## 5 Performance Evaluation
### System Parameters  
The system parameters used to obtain the analytical and simulation results correspond to those defined by the 802.11 Extended Rate PHY (ERP) specification with the Orthogonal Frequency Division Multiplexing (OFDM) modulation. This PHY mode can be enabled in either an 802.11b/g interface or an 802.11n/ac interface enabling a single antenna for communications. Such PHY mode provides transmission rates and frame transmission times that allow us to clearly show the significant influence of the awake and sleep transitions on the feasibility of the microsleep operation of TXOP PSM. More specifically, the available transmission rates of this PHY mode are 6, 9, 12, 18, 24, 36, 48, and 54 Mbps, with their respective Number of Data Bits Per OFDM Symbol (\(N_{DBPS}\)) 24, 36, 48, 72, 96, 144, 192, and 216. While any of these transmission rates can be used to transmit RTS, PS-Poll (only in PSM), and data frames, only the basic rates 6, 12, and 24 Mbps are allowed for the transmission of CTS and ACK frames. The selection of 6, 12, or 24 Mbps for the CTS and ACK transmissions depends on whether the RTS, PS-Poll, and data frames are sent at 6 or 9, 12 or 18, or 24, 36, 48, or 54 Mbps, respectively. In addition, the beacon frames are broadcast at the lowest basic rate of 6 Mbps. The specification of these basic rate selection rules is provided by the 802.11 Standard [6]. The time to transmit each frame type \(x\) using the ERP-OFDM PHY mode is computed as  
\[T_{x}=T_{pre}+T_{sig}+T_{sym}\left[\frac{L_{serp}+8L_{x}+L_{tail}}{N_{DBPS}} \right]+T_{sigEx}, \tag{19}\]where all the variables and their values are included in Table 1. More specifically, \(L_{x}\) denotes the Medium Access Control (MAC) frame length. For a MAC data frame, this length comprises the frame body or MAC Service Data Unit (MSDU) along with a MAC header and a Frame Check Sequence (FCS). For example, using an MSDU of 1500 bytes and RTS/data and CTS/ACK transmission rates of 54 and 24 Mbps, respectively, the values of \(T_{RTS}\), \(T_{CTS}\), \(T_{DATA}\), and \(T_{ACK}\) are 30, 34, 254, and 34 us, respectively. It is worth noting that the propagation delay following a frame transmission (\(\delta\)) was neglected in the performance evaluation of the mechanisms. In addition, other variables presented in Table 1 are calculated as follows. The PIFS period is obtained by [6] as \(T_{PIFS}=T_{SIFS}+\sigma\) and the DIFS period as \(T_{DIFS}=T_{SIFS}+2\sigma\). The EIFS period is computed by [6] as \(T_{EIFS}=T_{DIFS}+T_{SIFS}+T_{ACK}\) (6 Mbps). The holding time was set to 100 ms to run simulations since this duration enables the highest performance for all the evaluated mechanisms with \(\alpha>1\). The values of power consumption in transmission, reception, idle, and sleep states were obtained from [15; 16; 17; 18; 19]. The time and power consumption of the awake and sleep transitions were considered according to the results presented in [15; 16; 17; 18; 19]: (i) \(T_{i\to sl}\) is similar to \(T_{sl\to i}\), (ii) \(\rho_{i\to sl}\) is significantly lower than \(\rho_{sl}\), and iii) \(\rho_{sl\to i}\) is significantly higher than \(\rho_{i}\). Consequently, as shown in Figure 1 for the energy consumption of other STAs, it is assumed that: (i) \(T_{i\to sl}\) is equal to \(T_{sl\to i}\) (the value was obtained from [15; 16; 17; 18; 19]), (ii) \(\rho_{i\to sl}\) is equal to \(\rho_{sl}\), and (iii) \(\rho_{sl\to i}\) is modeled as \(\gamma\rho_{i}\), where \(\gamma\) is defined as the coefficient of power consumption during the transition from sleep to idle and \(\gamma>1\) (\(\gamma=1.5\) was used according to [15; 16; 17; 18; 19]).