*2.2. Clutter Measurements*

During the *p*-th scan, the number of clutter measurements can be considered as an inhomogeneous Poisson distribution. Each clutter component is related to a range measurement and a velocity measurement pair. It is assumed that the target range and velocity measurements of each clutter measurement are independent of each other. The density of each clutter component can be denoted as a product of the PDF of spatial clutter ρ*<sup>c</sup> <sup>p</sup>*,*<sup>i</sup>* and the PDF of clutter Doppler <sup>ρ</sup>*<sup>d</sup> <sup>p</sup>*,*<sup>i</sup>* [34]

$$
\rho\_{p,i} \triangleq \rho(\mathbf{z}\_{p,i}) = \rho(y\_{p,i}^c)\rho(y\_{p,i}^d). \tag{6}
$$

It is worth noting that we consider ρ % *yc p*,*i* & and ρ % *yd p*,*i* & as known a priori in this paper.
