This systematic retransmission option is simpler to

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Unformatted text preview: multiple copies of the CLTU containing the “Frames”. This systematic retransmission option is simpler to specify, compared to the ones discussed in sections 3.2.1 and 3.2.2. It probably needs less changes to the standards documents, which is an advantage compared to those options. However, there are also some disadvantages to be considered, as discussed in sections 3.3.1 to 3.3.5. Section 3.3.6 discusses the options for setting the Repetitions parameter in the Transfer Sublayer. 3.3.1 Response to FOP-1 events The option for systematic retransmission in the Synchronization and Channel Coding Sublayer would be less responsive to FOP-1 events, such as the removal of frames from the Sent_Queue. So, when a CLCW arrives which acknowledges a frame, the frame will still be retransmitted. This is inefficient, but should not happen often if the option is correctly applied for a mission with a long light delay. 3.3.2 Physical Channel or Virtual Channel If the option for systematic retransmission is in the Synchronization and Channel Coding Sublayer, then the retransmission would be done at the level of the Physical Channel, after Virtual Channel multiplexing. For missions with multiple Virtual Channels, it could cause unexpected disturbance to the performance of the multiplexing algorithm, because all the systematic retransmissions of a frame must be completed before another Virtual Channel can access the Physical Channel. So, for example, a high-priority Virtual Channel could experience a longer delay than intended. Note that the delay would affect all types of frames, including type-BD frames. Systematic retransmission inside FOP-1 is done at the level of the Virtual Channel, so the Virtual Channel multiplexing is unaffected. Another Virtual Channel can access the Physical Channel between the individual retransmissions in a set of systematic retransmissions for a frame. TCretrans7 2008Sep09 I.B. + M.A. DE LANDE LONG SOFTWARE + CONSULTANCY Options for repeated retransmissions for telecommand Page 10 Of course, for missions which make no significant use of Virtu...
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