车用以太网将取代现有不互通的汽车网络技术

上网时间: 2013年08月22日? 作者:Junko Yoshida? 我来评论 【字号: ? ?小】

关键字:车用以太网络? 车内网络解决方案? 车联网?

Ethernet Backbone in Car: Hype or Reality?

Junko Yoshida

MADISON, Wis. -- Can the traditionally conservative automotive industry's fixation for penny-pinching and proprietary technology ever be flipped?

Broadcom Corp., which has invented an automotive technology known as BroadR-Reach Ethernet, definitely believes so. The leading networking chip company, although still a novice in the automotive market, thinks carmakers are coming around at last to the wisdom of leveraging standard technologies such as Ethernet -- already well proven outside the car market.

Indeed, when BMW rolls out its X5 SUV later this year, champagne corks will be popping at Broadcom. The German carmaker -- in partnership with Freescale Semiconductor, a licensee of Broadcom's BroadR-Reach Ethernet technology -- will become the first OEM to commercialize the Ethernet for a 360-degree camera parking assist system.

Hyundai Motor Company is also said to be using Broadcom's BroadR-Reach Ethernet technology to offer next-gen connected infotainment systems.

In a recent interview with EE Times, Ali Abaye, senior director of product marketing for Broadcom's Infrastructure and Networking Group, claimed, as the amount of electronics rapidly grows inside a car, "Carmakers have come to a collective conclusion" to embrace automotive Ethernet. "They don't want another proprietary technology," he added.

Three reasons

Abaye listed three reasons why automakers are unclenching.

First, carmakers today are "paying more attention to what electronics devices their customers are bringing into the car -- moreso than a car's horsepower." They need to make sure their cars can accommodate everything from a navigation system to displays and other gizmos consumers use inside a car. "And this is not just for a high-end car," said Abaye.

Second, there are many "islands of networks" inside a car today, he said. Each automotive network technology such as low-voltage differential signaling (LVDS), media-oriented systems transport (MOST), and the controller area network (CAN), is connected to different electronics. They don't interoperate. "That is adding to the bottom line for carmakers," Abaye said.

Third, carmakers need scalable solutions for in-car networking. The quality of camera technology used for lane changing, for example, is running at higher data rates. With the use of tablets and smartphones, consumers audio-visual quality expectations are intensifying. As cars get connected to the external world through WiFi, 3G, 4G, and LTE, the bandwidth needed for in-car networking grows exponentially. "For scalable, ubiquitous, reliable, and useful" in-car networking, Abaye said, carmakers are now increasingly looking to OPEN Alliance SIG, an open industry consortium designed to encourage wide-scale adoption of Ethernet-based networks as the standard in automotive networking applications.

Cable Comparison

The MOST auto connectivity spec is on the way out as new unshielded single twisted-pair cable arrives for automotive Ethernet (compare it with regular Ethernet cable on the left). This means auto makers can leverage the ubiquitous Ethernet standard while reducing the connectivity cost and cabling weight.

Debate on Ethernet backbone

Broadcom is convinced that the Ethernet will become the electronic backbone in cars. In Abaye's mind, the use of automotive Ethernet for such applications as infotainment and camera-assisted parking with advanced driver assistance systems (ADAS) is almost a given. Automotive Ethernet will challenge LVDS and MOST, Abaye said. "We will start seeing automotive Ethernet replacing CAN in eight to 10 years." Noting the different network islands that don't interoperate in cars today, Abaye said, "These islands do not need to exist."

Given the slow-moving nature of the automotive industry, though, how soon the automotive Ethernet will really infiltrate cars -- and in what volume -- remains a topic of heated debate. Opinions are sharply divided even among automotive industry analysts. Forecasts of the number of Ethernet nodes used by the automotive industry by 2020 range from 120 million to 300 million units.

On one end of the spectrum, Frost & Sullivan's Telematics and Infotainment program manager Praveen Chandrasekar told EE Times, "By 2020, there will be more than 100 to 120 Ethernet ports in a luxury car owing clearly to drivers' increasing use of cameras for advanced driver assistance systems (ADAS), automated driving requiring high level sensor fusion and increasing infotainment content." Chandrasekar added, "On the other hand, more than 50 to 60 ports will be in a volume [mass-market] car because of similar reasons. This almost amounts to a total of 300 million Ethernet ports globally and the highest contributing markets will be North America and Europe."

However, Ian Riches, director of global automotive practice at Strategy Analysis, told EE Times, "Our current estimates are that in 2020 around 120 million Ethernet nodes will be fitted to light vehicles produced that year."

