Runtime Estimation of the Number of Active Devices in IEEE 802.15.4 Slotted CSMA/CA Networks with Deferred Transmission and No Acknowledgment Using ARMA Filters

Figure 1

An example of counting , , , and , and backoff procedure for two devices. In each box for the operation of devices 1 and 2, each number means the backoff value, CCA means that the device performs CCA, and three consecutive TXs mean that the device transmits a data frame during three slots.