Table 1.

Symbols and notations.

Symbol/Notation	Details
$l_{BS}$	Distance between CH to BS
${\delta }_{fs}$	Parametric values for the free space
${\delta }_{mp}$	Parametric values for the multipath
$C_{opt}$	Optimal number of clusters
$X$	Side length of the sensing area
$N$	Number of SNs in the sensing area
$k$	Message length in bits
l	Distance for transmitting k bits
$l_0$	Threshold
$E_{transmit-elec}\left(k\right)$	Transmit power by the electronic circuit to send k-bit of data
$E_{receive}\left(k\right)$	Energy required to receive the k-bits message at the receiving end
$E_{threshold}$	Threshold energy level
$n_{sn}$	Total SNs in the cluster
$c_k$	CHs unable to communicate or send data directly to the UAV
l UAV	Distance between each elected CH and UAV
$dv$	Current temperature
$Z_{ab}$	Distance between two cluster heads