To compress data, the LZ77 algorithm replaces portions of the data with references to matching data that has already passed through both the encoder and the decoder.

The fourth chapter is this paper's emphasis , focuses on the byte processing part(outer code) module by module: data reverse transformer, de-randomizer, RS decoder, de-interleaver and synchronization.

Decoder - This feature can be used to decode data to get back the original form, or to encode and encrypt data.