MAC layer is now a class rather than being a blob.
In addition to that Mac commands are now being handled in
a seperate subsystem (a class of its own). In future we
will do the same with othe sublayers of MAC like MLME, MCPS etc.
The drive behind this exercise is to make MAC and supporting layers
into an object oriented system.
Major bug fixes include:
- last join time inclusion in band parameters
- disabling rx2 window if we missed the slot already
- MLME uplink schdule hook
- nbRep according to spec
- maintaining datarate after successful joining
- suppressing MLME requests if MAC is in TX_DELAYED state
- Uplink dwell time verification
Some missing features are implemented. Details are as follows.
Support for LinkCheckRequet:
An application API is added, add_link_check_request() to delegate a
request for Link Check Request MAC command.
* Application provides a callback function that needs to be called on reception of
link check response.
* Mac command is piggybacked with data frames.
This API makes the sticky MAC command stick with the application payloads until/unless
the application un-sticks the said mac command using remove_link_check_request() API.
Handling fPending bit:
If in the Downlink, we get the fPending bit set in fctrl octet,
we attempt to send an empty message back to Network Server to
open additional Receive windows. This operation is independent
of the application. An RX_DONE event is queued bedore generating
the said empty message. Specification does not mention what can be the
type of that empty message. We have decided it to be of CONFIRMED
type as it gives us an added benefit of retries if the corresponding
RX slots are missed.
Radio event callbacks as Mbed callbacks:
radio_events_t structure has been carrying C-style callbacks which was
inherited from the legacy code. These callbacks has now been changed to
Mbed Callbacks that makes sure that we can be object oriented from now
on.
LoRaPHY is the abstract class for the LoRa PHY layer which governs
the LoRaRadio and provides some common functionality to all regional
implementations.
We support 10 regions and every region comes loaded with default parameters.
These parameters can be changed by the Mac layer or explicitely by the stack
controller layer using APIs provided. This layer in essence detaches Mac completely
from PHY and provides more modular approach to the entire system.
Apart from class structure, the internal functionality is directly deduced from
semtech reference implementation that's why most of the internal data structures are
used on 'as is' basis.
In addition to that, the PHY layer provides APIs to control the LoRaRadio layer, i.e.,
the lora radio driver, ensuring that the radio is accessed from a single entry point.
A seperate data structure file is added which is common to PHY layers only.
Hasnain Virk