The method 21, further comprising detecting errors in the signals at {TAIL ~ a receiving terminal}, when {HEAD ~ no error} is detected transmitting positive acknowledgment from a receiving terminal, and otherwise sending negative acknowledgments 
The method 21 , further comprising detecting errors in the signals at { TAIL ~ a receiving terminal } , when { HEAD ~ no error } is detected transmitting positive acknowledgment from a receiving terminal , and otherwise sending negative acknowledgments
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH