## 5 Simulation Results
### Radar-System Performance Evaluation  
Table 1 summarizes the simulation parameters that were chosen according to the design criteria presented previously in Section 2.5. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Symbol** & **Value** \\ \hline \multicolumn{3}{c}{**Overall parameters**} \\ \hline Subcarrier spacing & \(\Delta f\) & 120 kHz \\ Sampling time & \(T_{s}\) & \(\frac{1}{3/N_{c}^{2}}\) \\ Carrier frequency & \(f_{c}\) & 77 GHz \\ IDFT size & \(N_{c}\) & 2048 \\ Symbols & \(N_{gmb}\) & 175 \\ Slots & \(N_{slot}\) & 25 \\ Symbols per slot & \(N_{SpS}\) & 7 \\ CP length & \(N_{p}\) & 328 \\ QAM & - & 4-QAM \\ \hline \multicolumn{3}{c}{**Radar parameters**} \\ \hline Maximum range & \(d_{max}\) & 200 m \\ Range resolution & \(\Delta d\) & 0.6 m \\ Velocity resolution & \(\Delta v\) & 1.34 m/s \\ Probability of false alarm & \(P_{fa}\) & 1\(\times\) 10\({}^{-2}\) \\ Signal-to-noise ratio & SNR & 10 dB \\ \hline \multicolumn{3}{c}{**UFMC**} \\ \hline Filter type & - & Dolph–Chebyshev \\ Filter attenuation & - & 50 dB \\ \hline \multicolumn{3}{c}{**Targets**} \\ \hline Distance (m) & \(d_{i}\) & [55;55;60;80] \\ Velocity (m/s) & \(v_{i}\) & [35;37;30;20] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Simulation parameters. IDFT, inverse discrete Fourier transform; CP, cyclic prefix; QAM, quadrature amplitude modulation. For targets, we chose to simulate 4 targets in which 2 targets shared the same distance and very close velocity to verify velocity resolution. Target 1 at a distance \(d=55\) m with velocity \(v=35\) m/s, Target 2 with \(d=55\) m and \(v=37\) m/s, Target 3 at a distance \(d=60\) m distance \(d=60\) m and \(v=30\) m/s, and Target 4 with \(d=80\) m and \(v=20\) m/s. The UFMC parameters adopted in this case were sub-band size \(Q=64\) and filter length was 16 for optimal performance. In a vehicular context, relevant maximal target distance does not exceed \(d=200\) m. Considering the sampling time of the signals, receivers can efficiently mitigate the effect of ISI, when maximal delay is within the CP duration for OFDM. For UFMC, on the other hand, the filter ramp-up and -down at the edges of the symbol guarantees soft protection against ISI. The energy contained in the L last samples of the UFMC signal is relatively small. However, the choice of filter length also impacts the correct estimation of target distance and velocity, since energy is not equal among all subcarriers. Figure 5 depicts the periodogram of the two received signals computed using the parameters in Table 1. Results confirmed that both suggested waveforms are suitable for radar, as we can clearly see the four targets on the distance-velocity grid. Furthermore, the UFMC waveform reduces the high OOB power emission while retaining the simplicity of the conventional OFDM signal. This also offers increased spectral efficiency due to the omission of CP. Figure 5: UFMC waveform vs orthogonal frequency division multiplexing (OFDM) waveform: (**a**) UFMC. (**b**) OFDM. While UFMC proved to be suitable for radar application as a new 5G waveform, we suggest to implement MA techniques, more specifically CDMA, to study how the spreading can affect obstacle detection. The spreading sequences that we chose in our simulation are the Walsh-Hadamard sequences because of their ease of implementation, high autocorrelation, and low cross-correlation properties. The order of the used sequences is \(N_{c}\), and the evaluation of radar performance is performed with different scrambling patterns. The nature of the spreading sequences used by the transmitter changed the outcome of the simulation. As depicted in Figure 6, we chose three Walsh-Hadamard codes with the same length, categorized as follows: a nonscrambled sequence, which is a sequence of ones, and usually the first generated sequence in the Hadamard matrix; the second code is more scrambled compared to the first and sequels 64 chips of the same binary codeword; the last sequence is the most scrambled sequence that could be generated.