## 5 Results  
Results obtained using the research methodology and the experiment setup described in the previous section are presented for each interferer modulation (OFDM1-MCS1, OFDM2-MCS2, OFDM3-MCS3, OFDM4-MCS5 and OQPSK-DSSS) and packet length (20 bytes and 120 bytes) in Figures 5-9, respectively. Table 4 summarizes the required SIR (dB) to ensure PDR \(>80\%\) for each modulation and packet length.  
\begin{table}
\begin{tabular}{l c c c c c c c c c c} \hline \hline  & \multicolumn{8}{c}{**Interference Type and Packet Length (bytes)**} \\ \cline{2-11}  & \multicolumn{2}{c}{**OFDM1-MCS1**} & \multicolumn{2}{c}{**OFDM2-MCS2**} & \multicolumn{2}{c}{**OFDM3-MCS3**} & \multicolumn{2}{c}{**OFDM4-MCS5**} & \multicolumn{2}{c}{**OQPSK-DSSS**} \\ \cline{2-11}  & **20** & **120** & **20** & **120** & **20** & **120** & **20** & **120** & **20** & **120** \\ \hline
**OFDM1-MCS1** & 1 & 2 & 2 & 3 & 3 & 4 & 2 & 3 & \(-1\) & \(-1\) \\ \hline
**OFDM1-MCS2** & 2 & 4 & 5 & 6 & 5 & 6 & 5 & 7 & \(-5\) & \(-3\) \\ \hline
**OFDM3-MCS3** & 2 & 4 & 5 & 6 & 8 & 9 & 8 & 9 & \(-5\) & \(-3\) \\ \hline
**OFDM4-MCS5** & 5 & 7 & 8 & 10 & 10 & 12 & \(>\)12 & \(>\)12 & \(-2\) & 0 \\ \hline
**QQPSK-DSSS5** & 8 & 12 & 8 & 12 & 8 & 12 & 9 & 12 & 6 & 8 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Results summary. Each value in the table is the required SIR (dB) to ensure a PDR \(>80\%\) for each modulation (OFDM1-MCS1, OFDM2-MCS2, OFDM3-MCS3, OFDM4-MCS5, OQPSK-DSSS) and packet length (20, 120 bytes).  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Transmit Power (dBm)**} \\ \hline
**RFn\_PAX.TXPWR** & **OQPSK-DSSS** & **OFDM1-MCS1** & **OFDM2-MCS2** & **OFDM3-MCS3** & **OFDM4-MCS54** \\ \hline
**30** & 15 & 9 & 9 & 9 & 9 \\ \hline
**27** & 14 & 8 & 8 & 8 & 8 \\ \hline
**24** & 12 & 5 & 5 & 5 & 5 \\ \hline
**21** & 9 & 2 & 2 & 2 & 2 \\ \hline
**18** & 6 & \(-1\) & \(-1\) & \(-1\) & \(-1\) \\ \hline
**15** & 3 & \(-3\) & \(-3\) & \(-3\) & \(-3\) \\ \hline
**12** & 0 & \(-7\) & \(-7\) & \(-7\) & \(-7\) \\ \hline
**9** & \(-3\) & \(-11\) & \(-11\) &Figure 5: OFDM1-MCS1 interference results.  
Figure 6: OFDM2-MCS2 interference results.  
Figure 7: OFDM3-MCS3 interference results.  
For example, if we consider an interfering signal modulated using OFDM1-MCS1, we can observe that, for a 20 bytes PSDU, the OFDM1-MCS1, OFDM2-MCS2 and OFDM-MCS3 physical layers perform similarly, requiring SIR \(>\) 1 dB for PDR \(>\) 80%. OFDM4-MCS5 requires SIR \(>\) 5 dB to provide a PDR \(>\) 80%. In contrast, for a 120 B PSDU, OFDM1-MCS1 requires an SIR \(>\) 2 dB, OFDM2-MCS2 and OFDM3-MCS3 require SIR \(>\) 4 dB, and OFDM4-MCS5 requires an SIR \(>\) 7 dB. Finally, for a 20 byte and 120 byte PSDU, OQPSK-DSSS requires an SIR \(>\) 8 dB and an SIR \(>\) 12 dB for PDR \(>\) 80%, respectively.  
These results show that OQPSK-DSSS requires 6 dB higher SIR to achieve PDR \(>\) 80% when compared to OFDM1-MCS1 under the same interference. Considering that OQPSK-DSSS uses a 5 MHz channel bandwidth while OFDM1-MCS1 uses 1.2 MHz channel bandwidth, we can derive that OFDM provides increased spectral efficiency and robustness. Similar results can be derived for other combinations, as presented in Table 4.  
Interestingly, considering an interfering signal modulated using OQPSK-DSSS, if we consider a system using OFDM1-MCS1 and we compare it to the same system using OQPSK-DSSS, we can observe that OFDM1-MCS1 can still operate with PDR\(>\)80% even if the interference level is 1 dB above the signal level. This is particularly interesting because OQPSK-DSSS is widely used.  
Figure 8: OFDM4-MCS5 interference results.  
Figure 9: OQPSK-DSSS interference results.