Embodiments described herein provide a method for detecting motion. At a first wireless communication device capable of wirelessly communicating with a second wireless communication device, channel state information (CSI) for the wireless channel between the first and second wireless communication devices is received. A nulling matrix is calculated based on the received CSI. The calculated nulling matrix is applied to a plurality of short packets scheduled to be periodically transmitted from the first wireless communication device to the second wireless communication device. The first wireless communication device receives, from the second wireless communication device, received signal strength information (RSSI) determined for each of the transmitted plurality of short packets. The method further includes detecting motion based on detecting a change in the RSSI received from the second wireless communication device.