## 4 Experimental Results and Performance Analysis
### Smart Collaborative Positioning: Selection of the Best RS  
In the practical case, the measurements of RS1 and RS2 are almost identical as we observe in Table 1. In order to analyze the performance of the algorithm of the best RS selection and the best satellites selection, we will still focus on the key parameters (\(C/N_{0}\) and elevation angle) received by both RS and MS. The idea is that the CD algorithm is able to choose the best RS using the best satellites to optimize the CD process while reducing complexity with fewer satellites. Two criteria are used to choose which of RS1 and RS2 will be used to assist MS: \(C/N_{0}\) and elevation angle parameters. In Equations (20) and (21), the thresholds used for \(C/N_{0}\) and elevation angle are respectively 45 dB-Hz and 10\({}^{\circ}\). From Table 1, 11 satellites are received by RS1 and RS2 (SV 1, SV 3, SV 6, SV 11, SV 17, SV 18, SV 19, SV 22, SV 24, SV 28, SV 30) and nine satellites are received by MS (SV 1, SV 3, SV 6, SV 11, SV 17, SV 19, SV 22, SV 28, SV 30) at the end of the recording. On the 11 visible satellites, seven satellites received by RS1 (green part) are stronger than those received by RS2 (SV 1, SV 6, SV 11, SV 17, SV 18, SV 22, SV 28), one satellite received by RS1 (orange part) is weaker than those received by RS2 (SV 30), and the remainder have the same \(C/N_{0}\) level. This means that the satellites received by RS1 are stronger than those received by RS2 in terms of \(C/N_{0}\). Then, among these seven strong satellites received by RS1, there are six satellites which have elevation angles lower than those of RS2 (SV 1, SV 6, SV 11, SV 17, SV 22, SV 28). In order to choose the best RS to be used to help the MS to roughly estimate its position, we have compared the statistical characteristics of results obtained in code phase estimation from both RS. For each RS, the mean error and the standard deviation of the difference between the estimated code phase and the true code phase are compared. This leads to the logical choice of RS1 as an assistant to MS in the smart CD algorithm. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Rx**} & \multicolumn{2}{c}{**14 H**} & \multicolumn{2}{c}{**15 H**} & \multicolumn{2}{c}{**16 H**} & \multicolumn{2}{c}{**17 H**} & \multicolumn{2}{c}{**18 H**} & \multirow{2}{*}{**Mean C/N\({}_{0}\)**} & \multirow{2}{*}{**Mean Elevation**} \\ \cline{2-2} \cline{5-11}  & **SV** & & & & & & & & & & & \\ \hline \multirow{6}{*}{MS} & \multirow{6}{*}{7} & \multirow{6}{*}{54.94} & \multirow{6}{*}{7} & \multirow{6}{*}{77.69} & \multirow{6}{*}{7} & \multirow{6}{*}{58.88} & \multirow{6}{*}{7} & \multirow{6}{*}{21.02} & \multirow{6}{*}{7} & \multirow{6}{*}{36.75} & \multirow{6}{*}{25.13} \\  & & & & & & & & & & & & & \\ \cline{1-1} \cline{5-11}  & & & & & & & & & & & & \\ \cline{1-1} \cline{5-11}  & & & & & & & & & & & & \\ \cline{1-1} \cline{5-11}  & & & & & & & & & & & & \\ \cline{1-1} \cline{5-11}  & & & & & & & & & & & & & \\ \cline{1-1} \cline{5-11}  & & & & & & & & & & & & & \\ \cline{1-1} \cline{5-11}  & & & & & & & & & & & & & \\ \cline{1-1} \cline{5-11}  & & & & & & & & & & & & & \\ \cline{1-1} \cline{5-11}  & & & & & & & & & & & & & \\ \cline{1-1} \cline{5-11}  & & & & & & & & & & & & & \\ \cline{1-1} \cline{5-11}  & & & & & & & & & & & & & & \\ \cline{1-1} \cline{5-11}  & & & & & & & & & & & & & \\ \cline{1-1} \cline{5-11}  & & & & & & & &  
In this case, since we have been able to distinguish the satellites to be chosen according to the key parameters, we do not need to see which satellites form the best GDOP among those chosen. In addition, here we have a single satellite at more than 45 dB-Hz (strong) in view of the MS and the remains are considered weak satellites. Hence, based on the principle of CD, the algorithm will not be limited to the minimum of satellites, but will extend to use the best possible satellites.