## 5 Numerical Results and Discussion
### Synchronous Networks  
#### 5.2.1 Single-Slot Networks  
For the single-slot synchronous ISAL networks, as shown in Figure 9, we provide a comparison of the sensing SPEB results between the step-by-step and the integrated scheme in the four networks in Figure 7.  
Due to the fact that all active nodes in this study can both transmit and receive signals, the target sensing can be achieved by only two active nodes through twice TOA and once TSOA. In Figure 7, we set up a variably-sized partial network with one target and two active nodes. The networks with relatively close distances among three nodes are called \begin{table}
\begin{tabular}{l l l} \hline \hline
**Parameter** & **Symbol** & **Value** \\ \hline Carrier frequency & \(f_{\text{c}}\) & 77 GHz \\ Total energy & \(E_{\text{total}}\) & 10 J \\ Total bandwidth & \(B_{\text{total}}\) & 500 MHz \\ Antenna gain & G & 10 dB \\ Noise power spectral density & N\({}_{0}\) & \(-174\) dBm/Hz \\ Upper limit of anchor power & \(P_{\text{a,max}}\) & 1 \\ Upper limit of radar power & \(P_{\text{r,max}}\) & 1 \\ Radar cross section & \(\sigma\) & 10 m\({}^{2}\) \\ System loss & \(L\) & 3 dB \\ Variance of node velocity & \(\eta^{2}\) & 0.01 m\({}^{2}\)/s\({}^{2}\) \\ Variance of relative clock drift & \(\rho^{2}\) & \(1\times 10^{-10}\) \\ rate & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Simulation parameters. Figure 8: Four dual-slot networks. (**a**) Sensing-resource-abundant networks in both slots. (**b**) Sensing-resource-abundant network in the first slot and sensing-resource-limited network in the second slot. (**c**) Sensing-resource-limited network in the first slot and sensing-resource-abundant network in the second slot. (**d**) Sensing-resource-limited networks in both slots. sensing-resource-abundant networks. On the other hand, the networks with relatively far distances among three nodes are called sensing-resource-limited networks. According to Figure 9, we have the following observations. Firstly, when the distribution of nodes is relatively uniform in the ISAL network, in other words, when the length of the localization and sensing links in the network is basically the same level (such as \(1\times 10^{1}\sim 1\times 10^{2}\) m), the step-by-step optimization scheme will allocate the majority of the total energy to the second step for target sensing, as shown in the Figure 9d. This indicates that, in the networks with evenly distributed nodes, the difficulty of sensing passive targets is much higher than the difficulty of locating active nodes. Secondly, in the single-slot synchronous ISAL networks, when optimizing the sensing SPEB, the step-by-step optimization scheme is more suitable for the sensing-resource-simulated networks, as shown in Figure 9a,b. The integrated optimization scheme is more suitable for the sensing-resource-simulated networks, as shown in Figure 9c,d. In addition, from the SPEB results of the step-by-step scheme of the single-slot synchronous ISAL networks, we can observe the trade-off relationship between sensing and localization, as shown in Figure 9b,c. From the conclusions above, we provide the following interpretations. Firstly, it is not difficult to find that, when the length of the localization and sensing links is basically the same level, the RII of the sensing link is much smaller than that of the localization link. Therefore, when the network nodes are evenly distributed, the difficulty of sensing passive targets is relatively higher. Secondly, in the sensing-resource-abundant networks, target sensing requires less energy than radar positioning. Due to the flexibility of energy allocation between two steps, the step-by-step scheme can reduce the energy allocated for step 2 (target sensing) to allow more energy to be used for radar positioning, which is beneficial for improving radar positioning accuracy. We take the comparison between Figure 9b,c as an example.