# A Low-Power WLAN Communication Scheme for IoT WLAN Devices Using Wake-Up Receivers
## 7 Conclusions  
In this paper, the joint design of wake-up radio in IEEE 802.11 ba and the uplink MU OFDMA procedure in IEEE 802.11 ax has been proposed. The wake-up radio operation with a low-power  
Figure 13: The total transmission delay and average power consumption as the number of STA increased. (**a**) Total transmission delay; (**b**) average power consumption. EDCA = enhanced distributed channel access.  
operating wake-up receiver resolves the trade-off problem between power consumption and latency in duty-cycle operation of low-power communication method. In the case of a dense communication environment in massive uplink scenario, unicast transmission may not be able to meet the Quality of Service (QoS) requirements of the data, because transmission delay increases linearly as the number of STAs increases. The proposed approach of MU transmission in wake-up radio significantly reduces total transmission delay for large number of users. In addition, the scheduling method and modifying EDCA parameter for the TF reduces the total transmission delay further. However, because of the longer frame duration, the power consumption increases, as we assumed the same power consumption for different bandwidths. Moreover, waking up multiple STAs for uplink MU transmission results in increased collision probability, because the STAs may attempt to access the channel simultaneously. Although the consumed power is increased, the effect of power wastage owing to collisions is limited because of the modified EDCA operation. The simulation results verify these points.  
The proposed scheme provides delay-efficient communications in IoT applications that are based on the dense communication scenario, with low-power performance degradation. In particular, when the mobile device needs to acquire the sensed data from the massive number of sensors, the delay performance of the proposed scheme outperforms that of the conventional transmission procedure. With the proposed transmission scheme using wake-up radio operation in IEEE 802.11 ba, the AP may select the proper transmission procedure depending on the traffic and density of associated STAs, which enables the dynamic management of delay and power consumption of STAs. In the next generation IoT networks, where various types of IoT devices with various applications concurrently operate and massive uplink transmission is norm, it is anticipated that the proposed scheme will play an important role in power saving in battery powered IoT devices with reduced delay.  
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF), and funded by the Ministry of Science, ICT & Future Planning (NRF-2017R1A2B4003987).  
[PERSON], [PERSON], and [PERSON] conceived the study. [PERSON] and [PERSON] did the literature review. [PERSON] designed the model, collected the simulation results, and analyzed the performance. [PERSON], [PERSON], and [PERSON] wrote the paper. [PERSON] supervised the whole study. All authors reviewed and approved the manuscript.  
The authors declare no conflict of interest.