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 send and a receiver in the network infrastructure is configured to receive bursts containing pilot waveforms that include time spacing and/or phase changes between short sequences. The time spacing and/or phase changes can be selected to reduce out-of-phase autocorrelation and achieve robust performance.
1. A communication terminal suitable for sending burst messages to network infrastructure in a communication system, the network infrastructure having a receiver, the terminal comprising:
a transmitter configured to transmit the burst messages to the network infrastructure, the burst messages including a pilot waveform;
the pilot waveform comprising a series of repeated short sequences arranged such that an in-phase correlation peak has significantly higher magnitude than out-of-phase correlation peaks at the receiver of the network infrastructure.
2. The communication terminal of claim 1 , wherein the in-phase correlation peak is at least 8 dB higher than the out-of-phase correlation peaks.
3. The communication terminal of claim 2 , wherein the in-phase correlation peak is at least 12 dB higher than the out-of-phase correlation peaks.
4. The communication terminal of claim 1 , wherein the pilot waveform includes time spacing between the repeated short sequences.
5. The communication terminal of claim 4 , wherein a length of time of the time spacing between the repeated short sequences increases for each subsequent set of repeated short sequences.
6. The communication terminal of claim 4 , wherein the length of time of the time spacing between the repeated short sequences increases for each subsequent set of repeated short sequences for a first half of the pilot waveform and decreases for each subsequent set of repeated short sequences for a second half of the pilot waveform.
7. The communication terminal of claim 4 , wherein no energy is transmitted in the time spacing between the repeated short sequences.
8. The communication terminal of claim 4 , wherein non-integer offsets are transmitted in the time spacing between the repeated short sequences.
9. The communication terminal of claim 4 , wherein a length of the pilot waveform with time spacing is truncated to equal a length of the pilot waveform without time spacing and gaps between the repeated short sequences created by the time spacing are back-filled with short sequences which are truncated from the pilot waveform with time spacing.
10. The communication terminal of claim 1 , wherein the pilot waveform includes phase inversion of the repeated short sequences.
11. The communication terminal of claim 10 , wherein the phase inversion is set in 180 degree steps.
12. The communication terminal of claim 10 , wherein the phase inversion is set in 90 degree steps.
13. The communication terminal of claim 1 , wherein the pilot waveform includes time spacing between the repeated short sequences and phase inversion of the repeated short sequences.
14. A gateway in network infrastructure operating in a communication system, the gateway suitable for receiving burst messages from a communication terminal through the communication system, the gateway comprising:
a receiver configured to receive the burst messages from the communication terminal, the burst messages including a pilot waveform;
the pilot waveform comprising a series of repeated short sequences arranged in a manner such that an in-phase correlation peak has significantly higher magnitude than out-of-phase peaks at the receiver of the gateway.
15. The gateway of claim 14 , wherein the in-phase correlation peak is at least 8 dB higher than the out-of-phase correlation peaks.
16. The gateway of claim 15 , wherein the in-phase correlation peak is at least 12 dB higher than the out-of-phase correlation peaks.
17. The gateway of claim 14 , wherein the pilot waveform includes time spacing between the repeated short sequences.
18. The gateway of claim 17 , wherein a length of time of the time spacing between the repeated short sequences increases for each subsequent set of repeated short sequences.
19. The gateway of claim 17 , wherein the length of time of the time spacing between the repeated short sequences increases for each subsequent set of repeated short sequences for a first half of the pilot waveform and decreases for each subsequent set of repeated short sequences for a second half of the pilot waveform.
20. The gateway of claim 17 , wherein no energy is received in the time spacing between the repeated short sequences.
21. The gateway of claim 17 , wherein non-integer offsets are received in the time spacing between the repeated short sequences.
22. The gateway of claim 17 , wherein a length of the pilot waveform with time spacing is truncated to equal a length of the pilot waveform without time spacing and gaps between the repeated short sequences created by the time spacing are back-filled with short sequences which are truncated from the pilot waveform with time spacing.
23. The gateway of claim 14 , wherein the pilot waveform includes phase inversion of the repeated short sequences.
24. The gateway of claim 23 , wherein the phase inversion is set in 180 degree steps.
25. The gateway of claim 23 , wherein the phase inversion is set in 90 degree steps.
26. The gateway of claim 14 , wherein the pilot waveform includes time spacing between the repeated short sequences and phase inversion of the repeated short sequences.