Sensor node localization via spatial domain quasi-maximum likelihood estimation

A Sensor node localization algorithm for indoor quasi-static sensor environments using spatial domain quasi-maximum likelihood (QML) estimation is presented. A time of arrival (TOA) based algorithm is used to arrive at the “pseudo” range estimates from the base stations to the sensor nodes. The localization algorithm uses spatial domain quasi-maximum likelihood estimation to determine the actual sensor location. The algorithm is preceded by a calibration phase during which statistical characterization of the line-of-sight (LOS) and non-line-of-sight (NLOS) returns are derived. Using a synthesized bandwidth of 2GHz, a 4-bit analog-to-digital converter (ADC) and 5-10dB signal-to-noise ratio (SNR), localization with high accuracy is achieved.