## 5 Numerical Results and Discussion
### Asynchronous Networks  
#### 5.3.1 Single-Slot Networks  
For the single-slot asynchronous ISAL networks, due to the clock offset vector \(\mathbf{\tau}\) in the parameter vectors to be estimated, when analyzing the energy optimization allocation between each step of the step-by-step scheme, we adopt the method of fixing the energy allocated to one parameter vector and analyzing the energy allocation relationship between the other two parameter vectors. For the asynchronous single-slot ISAL networks, as shown in Figure 11, we provide a comparison of the sensing SPEB results of the step-by-step scheme and the integrated scheme in the four networks with different topologies in Figure 7.  
According to Figure 11, we have the following observations. Firstly, as shown in Figure 11a-d,m-p, when the energy allocated to step 2 is fixed, there is still a trade-off between localization and sensing. Moreover, when the network nodes are evenly distributed, the difficulty of target sensing is still much higher than that of radar positioning. From Figure 11e-h,q-t, it can be seen that, when the energy allocated to step 3 is fixed, the more energy allocated to step 1, the better the sensing accuracy. This means that, in the four single-slot asynchronous networks with different topologies, the difficulty of radar positioning is higher than that of estimating clock offset. Similarly, from Figure 11i-l,u-x, it can be seen that, when the energy allocated to step 1 is fixed, the more energy that is allocated to step 3, the better the sensing accuracy. This means that, in the four single-slot asynchronous networks with different topologies, the difficulty of target sensing is higher than that of estimating clock offset as well. In addition, similar to single-slot synchronous networks, in single-slot asynchronous networks, when the optimization objective function is the sensing SPEB, the step-by-step optimization scheme is more suitable for the sensing-resource-abundant network, as shown in Figure 11a-l. The integrated optimization scheme is more suitable for the sensing-resource-limited network, as shown in Figure 11m-x.  
Based on the conclusion that the difficulty of estimating clock offset in the single-slot asynchronous networks is lower than that of radar positioning and target sensing, we give the following interpretation. As the example given in Appendix A, compared to (A1) and (A2), the elements of (A3) do not contain the coefficient \(\frac{1}{c}\). Therefore, step 2 in which the clock offset is estimated in the step-by-step scheme requires less energy than the other two steps.  
Above all, for the practical asynchronous ISAL networks with relatively uniform node distribution, in order to reduce the time complexity of the step-by-step scheme if adopted, we can set the energy allocated to each of the three steps in the step-by-step scheme as energy for clock offset \(<\) energy for radar localization \(<\) energy for target sensing, thereby reducing the time of traversal.  
Figure 11: SPEB comparison between the step-by-step scheme and integrated scheme in four single-slot asynchronous networks. The images in the second and fourth columns are the plans of the stereograms in the first and third columns, respectively. (**a,b,e,f,i,j**) are, respectively, SPEB comparisons with step 2 energy, step 3 energy, and step 1 energy fixed in a single-slot asynchronous network (Figure 7a). (**c,d,g,h,k,l**) are, respectively, SPEB comparisons with step 2 energy, step 3 energy, and step 1 energy fixed in a single-slot asynchronous network (Figure 7b). (**m,n,q,r,u,v**) are, respectively, SPEB comparisons with step 2 energy, step 3 energy, and step 1 energy fixed in a single-slot asynchronous network (Figure 7c). (**o,p,s,t,w,x**) are, respectively, SPEB comparisons with step 2 energy, step 3 energy, and step 1 energy fixed in a single-slot asynchronous network (Figure 7d).