When asked how many Ethernet nodes are expected in a high-end car in 2020, Riches said, "I would be surprised if it hit 100 Ethernet nodes."

He counted up to five domain controllers on the backbone (powertrain, safety, chassis, body, infotainment), 10 to 20 infotainment nodes, 10 to 15 nodes for advanced safety, 1 node for diagnostics, and 10 to 20 additional nodes for other high-end features.

"That makes around 35 to 60 nodes by my reckoning," Riches noted.

In-Car Networking Scenario

Ethernet/IP will coexist with low-bandwidth standards like CAN.

(Source: Frost & Sullivan)

The big gap in forecasts could be partly explained by differences in expectations of how fast the ECU in the vehicle goes Ethernet.

Frost & Sullivan's Chandrasekar believes in the idea of a backbone network supporting other networks. But he made it very clear that "the backbone would be Ethernet-driven. The CAN, MOST, LIN and others will continue to exist on a small scale basis, but Ethernet will drive the majority of the work."

Strategy Analysis's Riches doesn't necessarily agree with that premise.

In Riches's opinion, "Not every function in the vehicle requires the 100Mbps-plus" offered by automotive Ethernet. A seat control motor, for example, won't gain extra functionality from being on an Ethernet network rather than the low-speed CAN or local interconnect network (LIN) that runs it today, explained Riches. "Unless Ethernet is cheaper than LIN, then LIN at the very least will remain for many low-end functions." He added that part of the backbone/domain controller architecture trend leans toward reducing the number of ECUs in the vehicle -- which means fewer Ethernet nodes than in Frost & Sullivan's forecast.

Tipping point

Luca De Ambroggi, senior analyst, IHS's Automotive Component and Device Electronics and Media, is more cautious about the rate of Ethernet adoption. He thinks Ethernet is still looking for a place to break through. "I believe this breakthrough point is infotainment, followed by basic ADAS application like Camera based functions," he said.

Obviously, for automotive Ethernet to succeed, "The target of Ethernet must be the entire auto wiring system from Infotainment down to the most safety and security critical segments like body." Nonetheless, De Ambroggi believes "Ethernet needs a small step approach to be mature and bullet-proof for automotive."

As Broadcom likes to point out, there is a definite upside in using Ethernet in a car -- in terms of savings in cost and weight.

Single-pair Automotive Ethernet, which uses un-shielded twisted pair (UTP) cable to deliver data at a rate of 100Mbps, along with smaller and more compact connectors “can reduce connectivity cost up to 80 percent and cabling weight up to 30 percent,” according to Broadcom.

While acknowledging potential savings, Strategy Analysis's Riches pointed out, "There are also significant risks when adopting a new technology."

For one, there is always a cost-to-change. At this stage, the additional costs are arguably easier to quantify than any potential savings, he said. While an Ethernet backbone would be an enabler for greater functionality in the vehicle, he also noted, "Whether that functionality will be required (or affordable) on a mass-market 2020 vehicle is far from certain."

In summary, Riches noted that there's a theoretical tipping point where the number of features and bandwidth required will be cheaper to "start again" with an Ethernet backbone-type architecture. "But I don't see us as being there before 2020 at the earliest for volume car makers,” he said.

Remaining technical issues

Broadcom insists that its BroadR-Reach Ethernet technology has already met rigorous automotive industry standards. Its Phy layer was specifically designed to meet the automotive industry's EMI and EMC requirements, noted Abaye.

Also, Automotive Ethernet uses a signaling scheme with higher spectral efficiency compared to the signaling scheme used in 100BASE-TX, according to Broadcom. This limits the signal bandwidth of Automotive Ethernet to 33.3MHz, which is about half the bandwidth of 100BASE-TX. As a result, "a lower signal bandwidth improves return loss, reduces crosstalk, and ensures that Automotive Ethernet passes the stringent automotive electromagnetic emission requirement," the company said.

Strategy Analysis's Riches, however, believes that some technical questions still remain. "I still hear concerns over EMC performance for Ethernet over UTP." Riches, however, quickly added that "how much of this is real as opposed to just fear-of-the-unknown is hard for me to judge."

Other criticism questions whether the current 100 Mbps of BroadR-Reach might be too slow, Riches added. "It essentially means that camera images will need to be compressed -- which some see as a big problem for safety systems."

There are players that seem to be waiting for Gbps in automotive, said Riches. "Moves are underway at IEEE level to standardize this -- but these things take time."

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