Interference-Free OFDM Embedding of Wake-Up Signals for Low-Power Wake-Up Receivers

The use of ultra-low power wake-up receivers (WuRx) can significantly reduce idle listening energy cost. To tailor a WuRx scheme to orthogonal frequency division multiplexing (OFDM) based systems, such as LTE-MTC or IEEE 802.11, the wake-up signal (WUS) also needs to follow OFDM principles to avoid interfering with other transmissions in the same shared bandwidth. Here, we address this particular issue and propose an approach where the OFDM transmitter is modified to also transmit WUSs designed for non-coherent low-power WuRxs, on a subset of the carriers, thus embedding the WUS correctly and ensuring orthogonality. The approach is evaluated for different system parameters and channel conditions. Its applicability across a wide range of OFDM-based systems is examined.