Doppler shift reporting in a single frequency network

An apparatus comprising:

• at least one processor;
• and
• at least one memory including computer program code,
• the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to:
• transmit, by a first transceiver of the apparatus, a first tracking reference signal to a user device in a wireless communication system;
• transmit, by a second transceiver of the apparatus, a second tracking reference signal to the user device;
• receive a channel state information (CSI) reporting signal via an uplink channel, the CSI reporting signal including power estimation information, the power estimation information having been estimated by the user device using the first and second tracking reference signals;
• determine whether to pre-compensate a frequency of a downlink signal with frequency offset information based on the power estimation information;
• and
• transmit, by at least one of the first transceiver or the second transceiver, the downlink signal with the pre-compensated frequency in response to the determination to pre-compensate the frequency of the downlink signal,
• wherein the power estimation information includes a first power estimation value associated with the first tracking reference signal, and a second power estimation value associated with the second tracking reference signal, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to:
• compute a difference between the first power estimation value and the second power estimation value;
• compare the difference to a power estimation threshold;
• determine to pre-compensate the frequency of the downlink signal with the frequency offset information in response to the difference being less than the power estimation threshold;
• transmit an activation signal to the user device, the activation signal indicating that frequency pre-compensation is activated;
• and
• transmit, by the first transceiver and the second transceiver, the downlink signal with the pre-compensated frequency.