Uplink timing and frequency synchronization
Methods and apparatuses for uplink timing and frequency synchronization in a wireless communication system. A method for operating a user equipment (UE) includes receiving, from a base station (BS), information indicating satellite ephemeris information of a communication satellite associated with the BS, a common timing advance (TA), and a compensated frequency offset (FO). The method further includes transmitting a physical random access channel (PRACH) based on the common TA and the compensated FO and receiving a random access response (RAR) indicating a UE-specific TA and FO. The method further includes, for transmission of an uplink (UL) channel, adjusting a TA and pre-compensating a FO based on the UE-specific TA and FO, respectively.
1. A user equipment (UE), comprising:
a transceiver configured to:
receive, from a base station (BS), information indicating satellite ephemeris information of a satellite associated with the BS and a common timing advance (TA), wherein the satellite ephemeris information includes (i) a first set of parameters coordX, coordY, coordZ and a predefined step size Δ c , related to position information of the satellite, and (ii) a second set of parameters velocityX, velocity Y, velocityZ and a predefined step size Δ v , related to velocity information of the satellite; and
a processor operably coupled to the transceiver, the processor configured to:
determine, based on the first set of parameters, a position of the satellite,
determine, based on the second set of parameters, a velocity of the satellite,
determine a TA based on: a global navigation satellite system (GNSS) position of the UE, the position of the satellite, the velocity of the satellite, and the common TA,
determine a frequency shift based on: the GNSS position, the position of the satellite, and the velocity of the satellite,
pre-compensate the TA, and
pre-compensate the frequency shift,
wherein the transceiver is further configured to transmit an uplink (UL) channel based on the pre-compensated TA and the pre-compensated frequency shift.
2. The UE of claim 1 , wherein:
the satellite ephemeris information is associated with a reference time, and
the reference time is indicated by at least a system frame number (SFN).
3. The UE of claim 1 , wherein the common TA includes a TA variation rate corresponding to variations of the common TA over time.
4. The UE of claim 1 , wherein the transceiver is further configured to transmit information indicating whether GNSS is supported.
5. A base station (BS), comprising:
a processor configured to identify satellite ephemeris information of a satellite associated with the BS and a common timing advance (TA), wherein the satellite ephemeris information includes (i) a first set of parameters coordX, coordY, coordZ and a predefined step size Δ c , related to position information of the satellite, and (ii) a second set of parameters velocityX, velocityY, velocityZ and a predefined step size Δ v , related to velocity information of the satellite; and
a transceiver operably coupled to the processor, the transceiver configured to transmit, to a user equipment (UE), information indicating the satellite ephemeris information and the common TA,
wherein the processor is further configured to:
determine, based on the first set of parameters, a position of the satellite,
determine, based on the second set of parameters, a velocity of the satellite,
determine a TA based on: a global navigation satellite system (GNSS) position of the UE, the position of the satellite, the velocity of the satellite, and the common TA,
determine a frequency shift based on: the GNSS position, the position of the satellite, and the velocity of the satellite,
pre-compensate the TA, and
pre-compensate the frequency shift, and
wherein the transceiver is further configured to receive an uplink (UL) channel based on the pre-compensated TA and the pre-compensated frequency shift.
6. The BS of claim 5 , wherein:
the satellite ephemeris information is associated with a reference time, and
the reference time is indicated by at least a system frame number (SFN).
7. The BS of claim 5 , wherein the common TA includes a TA variation rate corresponding to variations of the common TA over time.
8. The BS of claim 5 , wherein the transceiver is further configured to receive information indicating whether GNSS is supported.
9. A method for operating a user equipment (UE), the method comprising:
receiving, from a base station (BS), information indicating satellite ephemeris information of a satellite associated with the BS and a common timing advance (TA), wherein the satellite ephemeris information includes (i) a first set of parameters coordX, coordY, coordZ and a predefined step size Δ c , related to position information of the satellite, and (ii) a second set of parameters velocityX, velocity Y, velocityZ and a predefined step size Δ v , related to velocity information of the satellite;
determining, based on the first set of parameters, a position of the satellite;
determining, based on the second set of parameters, a velocity of the satellite;
determining a TA based on: a global navigation satellite system (GNSS) position of the UE, the position of the satellite, the velocity of the satellite, and the common TA;
determining a frequency shift based on: the GNSS position, the position of the satellite, and the velocity of the satellite;
pre-compensate the TA;
pre-compensating the frequency shift; and
transmitting an uplink (UL) channel based on the pre-compensated TA and the pre-compensated frequency shift.
10. The method of claim 9 , wherein:
the satellite ephemeris information is associated with a reference time, and
the reference time is indicated by at least a system frame number (SFN).
11. The method of claim 10 , wherein the common TA includes a TA variation rate corresponding to variations of the common TA over time.
12. The method of claim 10 , further comprising transmitting information indicating whether GNSS is supported.