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SLE Books Updates Status

SLE Books Updates Status. March / April 2014. Status Summary. All issues discussed at the beginning of the Bordeaux meeting implemented in all five Books (RAF, RCF, ROCF, F-CLTU, FSP)

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SLE Books Updates Status

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  1. SLE Books Updates Status March / April 2014

  2. Status Summary • All issues discussed at the beginning of the Bordeaux meeting implemented in all five Books (RAF, RCF, ROCF, F-CLTU, FSP) • Making (almost) all configuration parameters gettable completed for RAF and RCF, pending for ROCF, F-CLTU and FSP • For the case of LDPC coding, the text specifying what is to be delivered in case the codeblock does not decode needs to be more precise (no soft symbols) • F-CLTU minor change in the text to cover the sequence-counter wrap-around as per CSTS • The ASN.1 updates still need to be validated by compiling

  3. Status Summary • Above mentioned F-CLTU update has also to be made to FSP • For FSP consider the following scenario: • Commanding in AD-mode is on-going, then telemetry drops out • As a consequence of missing CLCWs, eventually the AD mode is terminated with ‘FOP alert-limit’ • At this point one does not know which packets made it into the spacecraft beyond the last one that was reported to be acknowledged • Telemetry comes back and based on the now available CLCW the FSP provider generates the ‘acknowledged’ notifications for all packets that made it into the spacecraft while no telemetry was available. With that the MCS knows from where to resume commanding

  4. Status Summary • Now consider the same scenario, but when telemetry comes back, the space link has been established via a different ground station (view period constraints) • At this point the MCS knows the last packet that was acknowledged using the outgoing station, but does not know which packets may have been accepted by the spacecraft while telemetry was lost • The FSP provider at the incoming station has no knowledge of which packets have been uplinked within which frames and therefore although getting the CLCWs cannot generate the acknowledgements for the packets that were radiated while telemetry was not available • The MCS does not know how to resume commanding without the risk of sending duplicate packets

  5. Status Summary • Agreed solution: • The conditional parameter frame-sequence-number is added to the FSP-ASYNC-NOTIFY operation • This parameter is present only if the notification-type is ‘radiated’ and it indicates the sequence number of the frame in which the packet reported to be radiated travelled • When getting telemetry again and therefore knowing the sequence number of the last frame accepted by spacecraft, the MCS can work out which packets made it into the spacecraft and can resume commanding at the correct point in the command stack • This recovery mechanism requires that the MCS knows the sequence number of the last frame accepted by the spacecraft. This can be obtained by performing a GET operation requesting the transmitter-frame-sequence-number parameter

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