System and method for self-calibrating, self-organizing and localizing sensors in wireless sensor networks

A method of localizing mobile sensor nodes in a wireless sensor network (WSN), the WSN comprising a plurality of mobile sensor nodes and fixed sensor nodes, wherein the plurality of mobile sensor nodes and fixed sensor nodes are connected to a master node, the method comprising:

• transmitting a first identification message of a series of identification messages from a mobile sensor node at a lowest transmit power level from a predefined set of transmit power levels;
• detecting receipt of the first identification message at each of the fixed sensor nodes and sending a response message to the mobile sensor node if the first identification message is received by each of the fixed sensor nodes, wherein said response message identifies each fixed sensor node receiving the first identification message without identification of a measured received signal strength of the first identification message;
• estimating, based on a reception range of the first transmitted message, the location of the mobile sensor node relative to the responding fixed sensor node(s) if the first identification message is received, else transmitting a second identification message from the mobile sensor node at a plurality of increasing second predefined transmit power levels, the second predefined transmit power levels being incrementally higher than the lowest transmit power level;
• detecting receipt of the second identification message at each of the fixed sensor nodes and sending a response message to the mobile sensor node as to the identity of each fixed sensor node receiving the second identification message and the second transmit power level of the second identification message which was received;
• and
• determining the location of the mobile sensor node relative to the fixed sensor nodes based on the lowest transmit power levels at which the first and second identification messages are received by the fixed sensor nodes.

A method of self-calibrating a wireless sensor network (WSN), the WSN comprising a plurality of sensor nodes connected to a master node, the method comprising:

• transmitting wireless signals at a plurality of pre-defined incrementally increasing transmitted power levels between each pair of neighboring sensor nodes among the plurality of sensor nodes;
• measuring received signal strength at each of the neighboring sensor nodes for each of the pre-defined incrementally increasing transmitted power levels at which the signal was transmitted;
• determining a transmission coefficient based on the received signal strength for messages transmitted at multiple pre-defined incrementally increasing transmitted power levels for each pair of neighboring sensor nodes;
• and
• determining a translation vector for each position between pairs of neighboring sensor nodes based on the corresponding transmission coefficients for the neighboring sensor nodes, wherein each said translation vector is operable to calibrate a localized position for a mobile node located at a position between a pair of sensor nodes.