Low density parity checking codes (LDPC) are one
of the most important issues in coding theory at present.
LDPC-code are a type of linear-block LDPC-codes. Channel
coding might be considered as the finest conversant and most
potent components of cellular communications systems, that was
employed for transmitting errors corrections imposed by noise,
fading and interfering. LDPC-codes are advanced coding gain,
i.e., new area in coding. the performances of LDPC-code are
similar to the Shannon-limiting, this led to the usage of decoding
in several applications in digital communications systems, like
DVB-S2 and WLAN802.1..This paper aims to know what is
LDPC,what its application and introduce encoding algorithms
that gives rise to a linear encoding time and also show that the
regular and irregular LDPC performance and also introduce
different methods for decoding LDPC. I discuss in detail LDPC
decoding algorithm: bit flipping algorithm, as a type from hard
decision .belief propagation algorithm, sum product algorithm
and minimum sum algorithm as examples from soft decision .I
expect that at least some students or researchers involved in
researching LDPC codes would find this paper helpful.