Uplink sender always locks after every window (LoRaWAN)

[felipe-canales]

In the SCHC over LoRaWAN draft, section 5.6.2, page 15, it is specified that some devices may not wait for a SCHC ACK after every window and that this behaviour is rule-dependant:

For non-battery powered devices, the SCHC receiver MAY also choose to
send a SCHC ACK only at the end of all windows.  This will reduce
downlink load on the LoRaWAN network, by reducing the number of
downlinks.

SCHC implementations MUST be compatible with both behaviors, and this
selection is part of the rule context.

Currently, only waiting after every window is supported.