Algorithm 3: CP Estimation on $\mathit{L}\mathit{O}\mathit{S}\mathit{L}\mathbf{\left(}\mathit{i}\mathbf{\right)}$ based on the Intercept Theorem.

Initialization: Obtain the coordinates of all wireless sensor nodes, as well as the topology information of all LOSLs, that is, their formulas.

Step 1. Launch the algorithm when $LOSL\left(i+1\right)$ is triggered; Step 2. Successively check whether $LOSL\left(i-n\right)$ is parallel with $LOSL\left(i+1\right)$ in the reverse order, $n\in \left[1, 2, \cdots ,i-1\right]$; $n=1;$ while (1)   if $LOSL\left(i-n\right)$ is parallel to $LOSL\left(i+1\right)$     Obtain the elapsed time ratio $R\left(i\right)$ according to Equation (14):      $R\left(i\right)={\sum }_{j=1}^{n}T\left(i-j\right)/T\left(i\right);$   else     Check next LOSL by: $n=n+1;$   end end Step 3. Retrieve the formula of $LOSL\left(i+1\right), LOSL\left(i\right), LOSL\left(i-n\right)$, and obtain the intersections: $M, \left(x_M,y_M\right)$ is the intersection of $LOSL\left(i+1\right)$ and $LOSL\left(i\right);$ $N, \left(x_N,y_N\right)$ is the intersection of $LOSL\left(i-n\right)$ and $LOSL\left(i\right)$ Step 4. Estimate the CP according to Equation (15): $P=(N+MR)/(1+R)$.