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发表时间:2019-06-29  来源:http://atwzntx.com/  浏览量:110

Before 5G can be deployed commercially on a large scale, engineers have to solve some stubborn problems—including how to make a hot technology a whole lot cooler.

机器翻译(仅供参考):在5G大规模商用之前,工程师必须解决一些顽固的问题 - 包括如何解决散热问题。

5G-capable modem chipsets are already on the market from Qualcomm, Samsung, Huawei, MediaTek, Intel and Apple, with some 5G service (LTE-Advanced/LTE-Advanced Pro) available in the U.S. But still mostly missing from the 5G equation are base stations powerful enough to shape and direct an individual RF connection to every subscriber within range, while performing feats of electromagnetic geometry to maintain that connection.

机器翻译(仅供参考):高通,三星,华为,联发科,英特尔和苹果已经在市场上推出具有5G功能的调制解调器芯片组,在美国有一些5G服务(LTE-Advanced / LTE-Advanced Pro),但5G程式中仍然缺少功能强大的基站,足以形成和引导单个RF连接到范围内的每个用户,同时执行电磁几何的功能以维持该连接。

A base station in the wireless world is a device that connects other wireless devices to a central hub. It is a wireless receiver and short-range transceiver that consists of an antenna and analog-to-digital converters (ADCs) to convert the RF signals into digital and back again. The 5G base station will have beamforming massive multiple-input, multiple-output (MIMO) antennas—an array of antennas that can focus and steer multiple beams simultaneously to different targets on the ground, such as a cell phone, using the millimeter wave spectrum. Sometimes that means bouncing the signal off an object to reach near the target rather than broadcasting a signal broadly over an area.

机器翻译(仅供参考):无线世界中的基站是将其他无线设备连接到中央集线器的设备。 它是一个无线接收器和短程收发器,由天线和模数转换器(ADC)组成,可将RF信号转换为数字信号,然后再转换回来。 5G基站具有波束成形的大规模多输入多输出(MIMO)天线 ,一组天线可以利用毫米波频谱将多个波束同时聚焦和引导到地面上的不同目标,例如手机。 有时这意味着将信号从物体上反射到达目标附近,而不是广泛地在一个区域上广播信号。

Although Ericsson, Samsung, Nokia and Huawei are producing 5G base station technology now, there are gaps in that technology. The base stations are still not powerful enough to track mobile customers and make sure each is connected every nanosecond.

机器翻译(仅供参考):虽然爱立信,三星,诺基亚和华为现在正在研发5G 基站技术 ,但该技术存在差距。 基站仍然不够强大,无法跟踪移动客户,并确保每个基站每纳秒连接一次。

What’s developed for base stations has to work seamlessly with handsets. They also have to be reliable enough to last for years, but the current technology is running too hot. And how that affects reliability and signal integrity isn’t clear because at that point now one is quite sure how the antenna arrays will be tested because there are no exposed leads. Those antennas are essential to form, steer and receive beams, both in the base station and in handsets and other mobile devices, including connected cars, health monitoring devices and even industrial equipment.

机器翻译(仅供参考):基站的开发必须与手机无缝协作。 它们还必须足够可靠,可以使用多年,但目前的技术尚不成熟, 这对可靠性和信号完整性的影响尚不清楚。因为在那一点上,现在可以确定如何测试天线阵列,因为没有暴露的引线。 这些天线对于在基站和手机以及其他移动设备(包括联网汽车,健康监测设备甚至工业设备)中形成,转换和接收波束至关重要。

“If you embed the antenna into the package, when the package heats up or cools down, that changes how the antennas work,” said Keith Schaub, vice president of business development for Advantest’s U.S. Applied Research & Technology unit. “That affects beam forming, beam steering, and it creates a power loss. It also affects the fabrication process, which needs to be tightly controlled.”

机器翻译(仅供参考):“如果你将天线嵌入封装中,当封装升温或降温时,这会改变天线的工作方式,” Advantest美国应用研究与技术部门业务开发副总裁Keith Schaub说。 “这会影响波束形成,波束转向,并产生功率损耗。 它还影响制造过程,需要严格控制。“

Schaub noted that base stations and handsets are all designed to standards, but the implementation of those standards can vary greatly. For example, when two major chip companies developed their first 5G chips, they adhered to the standards but the chips wouldn’t work with each other due to minor inconsistencies in the drivers.

机器翻译(仅供参考):Schaub指出,基站和手机都是按标准设计的,但这些标准的实施情况可能差异很大。 例如,当两家主要芯片公司开发出他们的第一批5G芯片时,他们都遵守标准,但由于驱动程序的轻微不一致,芯片之间不能相互协作。

Two-phase commitment/两阶段承诺
Despite the moniker, 5G is more of a statement of direction than a single technology. The sub-6GHz version, which is what is being rolled out today, is more like 4.5G. Signal attenuation is modest, and these devices behave much like cell phones today. But when millimeter wave technology begins rolling out—current projections are 2021 or 2022—everything changes significantly. This slice of the spectrum is so sensitive that it can be blocked by clothing, skin, windows, and sometimes even fog.

机器翻译(仅供参考):尽管有这样的绰号,5G更多的是方向声明而不是单一技术。 今天推出的低于6GHz的版本更像是4.5G。 信号衰减是适度的,这些设备的行为与今天的手机非常相似。 但是,当毫米波技术开始推出时,目前的预测是2021年或2022年 - 一切都发生了显着变化。 这片光谱非常敏感,可以被衣服,皮肤,窗户,有时甚至是雾气阻挡。

The result is that many more cells are needed to keep devices connected, and base-stations and handsets will be constantly searching for ways to stay connected. As anyone with a cell phone knows, searching for signals drains the battery faster. But it also keeps the logic circuits active, and that generates heat. In base stations, which are tightly packed with racks of equipment, thermal buildup can cause all sorts of problems. It can have an impact on signal integrity, and it can reduce the lifespan of all components.

机器翻译(仅供参考):结果是需要更多的单元来保持设备连接,并且基站和手机将不断寻找保持连接的方式。 任何拥有手机的人都知道,搜索信号会更快地耗尽电池电量。 同时也使逻辑电路保持活动状态,并产生热量。 在装有机架的基站中,热积聚会引起各种各样的问题。 它会对信号完整性产生影响,并且会缩短所有组件的使用寿命。

“When you have a frequency with a range that’s not as far as a cell tower, you have to add much more density to the network to get the same amount of connectivity,” Michael Foegelle, director of technology development at ETS-Lindgren. “When you design these, you have to assume they’ll be outside, and you have to design in a way to dissipate all that. Since you’re outside and don’t want to risk putting in active cooling, you might have to go fix a lot, that means a lot of ambient cooling,”

机器翻译(仅供参考):ETS-Lindgren技术开发总监Michael Foegelle表示,“当你的频率范围不如蜂窝塔时,你必须为网络增加更多密度才能获得相同数量的连接。” “当你设计这些时,你必须假设它们会在外面,你必须设计一种方式来消散所有这些。 既然你在外面并且不想承担主动冷却的风险,你可能需要修理很多,这意味着需要大量的环境冷却。“

Another source of heat stems from the analog circuitry used to generate RF signals. Power amplifiers and converters are needed to get the analog signal onto digital networks. But using silicon for those conversions isn’t efficient, so heat builds up. And while beamforming theoretically can save power, because you’re not broadcasting in every direction, that technology adds its own issues.

机器翻译(仅供参考):另一个热源来自于产生RF信号的模拟电路。 需要功率放大器和转换器将模拟信号传输到数字网络上。 但是使用硅进行转换效率不高,因此会产生热量。 虽然理论上波束成形可以节省功率,因为你不是在各个方向传播,但这种技术增加了它自己的问题。

“First, you need enough hardware to do the number of digital-to-analog conversions you have to do, and the cost is still prohibitive,” Foegelle said. “But it’s also power-hungry. One of the side effects of the arrays is that the circuits used for them aren’t terrifically efficient. They get hot, and you have to be able to dissipate a lot of heat because of the amount of equipment and conversions and the efficiency issues.”

