only ground-to-space or 
space-to-space communications links  without mentioning the downlink; i.e. 
the most appropriate space-to-ground link!
2) The same error remained there undiscovered till RED-1 version in June 
2002.
3) Then Agency Review RIDs were discussed - as usual -  in a dedicated se
ssions (formally under P1A, with P1B contribution) chaired by Yamada
4) One of the RIDs discovered  the absence of the space-to-ground link and 
drove to the correction that replaced “ground-to-space”  with 
“space-to-ground”   .
5) Actually the RID (see snapshot) called also for removing space-to-space 
(not originally mentioned in 101.0-B) , but the (agreed) disposition 
insisted in keeping it. The reason may have been the forthcoming 
Proximity-1 blue book, but clearly I cannot bet on it.

This is how the original statement in 101,0-B-6 (i.e. "the  codes  in this 
 recommendation  are  applicable  to  the  forward  and  return  links  of 
 Advanced  Orbiting  Systems  (AOS) ") got modified.

That's all

Gian Paolo

PS Many thanks to Tom Gannett for retrieving some old versions of  Red-0 
and Red-1 for 131.0-B.

From:   "Shames, Peter M\(US 312B\) via CESG" <cesg at mailman.ccsds.org>
To:     "Margherita.di.Giulio at esa.int" <Margherita.di.Giulio at esa.int>, 
"Barkley, Erik J (US 3970)" <erik.j.barkley at jpl.nasa.gov>
Cc:     "CESG -- CCSDS-Engineering Steering 
Group\(cesg at mailman.ccsds.org\)\(cesg at mailman.ccsds.org\)" 
<cesg at mailman.ccsds.org>
Date:   08-06-20 19:11
Subject:        Re: [CESG] [EXTERNAL] Re: Comments (and only comments) on 
space link directionality discussion yesterday
Sent by:        "CESG" <cesg-bounces at mailman.ccsds.org>

Dear Margherita,

Actually, this whole problem started in 2003 when the support for AOS 
forward links in the TM Sync & Channel coding books were erroneously 
removed during the slew of edits that were made at that time.  I have 
actually done the forensic analysis in the earlier documents and located 
exactly when that change was made. I cannot confirm why the change was 
made, but it had the effect of moving us backwards and this was truly 
unfortunate.

The WG has been asked to rectify this error and chose to throw up 
road-blocks instead of making the simple fix.  This is also unfortunate. 
This has nothing to do with being "input driven".

These changes took place during the "SLS restructuring" which was 
accomplished during 2001-2003.  This massive editing operation, which 
resulted in a real improvement in this set of specs, was aimed at the 
existing space data link protocol specs and the coding specs.  My interest 
in doing this research was to establish facts, not to assign blame.  My 
assertion is that all of these changes were puiblished in the 2002-2003 
era and that the Coding WG went backwards between 2002 and 2003 and 
abandoned support for AOS in the forward direction in the process.

According to the CCSDS Silver Book documents archived on the web site this 
is clearly the case.  Key items are highlighted for emphasis.  Follow the 
bouncing ball.

Coding & Synch
Prior to 2003 we had a CCSDS 101.0-B-6-S , Telemetry Channel Coding. 
Silver Book. Issue 6. October 2002. It said, in sec 1.3 Applicability "In 
addition to being applicable to conventional Packet Telemetry systems [1], 
the codes in this recommendation are applicable to the forward and return 
links of Advanced Orbiting Systems (AOS) [2]. "
This 2002 channel coding spec referenced both the current "TM" spec 
102.0-B-5, and the then current AOS spec, 701.0-B-3.  That spec, in sec 
1.2b, said "Advanced Orbiting Systems include manned and man-tended space 
stations, unmanned space platforms, free-flying spacecraft and new space 
transportation systems, many of which need services to concurrently 
transmit multiple digital data types (including audio and video) through 
space/ground and ground/space data channels. "
In Sept 2003 we got CCSDS 131.0-B-1-S, TM Synchronization and Channel 
Coding. Silver Book. Issue 1. September 2003.  It said, in sec 1.1 "The 
purpose of this Recommended Standard is to specify synchronization and 
channel coding schemes used with the TM Space Data Link Protocol 
(reference [1]) or the AOS Space Data Link Protocol (reference [2]). These 
schemes are to be used over space-to-ground or space- to-space 
communications links by space missions. "  Note that ground to space has 
been dropped.
So somehow, between the original "CCSDS 101x0 coding book" and the revised 
"CCSDS 131x0 coding book" the use these codes that was allowed on AOS 
forward links got removed.  This was right at the same time as the rest of 
the SLS document restructuring was done.
Similar changes were made to TC synch & channel coding in 2003.  And to 
Space Packet.  It was all part of the same set of sweeping changes, 
Takahiro was the lead tech editor and Gippo was the WG chair.  I think the 
Panel was led by Kaufeler at that time.

