CSI-RS Tracking Reference Signal

Hi Experts,
anybody has deep info related CSI-RS tracking reference signal in 5G? Here is the explanation : Tracking reference signals (TRS) are sparse set of reference signals, which are intended to assist the device in time and frequency tracking. The TRS does not exist independently, and a specific CSI-RS configuration is used as TRS. In addition to time and frequency tracking, the TRS is used for estimation of delay spread and Doppler spread at the UE side. It is transmitted with a limited bandwidth for a configurable period of time, controlled by the upper layer parameters. Green box called as TRS in the picture. How TRS helps UE to estimate doppler and delay spread plus to assist the device in tracking time & frequency. ??
It s periodicity generally equals to 80 ms in FR1 TDD.