[Sls-sea-dls] TR: No mandatory need for CRC-16 due to addition of SDLS in TC or USLP SDLPs

[Moury Gilles]

In view of our discussion yesterday, it seems we might have to modify the SDLS GB to recommend Frame CRC in all cases to guarantee that all transmission errors are detected. Your thoughts ?

Gilles MOURY
CNES Toulouse
De : Kazz, Greg (US 312B) <greg.j.kazz at jpl.nasa.gov>
Envoyé : mercredi 19 octobre 2022 18:03
À : Andres, Brent (GSFC-567.0)[SCIENCE SYSTEMS AND APPLICATIONS INC] <brent.r.andres at nasa.gov>; Matt Cosby <matt.cosby at goonhilly.org>; Sank, Victor J. (GSFC-567.0)[SCIENCE SYSTEMS AND APPLICATIONS INC] <victor.j.sank at nasa.gov>
Cc : Ignacio.Aguilar.Sanchez at esa.int; Moury Gilles <Gilles.Moury at cnes.fr>
Objet : No mandatory need for CRC-16 due to addition of SDLS in TC or USLP SDLPs

All,

Just cutting and pasting the relevant conclusion from CCSDS 350.5-G (SDLS Green Book) below:

As an example, ESA has adopted the SEC mode and the mandatory presence of CRC in its
TC Standard (reference [25]). With BER<10-4 , the achievable undetected frame error rate is
below 10 -15 . This is 6 orders of magnitude better than the requirement.
D5 TELECOMMAND CONCLUSION
A modification of the performance requirement for undetected error (10-9 ) does not appear to
be required.
As long as the BER conditions to fulfill this performance are met for the particular missions
(i.e., BER<10-5 ), undetected error is expected to be present typically once in 10 years of
operation.
Given this frequency of undetected error, it does not seem worthwhile to impose a mandatory
CRC for frames, when security is applied, in order to reduce even more the likelihood that an
undetected error is only detected by security (MAC). This conclusion is also valid for the
newly introduced short LDPC codes in reference [29], which demonstrate even lower
undetected error rates than TC BCH code.
Regards,
Greg


Greg Kazz
Principal Engineer
Technical Group Supervisor,
312B Project Protection, Project Software, and End to End Information System Engineering
Jet Propulsion Laboratory
4800 Oak Grove Dr., M/S 301-490
Pasadena, CA 91109
1+(818)393 6529(voice)
1+(818)393 6871(fax)
email: greg.j.kazz at jpl.nasa.gov<mailto:greg.j.kazz at jpl.nasa.gov>

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