Unbiased DOA estimation for CDMA based on self-interference cancellation

A new approach for unbiased direction-of-arrival (DOA) estimation suitable for dealing with CDMA multipath signals is presented. Normal DOA estimation methods such as MUSIC and ESPRIT produce biased results owing to the existence of coherent terms. However, it is shown that if data is first projected onto the orthogonal complement of the space spanned by the known steering vectors, then the coherent terms can be removed, thus allowing MUSIC/ESPRIT to be applied to obtain an unbiased result. It is shown that only two iterations of this process are needed to produce good results.