A monitoring system for monitoring activity in a predefined area, comprising: a network of sensor units arranged on a floor of the predefined area, individual sensor units of the network of sensor units comprising: a vibration sensor; a computing device in data communication with the sensor; and at least one application executable in the computing device, wherein, when executed, the at least one application is configured to cause the computing device to at least: receive sensor data from the sensor, the sensor data comprising vibrations associated with one or more subjects moving on the floor; isolate footstep vibrations from background noise vibrations included in the sensor data by applying a wavelet denoising technique; the monitoring system being characterized in that the at least one application is further configured to: communicate with at least one other sensor unit in the network of sensor units to obtain neighbor sensor data; and determine at least one of a trajectory for at least one subject or a location of the at least one subject based at least in part on the usage of phase constrained angle of arrival techniques (PAoA) on the footstep vibrations and on the sensor data received from the other sensor units of the network. a network of sensor units arranged on a floor of the predefined area, individual sensor units of the network of sensor units comprising: a vibration sensor; a computing device in data communication with the sensor; and at least one application executable in the computing device, wherein, when executed, the at least one application is configured to cause the computing device to at least: receive sensor data from the sensor, the sensor data comprising vibrations associated with one or more subjects moving on the floor; isolate footstep vibrations from background noise a vibration sensor; a computing device in data communication with the sensor; and at least one application executable in the computing device, wherein, when executed, the at least one application is configured to cause the computing device to at least: receive sensor data from the sensor, the sensor data comprising vibrations associated with one or more subjects moving on the floor; isolate footstep vibrations from background noise receive sensor data from the sensor, the sensor data comprising vibrations associated with one or more subjects moving on the floor; isolate footstep vibrations from background noise vibrations included in the sensor data by applying a wavelet denoising technique; the monitoring system being characterized in that the at least one application is further configured to: communicate with at least one other sensor unit in the network of sensor units to obtain neighbor sensor data; and determine at least one of a trajectory for at least one subject or a location of the at least one subject based at least in part on the usage of phase constrained angle of arrival techniques (PAoA) on the footstep vibrations and on the sensor data received from the other sensor units of the network. communicate with at least one other sensor unit in the network of sensor units to obtain neighbor sensor data; and determine at least one of a trajectory for at least one subject or a location of the at least one subject based at least in part on the usage of phase constrained angle of arrival techniques (PAoA) on the footstep vibrations and on the sensor data received from the other sensor units of the network. <EOS>