# Performance Comparisons of Broadband Power Line Communication Technologies
## 3 Bit Rate and Power Spectrum Comparisons  
The operating modes and data protection methods of the PLC technologies are summarized in Table 1. HPGP and HS PLC each have three operating modes, and each mode has its own diversity number. However, IoT PLC has Mini DF and Normal DF, and Normal DF has 15 different diversity numbers, enabling very flexible operations. In Normal DF mode of IoT PLC, the diversity number is determined by the diversity field setting in the physical layer (PHY) header. The diversity number of 15 of IoT PLC is the largest of the three PLC technologies, and provides powerful error correcting capabilities. CTC is known to have very strong error correcting capability against random errors. Thus, it is necessary to change burst errors that usually occur in the PLC channel into random ones. This is why IoT PLC and HPGP use interleavers for all modes. HS PLC uses an interleaver in NORMAL mode only. The size of \(N_{BPS}\) depends on the TM determined by the channel conditions. DV and EDV modes do not use an interleaver. As mentioned above, IoT PLC and HPGP use a rate 1/2 CTC for FEC. However, their constituent encoders are different. HS PLC uses a concatenated code of RS and convolutional code or RS code alone depending on the operation mode. Theses codes have relatively weak error correction capabilities compared to CTC. All three PLC technologies use the OFDM technique for transmission. The channel and OFDM parameters are summarized in Table 2. The frequency bands used for IoT PLC and HPGP are 2 to 28 MHz. However, HS PLC uses a narrower frequency bands. In these frequency bands, bands used by other wireless communications and regulated by emission laws can not be used. Therefore, the number of usable subcarriers is smaller than half of the IFFT size. The sampling frequency \(f_{s}\) and the IFFT size determine the subcarrier spacing. HPGP has the smallest subcarrier spacing, and HS PLC has the largest subcarrier spacing. The small value of the subcarrier spacing makes it easy to control the PLC signal spectrum where allowed and forbidden bands are closely located. The signal spectrum shape is also related to the RI value. The large RI value results in low out-of-band spectral components. IoT PLC has the largest RI value and HS PLC has the smallest RI. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**IoT PLC**} & \multicolumn{2}{c}{**HPGP**} & \multicolumn{2}{c}{**HS PLC**} \\ \hline
**Mode** & **Normal DF** & **Mini DF** & **STD** & **HS** & **MINI** & **NORMAL** & **EDV** & **DV** \\ \hline \(DV_{s}\) & 1–15 & 16 & 4 & 2 & 5 & 1 & 5 & 12 \\ \hline Interleaver size & \(720\times 8\) & \(24\times 8\) & \begin{tabular}{c} two of \\ (\(1040\times 4\)) \\ \end{tabular} & \begin{tabular}{c} two of \\ (\(1040\times 4\)) \\ \end{tabular} & \begin{tabular}{c} two of \\ (\(1040\times 4\)) \\ \end{tabular} & \begin{tabular}{c} two of \\ (\(272\times 4\)) \\ \end{tabular} & \(N_{BPS}\times 16\) & - & - \\ \hline FEC & \begin{tabular}{c} rate 1/2 \\ CTC \\ \end{tabular} & \begin{tabular}{c} rate 1/2 \\ CTC \\ \end{tabular} & \begin{tabular}{c} rate 1/2 \\ CTC \\ \end{tabular} & \begin{tabular}{c} rate 1/2 \\ CTC \\ \end{tabular} & \begin{tabular}{c} rate 1/2 \\ CTC \\ \end{tabular} & \begin{tabular}{c} (255,239) RS \\ + rate 1/2 CC \\ \end{tabular} & \
\begin{tabular}{c} (56,40) RS \\ \end{tabular} &
\begin{tabular}{c} (20,12) RS \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Operation modes and data protection schemes. CP and CS increase the symbol period, and decrease the symbol rate. However, CP and CS serve to reduce the influence of the ISI caused by the channel. IoT PLC has the largest CP and CS value among the three PLC technologies. HS PLC has the smallest CP values. IoT PLC and HS PLC have the same CP and CS values regardless of the operation modes, whereas HPGP has different CP values depending on the operation modes. The MINI mode of HPGP has a larger CP value than the STD and HS modes.