Issue link: https://read.uberflip.com/i/1490991
5177 Brandi n Court, Frem ont, CA94538 | Tel : +1 51 0 -4 9 2 -4044 | Fax : +1 510 -4 9 2 -4001 | www.l o ra -al l i anc e.org FUOTA FAQ Fragmented Data Block Transport proposes Forward Error Correction code (FEC) to enable reconstruction of lost fragments by sending extra redundancy packets. 9. How many fragments can be missed by an end-device whereby it will still be able to reconstruct the data block? There is no exact number as the reconstruction capability depends on multiple factors, including memory usage and network quality. The fragmentation session can be configured to send a given number of redundancy fragments. However, the end-device requires memory to reconstruct the missing fragments. More fragment recovery capability means more memory usage. That configuration must be adapted based on the overall network quality. 10. Can an end-device request a missed fragment? No, there is no means for an end-device to request a missing fragment with the proposed protocols. This was done on purpose to avoid massive uplinks from a fleet of end-devices requesting lost fragments. Fragmentation Forward Error Correction code (FEC) has been designed for that issue, so that end- devices with missing fragments continue to listen to the multicast session for recovery fragments, which will enable lost fragment reconstruction. The FUOTA server can request the status of the fragmentation session from the end-device, including the number of missed fragments and reconstruction errors. 11. Can fragments be received out-of-order? Yes, fragments can be received out-of-order. Since each fragment is numbered, an end-device will be able to receive out-of-order fragments and recovery fragments, which enable the reconstruction of lost fragments. 12. Is there an open-source implementation of FUOTA specifications? FUOTA WG specifications do not provide a generic uplink fragmentation method. Other standards, such as IETF SCHC RFC 8724, propose such methods. Static Context Header Compression (SCHC) fragmentation has been designed to work with LoRaWAN, as specified in RFC 9011.