Tight Integration of Wake-up Radio in Wireless LANs and the Impact of Wake-up Latency

In wireless LANs (WLANs), a power-hungry transceiver is used for both the control (carrier sense) and data exchanges. As a result, when many nodes contend to access a same channel, the WLAN transceiver performs carrier sense during most time, which wastes much energy. To solve this problem, we study separating the control and data operations in WLANs, by tightly integrating a lower power wake-up radio (WuR) with the WLAN module. Specifically, the WuR is used to monitor the channel and conduct carrier sense. It activates the WLAN module for actual transmissions when the channel gets ready. This is a contention-based self wake-up, which is different from previous schemes where a specific receiver is remotely activated. Due to the hardware constraint, a WLAN module is susceptible to a non-negligible wake-up latency. Our analysis shows that this wake-up latency may break the carrier sense mechanism and lead to false wake-up events. Then, we propose to recover the carrier sense mechanism by resetting the backoff counter of a falsely activated node in a way as if it is frozen in the wake-up period. Simulation evaluations confirm that the proposed scheme effectively mitigates the impact of wake-up latency by reducing the duty time of WLAN modules.