Ethernet VS traditional bus

Ethernet VS traditional bus

• 2024-12-10 12:22:09
• by Admin

Analysis of the basic knowledge of vehicle Ethernet   Common abbreviations of Ethernet

1） 1TPCE = One (1) Twisted Pair 100 Megabit (C = century = 100) Ethernet 1 Twisted pair cable 100MEthernet

2) RTPGE=Reduced Twisted Pair Gigabit Ethernet

3) GEPOF = Gigabit Ethernet Over Plastic Optical Fiber

4) 100BASE-T1 = 100 Megabit Baseband One Pair 100M Ethernet (1 twisted pair)

5) 1000BASE-T1 = 1 Gigabit Baseband One Pair 1000M Ethernet (1 twisted pair)

6) 1000BASE-RH = Gigabit Ethernet Over Plastic Optical Fiber

7) OPEN/OPEN Alliance = One Pair Ethernet Network Alliance

8） OABR = (OPEN Alliance) BroadR-Reach

An early name for 100BASE-T1, when the IEEE was not involved and the Open Alliance introduced Broadcom's BroadR-Reach technology to the automotive sector

9) TSN - Time Sensitive Network

10) AVB - Audio/Video bridging technology

What is 100BASE-T1

100BASE-T1 is an integration based on existing Ethernet technology.

1） IEEE 100BASE-TX

- Duplex simplex communication

- MLT-3 (multi-level transmission) - > 125Msps (million samples/second) 65~80MHz bandwidth)

- Two twisted pairs - no error correction coding

- No echo and crosstalk cancellation technology in DSP

Decision Feedback Equilibrium (DFE)

2) IEEE 1000BASE-T - full duplex communication

- 4D-PAM5 - > 125Msps (million samples per second) 65~80MHz bandwidth) - four twisted pairs

- Partial response transmission filter

- Additional levels of error correction coding

- DSP has echo and crosstalk cancellation technology

Decision Feedback Equilibrium (DFE)

3) IEEE 100BASE-T1 - full duplex communication - PAM3 - 66.7Msps (million samples per second) 27MHz bandwidth - single twisted pair

—— Echo cancellation technology —— Decision Feedback Equilibrium (DFE)

3. Ethernet VS traditional bus

3.1 Switch-based network communication

1) All nodes on a traditional bus are connected to the same transmission medium;for example, multiple terminal nodes (ECUs) can be attached to a single CAN bus, and electrical signals on the CAN bus can affect all terminals attached to the bus.

In general, we call CAN as CAN Bus or CAN Network.

2) Ethernet is a switched network communication method, where all terminal nodes must be connected through switches and all transmitted information must be forwarded by switches.In switched network communication, a single network cable can only connect two ports without branching.Therefore, we generally do not refer to Ethernet bus, but rather to Ethernet network.

4. Application of on-board Ethernet

4.1 Aerial image view - high-speed connection

1) Broadcom BroadR-Reach, 100 Mbit / s, full duplex, twisted pair -- replaces expensive shielded wire harnesses

- Two-way communication

2) Utilize high bandwidth

3) MAC-based video streaming with strict timing requirements

4) Enhanced ADAS functions (additional cameras, millimeter-wave radar, laser radar, etc.) - high resolution and frame rate, less compression

- Require a transmission rate of 1000Mbit/s and above

4.2 Ethernet as the backbone network of the vehicle interior

The future automotive bus will replace the CAN bus with Ethernet as the backbone network, and the subnets will be composed of several domain controllers.Each functional domain is provided with a domain controller, and the interconnection of systems within each domain can still use CAN and FlexRay communication buses.Different domain controllers are connected through higher-performance Ethernet as the backbone network, and data exchange is realized through Ethernet gateways, thus jointly forming an E/E architecture based on domain controllers.

4.3 On-board Ethernet for power transmission

Power over Ethernet (POE) is a technology that can transmit data over twisted-pair cables while simultaneously powering connected end devices, eliminating the need for external power cords for the terminals and reducing the complexity of power supply.

The main power supply characteristics of the POE standard power supply system are:

1) The voltage is between 44-57V, with a typical value of 48V.

2) The maximum allowable current is 550mA, and the maximum starting current is 500mA.

3) The typical operating current is 10-350mA, and the overload detection current is 350-500mA.

4) Under no-load conditions, the maximum demand current is 5mA.

5) Provide five levels of power requests for PD (Power device) devices ranging from 3.84 to 12.95W, with a maximum of 13W.

4.4 Wireless function of on-board Ethernet Wireless function is another advantage of on-board Ethernet. WiFi also has a variant for automotive use - WAVE (Wireless Access in Vehicle Environments).The introduction of on-board Ethernet will undoubtedly become the best catalyst for promoting the introduction of wireless communication technology WAVE into the automotive field, which provides a physical foundation for the implementation of audio and video and high-definition maps in real-time communication, and also provides more imagination space for the application of V2X technology.