Research Article

Energy Efficient Downlink Transmission in Wireless LANs by Using Low-Power Wake-Up Radio

Figure 2

Wake-up control for the downlink transmission scheduling in a WLAN with an AP and 3 nodes. The AP broadcasts a WuM, which carries a TIM. The WuR of each node, on receiving a TIM and detecting its normalized SNR above the threshold, performs carrier sense, contending to activate its WLAN module. An activated WLAN module initiates the receiving from the AP. Packets to the same nodes are spaced by SIFS, and packets to different nodes are spaced by DIFS and random backoff ( slots).