System and method for low density spreading modulation detection

1. A method for blindly detecting low density activity, the method comprising:

receiving, by a first node from a second node, a signal; and

executing a joint message passing algorithm (JMPA) on the signal, wherein executing the JMPA includes jointly producing a decoded signal and an activity list in accordance with the decoded signal, and calculating a plurality of a priori probabilities in accordance with a plurality of log likelihood ratios (LLRs) corresponding to the signal and a plurality of decoded LLRs.

2. The method of claim 1 , wherein the first node is a user equipment (UE) and the second node is a transmit point.

3. The method of claim 1 , wherein the first node is a transmit point and the second node is a UE.

4. The method of claim 1 , wherein executing the JMPA further comprises executing the JMPA in accordance with a factor graph.

5. The method of claim 4 , wherein an inactive signature is represented by a zero constellation point.

6. The method of claim 1 , wherein executing the JMPA further comprises:

executing a message passage algorithm (MPA) to produce the plurality of LLRs;

decoding the plurality of LLRs to obtain the plurality of decoded LLRs; and

executing the MPA in accordance with the signal and the plurality of a priori probabilities.

7. The method of claim 1 , wherein executing the JMPA further comprises performing hard detection on the signal.

8. The method of claim 1 , wherein executing the JMPA further comprises performing soft detection on the signal.

9. A first node comprising:

a processor; and

a non-transitory computer readable storage medium storing programming for execution by the processor, the programming including instructions to:

receive a signal from a second node, and

execute a joint message passing algorithm (JMPA) on the signal, to jointly produce an activity list in accordance with a decoded signal, and calculate a plurality of a priori probabilities in accordance with a plurality of log likelihood ratios (LLRs) corresponding to the signal and a plurality of decoded LLRs.

10. The first node of claim 9 , wherein the first node is a user equipment (UE) and the second node is a transmit point.

11. The first node of claim 9 , wherein the first node is a transmit point and the second node is a UE.

12. The first node of claim 9 , wherein the instructions to execute the JMPA further comprise instructions to execute the JMPA in accordance with a factor graph.

13. The first node of claim 12 , wherein an inactive signature is represented by a zero constellation point.

14. The first node of claim 12 , wherein the instructions to execute the JMPA further comprise instructions to:

execute a message passage algorithm (MPA) to produce the plurality of LLRs;

decode the plurality of LLRs to obtain the plurality of decoded LLRs; and

execute the MPA in accordance with the signal and the plurality of a priori probabilities.

15. The first node of claim 12 , wherein the instructions to execute the JMPA further comprise instructions to perform hard detection on the signal.

16. The first node of claim 12 , wherein the instructions to execute the JMPA further comprise instructions to perform soft detection on the signal.

17. A non-transitory computer readable storage medium storing programming for execution by a processor, the programming including instructions to:

receive a signal from a second node; and

execute a joint message passing algorithm (JMPA) on the signal, to jointly produce an activity list in accordance with a decoded signal, and calculate a plurality of a priori probabilities in accordance with a plurality of log likelihood ratios (LLRs) corresponding to the signal and a plurality of decoded LLRs.

18. The storage medium of claim 17 , wherein the instructions to execute the JMPA further comprise instructions to execute the JMPA in accordance with a factor graph.

19. The storage medium of claim 18 , wherein an inactive signature is represented by a zero constellation point.

20. The storage medium of claim 17 , wherein the instructions to execute the JMPA further comprise instructions to:

execute a message passage algorithm (MPA) to produce the plurality of LLRs;

decode the plurality of LLRs to obtain the plurality of decoded LLRs; and

execute the MPA in accordance with the signal and the plurality of a priori probabilities.