车用以太网将取代现有不互通的汽车网络技术

向来保守、小气又爱用独家技术的汽车产业有可能改变吗？发表车用以太网络系列产品BroadR-Reach的博通(Broadcom)一定认为答案是肯定的，这家网络芯片供货商虽然在汽车应用市场仍算是新手，却认为汽车制造商正在改变想法，开始接受利用诸如以太网络等已经在汽车以外市场经证实的标准技术。 据了解， 德国车厂BMW 将于今年稍晚上市的X5系列SUV休旅车，就将采用博通的技术──该公司与博通的 BroadR-Reach 以太网络技术授权客户飞思卡尔半导体(Freescale)合作，成为第一家将车用以太网络应用于360度摄影机停车辅助系统的车厂。此外韩国车厂Hyundai Motor也将采用 BroadR-Reach 技术提供新一代连网车用资通讯娱乐系统。 博通网络与基础建设产品部门资深产品行销总监Ali Abaye在最近接受EETimes美国版编辑采访时表示，随着越来越多电子组件进驻汽车：“各家车厂已经达成了采用车用以太网络的集体共识，他们不要其它的专属技术；”他指出，其原因有三： 第一， 今日的汽车制造商：“比起汽车马力，放更多的注意力到他们的客户将哪些电子产品带进车子里。”他们需要确保车子能容纳包括导航系统、显示器与其它消费性电子设备，而Abaye强调：“并不只是高阶车款。” 第二， 现在的车子里面有许多“网络孤岛”，那些汽车网络技术如 LVDS、MOST、CAN等各自与不同的电子设备连接，彼此之间是不互通的；Abaye指出：“这也成为汽车制造商的考量因素之一。” 第三，车厂需要能扩充的车内网络解决方案；举例来说，车道变换摄影机系统支持的画质、资料速率越来越高，随着智能手机、平板设备的使用，消费者对于影音品质的期望也跟着升高；而当汽车透过Wi-Fi、3G、4G LTE等技术与外部世界连结，车内网络的频宽需求也加倍成长。Abaye指出，为了寻求可扩充、无所不在、可靠且实用的车内网络技术，越来越多车厂转向支 持OPEN Alliance SIG──即一个推广以太网络技术成为标准车用网络的产业组织。

车用以太网络采用无外罩双绞线电缆(图中左)，与正规以太网络相较缆线重量更轻；且标准化技术亦能带来成本的降低
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博通相信，以太网络会成为车内的电子设备骨干网络(backbone)；以Abaye的观点，车用以太网络在车用资通讯娱乐系统、支持摄影机辅助停车的先进驾驶辅助系统(ADAS)的应用几乎已是既定事实，车用以太网络将会挑战LVDS、MOST等技术的地位，而且他表示：“我们将在8~10年内看到车用以太网络开始取代CAN。”那些在今日汽车内不互通的网络孤岛将会消失。 本文授权编译自EE Times，版权所有，谢绝转载 第2页：分析师对车用以太网络前景看法分歧 第3页：仍有技术门槛？

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{pagination} 分析师对车用以太网络前景看法分歧 但有鉴于汽车产业行动较为缓慢的特性，车用以太网络到底会在多快的时间内渗透到汽车，而且数量会有多少？仍是产业界所强烈质疑的问题；甚至汽车产业分析师们的意见也大不相同，对2020年车用以太网络节点数量的预测，从1.2亿到3亿都有。 如Frost & Sullivan分析师Praveen Chandrasekar表示：“到2020年，在一部高阶车款中将会有100至120个以太网络连接端口，以支持越来越多驾驶人使用ADAS摄影机、自动 驾驶所需的高阶传感器，以及不断增加的车用资通讯内容。”他指出，在另一方面，平价车款内则会搭载50~60个车用以太网络连接端口，估计全球车用以太网络 连接端口数量可达3亿，主要市场为北美与欧洲。 Strategic Analysis 分析师Ian Riches则表示：“我们目前的预测是，到2020年，总计约将有1.2亿个以太网络连接端口进驻该年度所生产的轻型车辆。”而他指出，如果届时一台高阶车款内搭载的以太网络节点超过100个，那就很令人惊讶；他估计汽车骨干网络会涵盖五大部位(动力系统、安全、底盘、车身与资通讯娱乐系统)，其中资通讯娱乐系统使用10~20个节点、安全系统使用10~15个，诊断运用1个，其它高阶功能使用10~20个，总计35~60个网络节点。

