Devices, methods, and systems for uplink synchronization in time division multiple access (TDMA) satellite network
Devices, methods, and systems for uplink synchronization in time division multiple access (TDMA) satellite network. In one embodiment, an earth-based satellite terminal is configured to communicate with a satellite hub through a satellite using the TDMA communication protocol. The earth-based satellite terminal is configured to determine its own location, a location of the satellite, estimate a distance between the location of the terminal and the location of the satellite, determine a Coarse Timing Advance based on the distance that is estimated, and transmit data to the satellite based on the Coarse Timing Advance and the TDMA communication protocol. The Coarse Timing Advance may allow uplink TDMA communication without a preamble transmission on a random access channel, the preamble transmission being required in many conventional systems.
1. An earth-based satellite terminal comprising:
a satellite transceiver configured to communicate with a satellite using a time division multiple access (TDMA) communication protocol,
a memory, and
an electronic processor communicatively connected to the memory and the satellite transceiver, the electronic processor configured to
determine a location of the earth-based satellite terminal,
determine a location of the satellite,
estimate a distance between the location of the earth-based satellite terminal and the location of the satellite,
determine a Coarse Timing Advance based on the distance that is estimated,
control the satellite transceiver to transmit data to the satellite based on the Coarse Timing Advance and the TDMA communication protocol,
receive a Fine Timing Advance from a satellite hub, wherein the Fine Timing Advance is determined by the satellite hub based on an error in an arrival time of a preamble burst sent by the earth-based satellite terminal, relative to an expected, true arrival time at the satellite, and
control the satellite transceiver to transmit second data to the satellite based on the Coarse Timing Advance, the Fine Timing Advance, and the TDMA communication protocol.
2. The earth-based satellite terminal of claim 1 , further comprising:
an input/output interface including a navigation transceiver,
wherein, to determine the location of the earth-based satellite terminal, the electronic processor is configured to
receive navigation information from the navigation transceiver, a terrestrial wireless navigation system, an inertial navigation system, or a combination thereof via the input/output interface, and
determine the location of the earth-based satellite terminal based on the navigation information.
3. The earth-based satellite terminal of claim 1 , wherein, to determine the location of the satellite, the electronic processor is configured to periodically receive an absolute location of the satellite from the satellite hub associated with the satellite, the absolute location specifying a latitude, a longitude, and a distance from the center of the Earth with respect to the satellite.
4. The earth-based satellite terminal of claim 3 , wherein the electronic processor is configured to periodically receive the absolute location of the satellite from the satellite hub via the satellite transceiver and the satellite.
5. The earth-based satellite terminal of claim 3 , further comprising:
an input/output interface including a wireless interface configured to communicate with a terrestrial communication network,
wherein the electronic processor is configured to periodically receive the absolute location of the satellite from the satellite hub via the wireless interface and the terrestrial communication network.
6. The earth-based satellite terminal of claim 1 , wherein, to determine the location of the satellite, the electronic processor is configured to
retrieve predefined information that is stored in the memory and represents a model of an approximate position of the satellite,
periodically receive a three dimensional error vector from the satellite hub, the three dimensional error vector representing an error between a present location of the satellite and a modeled position of the satellite, and
determine the location of the satellite based on the three dimensional error vector and the modeled position.
7. The earth-based satellite terminal of claim 6 , where the predefined information is indicative of a fixed point in space.
8. The earth-based satellite terminal of claim 6 , where the predefined information is indicative of a set of points in space that form a repetitive function of time.
9. The earth-based satellite terminal of claim 8 , where the repetitive function of time represents a figure of eight.
10. The earth-based satellite terminal of claim 1 , wherein, to determine the location of the satellite, the electronic processor is configured to
retrieve predefined information that is stored in the memory and represents a model of an approximate position of the satellite, and
set the location of the satellite based on the model of the approximate position of the satellite.
11. The earth-based satellite terminal of claim 1 , wherein the electronic processor is further configured to
receive a Delta Timing Advance from the satellite hub, wherein the Delta Timing Advance is determined by the satellite hub based on errors in actual arrival times of uplink traffic and control channel bursts at the satellite and sent by the earth-based satellite terminal according to the TDMA communication protocol, relative to their expected, true arrival times at the satellite, and
control the satellite transceiver to transmit third data to the satellite based on the Coarse Timing Advance, the Fine Timing Advance, the Delta Timing Advance, and the TDMA communication protocol.
12. A wireless communication method comprising:
determining, with an electronic processor of an earth-based satellite terminal, a location of the earth-based satellite terminal;
determining, with the electronic processor, a location of a satellite;
estimating, with the electronic processor, a distance between the location of the earth-based satellite terminal and the location of the satellite;
determining, with the electronic processor, a Coarse Timing Advance based on the distance that is estimated;
controlling, with the electronic processor, a satellite transceiver of the earth-based satellite terminal to transmit data to the satellite based on the Coarse Timing Advance and a time division multiple access (TDMA) communication protocol;
receiving, with the electronic processor, a Fine Timing Advance from a satellite hub, wherein the Fine Timing Advance is determined by the satellite hub based on an error in an arrival time of a preamble burst sent by the earth-based satellite terminal, relative to an expected, true arrival time at the satellite; and
controlling, with the electronic processor, the satellite transceiver of the earth-based satellite terminal to transmit second data to the satellite based on the Coarse Timing Advance, the Fine Timing Advance, and the TDMA communication protocol.
13. The wireless communication method of claim 12 , wherein determining the location of the earth-based satellite terminal further includes
receiving navigation information from a navigation transceiver, a terrestrial wireless navigation system, an inertial navigation system, or a combination thereof via an input/output interface of the earth-based satellite terminal; and
determining the location of the earth-based satellite terminal based on the navigation information.
14. The wireless communication method of claim 12 , wherein determining the location of the earth-based satellite terminal further includes setting a last known location of the earth-based satellite terminal as the location of the earth-based satellite terminal.
15. The wireless communication method of claim 12 , wherein determining the location of the satellite further includes periodically receiving an absolute location of the satellite from the satellite hub associated with the satellite, the absolute location specifying a latitude, a longitude, and a distance from the center of the Earth with respect to the satellite.
16. The wireless communication method of claim 15 , wherein periodically receiving the absolute location of the satellite from the satellite hub further includes periodically receiving the absolute location of the satellite from the satellite hub via the satellite transceiver and the satellite.
17. The wireless communication method of claim 15 , wherein periodically receiving the absolute location of the satellite from the satellite hub further includes periodically receiving the absolute location of the satellite from the satellite hub via a wireless interface of the earth-based satellite terminal and a terrestrial communication network.
18. The wireless communication method of claim 12 , wherein determining the location of the satellite further includes
retrieving predefined information that is stored in a memory and represents a model of an approximate position of the satellite;
periodically receiving a three dimensional error vector from the satellite hub, the three dimensional error vector representing an error between a present location of the satellite and a modeled position of the satellite; and
determining the location of the satellite based on the three dimensional error vector and the modeled position.
19. The wireless communication method of claim 12 , wherein determining the location of the satellite further includes
retrieving predefined information that is stored in a memory and represents a model of an approximate position of the satellite; and
setting the location of the satellite based on the model of the approximate position of the satellite.
20. A wireless communication method comprising:
determining, with an electronic processor of an earth-based satellite terminal, a location of the earth-based satellite terminal;
determining, with the electronic processor, a location of a satellite;
estimating, with the electronic processor, a distance between the location of the earth-based satellite terminal and the location of the satellite;
determining, with the electronic processor, a Coarse Timing Advance based on the distance that is estimated;
receiving, with the electronic processor, a Fine Timing Advance from a satellite hub, wherein the Fine Timing Advance is determined by the satellite hub based on an error in an arrival time of a preamble burst sent by the earth-based satellite terminal, relative to an expected, true arrival time at the satellite; and
controlling, with the electronic processor, a satellite transceiver of the earth-based satellite terminal to transmit data to the satellite based on the Coarse Timing Advance, the Fine Timing Advance, and a time division multiple access (TDMA) communication protocol.
21. The wireless communication method of claim 20 , further comprising:
receiving, with the electronic processor, a Delta Timing Advance from the satellite hub, wherein the Delta Timing Advance is determined by the satellite hub based on errors in actual arrival times of uplink traffic and control channel bursts at the satellite and sent by the earth-based satellite terminal according to the TDMA communication protocol, relative to their expected, true arrival times; and
controlling, with the electronic processor, the satellite transceiver of the earth-based satellite terminal to transmit third data to the satellite based on the Coarse Timing Advance, the Fine Timing Advance, the Delta Timing Advance, and the TDMA communication protocol.
22. A time division multiple access (TDMA) communication system comprising:
a satellite; and
an earth-based satellite terminal including
a satellite transceiver configured to communicate with the satellite using the TDMA communication protocol,
a memory, and
an electronic processor communicatively connected to the memory and the satellite transceiver, the electronic processor configured to
determine a location of the earth-based satellite terminal,
determine a location of the satellite,
estimate a distance between the location of the earth-based satellite terminal and the location of the satellite,
determine a Coarse Timing Advance based on the distance that is estimated, and
control the satellite transceiver to transmit data to the satellite based on the Coarse Timing Advance and a time division multiple access (TDMA) communication protocol; and
a satellite hub communicatively coupled to the satellite and configured to
determine a Fine Timing Advance based on an error in an arrival time of a preamble burst sent by the earth-based satellite terminal, relative to an expected, true arrival time at the satellite, and
transmit the Fine Timing Advance to the earth-based satellite terminal,
wherein the electronic processor is further configured to
receive the Fine Timing Advance from the satellite hub, and
control the satellite transceiver to transmit second data to the satellite based on the Coarse Timing Advance, the Fine Timing Advance, and the TDMA communication protocol.
23. The time division multiple access (TDMA) communication system of claim 22 , wherein the satellite hub is further configured to
determine a Delta Timing Advance based on errors in actual arrival times of uplink traffic and control channel bursts at the satellite and sent by the earth-based satellite terminal according to the TDMA communication protocol, relative to their expected, true arrival times at the satellite, and
transmit the Delta Timing Advance to the earth-based satellite terminal, and wherein the electronic processor is further configured to
receive the Delta Timing Advance from the satellite hub, and
control the satellite transceiver to transmit third data to the satellite based on the Coarse Timing Advance, the Fine Timing Advance, the Delta Timing Advance, and the TDMA communication protocol.