Repetition coding in a satellite-based communications system
View Patent ↗A satellite communications system comprises a transmitter, a satellite transponder and a receiver. The transmitter transmits an uplink multi-level modulated signal (hierarchical modulation or layered modulation) to the satellite transponder, which broadcasts the multi-level modulated signal downlink to one, or more, receivers. The transmitter includes a repetition coder for repetition coding at least one level, e.g., a lower level, of the multi-level modulated signal. In complementary fashion, the receiver includes a repetition decoder for use in decoding the at least one repetition coded level of the received multi-level modulated signal.
1. A receiver comprising:
a demodulator for demodulating a multi-level received signal to provide K demodulated signals, where K>1; and
a repetition decoder for removing duplicated data from at least one of the K demodulated signals;
wherein the multi-level received signal is a layered modulated signal including at least an upper layer and a lower layer; and
wherein the repetition decoder provides a repetition decoded signal and wherein the receiver further comprises a decoder for decoding the repetition decoded signal.
2. The receiver of claim 1 , wherein the repetition decoder operates on the lower layer.
3. The receiver of claim 1 , wherein the repetition decoded signal represents an average log-likelihood ratio (LLR) for every J received signal points of the at least one demodulated signal, where J>1.
4. The receiver of claim 1 , wherein the repetition decoded signal represents an average of every J received signal points of the at least one demodulated signal, where J>1.
5. The receiver of claim 1 , wherein the repetition decoder further comprises:
a number of averaging elements, each averaging element averaging soft input data derived from the at least one demodulated signal over a different respective alignment and providing a respective averaged signal;
a comparator for determining which averaged signal represents a better alignment as compared to the remaining averaged signals; and
a selector for providing the averaged signal determined to represent the better alignment.
6. The receiver of claim 5 , wherein the soft input data is a function of log-likelihood ratio (LLR) values associated with the at least one demodulated signal.
7. A receiver comprising:
a demodulator for demodulating a multi-level received signal to provide K demodulated signals, where K>1; and
a repetition decoder for removing duplicated data from at least one of the K demodulated signals;
wherein the demodulator has a number of operating modes, wherein at least two of the modes are a hierarchical mode and a layered mode; and
wherein the repetition decoder provides a repetition decoded signal and wherein the receiver further comprises a decoder for decoding the repetition decoded signal.
8. The receiver of claim 7 , wherein the multi-level received signal is a hierarchically modulated signal including at least an upper layer and a lower layer.
9. The receiver of claim 8 , wherein the repetition decoder operates on the lower layer.
10. The receiver of claim 7 , wherein the multi-level received signal is a layered modulated signal including at least an upper layer and a lower layer.
11. The receiver of claim 10 , wherein the repetition decoder operates on the lower layer.
12. The receiver of claim 7 , wherein the repetition decoded signal represents an average log-likelihood ratio (LLR) for every J received signal points of the at least one demodulated signal, where J>1.
13. The receiver of claim 7 , wherein the repetition decoded signal represents an average of every J received signal points of the at least one demodulated signal, where J>1.
14. The receiver of claim 7 , wherein the repetition decoder further comprises:
a number of averaging elements, each averaging element averaging soft input data derived from the at least one demodulated signal over a different respective alignment and providing a respective averaged signal;
a comparator for determining which averaged signal represents a better alignment as compared to the remaining averaged signals; and
a selector for providing the averaged signal determined to represent the better alignment.
15. The receiver of claim 14 , wherein the soft input data is a function of log-likelihood ratio (LLR) values associated with the at least one demodulated signal.
16. A receiver comprising:
a demodulator for demodulating a multi-level received signal to provide K demodulated signals, where K>1; and
a repetition decoder for removing duplicated data from at least one of the K demodulated signals; wherein the repetition decoder further comprises
a number of averaging elements, each averaging element averaging soft input data derived from the at least one demodulated signal over a different respective alignment and providing a respective averaged signal;
a comparator for determining which averaged signal represents a better alignment as compared to the remaining averaged signals; and
a selector for providing the averaged signal determined to represent the better alignment.
