A method of detecting an intrusion in a site comprising: forming a wireless network among a plurality of door/window sensor nodes (N1-N10) and at least a base station ; continuously collecting and processing, by at least one sensor node of the plurality of sensor nodes (N1-N10), vibration or motion measurements, wherein the at least one of the plurality of sensor nodes (N1-N10) operates in a low power mode; transmitting, by the at least one sensor node, the processed vibration or motion measurements to the base station at a very low heartbeat rate; transmitting, by the at least one sensor node, an event notification to the base station , if the at least one of the plurality of sensor nodes (N1-N10) detects an event such as an intruder or burglar entering into the site; in response to receiving the event notification from the at least one sensor node, placing, by the base station , all the sensor nodes (N1-N10) into a continuous transmitting mode, if a size of the room is below a predetermined threshold, or placing the sensor node detecting the event and at least one of the other sensor nodes located proximal to the base station or the sensor node that detects the event into the continuous transmitting mode; monitoring, by the base station , a variation in received signal strength of at least one link between the at least one sensor node of the plurality of sensor nodes (N1-N10) operating in the continuous transmitting mode and the base station to confirm the event; triggering, by the base station , an alarm event to a stakeholder, if the event is confirmed, including time and date when an intrusion occurred, identity of the sensor node, identity of a window or door, location or address of an area of interest when the intrusion occurred; and otherwise transmitting, by the base station , a message to the at least one sensor node operating in the continuous transmitting mode to return the at least one sensor node to the low power mode, if the event is not confirmed. forming a wireless network among a plurality of door/window sensor nodes (N1-N10) and at least a base station ; continuously collecting and processing, by at least one sensor node of the plurality of sensor nodes (N1-N10), vibration or motion measurements, wherein the at least one of the plurality of sensor nodes (N1-N10) operates in a low power mode; transmitting, by the at least one sensor node, the processed vibration or motion measurements to the base station at a very low heartbeat rate; transmitting, by the at least one sensor node, an event notification to the base station , if the at least one of the plurality of sensor nodes (N1-N10) detects an event such as an intruder or burglar entering into the site; in response to receiving the event notification from the at least one sensor node, placing, by the base station , all the sensor nodes (N1-N10) into a continuous transmitting mode, if a size of the room is below a predetermined threshold, or placing the sensor node detecting the event and at least one of the other sensor nodes located proximal to the base station or the sensor node that detects the event into the continuous transmitting mode; monitoring, by the base station , a variation in received signal strength of at least one link between the at least one sensor node of the plurality of sensor nodes (N1-N10) operating in the continuous transmitting mode and the base station to confirm the event; triggering, by the base station , an alarm event to a stakeholder, if the event is confirmed, including time and date when an intrusion occurred, identity of the sensor node, identity of a window or door, location or address of an area of interest when the intrusion occurred; and otherwise transmitting, by the base station , a message to the at least one sensor node operating in the continuous transmitting mode to return the at least one sensor node to the low power mode, if the event is not confirmed. <EOS>