Successive interference cancellation and multi-user minimum mean square channel estimation based on soft decoding information

An apparatus comprising:

• a transceiver configured to receive a first signal that is a superposition of symbols transmitted concurrently by a set of users in shared resources of an air interface;
• and
• a processor configured to perform successive interference cancellation for the set of users, wherein an iteration of successive interference cancellation for a current user in the set of users comprises:
• canceling, for the current user, interference produced in the first signal by the symbols transmitted by previous users in the set of users based on soft estimates of symbols transmitted by the previous users, wherein the soft estimates of the symbols transmitted by the previous users were reconstructed in previous iterations of the successive interference cancellation based on previous log likelihood ratios (LLRs) generated by decoding of the symbols transmitted by the previous users;
• decoding a current symbol transmitted by the current user and received in the first signal after canceling the interference based on the soft estimates of the symbols transmitted by the previous users;
• reconstructing a current soft estimate of the current symbol transmitted by the current user based on a current LLR that represents a likelihood that the decoded current symbol is the same as the current symbol transmitted by the current user;
• and
• feeding back the current soft estimate of the current symbol transmitted by the current user to cancel interference in at least one subsequent iteration of the successive interference cancellation.

An apparatus comprising:

• a receiver configured to receive a first signal that is a superposition of data streams transmitted concurrently in shared resources of an air interface;
• and
• a processor configured to perform successive interference cancellation (SIC) on the first signal, wherein an iteration of the SIC comprises:
• canceling, for a first data stream in the superposition of data streams, interference produced in the first signal based on soft estimates of symbols transmitted in at least one second data stream in the superposition of data streams, wherein the soft estimates were reconstructed in previous iterations of the SIC based on previous log likelihood ratios (LLRs) generated by decoding of the symbols transmitted in the at least one second data stream;
• decoding a first symbol transmitted in the first data stream and received in the first signal after canceling the interference based on the soft estimates of the symbols transmitted in the at least one second data stream;
• reconstructing a first soft estimate of the first symbol in the first data stream based on a first LLR that represents a first likelihood that the decoded first symbol is the same as the first symbol transmitted in the first data stream;
• and
• feeding back the first estimate of the first symbol transmitted in the first data stream to cancel interference in at least one subsequent iteration of the SIC.