Single Pair Ethernet, the Automotive Ethernet

In today’s rapidly evolving automotive industry, the need for faster, more reliable communication between vehicle systems has never been greater. Automotive Ethernet has emerged as a robust wired network technology designed to seamlessly connect various components within a vehicle. Engineered to satisfy the industry’s demands for bandwidth, latency, synchronization, and network management, it also addresses critical electrical requirements such as minimizing electromagnetic and radio frequency interference (EMI/RFI). Offering data speeds ranging from 10 Mbps to 10 Gbps, Automotive Ethernet supports in-vehicle networking (IVN) through lightweight, unshielded single-pair twisted cables to create the most economical cabling alternative; an Ethernet description summarized into Single Pair Ethernet (SPE).

Single Pair Ethernet in Automotive:

Single Pair Ethernet (SPE) as its name implies is simply the transmission and reception of data over a single pair of cables. SPE started in the automotive industry because of the requirements for smaller yet powerful devices and has established itself in the industry due to its high performance, low weight, and compactness.

This technology can provide deterministic, time-synchronized network links using flexible, lightweight unshielded twisted pair cables paired with deterministic, time-synchronized network links using flexible, lightweight unshielded twisted pair cables, while reaching enormous speeds of up to 10 Gbps (MultiGBASE-T1). With SPE, it is not only possible to transmit data over a single pair of cables, but it is also possible to simultaneously supply power to end devices. This is known as Power over Data Line (PoDL) as specified by the IEEE 802.3bu. Under typical operation, devices can be powered with up to 50 W at a current of up to 1360 mA. Note, that PoDL differs from the well-known Power over Ethernet (PoE).

Automotive Standards:

The IEEE standards are the outcome of the development of automotive Ethernet. The goal in establishing these standards is to specify the maximum values for cables and connections, as well as the methods of measurement based on the total channel requirements. Multiple new specifications and updates to existing ones are constantly worked on by the IEEE 802.3 and 802.1 groups to properly address automotive needs. The Multi-Gig Automotive Ethernet (MultiGigBase-T1 or MultiGBase-T1) specified in the IEEE 802.3ch is still under development.

Table 1: Automotive Ethernet Standards

Why is SPE useful in the automotive industry?

• Advanced Driver Assistance (ADAS) features like camera systems or cruise control, which need higher data throughput with low latency, are becoming extremely necessary and possible with SPE.
• Ethernet standards enable new applications including Time Sensitive Networks (TSN) and Audio Video-Bridging.
• SPE's twisted pair of cables without shielding enable easier handling, more compact and lighter constructions and are cheaper.
• SPE supports Power over Data Line (PoDL), also called Single-pair Power over Ethernet (SPoE), which integrates power and SPE on a single cable with no need for additional lines and which makes it possible to power cameras, and sensors.
• Complexity can be decreased by reusing TCP/IP in various applications such as flashes, cameras, and smart antennas.

Conclusion:

Single Pair Ethernet (SPE) represents a transformative step in advancing communication systems within modern vehicles. As the automotive industry shifts from dispersed architectures to domain and zonal designs, SPE’s lightweight, compact, and flexible cabling has become a crucial component, particularly in electric vehicles. Its ability to meet the real-time demands of Advanced Driver Assistance Systems (ADAS) and autonomous driving networks, while supporting Time-Sensitive Networking (TSN) underscores its importance. SPE delivers high data throughput with minimal latency, simplifies handling, reduces weight and cost, and supports Power over Data Line (PoDL). Positioning it as a cornerstone of future automotive innovation. Beyond vehicles, the success of SPE has led to it being seen as an enabler of Industry 4.0 and the Industrial Internet of Things (IIoT).