Please check the LLR inputs provided to the decoder object - these need to be accurately scaled based on the noise variance modeled in the link. An incorrect scaling of the LLRs may result in this error from the object.
Often, the incorrect scaling is due to the lack of noise variance specification on the upstream demodulator (e.g. qamdemod, which assumes a default variance of 1) OR on the constellation power used by the demodulator.
We will update the object to yield a more informative error message.