Space Data Link
Prior to 2003 we had CCSDS 103.0-B-2-S , Packet Telemetry Service 
Specification. Silver Book. Issue 2. June 2001.  It said, in Sec 1.1 "The 
layered model and services are based on the CCSDS Recommendations for 
Packet Telemetry and Telemetry Channel Coding, references [1] and [2]. 
These referenced Recommendations define the formats of the 
protocol-data-units used to transfer telemetry from spacecraft to ground 
or spacecraft to spacecraft, as well as the protocol procedures that 
support that transfer. "  And in Sec 1.2 it said "This Recommendation 
defines only the services provided between protocol layers of the CCSDS 
space to ground link."
Contemporaneous with this TM Service spec was the TM spec itself, CCSDS 
102.0.  It was also explicit in stating, in Sec 1.2 "The end-to-end 
transport of space mission data sets from source application processes 
located in space to distributed user application processes located on the 
ground. "
In Sept 2003 we got CCSDS 132.0-B-1-S, TM Space Data Link Protocol. Silver 
Book. Issue 1. September 2003.  It said, in sec 1.1 "This protocol is a 
Data Link Layer protocol (see reference [1]) to be used over 
space-to-ground or space-to-space communications links by space missions. 
"
The 2003 revised AOS spec, as already noted, explicitly supported 
space/ground and ground/space. There is apparently not an extant copy of 
the original AOS spec.  All that is available in the CCSDS Silver docs is 
CCSDS 701.00-R-3 (Red Book) , Advanced Orbiting Systems, Networks and Data 
Links: Architectural Specification. Silver Book. Issue 3. June 1989.  That 
AOS spec, or really set of specs, which supported space/ground and 
ground/space, were quite thorough and comprehensive.  I do not think that 
all of these features were ever implemented, but someone familiar with the 
ISS comm architecture would have to confirm that. 
I do know that AOS has been used for years in both the forward and return 
directions, since I know that we created the EF-CLTU Orange Book, CCSDS 
912.11-O-1, in 2012, explicitly to provide JSC with a variant of the SLE 
F-CLTU that would support AOS forward, synchronous, encoded links.  Prior 
to that they had been using F-CLTU for AOS with some awkward work-arounds 
to keep the forward link synchronous.  This was all to be replaced by 
FF-CLTU, which is still hung up, in part, because there is no longer a 
"formal" CCSDS forward coding standard for AOS.
In 2003 we got CCSDS 732.0-B-1-S , AOS Space Data Link Protocol. Silver 
Book. Issue 1. September 2003. As a part of that same restructuring 
package.  In sec 1.1 it says "This protocol is a Data Link Layer protocol 
(see reference [1]) to be used over space-to-ground, ground-to-space, or 
space-to-space communications links by space missions. "  So the AOS spec 
covers all of the directions, but the coding specs no longer support that 
with any formal text.  Hence the dilemma, in place since 2003.
The 2003 AOS spec did directly reference CCSDS 131.0-B-1 , but as we have 
already seen that spec had already been neutered and no longer supported 
use of the TM codes for forward links.  This was an issue that could have 
been easily remedied, as was requested on a number of occasions, but 
making that change has consistently been thwarted by the C&S WG.

To this date there is no longer a published CCSDS coding and synch spec 
that actually supports the AOS capabilities that have been on the books 
since that spec was first published.

Kind regards, Peter

From: CESG <cesg-bounces at mailman.ccsds.org> on behalf of 
"Margherita.di.Giulio at esa.int" <Margherita.di.Giulio at esa.int>
Date: Sunday, June 7, 2020 at 3:30 AM
To: Erik Barkley <erik.j.barkley at jpl.nasa.gov>
Cc: CCSDS Engineering Steering Group - CESG Exec <cesg at mailman.ccsds.org>
Subject: [EXTERNAL] Re: [CESG] Comments (and only comments) on space link 
directionality discussion yesterday

Dear Erik, 
        indeed all started in 2017 and at Fall 2017 C&S WG had a principle 
agreement for re-introducing the codes already used for AOS uplink, 
together with a down selection of more recent codes. It is therefore very 
unfortunate that this issue has not been finalised. 
As you know, WGs are input driven . Since Fall 2017 such inputs have been 
either missing or modifying the (previous) position(s). Consequently, the 
progress has been slow. 
The history was reported at the CESG telecon on 10 March 2020, as per 
second slide of the attached ppt (also available in CWE). 

