Selective joint demodulation
View Patent ↗Systems, methods and apparatuses for jointly demodulating data signals are disclosed. In accordance with the method, pilot signals are received from a base station and are processed. In addition, from a set of expected co-scheduled data streams, a subset of the co-scheduled data streams that are actually transmitted by the base station are determined based on the pilot signals. Further, a group of the transmitted co-scheduled data streams are selected from the determined subset. The data signals are received and jointly demodulated by employing the selected group of co-scheduled data streams and by suppressing non-selected data streams from the determined subset.
1. A method for jointly demodulating data signals, the method comprising:
receiving and processing pilot signals from a base station;
determining, from a set of expected co-scheduled data streams, a subset of the co-scheduled data streams that are actually transmitted by the base station and which of the expected co-scheduled data streams are missing, by comparing an energy or a norm of each of the pilots signals corresponding to the data streams in the set of expected co-scheduled data streams to a threshold;
selecting a group of the transmitted co-scheduled data streams from the determined subset; and
receiving the data signals and jointly demodulating the data signals by employing the selected group of co-scheduled data streams and suppressing non-selected data streams from the determined subset.
2. The method of claim 1 , wherein the method further comprises:
receiving an indication of a modulation scheme assignment for at least one of the expected co-scheduled data streams, wherein the selecting further comprises determining at least one modulation scheme assignment for at least one data stream in the selected group for which the indication is not received.
3. The method of claim 2 , wherein the selecting further comprises:
determining the at least one modulation scheme assignment for at least one data stream in the selected group for which the indication is not received by drawing symbols from a super-constellation including symbols from a set of modulation schemes using a respective pre-determined and tuned probability parameter for each of the modulation schemes in the set of modulation schemes.
4. The method of claim 1 , wherein the selecting further comprises:
selecting co-scheduled data streams that maximize a metric over choices of co-scheduled data streams from the determined subset.
5. The method of claim 4 , wherein the metric is a mutual information metric that is computed for a given choice of co-scheduled data streams from the determined subset.
6. The method of claim 4 , wherein the metric is based on an optimal joint decoder for all data streams in a given choice of co-scheduled data streams from the determined subset for a multiple access channel model.
7. The method of claim 1 , wherein the selecting further comprises:
tuning the selecting based on at least one of: a rate of a given user for which the data signals are demodulated, a rate of at least one user to which at least one of the data streams in the selected group is directed or a penalty factor accounting for non-Gaussian and finite properties of a modulation scheme assigned to the at least one user.
8. The method of claim 1 , wherein the selecting comprises:
determining whether the group satisfies a minimum performance criterion.
9. A system for jointly demodulating data signals, the system comprising:
a receiver configured to receive and process pilot signals from a base station; and
a processor configured to determine, from a set of expected co-scheduled users, a subset of the co-scheduled users to which the base station actually transmits data streams and which of the expected co-scheduled users are missing data streams, by comparing an energy or a norm of each of the pilot signals directed to the set of expected co-scheduled users to a threshold, and configured to select a group of the co-scheduled users from the determined subset,
wherein the receiver is further configured to receive the data signals and wherein the processor is further configured to jointly demodulate the data signals by employing symbols directed to the selected group of co-scheduled users and by suppressing symbols directed to non-selected co-scheduled users from the determined subset.
10. The system of claim 9 , wherein the receiver is further configured to receive an indication of a modulation scheme assignment for at least one of the expected co-scheduled users and wherein the processor is further configured to determine at least one modulation scheme assignment for at least one co-scheduled user in the selected group for which the indication is not received.
11. The system of claim 10 , wherein the processor is further configured to determine the at least one modulation scheme assignment for at least one co-scheduled user in the selected group for which the indication is not received by drawing symbols from a super-constellation including symbols from a set of modulation schemes using a respective pre-determined and tuned probability parameter for each of the modulation schemes in the set of modulation schemes.
12. The system of claim 9 , wherein the processor is further configured to select the co-scheduled users for inclusion in the group that maximize a metric over choices of co-scheduled users from the determined subset.
13. The system of claim 12 , wherein the metric is a mutual information metric that is computed for a given choice of co-scheduled users from the determined subset.
14. The system of claim 12 , wherein the metric is based on an optimal joint decoder for all users in a given choice of co-scheduled users from the determined subset for a multiple access channel model.
15. The system of claim 9 , wherein the processor is further configured to tune the selection based on at least one of: a rate of a given user for which the data signals are demodulated, a rate of at least one user in the selected group or a penalty factor accounting for non-Gaussian and finite properties of a modulation scheme assigned to the at least one user.
16. The system of claim 9 , wherein the processor is further configured to determine whether the group satisfies a minimum performance criterion.
17. A non-transitory computer readable storage medium comprising a computer readable program, wherein the computer readable program when executed on a computer causes the computer to perform a method for jointly demodulating data signals, the method comprising:
receiving and processing pilot signals from a base station;
determining, from a set of expected co-scheduled data streams, a subset of the co-scheduled data streams that are actually transmitted by the base station and which of the expected co-scheduled data streams are missing, by comparing an energy or a norm of each of the pilots signals corresponding to the data streams in the set of expected co-scheduled data streams to a threshold;
selecting a group of the transmitted co-scheduled data streams from the determined subset; and
receiving the data signals and jointly demodulating the data signals by employing the selected group of co-scheduled data streams and suppressing non-selected data streams from the determined subset.