To avoid interference, {HEAD ~ neither} of {TAIL ~ these inter segment interfaces} uses terrestrial cellular operating frequencies 
To avoid interference , { HEAD ~ neither } of { TAIL ~ these inter segment interfaces } uses terrestrial cellular operating frequencies
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH