Add support for Class B

[RiyazPishori]

LoRaWAN in TVWS (TV White space) bands can enable several new scenarios, such as agriculture (FarmBeats: An IoT Platform for Data-Driven Agriculture). TVWS are unused TV broadcast spectrum (VHF/UHF), namely "snowy" channels. At Microsoft Research, we have developed an end-to-end PoC network operating in the TVWS spectrum leveraging LoRaWAN (Can the Wi-Fi chip in your phone help feed the world? | Bill Gates (gatesnotes.com). We would like to migrate to build on top LoRaWAN stack, such that the LoRaWAN community can leverage this work and also enable the TVWS IOT use cases. To enable this use case, we need Class B support for operation in TVWS spectrum to comply with the FCC regulations. As a result, we request support for Class B in your stack.

[Mandur]

Hello @RiyazPishori, we implemented a PoC of the specification of the Basics Station on this branch. However at the moment it doesn't seem to work as expected because of our hardware. We could have a try with your team to see if these changes do the trick or not...