Decoder Callbacks#

DecoderStatisticsCallback(num_iter[, device])

Callback for the LDPCBPDecoder to track decoder statistics.

EXITCallback(num_iter[, device])

Callback for the LDPCBPDecoder to track EXIT statistics.

WeightedBPCallback(num_edges[, pcm, ...])

Callback for the LDPCBPDecoder to enable weighted BP [Nachmani].

The LDPCBPDecoder and LDPC5GDecoder have the possibility to register callbacks that are executed after each iteration. This allows to customize the behavior of the decoder (for example to implement weighted BP [Nachmani]) or to track the decoding process.

A simple example to track the decoder statistics is given in the following example

num_iter = 10

# init decoder stats module
dec_stats = DecoderStatisticsCallback(num_iter)

encoder = LDPC5GEncoder(k = 100, # number of information bits (input)
                        n = 200) # number of codeword bits (output)

decoder = LDPC5GDecoder(encoder           = encoder,
                        num_iter          = num_iter, # number of BP iterations
                        return_infobits   = True,
                        c2v_callbacks     = [dec_stats,]) # register stats callback

source = GaussianPriorSource()

# generate LLRs
noise_var = 0.1
batch_size = 1000
llr_ch = source([batch_size, encoder.n], noise_var)

# and run decoder (this can be also a loop)
decoder(llr_ch)

# and print statistics
print("Avg. iterations:", dec_stats.avg_number_iterations.numpy())
print("Success rate after n iterations:", dec_stats.success_rate.numpy())

>> Avg. iterations: 5.404
>> Success rate after n iterations: [0.258 0.235 0.637 0.638 0.638 0.638 0.638 0.638 0.638 0.638]

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