# IEEE 802.11 ah: A Technology to Face the IoT Challenge
## 3 Comparative Analysis of IEEE 802.11 ah with Previous IEEE 802.11 Amendments
### Comparison of IEEE 802.11 Amendments Based on MAC Features
#### 3.2.Throughput and Range Characterization of IEEE 802.11 Amendments
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Specification** & **SIFS** & **DIFS** & **T\({}_{\text{Preamble attacker}}\)** & **MAC@LLC Header** & **Signal Extension** & **T\({}_{\text{Syn}}\)** & **T\({}_{\text{Silot}}\)** & **CW\({}_{\text{min}}\)** & **CW\({}_{\text{max}}\)** \\  & **(us)** & **(us)** & **(us)** & **Size (Bytes)** & **(us)** & **(us)** & **(us)** & **(us)** & **(us)** & **CW\({}_{\text{max}}\)** \\ \hline
802.11 ah CBW 1 MHz & 160 & 264 & 560 & 26 (Short) & n/a & 40 (long CI) & 52 & 15 & 1023 \\  & & & & 36 (Long) & & 36 (short CI) & & 36 (short CI) & \\ \hline
802.11 ah Short Preamble CW 2, 4, 8 and 16 MHz & 160 & 264 & 240 & 26 (Short) & n/a & 40 (long CI) & 52 & 15 & 1023 \\  & & & & 36 (Long) & & 36 (short CI) & & 36 (short CI) & 52 & 15 & 1023 \\ \hline
802.11 ah Long Preamble CW 2, 4, 8 and 16 MHz & 160 & 264 & 320 & 26 (Short) & n/a & 40 (long CI) & 52 & 15 & 1023 \\  & & & & 36 (Long) & & n/a & 36 (short CI) & 52 & 15 & 1023 \\ \hline
802.11 ac & 16 & 34 & 40 & 36 & n/a & 4 & 9 & 15 & 1023 \\
802.11n 2.4 GHz & 10 & 28 & 36 & 36 & 6 & 4 & 9 & 15 & 1023 \\
802.11n 5 GHz & 16 & 34 & 36 & 36 & 0 & 4 & 9 & 15 & 1023 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: MAC/PHY Parameters. \(T_{DATA}\) calculation for IEEE 802.11 ah includes three different cases:  
1. 1 MHz CBW case with short and long Guard Interval (GI) subcases, following Equations (5) and (6), respectively. Note that with 1 MHz CBW only one PHY preamble/header type applies (cf. Table 3). 2. Short preamble case for 2, 4, 8 and 16 MHz CBW with short and long GI subcases, which also follow Equations (5) and (6), respectively; in this case, a different value for the PHY preamble/header length should be used (cf. Table 3). 3. Long preamble case for 4, 8 and 16 MHz CBW with short and long GI subcases, following Equations (7) and (8), respectively: \[T_{shortGI}=T_{Preamble\&Header}+40\times(N_{LTF}-1)+T_{Symsl}+T_{Syms}\times \left(N_{sym}-1\right)\] (5) \[T_{longGI}=T_{Preamble\&Header}+40\times(N_{LTF}-1)+T_{Symsl} \times N_{sym}\] (6) \[T_{shortGI\ long_{\text{-}}preamble}=T_{Preamble\&Header}+40\times N_{LTF}+T_{ Symsl}+T_{Syms}\times\left(N_{sym}-1\right)\] (7) \[T_{longGI\ long_{\text{-}}preamble}=T_{Preamble\&Header}+40 \times N_{LTF}+T_{Symsl}\times N_{sym}\] (8)  
\(T_{\text{}Preamble\&Header}\) is given in Table 3 for the different configuration setups, \(T_{Syml}\) is the duration of a symbol with the long GI and \(T_{Syms}\) corresponds to the duration of a symbol with the short GI. \(N_{LTF}\) corresponds to the number of long training symbols, which depends on the number of SS. Without Space-Time Block Coding (STBC), \(N_{LTF}\) equals the number of spatial streams, except for three SS, in which case four training symbols are required. \(N_{sym}\) is the number of symbols and is given in Equation (9):  
\[N_{symAH}=\left\lceil\frac{8+6\times N_{ES}+8\times K\times(L_{Header}+L_{ data})+(K-1)\times L_{deli}\times 8}{NDBPS}\right\rceil \tag{9}\]  
\(L_{deli}\) is the size of the delimiter between aggregated frames (4 Bytes). \(T_{BA}\) calculation employs previously exposed \(T_{DATA}\) equations but a frame of 32 Bytes is considered instead of \(L_{Header}+L_{data}\). \(N_{ES}\) and \(N_{DBPS}\) depend on the MCS chosen and are fixed in the standard specification. We consider data frames with maximum payload size of 1500 Bytes to build the MPDU aggregation (A-MPDU). Up to 64 individual frames are allowed to assemble an A-MPDU. Note, however, that the standard imposes other restrictions that may reduce the number of aggregated frames carried by an A-MPDU. IEEE 802.11 ah presents a maximum length for an A-MPDU of 511 symbols and a maximum duration of 27.930 ms. On the other hand, IEEE 802.11n allows up to 65,535 Bytes, whereas IEEE 802.11 ac is able to deal with 1,048,575 Bytes of maximum length. In both amendments, the maximum frame duration is of 5.484 ms. Different from [PERSON] et al.