With respect to the Forward Frame Blue Book, this book specifies the 
service provision, leaving to other books the service production. The way 
forward is to mention, w.r.t. the supported uplink options,  the relevant 
CCSDS books in progress , with eventual Editorial Corrigenda at due time. 
This has been the approach taken by many other CCSDS recommendations, and 
it has been no problem. 
Notice that in FF CSTS those books are, correctly, referred to only as 
informative reference. 

It is my understanding that currently C&S WG is working at the update of 
131.0-B, 131.2-B and 131.3-B, and hopefully they can quickly converge on 
this. 
Kind regards,
Margherita 

--------------------------------------------------------------
Margherita di Giulio 
Ground Station Systems Division 
Backend Software Section (OPS-GSB) 

European Space Agency ESA/ESOC
Robert-Bosch-Str. 5
D-64293 Darmstadt - Germany
Tel: +49-6151-902779
e-mail: Margherita.di.Giulio at esa.int

From:        "Barkley, Erik J (US 3970)" <erik.j.barkley at jpl.nasa.gov> 
To:        "Margherita.di.Giulio at esa.int" <Margherita.di.Giulio at esa.int>, 
"Tai, Wallace S (US 9000)" <wallace.s.tai at jpl.nasa.gov> 
Cc:        "CESG -- CCSDS-Engineering Steering Group 
(cesg at mailman.ccsds.org) (cesg at mailman.ccsds.org)" 
<cesg at mailman.ccsds.org> 
Date:        04/06/2020 18:40 
Subject:        Comments (and only comments) on space link directionality 
discussion yesterday 

Dear CESG Chairs,

Now that I have had a little time to digest yesterday’s proceedings, I 
offer some comments and observations with regard to the CESG discussion 
yesterday on the directionality of space links and related conversation. 

1.        The apparent lack of progress/resolution of the issue leaves the 
CSS Area with a dilemma of how to proceed with publication polling for the 
FF-CSTS (Forward Frame) recommendation.  From all reports that I have from 
the CSTS working group, the book will be ready for publication very soon 
as prototyping has been satisfactorily completed. To the best of my 
recollection it was three years ago, the spring meetings of 2017, where a 
request was made to see if some sort of reference could be provided such 
that we could include it in the forward frame book. At this point I 
suspect the forward frame book will be ready for publication long before 
the issue is resolved -- in the CSS area we may have to figure out some 
sort of wording to work around the fact that there is no CCSDS standard 
that can be referenced -- this could be something to indicate that as per 
common usage in the real world FF-CSTS can use this for forwarding of AOS 
frames etc. 
2.        I believe the comments yesterday about AOS already being used in 
real world operations in the forward direction are correct. As such I find 
it concerning that CCSDS as a whole cannot muster the ability to document 
this as a proper use of the AOS standard. It is also troubling as, if it 
is correctly reported, this was already indicated in prior versions of 
documentation and changed circa 2004. 
3.        We have seen this past week very real evidence of the ascendancy 
of commercial ventures with the launch of a privately developed rocket 
contracted to NASA for carrying astronauts to the ISS (which I believe 
uses AOS in the forward direction). I'm concerned that in this case, CCSDS 
seems to be unable to keep up with current developments on the world stage 
and that this may present a risk to long term CCSDS relevancy. 

The above is offered only as commentary and is not meant to impugn the 
integrity or good work of anybody that labors for the cause of CCSDS 
standardization. Rather I'm concerned that this issue, if not resolved 
sooner rather than later, will impact CCSDS as a whole and may serve to 
make CCSDS less viable in general, thereby exacerbating what I see as 
already an issue of succession planning toward the next generation of 
engineers who may have an interest in international standardization. 

These are only my comments – I do not speak for any other parties.  The 
comments are meant only for consideration by the CESG Chairs, with CESG 
copied for cognizance. 

Best regards,
-Erik
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