Hybrid TDOA/AOA mobile user location for wideband CDMA cellular systems

TLDR

Wide‑band CDMA’s high chip rates enable accurate TDOA, and smart antennas at base stations provide precise AOA in macrocell environments. The study proposes a mobile‑user location scheme for wideband CDMA wireless systems. The scheme fuses forward‑link TDOA with reverse‑link AOA and applies a two‑step least‑squares estimator based on a linear AOA model. Numerical simulations show the hybrid TDOA/AOA method yields substantially higher accuracy than TDOA alone, especially when few base stations are available or TDOA measurements are noisy.

Abstract

This paper proposes a mobile user location scheme for wideband code-division multiple-access (CDMA) wireless communication systems. To achieve high location accuracy and low cost of the mobile receiver, the location scheme combines the time difference of arrival (TDOA) measurements from the forward link pilot signals with the angle of arrival (AOA) measurement from the reverse link pilot signal. High chip rates in wideband CDMA systems facilitate accurate TDOA measurements, and a smart antenna used at the home base station (BS) can provide accurate AOA measurement in a macrocell environment. A two-step least square location estimator is developed based on a linear form of the AOA equation in the small error region. Numerical results demonstrate that the proposed hybrid TDOA/AOA location scheme gives a much higher location accuracy than TDOA only location, when the number of base stations is small and/or when the TDOA measurements have a relatively poor accuracy.