Cost-Efficient DOA Estimation Method in Multipath Environment

Abstract

본 석사논문에서는 고정된 한 개의 안테나와 직선을 따라 움직이는 다른 한 개의 안테나를 이용한 비용-효율적인 도래각 추정 알고리즘을 제안한다. 각 안테나 분리에서 두 안테나 출력을 나누어 새로운 관찰 값으로 봄으로써 기존의 서로 상관된 신호원이 있는 MUSIC 알고리즘에서의 관찰 모델과 유사한 관찰 모델을 얻을 수 있음을 보였다. 스무딩 방법을 이용한 고-해상도 MUSIC 알고리즘을 통해 서로 상관된 신호들의 도래각을 정확하게 추정할 수 있다. 시뮬레이션을 통해 제안한 방법이 적당한 SNR 환경에서 기존의 MUSIC 알고리즘과 비교하여 비슷한 도래각 해상도와 평균제곱오차를 얻을 수 있음을 확인하였다.

Array signal processing has played an important role in many applications in signal processing. The ultimate goal of sensor array signal processing is to estimate the values of parameters by using available temporal and spatial information, collected through sampling a wave-field with a set of antennas that have a precise geometry description. These parameters include multipath coefficients, Doppler shifts, delays and direction of departure and arrival. The ability to estimate the direction of impinging signals at receiver has attracted a great deal of attention, which had a separate topic known as direction-of-arrival (DOA) estimation.

The DOA estimation is considered one of the most important parameters to be estimated in array signal processing. However, low-cost practical implementation of DOA estimation methods requires more array elements and high-cost receiver parts for each array element in most of the current methods. Moreover, this increase in array elements becomes larger in an environment in which signals are highly correlated or coherent as in a multipath environment, where preprocessing coherence elimination techniques are required. These preprocessing steps reduce the aperture size and require more antenna elements to compensate for this reduction; this necessity increases the implementation cost.

We propose a method to reduce the implementation cost in a multipath environment by using only two antenna elements, where one antenna element is fixed and the other moves to different positions with multiples of λ/2 spacing to construct a synthetic N-element ULA. The method is based on extracting the phase difference between the two elements at each round, then MUSIC or other high-resolution DOA estimation methods can be applied to the constructed N-element ULA.