Apparatus and method for stopping iterative decoding in a CDMA mobile communication system

A method for stopping iterative decoding in a turbo decoder performing iterative decoding on a received frame comprised of information bits and then outputting iteratively decoded results, comprising the steps of:

• sequentially outputting absolute LLR (|LLR|) values associated with respective information bits of the received frame by the iterative decoding;
• selecting a minimum value M(i) among the sequentially output absolute LLR (|LLR|)values;
• issuing a command to stop the iterative decoding when the selected minimum value M(i) is satisfied with both of the following two conditions, (1) the one is a case where the minimum value M(i) is larger than a first threshold T1(i) determined based on a minimum value Fmin among minimum values M(i) output through previous iterative decoding, and (2) the other is a case where the minimum value M(i) is larger than a second threshold T2(i) determined based on a minimum value Imin among minimum values M(i) satisfying the aforesaid condition (1);
• and
• stopping the iterative decoding in response to the command and then outputting the decoded results at the stop point.

An apparatus for stopping iterative decoding in a turbo decoder performing iterative decoding on a received frame comprised of information bits and then outputting iteratively decoded results, comprising:

• a turbo decoder for sequentially outputting absolute LLR (|LLR|) values associated with respective information bits of the received frame by the iterative decoding, and stopping the iterative decoding in response to a stop command for the iterative decoding;
• a minimum absolute LLR detector for selecting a minimum value M(i) among the sequentially output absolute LLR (|LLR|) values;
• a comparison selector for comparing said minimum value M(i) with a first threshold and updating threshold in accordance with the minimum absolute LLR values output from the minimum absolute LLR detector;
• and
• a controller for issuing a command to stop the iterative decoding, if the minimum value M(i) is larger than the first threshold determined based on a minimum value Fmin among absolute LLR (|LLR|) values output through previous iterative decoding.

An apparatus for stopping iterative decoding in a turbo decoder performing iterative decoding on a received frame comprised of information bits and then outputting iteratively decoded results, comprising:

• a turbo decoder for sequentially outputting absolute LLR (|LLR|) values associated with respective information bits of the received frame by the iterative decoding, and stopping the iterative decoding in response to a stop command for the turbo decoding;
• a minimum LLR detector for selecting a minimum value M(i) among the sequentially output absolute LLR (|LLR|) values;
• a comparison selector for comparing said minimum value M(i) with a first threshold and in sequence comparing said minimum value M(i) with a second threshold and updating thresholds in accordance with the minimum absolute LLR values output from the minimum absolute LLR detector;
• and
• a controller for issuing a command to stop the iterative decoding, if the minimum value M(i) is larger than the first threshold T1(i) determined based on a minimum value Fmin among absolute LLR (|LLR|) values output through previous iterative decoding and is also larger than the second threshold T2(i) determined based on a minimum value Imin representing the minimum value among minimum absolute LLR (|LLR|) values that has satisfied the first stop condition in up to the previous decoding process for a currently decoded frame.

A method for stopping iterative decoding in a turbo decoder, comprising the steps of:

• outputting results of iterative decoding performed on a received frame comprised of information bits, and sequentially outputting absolute LLR (|LLR|) values associated with the respective information bits;
• performing error checking on the received frame using CRC (Cyclic Redundancy Check) bits for the decoded results, and outputting error checking results;
• requesting a stop to the iterative decoding, if a minimum value M(i) among the sequentially output absolute LLR (|LLR|) values is larger than a threshold determined based on a minimum value Fmin among absolute LLR (|LLR|) values output through previous iterative decoding;
• issuing a command to stop the iterative decoding, based on the error checking results and in response to the stop request for the iterative decoding;
• and
• stopping the iterative decoding after additionally performing the iterative decoding once on the received frame in response to the command, and then outputting the decoded results upon stopping.

An apparatus for stopping iterative decoding in a turbo decoder, comprising:

• a turbo decoder for outputting results of iterative decoding performed on a received frame comprised of information bits, and sequentially outputting absolute LLR (|LLR|) values associated with the respective information bits;
• a CRC detector for performing error checking on the received frame using CRC bits for the decoded results, and outputting error checking results;
• an LLR stop controller for requesting a stop to the iterative decoding, if a minimum value M(i) among the sequentially output absolute LLR (|LLR|) values is larger than a threshold determined based on a minimum value Fmin among absolute LLR (|LLR|) values output through previous iterative decoding and additionally is larger than a threshold determined based on a minimum value Imin represented the minimum value among minimum absolute LLR (|LLR|) values that has satisfied the first stop condition in up to the previous decoding process for a currently decoded frame;
• and
• a stop selection controller for issuing a command to stop the iterative decoding being performed by the turbo decoder, based on the error checking results and in response to the stop request for the iterative decoding.