## 6 Comparison of LW-CCA with ContikiMAC
### Network Power Consumption  
The total power consumption of each node comprises the power consumption of the node in different states such as CPU, LPM, Rx, and Tx. In this section, the average power consumption on indicated states in LW-CCA nodes is compared with the ContikiMAC nodes in both low and high rate scenarios and evaluates the effect of the proposed method on the total power consumption and finally the packet delivery rate (PDR). The power and time parameters in the power consumption calculation are obtained from Tables 2 and 8. The average of power consumption in CPU, LPM, Rx, and Tx states in network is calculated by Equations (6)-(9) respectively. The average of total power consumption (P) is calculated according to Equation (1). For example, average of listen power for LW-CCA nodes in high rate is calculated in Equation (10).  
\[\text{P\_CPU(mW)} = \frac{\text{CPU\_time}\times\text{VCC}\times\text{PC\_CPU}}{ \text{CPU\_time}+\text{LPM\_time}} \tag{6}\] \[\text{P\_LPM(mW)} = \frac{\text{LPM\_time}\times\text{VCC}\times\text{PC\_LPM}}{\text{ CPU\_time}+\text{LPM\_time}}\] (7) \[\text{P\_Rx(mW)} = \frac{\text{Rx\_time}\times\text{VCC}\times\text{PC\_Rx}}{\text{ CPU\_time}+\text{LPM\_time}}\] (8) \[\text{P\_Tx(mW)} = \frac{\text{Tx\_time}\times\text{VCC}\times\text{PC\_Tx}}{\text{ CPU\_time}+\text{LPM\_time}}\] (9) \[\text{P\_Rx(LW-CCA,High\_Rate)} = \frac{\text{Rx\_time}\times\text{VCC}\times\text{PC\_Rx}}{\text{ CPU\_time}+\text{LPM\_time}}=\frac{601.5\times 3\times 20}{5066.35+48036.60}\] (10) \[= 0.679(\text{mW})\]  
Table 10 compares the network states in terms of average power consumption for LW-CCA and ContikiMAC in CPU, LPM, Rx, Tx states, and finally considers the average total power consumption and packet delivery rates. The outputs show that the average power consumption in the LPM mode for both methods is relatively similar. The average power consumption in the high-rate scenario in the LW-CCA represents a relatively higher value in CPU state, which may be due to the processing overhead imposed on the CPU in the LW-CCA. However, the reduction in average power consumption in the listening state and finally, the overall average energy consumption in LW-CCA nodes justify this overhead. The LW-CCA is able to reduce average listening power by 0.113 and 0.144 mW in low and high rates, respectively. The average power consumed in the transmit state in both methods shows a relatively similar value. Finally, the overall average power consumption in LW-CCA nodes has decreased by 0.121 and 0.124 mW in low and high rates, respectively compared to ContikiMAC. Table 10 shows that LW-CCA is able to retain a 99% packet delivery rate similar to ContikiMAC by decreasing overall power consumption by 7.1% and 8.7% for high and low rate scenarios, respectively.  
As the outputs of the simulator show, the proposed method has acceptable performance at both the 60 s and 30-s transmission rates. On the other hand, the results show that the performance of the proposed method in saving power in high-throughput applications is reduced. Figure 9 compares average power consumption improvement in the LW-CCA method compared to the basic ContikiMAC method at 60, 50, 40, 30, 20, and 10-s transmission rates. As shown in Figure 9, as the sequence of data transmission in the nodes is shorter, the average energy consumption improvement is also lower. It is due to the higher rate of interaction between the nodes for data transfer. Because network interference is higher and the CPU overhead of nodes is increased to compare the signal intensity. Therefore, the proposed method is suitable for applications where the data transmission times of the nodes are not short.