IMPACT IoT firmware upgrade – alternate call flow

This section details the alternate call flow for firmware upgrade to cater for LWM2M clients that have not implemented UQS bind mode or OBSERVE/NOTIFY function of LWM2M specification.

The key change in this alternative flow is to do a “READ” operation on the STATE node in a loop. The system will implement the following system wide parameters:

  • Interval: Seconds to wait before doing a new READ. This will be defaulted to 10 seconds and Nokia recommends to leave it at that interval. Any longer interval may result in failed delivery of UDP packets.
  • Count: This is the number of times the server will do a READ. The default value is 50.
  • Expiry: This is the duration beyond which a pending firmware update operation is deemed to have failed. The default value for this is 24 hours.
The call flow below details the server interaction depending on binding mode:
  • UQ binding mode: Server waits for Registration Update from device
  • UQS binding mode: Server sends SMS to device to trigger Register Update
Figure 1. Firmware update state machine (alternate flow)