Direction-of-arrival methods (DOA) and time difference of arrival (TDOA) position location technique

This paper provides a detailed overview of the various methods for estimation of direction-of-arrival (also called angle-of-arrival) of a radio signal using an antenna array. The array-based directional-of-arrival (DOA) estimation techniques considered here are broadly divided into two different types: conventional techniques, and subspace based techniques. Conventional methods are based on classical beam forming techniques and require a large number of elements to achieve high resolution. Subspace based methods are high resolution sub-optimal techniques which exploit the eigen structure of the input data matrix. This paper also uses the time-difference-of-arrival (TDOA) technique for estimating the time difference between the received signals to base stations of a certain subscriber using the generalized cross correlation method. The Fang´s method and Chan´s method are used in solving the resulting hyperbolic equations for finding the position location (PL) of a certain subscriber. The Fang´s method and Chan´s method give accurate and same result. This means that, an accurate position location estimation of a certain subscriber requires an efficient hyperbolic position location estimation method. The paper also clarifies that a more data samples give a more accurate result