车内网络应用概况
Source：Frost & SullivangYcesmc

不同预测数据之间的庞大差距，或许也显示了对车内电子控制单元(ECU)会多快支持以太网络技术的不同预期。Frost & Sullivan的Chandrasekar认为，车内网络应该是有一个骨干网络支持其它网络，但他清楚指出，该骨干网络会采用以太网络技术；CAN、 MOST、LIN等车用网络技术还会存在，支持小区域的功能，但以太网络还是扮演主角。 但Strategic Analysis的Riches就不完全同意以上看法，他认为，汽车内并非每项功能都需要以太网络100Mbp以上的速率；举例来说，座椅控制马达并不会 因为采用以太网络而添加额外功能性，还不如目前使用的低速度CAN或LIN：“虽然以太网络比LIN便宜，但LIN还是会保留给许多低阶功能。”而他也指出，车内骨干网络/局域网络控制器架构应该是往减少ECU数量的方向发展──这意味着以太网络节点数量不会像Frost & Sullivan预测的那么多。 IHS的资深分析师Luca De Ambroggi对于车用以太网络渗透率的预测又更为谨慎，他认为，车用以太网络仍在寻找突破点：“我相信该突破点会是资通讯娱乐设备，接着是基本的ADAS应用，例如摄影机相关功能。” De Ambroggi指出，车用以太网络要取得成功，其目标必然是涵盖整个汽车有线网络系统，从车用资通讯娱乐设备，到最关键的安全系统、车身等；但无论如何：“以太网络对汽车应用领域来说，还需要达到成熟以及证实无坚不摧的那一小步。” 而 就像博通所说，以太网络在汽车内的应用至少有一个绝对明确的好处──在节省成本与减轻重量方面。该公司表示，车用以太网络采用无屏蔽双绞线(un- shielded twisted pair，UTP)电缆，可提供100Mbps传输速率，连接器的尺寸也较小巧，能将连网成本降低80%，整体电缆重量则可降低30%。 本文授权编译自EE Times，版权所有，谢绝转载 第3页：仍有技术门槛？

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{pagination} 虽然有以上好处，但Strategic Analysis的Riches仍强调，采用一种新技术仍有风险；首先，总是会有因改变所带来的成本，在这方面，掂量额外费用应该比任何其它潜在成本节省容易得多。他指出，虽然以太网络骨干可望为车辆带来更多功能：“那些功能是否为2020年上市的大众车款所需求(或负担得起)，恐怕还是个未知数。” Riches总结指出，理论上应该会有一个功能与网络频宽需求的临界点，让汽车厂商认为“从头开始”改用以太网络骨干架构会是可以节省成本的：“但我并不认为我们会在2020年以前看到那个临界点出现。” 仍有技术门槛？ 博通坚称，其BroadR-Reach车用以太网络技术已经符合严苛的汽车产业要求；该公司的Abaye指出，其实体层(PHY)规格特别能符合汽车产业的 EMI/EMC要求。此外博通表示，车用以太网络的信令架构(signaling scheme)与100BASE-TX以太网络所采用的信令架构相较，具有更高的频谱效率，这将车用以太网络的讯号频宽限制在33.3MHz，是 100BASE-TX的一半；较低的信号频宽可改善回波耗损(return loss)、降低串扰(crosstalk)并确保车用以太网络能通过严苛的汽车电磁辐射需求。 对此Strategic Analysis的Riches则认为，该技术还是有一些问题：“我仍听说以太网络使用UTP电缆时，在EMC性能上会有疑虑。”不过他也立即表示：“这些疑虑有多少是真实的、有多少只是对于未知的恐惧，我很难判断。” 其 他意见包括质疑目前BroadR-Reach的100 Mbps速率稍嫌太慢，Riches表示：“这意味着摄影机的影像需要经过压缩，这对安全系统来说可能会是个大问题。”他指出，有些厂商正在期待Gbps 等级的以太网络技术：“这方面还有待IEEE的标准化程序，都需要时间。” 编译：Judith Cheng 参考英文原文：Ethernet Backbone in Car: Hype or Reality?，by Junko Yoshida

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{pagination} 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."