Method and device for estimating time and frequency offsets in communication system

A method of a user equipment (UE) in a wireless communication system, the method comprising:

• transmitting, to a network entity via a satellite, a physical random access channel, (PRACH) preamble;
• and
• receiving, from the network entity via the satellite, a frequency offset, a unit of the frequency offset, and a change rate of the frequency offset,
• wherein the frequency offset is estimated based on a first peak value, a second peak, and a length of the PRACH preamble,
• wherein the first peak value comprises a largest value among correlation values obtained based on a correlation operation for the PRACH preamble, and a second peak value comprises a second largest value among the correlation values obtained based on the correlation operation for the PRACH preamble,
• wherein the unit of the frequency offset is determined based on a radius of a beam and a center frequency provided by the satellite, and
• wherein the change rate of the frequency offset is a variation in the frequency offset to be applied at a specific time.

A network entity in a wireless communication system, the network entity comprising:

• a transceiver;
• and
• a controller operably coupled with the transceiver, the controller configured to:
• receive, from a user equipment (UE) via a satellite, a physical random access channel (PRACH) preamble,
• obtain, based on a correlation operation, correlation values for the PRACH preamble and identify a first peak value that includes a largest value among the correlation values and a second peak value that includes a second largest value among the correlation values,
• estimate a frequency offset based the first peak value, the second peak value, and a length of the PRACH preamble, and
• transmit, to the UE via the satellite, the frequency offset, a unit of the frequency offset, and a change rate of the frequency offset,
• wherein the unit of the frequency offset is determined based on a radius of a beam and a center frequency provided by the satellite, and
• wherein the change rate of the frequency offset is a variation in the frequency offset to be applied at a specific time.

A user equipment (UE) in a wireless communication system, the UE comprising:

• a transceiver;
• and
• a controller operably coupled with the transceiver, the controller configured to:
• transmit, to a network entity via a satellite, a physical random access channel (PRACH) preamble, and
• receive, from the network entity via the satellite, a frequency offset, a unit of the frequency offset, and a change rate of the frequency offset,
• wherein the frequency offset is estimated based on a first peak value, a second peak value, and a length of the PRACH preamble,
• wherein the first peak value comprises a largest value among correlation values obtained based on a correlation operation for the PRACH preamble, and the second peak value comprises a second largest value among the correlation values obtained based on the correlation operation for the PRACH preamble,
• wherein the unit of the frequency offset is determined based on a radius of a beam and a center frequency provided by the satellite, and
• wherein the change rate of the frequency offset is a variation in the frequency offset to be applied at a specific time.