The message passing decoder 8, wherein {HEAD ~ the LDPC codes} have {TAIL ~ a fixed column weight} 
have
The message passing decoder 8 , wherein { HEAD ~ the LDPC codes } have { TAIL ~ a fixed column weight }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL