OTA-Firmware-Updates uber Mobilfunk: Delta spart 95% Bandbreite — NB-IoT schafft keine 2MB
· 7 min read · Technical Whitepapers
2 MB Firmware uber NB-IoT mit 20 kbps dauert 13 Minuten. LTE-M mit 350 kbps: 45 Sekunden. Mit xdelta3-Delta: 120 KB in 6 Sekunden. Ihre OTA-Strategie bestimmt Ihre Datenrechnung.
Ein 2 MB Firmware-Image an 10.000 Gerate ubertragen kostet 20 GB Daten. Die wahren Kosten sind nicht die Daten —es ist die Ausfallzeit. NB-IoT mit 20 kbps: 13 Minuten offline pro Gerat.
Full vs Delta
zstd komprimiert: 800 KB. xdelta3 Delta: 50-120 KB —94-97% Reduktion. NB-IoT wird von unmoglich zu machbar. LTE-M wird von akzeptabel zu unsichtbar.
Häufig gestellte Fragen
How much bandwidth does delta OTA actually save?
xdelta3 delta compression reduces firmware update size by 94-97% compared to a full binary image. A 2 MB firmware becomes 50-120 KB on the wire. Combined with zstd compression, the final package is 60-90 KB — a 95-97% total reduction. On NB-IoT at 20 kbps, this brings transfer time from 13 minutes to under 1 minute.
Can NB-IoT handle firmware updates in production?
Yes, with constraints. China Mobile IoT demonstrated it using delta updates under 200 KB, flash-based breakpoint resume, and region-staggered deployment. If firmware changes after delta compression regularly exceed 500 KB, the device should use LTE-M or Cat-1 bis. NB-IoT OTA works for quarterly small updates — not for frequent large firmware revisions.
xdelta3 or bsdiff — which delta algorithm should I use?
Use bsdiff on the server to generate patches (highest compression, needs >1 MB RAM). Use xdelta3 on the device to apply patches (low memory, streaming, ~40 KB RAM). For ultra-constrained devices with under 50 KB RAM, use HDiffPatch on the device.