Low data volume satellite communication system
Systems are disclosed for a communication system optimized for low data volume communications. In embodiments of the invention, a terminal in the communication system is configured to receive beam shape information from a satellite and use the beam shape information for calculating the terminal's initial transmit power based on the beam shape information. The terminal can also determine the terminal's location and calculate an achievable information data rate of transmitted bursts based on the beam shape information. The terminal can also determine an estimated terminal position based on correlating signal-to-noise ratio measurements on the camped beam and at least one neighbor beam neighboring the camped beam.
1. A communication system, comprising:
at least one terminal;
at least one satellite which creates a beam having a beam shape that enables communication with the at least one terminal when the at least one terminal is located inside the beam;
at least one network infrastructure in wireless communication with the at least one terminal, the at least one network infrastructure having an information element which includes beam shape information representing the beam shape;
wherein, the at least one terminal receives the information element from the at least one network infrastructure and calculates the at least one terminal's initial transmit power based on the beam shape information.
2. The communication system of claim 1 , wherein the information element also includes scheduled transmission information and wherein the at least one terminal is configured to communicate with the at least one network infrastructure by sending a burst comprising a message at a pre-scheduled time such that the at least one network infrastructure can derive a terminal identity for the at least one terminal by comparing the time of the burst with the scheduled transmission information in the information element without having to include terminal identity information in the message.
3. The communication system of claim 1 , wherein the beam shape information describes the beam shape in terms of gain as a function of spatial location formed by a transmitter of the at least one satellite.
4. The communication system of claim 1 , wherein the beam shape information describes the beam shape in terms of gain as a function of spatial location formed by a receiver of the at least one satellite.
5. The communication system of claim 1 , wherein the beam shape information describes the beam shape in terms of gain differences between a transmitter and receiver of the at least one satellite as a function of spatial location.
6. The communication system of claim 1 , wherein the beam shape has a cross section corresponding to a defined function.
7. The communication system of claim 6 , wherein the defined function is a sinc function.
8. The communication system of claim 1 , wherein the terminal determines an estimated terminal position based on the beam shape information.
9. The communication system of claim 1 , wherein the terminal determines an estimated terminal position based on correlating signal-to-noise ratio measurements on the beam and at least one neighbor beam neighboring the beam.
10. The communication system of claim 1 , wherein the terminal calculates an achievable information data rate of transmitted bursts based on the beam shape information.
11. A communication system, comprising:
a terminal;
a satellite which creates a beams having beam shapes, the beams including a camped beam and at least one neighboring beam which neighbors the camped beam, the camped beam enabling communication with the terminal when the terminal is located inside the camped beam such that the satellite communicates with the terminal using a forward link and the terminal communicates with the satellite using a reverse link;
network infrastructure in wireless communication with the satellite and the terminal, the network infrastructure having an information element which is sent to the satellite and which is broadcast by the satellite along with system information, the information element including scheduled transmission information and beam shape information representing the beam shapes;
wherein, the terminal is configured to:
wake up at a pre-scheduled time;
read system information broadcast by the satellite;
read the information element;
derive a location estimate of the terminal;
determine a reverse link transmit power for the terminal based on the beam shape information;
determine an information data rate for the terminal based on a threshold signal-to-noise ratio for the reverse link; and
communicate with the network infrastructure by sending a burst at the determined reverse link transmit power and information data rate, the communication comprising a message at a pre-scheduled time such that the network infrastructure can derive a terminal identity for the terminal by comparing the time of the burst with the scheduled transmission information in the information element without having to include terminal identity information in the message.
12. The communication system of claim 11 , wherein the beam comprises a camped beam and the satellite further creates at least two neighboring beams which neighbor the camped beam, the at least two neighboring beams having beam shapes, the information element further including beam shape information for the at least two neighboring beams; and
wherein, deriving a location estimate further comprises obtaining a signal-to-noise ratio for the camped beam and the at least two neighboring beams from correlations and matching the obtained signal-to-noise ratio for the camped beam and the at least two neighboring beams with the beam shape information to obtain the location estimate of the terminal.
13. The communication system of claim 11 , wherein the beam shape information describes the beam shape in terms of gain as a function of spatial location formed by a transmitter of the at least one satellite.
14. The communication system of claim 11 , wherein the beam shape information describes the beam shape in terms of gain as a function of spatial location formed by a receiver of the at least one satellite.
15. The communication system of claim 11 , wherein the beam shape information describes the beam shape in terms of gain differences between a transmitter and receiver of the at least one satellite as a function of spatial location.
16. The communication system of claim 11 , wherein the beam shape has a cross section corresponding to a defined function.
17. The communication system of claim 16 , wherein the defined function is a sinc function.
18. The communication system of claim 11 , wherein a perceived signal-to-noise ratio of a forward link pilot signal is used in determining the reverse link transmit power.
19. The communication system of claim 11 , wherein a parameterized power increment provided by the network infrastructure is used in determining the reverse link transmit power.
20. The communication system of claim 11 wherein a long-term estimate correcting for perceived differences in forward and return link gains is used in determining the reverse link transmit power.
21. The communication system of claim 11 wherein a parameterized value representing a gain difference between forward and return link gains at the satellite is used in determining the reverse link transmit power.
22. The communication system of claim 11 , wherein a parameterized constant providing an offset associated with a link budget is used in determining the reverse link transmit power.