Two-stage DOA estimation for CDMA multipath signals

This paper mainly estimates the direction-of-arrival (DOA) of the code-division multiple access (CDMA) signal in a multipath environment using a two-stage procedure. In general, in a multipath environment, signal DOA would nominally be a DOA phenomenon, causing the DOA estimation method to be biased. However, if the received signal is first projected onto an appropriate beamspace, then the multipath effect will decrease. Therefore, we have proposed a two-stage method to address this issue. The procedure that we used is as follows: first, we used the received signal and particle swarm optimization (PSO) to estimate the signal DOA. Second, the DOA estimated in stage I was used to set up the beamspace multiple signal classification (BMUSIC) method, after which Taylor expansions were used to expand the stage I DOA and to set up a first-order iteration BMUSIC (IBMUSIC) method, the purpose of which was to reduce the multipath effect and the search complexity. This method was a DOA estimation method that combined PSO/IBMUSIC and aimed to reduce the search complexity and estimation bias for multipath signals. Finally, several simulation examples were used to illustrate the designed procedure and confirm the performance of this method.