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