Algorithm 1 A novel sensing framework [39].

Input:$x\left(i\right)(i=0,1,\cdots ,I-1)$ (a copy of communication-transmitted signal sequence), $y\left(i\right)$ (echo signal at a sensing receiver), $\tilde{N}$ (SB length), $\tilde{Q}$ (VCP length), $\overline{Q}$ (overlapping between adjacent SBs)

Segment $x\left(i\right)$ and $y\left(i\right)$ evenly into consecutive sub-blocks (SBs), as given by $x_m\left(n\right)$ and $y_m\left(n\right)$. The m-th $(m=0,1,\cdots ,\tilde{M})$ sub-block consists of samples $i=m(\tilde{N}-\overline{Q})+(0,1,\cdots ,\tilde{N}-1)$; Add VCP, i.e, the $\tilde{Q}$ samples right after $y_m\left(n\right)$, onto the beginning of $y_m\left(n\right)$, leading to ${\tilde{y}}_m\left(n\right)$; Take the DFT (w.r.t. n) of $x_m\left(n\right)$ and ${\tilde{y}}_m\left(n\right)$, yielding $X_m\left(k\right)$ and $Y_m\left(k\right)$; Under PWD, we have ${\tilde{U}}_m\left(k\right)=Y_m\left(k\right)./X_m\left(k\right)$, whereas using PWP, we obtain ${\tilde{V}}_m\left(k\right)=Y_m\left(k\right)\times X_m^{*}\left(k\right)$; Taking the 2D-DFT of ${\tilde{U}}_m\left(k\right)$ and ${\tilde{V}}_m\left(k\right)$, generate the RDMs $U_b\left(n\right)$ and $V_b\left(n\right)$, respectively.