17. The receiver of claim 16 , wherein the soft input data is a function of log-likelihood ratio (LLR) values associated with the at least one demodulated signal.
18. A method for use in a receiving apparatus, the method comprising:
using the receiving apparatus to perform the steps of:
demodulating a multi-level received signal to provide K demodulated signals, where K>1; and
removing duplicated data from at least one of the K demodulated signals; and
wherein the multi-level received signal is a layered modulated signal including at least an upper layer and a lower layer; and
wherein the removing step includes the step of providing a repetition decoded signal and the method further comprises the step of decoding the repetition decoded signal.
19. The method of claim 18 , wherein the repetition decoder operates on the lower layer.
20. The method of claim 18 , wherein the repetition decoded signal represents an average log-likelihood ratio (LLR) for every J received signal points of the at least one demodulated signal, where J>1.
21. The method of claim 18 , wherein the repetition decoded signal represents an average of every J received signal points of the at least one demodulated signal, where J>1.
22. The method of claim 18 , wherein the removing step comprises:
averaging soft input data derived from the at least one demodulated signal over a number of different alignments and providing a respective averaged signal associated with each alignment;
determining which averaged signal represents a better alignment as compared to the remaining averaged signals; and
providing that averaged signal determined to represent the better alignment.
23. The method of claim 22 , wherein the soft input data is a function of log-likelihood ratio (LLR) values associated with the at least one demodulated signal.
24. A method for use in a receiving apparatus, the method comprising:
using the receiving apparatus to perform the steps of:
demodulating a multi-level received signal to provide K demodulated signals, where K>1; and
removing duplicated data from at least one of the K demodulated signals;
wherein the demodulating step includes the steps of:
selecting one of at least two demodulation modes; and
performing the demodulation in accordance with the selected mode; and
wherein the at least two demodulation modes is a hierarchical demodulation mode and a layered demodulation mode.
25. The method of claim 24 , wherein the multi-level received signal is a hierarchically modulated signal including at least an upper layer and a lower layer.
26. The method of claim 25 , wherein the repetition decoder operates on the lower layer.
27. The method of claim 24 , wherein the multi-level received signal is a layered modulated signal including at least an upper layer and a lower layer.
28. The method of claim 27 , wherein the repetition decoder operates on the lower layer.
29. The method of claim 24 , wherein the removing step includes the step of providing a repetition decoded signal and the method further comprises the step of decoding the repetition decoded signal.
30. The method of claim 29 , wherein the repetition decoded signal represents an average log-likelihood ratio (LLR) for every J received signal points of the at least one demodulated signal, where J>1.
31. The method of claim 29 , wherein the repetition decoded signal represents an average of every J received signal points of the at least one demodulated signal, where J>1.
32. The method of claim 24 , wherein the removing step comprises:
averaging soft input data derived from the at least one demodulated signal over a number of different alignments and providing a respective averaged signal associated with each alignment;
determining which averaged signal represents a better alignment as compared to the remaining averaged signals; and
providing that averaged signal determined to represent the better alignment.
33. The method of claim 32 , wherein the soft input data is a function of log-likelihood ratio (LLR) values associated with the at least one demodulated signal.
34. A method for use in a receiving apparatus, the method comprising:
using the receiving apparatus to perform the steps of:
demodulating a multi-level received signal to provide K demodulated signals, where K>1; and
removing duplicated data from at least one of the K demodulated signals; and
wherein the removing step comprises:
averaging soft input data derived from the at least one demodulated signal over a number of different alignments and providing a respective averaged signal associated with each alignment;
determining which averaged signal represents a better alignment as compared to the remaining averaged signals; and
providing that averaged signal determined to represent the better alignment.
35. The method of claim 34 , wherein the soft input data is a function of log-likelihood ratio (LLR) values associated with the at least one demodulated signal.