Stopping iterative decoding in a turbo decoder when a minimum absolute LLR is greater than a dynamic threshold

摘要

A turbo decoder outputs an absolute LLR (Log Likelihood Ratio) value for each of the N information bits of a received frame. This process is repeated iteratively. For each iteration, i, a minimum LLR detector selects a minimum value M(i) among the N sequentially output absolute LLR values. A controller issues a command to stop the iterative decoding, if the minimum value M(i) is larger than a first threshold. The first threshold is based on Fmin, which is the minimum one of the values M(1), M(2),...M(i-1) calculated for the preceding iterations of a current frame. Fmin is updated as further iterations are carried out. In a preferred embodiment, one further iteration is performed after the stop command is issued. In one embodiment the early stopping command is only given when M(i) also exceeds a second threshold. The method of the present invention may also be used in combination with a prior art CRC method of early stopping.