RSTD (reference 3gpp 36.133 and 36.214) reference signal time difference measure the subframe timing difference of reference cell and neighbor cell. RSTD used for location based services and introduced in LTE release 9 . RSTD measurement done by UE and it uses the power received in positioning reference signal (PRS) transmitted by eNodeB. PRS is also introduced in LTE release 9.
