Channel Monitoring

This module includes functions for channel monitoring feature.

Summary

The functions in this module are available when channel monitor feature (OPENTHREAD_ENABLE_CHANNEL_MONITOR) is enabled.

Channel monitoring will periodically monitor all channels to help determine the cleaner channels (channels with less interference).

When channel monitoring is active, a zero-duration Energy Scan is performed, collecting a single RSSI sample on every channel per sample interval. The RSSI samples are compared with a pre-specified RSSI threshold. As an indicator of channel quality, the channel monitoring module maintains and provides the average rate/percentage of RSSI samples that are above the threshold within (approximately) a specified sample window (referred to as channel occupancy).

Functions

otChannelMonitorGetChannelOccupancy(otInstance *aInstance, uint8_t aChannel)
uint16_t
Gets the current channel occupancy for a given channel.
otChannelMonitorGetRssiThreshold(otInstance *aInstance)
int8_t
Get channel monitoring RSSI threshold in dBm.
otChannelMonitorGetSampleCount(otInstance *aInstance)
uint32_t
Get channel monitoring total number of RSSI samples (per channel).
otChannelMonitorGetSampleInterval(otInstance *aInstance)
uint32_t
Get channel monitoring sample interval in milliseconds.
otChannelMonitorGetSampleWindow(otInstance *aInstance)
uint32_t
Get channel monitoring averaging sample window length (number of samples).
otChannelMonitorIsEnabled(otInstance *aInstance)
bool
This function indicates whether the Channel Monitoring operation is enabled and running.
otChannelMonitorSetEnabled(otInstance *aInstance, bool aEnabled)
This function enables/disables the Channel Monitoring operation.

Functions

otChannelMonitorGetChannelOccupancy

uint16_t otChannelMonitorGetChannelOccupancy(
  otInstance *aInstance,
  uint8_t aChannel
)

Gets the current channel occupancy for a given channel.

The channel occupancy value represents the average rate/percentage of RSSI samples that were above RSSI threshold ("bad" RSSI samples).

For the first "sample window" samples, the average is maintained as the actual percentage (i.e., ratio of number of "bad" samples by total number of samples). After "window" samples, the averager uses an exponentially weighted moving average. Practically, this means the average is representative of up to 3 * window last samples with highest weight given to the latest kSampleWindow samples.

Max value of 0xffff indicates all RSSI samples were above RSSI threshold (i.e. 100% of samples were "bad").

Details
Parameters
[in] aInstance
A pointer to an OpenThread instance.
[in] aChannel
The channel for which to get the link occupancy.
Returns
The current channel occupancy for the given channel.

otChannelMonitorGetRssiThreshold

int8_t otChannelMonitorGetRssiThreshold(
  otInstance *aInstance
)

Get channel monitoring RSSI threshold in dBm.

Details
Parameters
[in] aInstance
A pointer to an OpenThread instance.
Returns
The RSSI threshold in dBm.

otChannelMonitorGetSampleCount

uint32_t otChannelMonitorGetSampleCount(
  otInstance *aInstance
)

Get channel monitoring total number of RSSI samples (per channel).

The count indicates total number samples per channel by channel monitoring module since its start (since Thread network interface was enabled).

Details
Parameters
[in] aInstance
A pointer to an OpenThread instance.
Returns
Total number of RSSI samples (per channel) taken so far.

otChannelMonitorGetSampleInterval

uint32_t otChannelMonitorGetSampleInterval(
  otInstance *aInstance
)

Get channel monitoring sample interval in milliseconds.

Details
Parameters
[in] aInstance
A pointer to an OpenThread instance.
Returns
The channel monitor sample interval in milliseconds.

otChannelMonitorGetSampleWindow

uint32_t otChannelMonitorGetSampleWindow(
  otInstance *aInstance
)

Get channel monitoring averaging sample window length (number of samples).

Details
Parameters
[in] aInstance
A pointer to an OpenThread instance.
Returns
The averaging sample window.

otChannelMonitorIsEnabled

bool otChannelMonitorIsEnabled(
  otInstance *aInstance
)

This function indicates whether the Channel Monitoring operation is enabled and running.

Details
Parameters
[in] aInstance
A pointer to an OpenThread instance.
Returns
TRUE if the Channel Monitoring operation is enabled, FALSE otherwise.

otChannelMonitorSetEnabled

otError otChannelMonitorSetEnabled(
  otInstance *aInstance,
  bool aEnabled
)

This function enables/disables the Channel Monitoring operation.

Once operation starts, any previously collected data is cleared. However, after operation is disabled, the previous collected data is still valid and can be read.

Details
Parameters
[in] aInstance
A pointer to an OpenThread instance.
[in] aEnabled
TRUE to enable/start Channel Monitoring operation, FALSE to disable/stop it.
Return Values
OT_ERROR_NONE
Channel Monitoring state changed successfully
OT_ERROR_ALREADY
Channel Monitoring is already in the same state.