One Pair Ethernet vs. Energy Efficient Ethernet vs. PoE vs. Gigabit Ethernet

This page compares One Pair Ethernet (OPEN), Energy Efficient Ethernet, Power Over Ethernet (PoE), and Gigabit Ethernet (GIG-E). These are types of Automotive Ethernet used in the automotive industry for communication between components. The following sections outline the features of each of these automotive ethernet types.

One Pair Ethernet (OPEN)

Here are the key features of One Pair Ethernet (OPEN):

• Supports distances of approximately 700 meters.
• Utilizes PAM-3 signaling and encoding to reduce bandwidth over the cable.
• Employs an echo canceller, enabling bi-directional data transfer over a single pair.
• Meets EMI specifications due to its lower bandwidth (e.g., 27 MHz or 62.5 MHz).
• The 802.3bp standard supports 1G data rates over a single twisted pair, linking up to 15-meter connections.

This new physical layer (PHY) is known as 1000Base-T1, where the digit ‘1’ in ‘T1’ indicates a single pair.

Energy Efficient Ethernet

In cars, electrical components often remain active even when the engine is off, which can drain the battery. To minimize power consumption, Energy Efficient Ethernet (EEE) is used.

• Network segments are turned off when the engine is off.
• EEE type ethernet is used when the engine is on.

The name “Energy Efficient Ethernet” comes directly from this power-saving functionality.

Power Over Ethernet (PoE)

The following are features of Power Over Ethernet (PoE):

• Developed with minor modifications to the existing PoE standard.
• Reduces wiring complexity.
• The 802.3bu standard, currently under development, specifies PoE over a single pair.
• It is known as PoDL, which stands for One Pair Power Over Data Lines.

Gigabit Ethernet (GIG-E)

Key features of Gigabit Ethernet:

• Meets the EMC (Electromagnetic Compatibility) requirements of automotive vehicles.
• Supports a range of 15 meters over unshielded automotive cabling.
• Supports Gigabit Ethernet MAC interfaces (e.g., SGMII/RGMII/GMII) as defined in IEEE standard specifications.
• The 1000Base-T1 draft standard is under development and defines Gigabit Ethernet PHY transceiver specifications.

The merits of 1000Base-T1 include:

• Suitable for High Speed Video links.
• Supports 100 Mbps uplink video channels.
• Can utilize cost-effective unshielded cables.
• Lightweight and flexible.