Sets	Explanation
$r\in \mathcal{R}$	set of RBs in one time interval
$t\in \mathcal{T}$	set of time intervals
$i\in \mathcal{I}$	set of UEs
$\langle i,t\rangle \in \langle \mathcal{I},\mathcal{T}\rangle$	tuple of demands
$l\in \mathcal{L}$	set of $D{U}^{LP}$
$k\in \mathcal{K}$	type of traffic
Variables	Explanation
$a_{\langle i,t\rangle r{t}^{\prime }}$	indicates $r{t}^{\prime }$ is assigned for $\langle i,t\rangle$
$b_{lt}$	indicates NFs of $D{U}^{LP}$ l migrates to $D{U}^{HP}$ in t
$y_{\langle i,t\rangle t^{\prime }}$	indicates any r in $t^{\prime }$ is assigned for $\langle i,t\rangle$
$u_{\langle i,t\rangle k}$	user traffic indicator
Given Data	Explanation
$D_{lt}^P$	propagation delay
$E_l^F$	fixed energy consumption at l
$E_l^D$	dynamic energy consumption coefficient at l
$E^{HP}$	total energy consumption at $D{U}^{HP}$
$S_{ir{t}^{\prime }}$	max service rate
$U_{\langle i,t\rangle k}$	user traffic demand size
${\Delta }_{\langle i,t\rangle k}$	delay budget
$\xi$	max. number of $D{U}^{LP}$ that can migrate their NFs
$M\left(i\right)$	user & $D{U}^{LP}$ map
$TTI$	length of transmission time interval
W	energy consumption weight in objective function
$\Omega$	scaling factor between en. cons. and mean delay