One-Pair Ethernet (OPEN) is an alternative to Single-Pair Ethernet( SPE). It is a transmission technology for Ethernet that was developed for the physical layer as part of BroadR-Reach. With this technology, the bridgeable distances for Fast Ethernet have been extended to 700 m.
One-pair Ethernet uses a UTSP cable, Unshielded Twisted Single Pair (UTSP), as the transmission medium and works with Fast Ethernet according to 100Base- TX with ternary pulse amplitude modulation (PAM3), an improved coding with which the required bandwidth is reduced and echo cancellation. Communication is bidirectional over a single wire pair.
OPEN meets the stricter electromagnetic compatibility( EMC) requirements of automotive technology and is used in automotive Ethernet, among other applications. The specifications of One-Pair Ethernet are developed by the OPEN Alliance BroadR Reach( OABR) and standardized by the IEEE working groups802.3bw under 100Base- T1 and 802.3bp under 1000Base-T1.