Example to use python encoder/decoder

[FranzForstmayr]

Hi,

I expected to use the encoder/decoder as followed

ldpc = LDPC(...)
x = np.random.randint(0,2, 128) # generate some random bits
enc = ldpc.encode(x)
x_r = ldpc.decode(enc)[0]

The decode method delivers float values, however it's not obvious how to get the decoded bits out of the stream.

Could you please clarify if this is possible?

Thanks!
Franz

[heat1q]

Hi,
the decode method operates on the actual log-likelihood-ratios (LLRs). In other words, you have to first calculate the LLRs for the input (usually a codeword + some noise). The decoder then outputs the decode LLRs which you can then use for decision making (depending on your channel).

See also:

    def decode(self, llr_in: np.array, early_term=True, iters=50, dec_type="BP") -> np.array:
        """Decode array of input LLRs.
        Args:
            llr_in (np.array): Input LLR, length n (transmitted)
            early_term (bool, optional): Terminate decoding if codeword 
            is valid. Defaults to True.
            iters (int, optional): Number of iterations. Defaults to 50.
            dec_type (str, optional): Type of decoding. See libldpc documentation
            Defaults to "BP".
        Returns:
            np.array: Output LLR, length n (transmitted)
        """
...