  Reconfigurable Intelligent Surface (RIS) plays a pivotal role in the sixth
generation networks to enhance communication rate and localization accuracy. In
this letter, we propose a positioning algorithm in a RIS-assisted environment,
where the Base Station (BS) is multi-antenna, and the Mobile Station (MS) is
single-antenna. We show that our method can achieve a high-precision
positioning if the line-of-sight (LOS) is obstructed and three RISs are
available. We send several known signals to the receiver in different time
slots and change the phase shifters of the RISs simultaneously in a proper way,
and we propose a technique to eliminate the destructive effect of the
angle-of-departure (AoD) in order to determine the distances between each RISs
and the MS. The accuracy of the proposed algorithm is better than the
algorithms which do not estimate the AoD, shown in the numerical result
section.
