Meaning
Averaging techniques measure the percentage of time a radio channel is occupied by a specific transmitter over a moving temporal period. Using sliding window airtime allows the system to enforce duty cycle limits without being tied to a fixed clock. This method provides a more accurate representation of the impact a device has on the shared spectrum.
Interval Length
Measurement periods are defined by the regulatory standard and vary depending on the frequency band. For many unlicensed devices, the window is one hundred milliseconds, while others use a one-hour period. The system continuously drops the oldest data point and adds the newest to calculate the current occupancy.
This constant update cycle ensures that the device never exceeds its allocated bandwidth during any arbitrary time slice.
Duty Cycle
Limits on the total transmission time prevent any single node from blocking others for an extended duration. If the sliding average exceeds the allowed threshold, the device must pause its transmissions until the average drops.
Collision Avoidance
Randomizing the start time of transmissions within the window helps prevent multiple devices from syncing their bursts. By spreading the traffic, the network reduces the probability of packets overlapping and being lost.
