# WLAN Aware Cognitive Medium Access Control Protocol for IoT Applications
## 6 Simulation Results  
We consider a beacon-enabled star topology IoT network for performance evaluation. A WLAN access point covers an area where IoT nodes are deployed. Both WLAN and IoT nodes are static and operating at 2.4 GHz ISM band. In the proposed model, the considered wireless sensor network (WSN) load is very low; thus contention, congestion, and in-network interference have a minimal impact on WSN, which we aim to loosen in future work. A single interfering WLAN user with a payload size of 512 bytes that resides within transmission range of the Access Point is considered for simulation. Frequency of WLAN transmission is modeled using Poisson distribution. Five active IoT devices having different energy levels from one another are considered. Each IoT node sends uplink data to the network coordinator (sink node) having uplink data of 15 bytes in size. IoT nodes reside within the transmission range of WLAN users, having a radius of 50 m. The distance between the IoT sensor nodes and the coordinator is kept at 15 m. Simulations are performed using MATLAB and IEEE 802.15.4-compliant MicaZ IoT sensor nodes are considered [44]. Parameters for an energy and channel model for an IEEE 802.15.4-compliant IoT device are presented in Table 2. In the simulations, beacons are sent by the coordinator at regular intervals to the sensor nodes. Simulation parameters for WLAN and IoT sensors node are shown in Table 3.  
We compare the proposed WAC-MAC protocol with the protocol in the IEEE 802.15.4 standard. Metrics used for comparison include the number of packets received, end-to-end delay, network energy consumption, the energy consumption of individual nodes, and network lifetime.  
\begin{table}
\begin{tabular}{c c} \hline \hline \multicolumn{2}{c}{**Parameters Setup for Performance Evaluation**} \\ \hline
**Parameter** & **Value** \\ \hline Path Loss Exponent & 4.0 \\ Noise Power & \(-103\) dBm \\ Path Loss Attenuation & \(9.98\times 10^{-5}\) \\ Sensing Time & \(0.512\times 10^{-3}\) \\ Sampling Frequency & 5 MHz \\ Battery & 3 V \\ Sleeping Current & 0.001 mA \\ Idle Current & 0.02 mA \\ Receive Current & 19.7 mA \\ Transmit Current & 17.4 mA \\ Sensing Current & 15.3 mA \\ \hline \hline \end{tabular}
\end{table}
Table 2: Energy model and channel model for IoT nodes.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{2}{c}{**System Parameters Used for Simulation**} \\ \hline
**Parameter** & **IEEE 802.15.4** & **IEEE 802.11b/g** \\ \hline Bandwidth & \(5\) MHz & 22 MHz \\ Transmission Power & \(0\) dBm & \(12\) dBm \\ Receiver Sensitivity & \(-85\) dBm & \(-82\) dBm \\ Transmission Rate & \(260\) kbps & \(54\) Mbps \\ Backoff unit time & \(320\) μs & \(20\) μs \\ CCA & \(128\) μs & N/A \\ DIFS & N/A & \(50\) μs \\ CWmin & N/A & \(15\) \\ Payload Size & \(15\) byte & \(512\) bytes \\ BO = SO & \(0\) & N/A \\ macMinBE & \(3\) & N/A \\ macMaxBE & \(5\) & N/A \\ Max Retransmission & \(5\) & N/A \\ \hline \hline \end{tabular}
\end{table}
Table 3: Simulation parameters for WLAN and IoT nodes. CW = Contention Window; BO = Beacon Order; SO = Superframe Order.