{HEAD ~ The common format} includes at least the transmission data length, {TAIL ~ the transmission data}, the data frame number and the repeat request frame number, and is added with the error detection code for all the data 
{ HEAD ~ The common format } includes at least the transmission data length , { TAIL ~ the transmission data } , the data frame number and the repeat request frame number , and is added with the error detection code for all the data
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH