Timing half-duplex transmissions
Systems, methods, and non-transitory media are provided for timing transmissions in a wireless communication system. An example method can include determining, at a satellite, a maximum round-trip propagation delay associated with one or more user terminals of a plurality of user terminals, determining, based on the maximum round-trip propagation delay, a respective downlink to uplink (DL/UL) offset for each user terminal, wherein the DL/UL offset comprises a time difference between a first downlink frame at the satellite and a first corresponding uplink frame at the satellite, transmitting a first downlink frame, receiving a first uplink frame from a first user terminal associated with the maximum round-trip propagation delay during the first corresponding uplink frame at the satellite, and receiving a second uplink frame from a second user terminal associated with a round-trip propagation delay less than the maximum round-trip propagation delay during the first corresponding uplink frame at the satellite.
1 . A method comprising:
determining, at a satellite in communication with a plurality of half-duplex user terminals, a maximum round-trip propagation delay associated with one or more half-duplex user terminals of the plurality of half-duplex user terminals, wherein each half-duplex user terminal of the plurality of half-duplex user terminals is associated with a propagation delay less than or equal to the maximum round-trip propagation delay;
determining, based on the maximum round-trip propagation delay and one or more additional delays, a respective downlink to uplink (DL/UL) offset for each half-duplex user terminal of the plurality of half-duplex user terminals, wherein the DL/UL offset comprises a time difference between a first downlink frame at the satellite and a first corresponding uplink frame at the satellite;
transmitting, from the satellite, a first downlink frame to the plurality of half-duplex user terminals, wherein the first downlink frame comprises the DL/UL offset;
receiving, at the satellite, a first uplink frame from a first half-duplex user terminal of the plurality of half-duplex user terminals during the first corresponding uplink frame at the satellite, wherein a first propagation delay associated with the first half-duplex user terminal comprises the maximum round-trip propagation delay; and
receiving, at the satellite, a second uplink frame from a second half-duplex user terminal of the plurality of half-duplex user terminals during the first corresponding uplink frame at the satellite, wherein a second propagation delay associated with the second half-duplex user terminal is shorter than the maximum round-trip propagation delay.
2 . The method of claim 1 , wherein the plurality of half-duplex user terminals is grouped in a plurality of half-duplex user terminal groups.
3 . The method of claim 2 , wherein a duration of the DL/UL offset is greater than a duration of N number of downlink frames at the satellite, where Nis an integer, and wherein a number of groups included in the plurality of half-duplex user terminal groups is less than N.
4 . The method of claim 2 , wherein the first half-duplex user terminal of the plurality of half-duplex user terminals associated with the maximum round-trip propagation delay is included in a first group of the plurality of half-duplex user terminal groups associated with the first downlink frame and the second half-duplex user terminal is included in a second group of the plurality of half-duplex user terminal groups associated with the first downlink frame.
5 . The method of claim 1 , further comprising:
determining, at a different location of the satellite, a second DL/UL offset for a first group of the plurality of half-duplex user terminals, wherein the first group of the plurality of half-duplex user terminals comprises the first half-duplex user terminal of the plurality of half-duplex user terminals associated with the maximum round-trip propagation delay, and wherein the second DL/UL offset is less than the DL/UL offset; and
determining a transmit offset delay for transmitting a third downlink frame to the first group of the plurality of half-duplex user terminals, wherein the transmit offset delay comprises a difference between the second DL/UL offset and the DL/UL offset.
6 . The method of claim 1 , wherein the one or more additional delays comprises at least one or more of a user terminal processing delay, a user terminal transmit (Tx) mode to receive (Rx) mode transition delay, or a user terminal Rx mode to Tx mode transition delay.
7 . The method of claim 1 , wherein the second half-duplex user terminal begins transmission of the second uplink frame after the first half-duplex user terminal begins transmission of the first uplink frame.
8 . The method of claim 1 , wherein a beginning time of the first uplink frame is misaligned in time with a beginning time of a concurrent downlink frame at the satellite.
9 . At least one non-transitory computer-readable storage medium comprising instructions stored thereon which, when executed by one or more processors, cause the one or more processors to:
determine, at a satellite in communication with a plurality of half-duplex user terminals, a maximum round-trip propagation delay associated with one or more half-duplex user terminals of the plurality of half-duplex user terminals, wherein each half-duplex user terminal of the plurality of half-duplex user terminals is associated with a propagation delay less than or equal to the maximum round-trip propagation delay;
determine, based on the maximum round-trip propagation delay and one or more additional delays, a respective DL/UL offset for each half-duplex user terminal of the plurality of half-duplex user terminals, wherein the DL/UL offset comprises a time difference between a first downlink frame at the satellite and a first corresponding uplink frame at the satellite;
transmit, from the satellite, a first downlink frame to the plurality of half-duplex user terminals, wherein the first downlink frame comprises the DL/UL offset;
receive, at the satellite, a first uplink frame from a first half-duplex user terminal of the plurality of half-duplex user terminals during the first corresponding uplink frame at the satellite, wherein a first propagation delay associated with the first half-duplex user terminal comprises the maximum round-trip propagation delay; and
receive, at the satellite, a second uplink frame from a second half-duplex user terminal of the plurality of half-duplex user terminals during the first corresponding uplink frame at the satellite, wherein a second propagation delay associated with the second half-duplex user terminal is shorter than the maximum round-trip propagation delay.
10 . The at least one non-transitory computer-readable storage medium of claim 9 , wherein the plurality of half-duplex user terminals is grouped in a plurality of half-duplex user terminal groups.
11 . The at least one non-transitory computer-readable storage medium of claim 10 , wherein the first half-duplex user terminal of the plurality of half-duplex user terminals associated with the maximum round-trip propagation delay is included in a first group of the plurality of half-duplex user terminal groups associated with the first downlink frame and the second half-duplex user terminal is included in a second group of the plurality of half-duplex user terminal groups associated with the first downlink frame.
12 . The at least one non-transitory computer-readable storage medium of claim 9 , further comprising instructions stored thereon which, when executed by one or more processors, cause the one or more processors to:
determine, at a different location of the satellite, a second DL/UL offset for a first group of the plurality of half-duplex user terminals, wherein the first group of the plurality of half-duplex user terminals comprises the first half-duplex user terminal of the plurality of half-duplex user terminals associated with the maximum round-trip propagation delay, and wherein the second DL/UL offset is less than the DL/UL offset; and
determine a transmit offset delay for transmitting a third downlink frame to the first group of the plurality of half-duplex user terminals, wherein the transmit offset delay comprises a difference between the second DL/UL offset and the DL/UL offset.
13 . The at least one non-transitory computer-readable storage medium of claim 9 , wherein the one or more additional delays comprises at least one or more of a user terminal processing delay, a user terminal Tx mode to Rx mode transition delay, or a user terminal Rx mode to Tx mode transition delay.
14 . The at least one non-transitory computer-readable storage medium of claim 9 , wherein a beginning time of the first uplink frame is misaligned in time with a beginning time of a concurrent downlink frame at the satellite.
15 . A system comprising:
at least one memory; and
at least one processor coupled to the at least one memory and configured to:
determine, at a satellite in communication with a plurality of half-duplex user terminals, a maximum round-trip propagation delay associated with one or more half-duplex user terminals of the plurality of half-duplex user terminals, wherein each half-duplex user terminal of the plurality of half-duplex user terminals is associated with a propagation delay less than or equal to the maximum round-trip propagation delay;
determine, based on the maximum round-trip propagation delay and one or more additional delays, a respective DL/UL offset for each half-duplex user terminal of the plurality of half-duplex user terminals, wherein the DL/UL offset comprises a time difference between a first downlink frame at the satellite and a first corresponding uplink frame at the satellite;
transmit, from the satellite, a first downlink frame to the plurality of half-duplex user terminals, wherein the first downlink frame comprises the DL/UL offset;
receive, at the satellite, a first uplink frame from a first half-duplex user terminal of the plurality of half-duplex user terminals during the first corresponding uplink frame at the satellite, wherein a first propagation delay associated with the first half-duplex user terminal comprises the maximum round-trip propagation delay; and
receive, at the satellite, a second uplink frame from a second half-duplex user terminal of the plurality of half-duplex user terminals during the first corresponding uplink frame at the satellite, wherein a second propagation delay associated with the second half-duplex user terminal is shorter than the maximum round-trip propagation delay.
16 . The system of claim 15 , wherein the plurality of half-duplex user terminals is grouped in a plurality of half-duplex user terminal groups.
17 . The system of claim 16 , wherein the first half-duplex user terminal of the plurality of half-duplex user terminals associated with the maximum round-trip propagation delay is included in a first group of the plurality of half-duplex user terminal groups associated with the first downlink frame and the second half-duplex user terminal is included in a second group of the plurality of half-duplex user terminal groups associated with the first downlink frame.
18 . The system of claim 15 , wherein the at least one processor is configured to:
determine, at a different location of the satellite, a second DL/UL offset for a first group of the plurality of half-duplex user terminals, wherein the first group of the plurality of half-duplex user terminals comprises the first half-duplex user terminal of the plurality of half-duplex user terminals associated with the maximum round-trip propagation delay, and wherein the second DL/UL offset is less than the DL/UL offset; and
determine a transmit offset delay for transmitting a third downlink frame to the first group of the plurality of half-duplex user terminals, wherein the transmit offset delay comprises a difference between the second DL/UL offset and the DL/UL offset.
19 . The system of claim 15 , wherein the one or more additional delays comprises at least one or more of a user terminal processing delay, a user terminal Tx mode to Rx mode transition delay, or a user terminal Rx mode to Tx mode transition delay.
20 . The system of claim 15 , wherein a beginning time of the first uplink frame is misaligned in time with a beginning time of a concurrent downlink frame at the satellite.