CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 1 Proposal to P1A & P1B Increasing allowed frame lengths and interleaving depths for AOS TM

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 2 Summary u Background u Targeted applications : e.g. Pleiades-HR u Rationale for changes u Impacts w.r.t. blue books u Conclusion

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 3 Background u Present limitations w.r.t. frame length & interleaving : é AOS blue book limits VCDU length to 5 x 223 = 1115 octets when RS is used not consistent with new RS option (239, 255, E=8) introduced in TM channel coding blue book frame length limitations should be removed from AOS in the « Yamada » restructured edition é TM channel coding blue book (June 2001) limits transfert frame (VCDU) length to :  1115 octets (RS(223,255)), 1195 octets (RS(239,255)) when RS is used  interleaving depths for RS, I = 1, …, 5

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 4 Background (cnt ’d) é Packet TM blue book max frame length of 2048 octets (max capability of 11-bit FHP) é ESA TM channel coding & Packet TM standards allows interleaving depths for RS, I = 1, 2, 3, 4, 5 & 8 max frame length : 2040 octets (both for coded & uncoded cases)

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 5 Background (cnt ’d) u Rationale for theses limitations é loss of power efficiency was considered small (for low rate systems) between I = 5 and [I=8 or 16] for « Conv(7,1/2)+RS(223,255) » over BPSK approx. 0,4 dB loss FER = (between I=5 and I=8) é provide acceptable frame sync rate for low to medium data rate mission : few kbps to few Mbps é limit the number of packets being lost whenever a frame is lost : optimization in terms of FER ? é limit the complexity of the RS encoder ?

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 6 Background (cnt ’d) é New channel coding options and modulation schemes are being introduced in CCSDS blue books to cover the needs of « bandwidth limited & high rate » earth orbiting missions RS (239, 255, E=8) code punctured convolutional code (7,1/2) with punctured rates : 2/3, 3/4, 5/6, 7/8 (as per DVB-S standard) Multidimentional Treillis Coded Modulation (MTCM) 8-PSK modulation scheme é Example of such « bandwidth limited & high rate » missions PLEIADES-HR

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 7 Targeted applications : e.g. PLEIADES-HR u High resolution earth observation satellites : é Mission parameters : sun synchronous orbit : km resolution (optical) : 0.6 to 2.5 m radiometric precision : 8 to 12 bits/pixel swath : 15 to 60 km instrument data rates : 128 Mbits/s to 2 Gbits/s image compression - Compression Ratio : 3 to 6 :  compressed rate per instrument : 50 Mbits/s to 500 Mbits/s  BER requirement : BER < to due to compression

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 8 Targeted applications : e.g. PLEIADES-HR é Constraints : minisats or small sats :  severely mass & power limited Payload TM at X-band : 375 MHz in total  band limited Transmission data rates needed : 128 Mbits/s to 600 Mb/s  depending on : nb of ground stations, on-board mass memory capacity Rate can be splitted into up to 4 channels :  150 Mb/s max per channel standard P/L TM I/F would be a plus for interoperability and standardisation of equipment in multimission X-band recieving stations

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 9 Targeted applications : e.g. PLEIADES-HR u PLEIADES-HR payload TM characteristics é 0.65 m resolution, 20 km swath é 620 Mb/s of user data rate to ground at X-band 4 carriers : 155 Mb/s user data rate each MTCM 8-PSK 2.5 bits/symbol (compliant with future CCSDS recommendation) RS (238,254) used as outer code, interleave depth : 5, 8 or 16 ? é required BER of due to image compression é compressed image data formated as CCSDS source packets each packet contains 8 compressed lines (for a portion of swath)

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 10 Targeted applications : e.g. PLEIADES-HR é packets inserted in AOS frames AOS selected because of high rates (24-bit frame counter) Insert zone of transfer frame used to carry 12 bytes of ancillary data é interest on this project to develop generic equipment with interfaces based on non-proprietary standards equipments : image compression unit, mass memory, modulator standard I/F :  CCSDS image lossy compression (algorithm & source format) ?  CCSDS source packet  AOS VCDU, AOS CVCDU and CADU  CCSDS 8-PSK RF interface.

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 11 Rationale for changes u 2 penalties identified for PLEIADES-HR w.r.t. CCSDS compatibility é transfer frame format overhead due to limited allowed frame length é loss of power efficiency on the link due to limited allowed interleaving depth for RS outer code

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 12 Rationale for changes (ctn ’d) u Frame format overhead é overhead VCDU frame header : 6 octets M-PDU header : 2 octets Insert : 12 octets  ancillary data 8 Hz max Frame rate : 5 I=16, 16 I=5

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 13 Rationale for changes (ctn ’d) é Vast oversampling of ancillary data é frame sync rate much higher than needed é between I=5 and I=16 represents a net capacity loss of 7.5 Mbps é as a reference SPOT5 TM proprietary format has an overhead of : 0.52%

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 14 Rationale for changes (ctn ’d) u Loss of power efficiency é comparison of BER (and FER) performance for various interleave depth of the RS(238, 254) outer code I = 5, I = 8, I = 16 and infinite interleave é 2 modulation schemes taken as reference MTCM 2 bits/symbol MTCM 2.5 bits/symbol (PLEIADES-HR) é 2 performance levels in terms of BER : é simulations were feasible down to BER=10 -9 (typ.) extrapolations were done for lower BER

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 15 Rationale for changes (ctn ’d) u Simulations were cross-verified by experiment on modulator breadboard : é for I = 16 only é implementation losses (FI 720 MHz w.r.t. simus) were substracted 0.2 2b/symbol b/symbol

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 16

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 17

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 18 Rationale for changes (ctn ’d) u 1st case : MTCM 2 bits/symbol

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 19 Rationale for changes (ctn ’d) u 2nd case : MTCM 2.5 bits/symbol

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 20 Rationale for changes (ctn ’d) é I = 8 gives a 1 dB over I = 5 for 8-PSK 2.5 b/s/Hz é I= 16 gives a 0.4 dB over I = 8 for 8-PSK 2.5 b/s/Hz é very significant gain for power constrained spacecraft transmiting at 600 Mbps

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 21 Proposed changes to existing Blue Books u 1st solution : add I = 8 as a valid interleaving depth for RS é impacts TM channel coding blue book é impacts AOS blue book if frame length constraints left in that book frame length constraints will be removed anyway from that book in the restructured version u 2nd solution : add I = 8 and I = 16 as valid interleaving depths for RS é impacts TM channel coding blue book é impacts AOS blue book need to use one of the 5 spare bits of the M-PDU header to have a 12- bit First Header Pointer (minor change).

CCSDS P1A/B Meeting - Frascati - Nov 8, Gilles Moury, Guy Lesthievent - 22 Conclusion u 2nd solution (add I=8 & 16) is our preferred solution é I=16 provides near optimal performance in terms of power é improves significantly the suitability of CCSDS AOS and TM channel coding to high rate / power&bandwidth constrained systems u changes to existing books are minor but impact on existing AOS infrastructure is to be assessed