${\mathbf{x}}_k$	The state of a dynamic target at time k
${\mathbf{z}}_k$	The observation of a dynamic target at time k
${\gamma }_k(·)$	The intensity of birth target at time k
$L_k$	The number of the survival particles at time k
$J_k$	The number of the birth particles at time k
$p_s(·)$	The survival probability of target
$p_d(·)$	The detected probability of target
$\pi (·,·)$	The IS function of birth intensity
$q(·|·)$	The IS function of survival intensity