Patent ID: 8433337

Claim:
A method for received signal strength (RSS)-based direction-of-arrival (DOA) location estimation for one or more wireless target in an indoor environment, comprising: providing and deploying a DOA sensor node, the DOA sensor node comprising three antennas, antennas A, B, and C, forming a triangular antenna array, configured substantially in a center of a predetermined confined indoor space; fixing one or more wireless target to one or more localizing object; sending out a plurality of packet signals by the DOA sensor node to the wireless target, each packet comprising of a fixed sensor node cover range, and a combined packet signals covering entire confined indoor space; obtaining RSSI values for the respective RSSI states received from the wireless target by a plurality of beams at a plurality of incident angles θ and φ using the triangular antenna array, a Single-Pole-Double-Throw (1P2T) switch, and a vector signal deconstructor (VSD); collecting and comparing eight packet signals by the DOA sensor node to obtain a strongest packet signal having a maximum RSSI value; and calculating a location (θ, φ) of the localized object using a RSS-based DOA algorithm on the data obtained from the strongest packet signal having the maximum RSSI value, the RSS-based DOA algorithm comprising of performing the following steps: a) calculating θ, φ using values for E Ant1 , E Ant2 , E Ant3 and three sets of equations as follow: E Ant 1 = A 1 ⁢ ⅇ jψ 1 = αⅇ j ⁡ ( 2 ⁢ π ⁢ ⁢ r λ ⁢ sin ⁢ ⁢ θsin ⁢ ⁢ ϕ ) E Ant 2 = A 2 ⁢ ⅇ jψ 2 = αⅇ j ⁡ ( 2 ⁢ π ⁢ ⁢ r λ ⁢ sin ⁢ ⁢ θcos ⁡ ( 30 ⁢ ° + ϕ ) ) E Ant 3 = A 3 ⁢ ⅇ jψ 3 = αⅇ j ⁡ ( - 2 ⁢ π ⁢ ⁢ r λ ⁢ sin ⁢ ⁢ θcos ⁡ ( 30 ⁢ ° - ϕ ) ) b) calculating a plurality of phase differences, ψ 21 and ψ 23 , using the following two sets of equations, wherein ψ 21 is obtained from RSSI Values |E 1 | 2 to |E 4 | 2 , and ψ 23 is obtained from RSSI Values |E 5 | 2 to |E 8 | 2 ψ 21 = Phase ⁡ ( E Ant 2 ) - Phase ⁡ ( E Ant 1 ) = - Tan - 1 ⁡ (  E 3  2 -  E 4  2  E 1  2 -  E 2  2 ) , and ψ 23 = Phase ⁡ ( E Ant 2 ) - Phase ⁡ ( E Ant 3 ) = - Tan - 1 ⁡ (  E 7  2 -  E 8  2  E 5  2 -  E 6  2 ) c) calculating the location (θ, φ) of the localized object using values for ψ 21 and ψ 23 and the following two sets of equations: θ = sin - 1 ⁢ ( ψ 23 - 2 ⁢ ψ 21 ) 2 + 3 ⁢ ψ 23 2 9 ⁢ ( 2 ⁢ π ⁢ ⁢ r λ ) 2 ϕ = tan - 1 ⁡ ( ψ 23 - 2 ⁢ ψ 21 3 ⁢ ψ 23 ) d) converting to (X, Y) of the localized object using the location (θ, φ) of the localized object and a plurality of location data from a location map of the predetermined confined indoor space.