## 2 M&S Software Design for Multi-Radio Integrated Navigation System
### Design of a Message Broker-Based M&S Software for the Multi-Radio Integrated Navigation System
#### 2.3.1 Navigation Environment Generation Module  
In the navigation environment generation module, the reference trajectory and errors were generated, and signal source visibility was determined. The reference trajectory represented the motion of the vehicle. The position of the vehicle and the navigation signal source determined the visibility of the signal sources. If the signal sources were visible to the vehicle, true measurements were generated and measurement errors were added. If the jammer attacked, the measurements included the effect as an error. Figure 7 shows the navigation environment generation module block diagram. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**CurrentNext**} & \multirow{2}{*}{**Initialization**} & \multirow{2}{*}{**Stand-By**} & **Coverage** & **Measurement Generation** & **Navigation** \\  & & & **Analysis** & **and Navigation** & **Only** \\ \hline \multirow{2}{*}{**Initialization**} & \(\mathrm{--}\) & 1 & N/A 1 & N/A & N/A \\
**Stand-by** & 2 & \(\mathrm{--}\) & 3 & 4 & 5 \\
**Coverage analysis** & N/A & 6 & \(\mathrm{--}\) & N/A & N/A \\
**Measurement generation** & N/A & 6 & N/A & \(\mathrm{--}\) & N/A \\
**and navigation** & N/A & 6 & N/A & N/A & \(\mathrm{--}\) \\
**Navigation only** & N/A & \(\mathrm{6}\) & N/A & N/A & \(\mathrm{--}\) \\ \hline \hline \end{tabular}  
* Not allowed.  
\end{table} 
Table 2: State transition. Figure 6: State diagram of the M&S software for multi-radio integrated navigation system. \begin{table}
\begin{tabular}{c c} \hline \hline \multicolumn{1}{c}{**Condition No.**} & **Description** \\ \hline
1 & Function module parameters are available \\
2 & \(\mathrm{{}^{\prime}}\)Initialization Mode\({}^{\prime}\) command is received \\
3 & \(\mathrm{{}^{\prime}}\)Coverage analysis Mode\({}^{\prime}\) command is received \\
4 & \(\mathrm{{}^{\prime}}\)Function module parameters are available and \(\mathrm{{}^{\prime}}\)Measurement \\ generation and navigation Mode\({}^{\prime}\) command is received \\
5 & \(\mathrm{{}^{\prime}}\)Function module parameters and measurements are available and \\
7 & \(\mathrm{{}^{\prime}}\)Navigation only Mode\({}^{\prime}\) command is received \\
6 & \(\mathrm{{}^{\prime}}\)Operation is completed, or \(\mathrm{{}^{\prime}}\)Stop\({}^{\prime}\) command is received \\ \hline \hline \end{tabular}  
\end{table} 
Table 3: Condition for state transition. In Figure 7, the measurement error \(\sigma_{jam}\) of GNSS caused by a setting of parameters jamming attack is modeled as Equation (1). \[\sigma_{jam}=\left\{ \begin{array}{ll}\left(\frac{c}{\Gamma 023}\right)\sqrt{\frac{0 2}{2(C/N_{0})}\,\left[1+\frac{2}{T(C/N_{0})}\right]},&1\geq\frac{\pi R_{c}}{B _{fe}}\\ \left(\frac{c}{\Gamma 023}\right)\sqrt{\frac{02}{2(C/N_{0})}\left(\frac{1}{B_{fe}T_{c} }+\frac{B_{fe}T_{c}}{\pi-1}\left(1-\frac{1}{B_{fe}T_{c}}\right)^{2}\right) \left[1+\frac{2}{T(C/N_{0})}\right]},&\frac{R_{c}}{B_{fe}}<1<\frac{\pi R_{c}}{B _{fe}}\\ \left(\frac{c}{\Gamma 023}\right)\sqrt{\frac{02}{2(C/N_{0})}\left(\frac{1}{B_{fe}T_{c} }\right)\left[1+\frac{1}{T(C/N_{0})}\right]},&1\leq\frac{R_{c}}{B_{fe}}\end{array} \right. \tag{1}\]  
where \(B_{fe}\) and \(T_{c}\) denote the double-sided front-end bandwidth and the code chip rate of GPS receiver, respectively. \(c\) denotes the speed of light and \(T\) is the integration time. Carrier power to noise density ratio \(C/N_{0}\) is given in Equation (2). \[C/N_{0}=-10\log_{10}\left(10^{-\frac{(C/N_{0})_{eff,AB}}{10}}-\frac{1}{2.22R_{ c}}10^{\frac{(I/S)_{dB}-45}{10}}\right) \tag{2}\]  
where \((C/N_{0})_{eff,AB}\) is the effective carrier-to-noise power ratio. The jamming-to-signal power ratio \((I/S)_{dB}\) is given in Equation (3). \[\left(J/S\right)_{dB}=10\log_{10}\left(J_{t,W}\right)+\left(G_{t}\right)_{dB}+ \left(G_{j}\right)_{dB}-20\log_{10}\left(\frac{4\pi}{\lambda_{j}}r\right)_{dB }-\left(S_{r}\right)_{dB} \tag{3}\]  
where \(J_{t,W}\), \(G_{t}\), and \(G_{j}\) denote jammer transmitted power, jammer transmitter antenna gain, and receiver antenna gain toward the jammer, respectively.