12.1 Minimal beacon-less operation time
- In the event of beacon loss, a device shall be capable of maintaining Class B operation for 2
- hours (120 minutes) after it received the last beacon. This temporary Class B operation
- without beacon is called ―beacon-less‖ operation. It relies on the end-device‘s own clock to
- keep timing.
- During beacon-less operation, unicast, multicast and beacon reception slots must all be
- progressively expanded to accommodate the end-device‘s possible clock drift.
19
| Beacon reception | Reception window |
|---|---|
| window | enlarges to |
| accommodate clock drift |
End-device
| End-device | End-device | End-device receives a |
|---|---|---|
| receives the | temporarily stop | beacon and resets the |
| beacon | receiving beacon | reception window length |
| 20 | ||
| 21 | Figure 11 : beacon-less temporary operation |