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.

Actualizaciones OTA sobre Celular: Delta Ahorra 95% de Ancho de Banda — NB-IoT Aun No Puede con 2MB

June 5, 2026 · 7 min read · Technical Whitepapers

2 MB de firmware sobre NB-IoT a 20 kbps toma 13 minutos. LTE-M a 350 kbps toma 45 segundos. Con compresion delta xdelta3: 120 KB en 6 segundos. Su estrategia OTA determina su factura de datos.

Una imagen de firmware de 2 MB transmitida a 10,000 dispositivos cuesta 20 GB de datos. El costo real no son los datos —es el tiempo de inactividad. NB-IoT a 20 kbps: 13 minutos offline por dispositivo.

Full vs Delta

zstd comprimido: 800 KB. xdelta3 delta: 50-120 KB —reduccion del 94-97%. NB-IoT pasa de imposible a viable. LTE-M pasa de aceptable a invisible.

References

SEGGER — emCompress and emCompress-ToGo for Indian IoT (2025)
IEEE — Evaluating Differential Firmware Updates for Embedded IoT Device Fleets (2025)
Redstone OTA — How China Mobile IoT Leverages Redstone OTA for NB-IoT (2025)