## 4 Simulation Results and Performance Analysis
### Simulation Results
\begin{table}
\begin{tabular}{l l l l l l l l l l} \hline \hline \multirow{2}{*}{**Method**} & \multirow{2}{*}{\begin{tabular}{c} **Traditional (Serial search)** \\ **(Fixed search space bound)** \\ \end{tabular} } & \multicolumn{2}{c}{\begin{tabular}{c} **Parallel code delay [28]** \\ **(Fixed code/Doppler search** \\ **space bound)** \\ \end{tabular} } & \multicolumn{2}{c}{\begin{tabular}{c} **Parallel frequency [28]** \\ **(Fixed code/Doppler search space bound)** \\ \end{tabular} } & \multicolumn{2}{c}{\
\begin{tabular}{c} **Parallel code delay [12]** \\ **(Adaptive logic** \\ **(GC with adaptive \\ **scaling scheme)** \\ \end{tabular} } & \multicolumn{2}{c}{
\begin{tabular}{c} **Parallel code delay** \\ **(GC with adaptive \\ **scaling scheme)** \\ \end{tabular} } \\ \hline
**Type** & C/A-code & \begin{tabular}{c} P-code/ \\ BOC \\ \end{tabular} & C/A code & \begin{tabular}{c} P-code/ \\ BOC \\ \end{tabular} & C/A-code & \begin{tabular}{c} P-code/ \\ BOC \\ \end{tabular} & C/A-code & \
\begin{tabular}{c} P-code/ \\ BOC \\ \end{tabular} & C/A-code &
\begin{tabular}{c} P-code/ \\ BOC \\ \end{tabular} \\ \hline
**Execute time** & 1505.2 & \begin{tabular}{c} 220.3/ \\ 1704.3 \\ \end{tabular} & 720.5 & \begin{tabular}{c} 1392.3/ \\ 983.2 \\ \end{tabular} & 901.2 & \begin{tabular}{c} 1793.8/ \\ 1103.6 \\ \end{tabular} & 700.4 & \
\begin{tabular}{c} 1226.1/ \\ 960.4 \\ \end{tabular} & 650.4 &
\begin{tabular}{c} 1783.2/ \\ 850.9 \\ \end{tabular} \\ \hline
**Repetitions** & & & & & & & \\ \begin{tabular}{c} **(Without** \\ **without** \\ step size) \\ \end{tabular} & \begin{tabular}{c} 401 (50 Hz \\ step size) \\ \end{tabular} & \begin{tabular}{c} 401 (50 Hz \\ step size) \\ \end{tabular} & \begin{tabular}{c} 1 ms \\ step size) \\ \end{tabular} & \begin{tabular}{c} 0.5 s/4 ms \\ 400 (50 Hz \\ step size) \\ \end{tabular} & \
\begin{tabular}{c} 34 \\ code chip \\ length \\ \end{tabular} &
\begin{tabular}{c} 140.78 \\ 100- \\ length \\ \end{tabular} & 39 & 145.96 \\ \hline
**Parameter** & \begin{tabular}{c} Poor \\ (Count on \\ number of \\ bins) \\ \end{tabular} & \
\begin{tabular}{c} Poor \\ (Count on \\ number of \\ bins) \\ \end{tabular} &
\begin{tabular}{c} Fair \\ (Count on \\ number of \\ bins) \\ \end{tabular} & Fair & Poor & High & Fair & High & Fair \\ \hline
**Complexity** & Low & Fair & \begin{tabular}{c} High \\ (Count on \\ FFT size) \\ \end{tabular} & \begin{tabular}{c} Fair \\ (Count on \\ FFT size) \\ \end{tabular} & \begin{tabular}{c} High \\ (Count on \\ FFT size) \\ \end{tabular} & \begin{tabular}{c} Fair \\ (Count on \\ FFT size) \\ \end{tabular} & \
\begin{tabular}{c} High \\ (Count on \\ FFT size) \\ \end{tabular} & Fair & High & Fair &
\begin{tabular}{c} High \\ (Count on \\ number of \\ population) \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Performance comparison of different acquisition methods (simulated). In addition, the system computation time of GC depends on the maximum initial population size \(Z\) and iteration number \(M\), which takes O(\(ZM\)). For example, regarding the hardware implementation, the standard GC method takes 2 \(\times\)1500 plus 1500 multiplications and 2 \(\times\)1500 additions for C/A-code. Therefore, the total required number of operations equals 4500 multiplications and 3000 additions. The adoption of GC with an adaptive scaling scheme takes additional memory for the adaptive adjustment. Table 1 compares the simulated performances of our proposed method with those of the existing methods. The execution time is measured using the tic and toc functions in MATLAB. An average personal computer (PC) is adopted for 20 execution time measurements, with the mean computed as well [28]. The table indicates that the proposed method is superior in time and more precise in parameter than other methods in acquiring three different types of signal. It is noteworthy that because P-code has a longer period time, code length of only that segment (about 2 ms) is utilized for signal acquisition during simulation.