De-Mapping Technique with Provision of Probability Information Including a Priori Information

A method of de-mapping a point in a constellation diagram into a bit sequence, wherein the de-mapping provides, for each bit of the bit sequence, extrinsic probability information in the form of an output value, with a sign of the output value indicating a bit value and a magnitude of the output value indicating probability information in the form of a distance to a decision boundary in the constellation diagram, the method comprising:

• receiving a signal indicative of a constellation point, wherein the constellation point represents a bit sequence having a most significant bit and at least one next significant bit;
• deriving a first output value (L0) for the most significant bit;
• receiving a priori information (L0a priori) for the most significant bit;
• and
• deriving a second output value (L1) for the next significant bit based on the first output value (L0), the a priori information and a decision boundary.

A non-transitory computer-readable medium comprising, stored thereupon, a computer program product comprising program code portions for, when the computer program product is run on a computing device:

• de-mapping a point in a constellation diagram into a bit sequence, wherein the de-mapping provides, for each bit of the bit sequence, extrinsic probability information in the form of an output value, with a sign of the output value indicating a bit value and a magnitude of the output value indicating probability information in the form of a distance to a decision boundary in the constellation diagram, and wherein the de-mapping comprises:
• receiving a signal indicative of a constellation point, wherein the constellation point represents a bit sequence having a most significant bit and at least one next significant bit;
• deriving a first output value (L0) for the most significant bit;
• receiving a priori information (L0a priori) for the most significant bit;
• and
• deriving a second output value (L1) for the next significant bit based on the first output value (L0), the a priori information and a decision boundary.

A de-mapper apparatus for de-mapping a point in a constellation diagram into a bit sequence, wherein the de-mapping provides for each bit of the bit sequence extrinsic probability information in the form of an output value with a sign of the output value indicating a bit value and a magnitude of the output value indicating probability information in the form of a distance to a decision boundary in the constellation diagram, the de-mapper comprising:

• a first interface circuit configured to receive a signal indicative of a constellation point, wherein the constellation point represents a bit sequence having a most significant bit and at least one next significant bit;
• a second interface circuitry configured to receive a priori information for the most significant bit;
• and
• at least one of a processor and circuitry, configured to derive a first output value for the most significant bit, and to derive a second output value for the next significant bit based on the first output value, the a priori information and a decision boundary.