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BroadR-Reach: Advantages and Disadvantages

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This page explores the pros and cons of BroadR-Reach technology.

What is BroadR-Reach?

Introduction:

BroadR-Reach is essentially automotive Ethernet. It serves as the physical network infrastructure to connect various components within a car using a wired network. It’s designed to meet the stringent requirements of the automotive environment, addressing concerns like EMI (Electromagnetic Interference), RFI (Radio Frequency Interference), bandwidth, latency, synchronization, and network management.

  • It’s a point-to-point Ethernet PHY (Physical Layer) technology initially developed by Broadcom and later adopted by the OPEN Alliance.
  • It operates in full-duplex mode over a single pair of UTP (Unshielded Twisted Pair) cable, delivering data rates of 100 Mbps.
  • The BroadR-Reach PHY supports MAC (Media Access Control) interfaces through the MII (Media Independent Interface), as defined in IEEE 802.3 clause 22.
  • The specifications for BroadR-Reach PHY (BR-PHY), BR-PCS (Physical Coding Sublayer), and BR-PMA (Physical Medium Attachment) are defined in IEEE 802.3-2012.
  • BR-PHY employs 3-level signaling (PAM-3 with 66.7 MSPS) along with echo cancellation techniques.
  • It enables simultaneous access to information over a single UTP cable by multiple in-vehicle systems.
  • This facilitates a single, open, and scalable Ethernet-based network within the automobile.

Benefits or Advantages of BroadR-Reach

Here are the key advantages of BroadR-Reach:

  • It provides 100 Mbps data rates over UTP (or better cable) in full-duplex mode, achieving a Bit Error Rate (BER) better than 1 x 10-10.
  • It utilizes a 33.3 MHz bandwidth, allowing for aggressive filtering, which improves both emissions and immunity performance.
  • Simultaneous information access over a single cable reduces the complexity of cable wiring and, consequently, the cable weight. This contributes to lower overall connectivity costs.
  • Automotive manufacturers can easily integrate various electronic systems for functionalities such as parking assistance, security features, collision avoidance, infotainment systems, and comfort features.
  • It utilizes a signaling scheme that boasts higher spectral efficiency compared to 100Base-Tx. This reduces the signal bandwidth to 33.3 MHz, improving return loss (i.e., VSWR) and reducing cross-talk. As a result, this automotive Ethernet solution meets stringent automotive EM emission requirements.
  • It’s a media-independent Ethernet standard interface, allowing for the use of different media types, including UTP copper, STP copper, fiber optic cables, coaxial cables, and POF (Polymer Optical Fiber).

Drawbacks or Disadvantages of BroadR-Reach

While BroadR-Reach offers numerous advantages, it also has some drawbacks:

  • It’s a relatively “newcomer” in the automotive market and faces stiff competition from established technologies such as CAN (Controller Area Network), LIN (Local Interconnect Network), FlexRay, MOST (Media Oriented Systems Transport), and LVDS (Low-Voltage Differential Signaling).
  • It offers a limited distance of up to 15 meters using UTP (Unshielded Twisted Pair) and 40 meters using STP (Shielded Twisted Pair) for 100 Mbps data rates.