机器翻译(仅供参考):“首先,你需要足够的硬件来完成你必须做的数字到模拟转换的数量,而且成本仍然过高,”Foegelle说。 “它也是耗电的。 阵列的副作用之一是用于它们的电路不是非常有效的。 由于设备和转换的数量以及效率问题,它们变热了,你必须能够消散大量的热量。“

It’s not entirely clear if this technology will be replaced with digital technology. It’s also not clear how digital technology would impact effects such as heat, particularly if designs are pushed to the most advanced process geometries.

机器翻译(仅供参考):目前尚不清楚这项技术是否会被数字技术所取代。 也不清楚数字技术如何影响热效应,特别是如果将设计推向最先进的工艺。

“The 5G standard allows for both,” said David Hall, chief marketer at National Instruments. “Analog circuits are less efficient, which creates more heat in the base station. With a digital beam, there is a change in the waveform itself, particularly with multiple access. So you have to adjust the phase to the wave carriers.”

机器翻译(仅供参考):“5G标准允许两者兼有,” National Instruments的首席营销人David Hall说。 “ 模拟电路效率较低,会在基站产生更多热量。 使用数字波束时,波形本身会发生变化,尤其是多次访问时。 所以你必须调整相位到波浪载波。“

Hall noted that heat exacerbates non-linear effects. “If you add heat, distortion is not as repeatable.”

机器翻译(仅供参考):霍尔指出,热量会加剧非线性效应。 “如果过热,失真就是不可逆的了。”

That makes it more difficult to identify any heat-related issues. One solution may involve the testing itself. “Historically, we have been using box instruments,” said Heath Noxon, market development manager at NI. “Now you have to hit this more quickly and process test much faster.”

机器翻译(仅供参考):这使得识别任何与热有关的问题变得更加困难。 一种解决方案可能涉及测试本身。 “从历史上看,我们一直在使用盒式仪器,”NI的市场开发经理Heath Noxon说。 “现在你必须更快地完成这项工作并更快地进行测试。”

Different materials can help, as well, but they add to the cost. “You can get efficiencies using GaN or GaAS that are probably 60% or 70% compared to silicon, which is more like 20% to 30% efficient, but those are much more /expensive, ” Foegelle says.

机器翻译(仅供参考):不同的材料也可以提供帮助,但它们会增加成本。 “使用GaN或GaAS可以提高效率,与硅相比可能提高60%或70%,整体效率提高20%到30%,但这些效率更昂贵,”Foegelle说。

That issue could be sorted out if there is enough volume for either gallium nitride (GaN) or gallium arsenide (GaAs) so that economies of scale begin to kick in. Both of those materials are well understood and there is plenty of expertise in working with them. “Engineers have spent 20 years optimizing the efficiency of gallium arsenide power amplifiers,” said NI’s Hall.

机器翻译(仅供参考):如果氮化镓(GaN)或砷化镓(GaAs)的体积足够大,那么这个问题就可以解决,这样规模经济就可以开始发挥作用。这两种材料都得到了很好的理解,并且在使用它们方面有很多专业知识。 “工程师花了20年的时间来优化砷化镓功率放大器的效率,”NI的Hall说。

“The problem may not be as big as it sounds, though,” Foegelle says. “With millimeter wave the bandwidth is high enough you don’t have to spend much time communicating. It moves quickly, which could minimize heat buildup as well as reduce the amount of energy you broadcast. But we won’t know that until we’re able to see more work on base stations.”

机器翻译(仅供参考):“但问题可能并不像听起来那么大,”Foegelle说。 “对于毫米波,带宽足够高,您不必花太多时间进行通信。 它移动迅速,可以最大限度地减少热量积聚,并减少您散布的能量。 但是,在我们能够看到更多关于基站的工作之前,我们不会知道这一点。“

The volume problem/体积问题
Heat is just one of the many issues cropping up in the 5G world. This is an entirely different wireless technology, particularly when it comes to millimeter wave. The amount of pressure put on technology and service providers trying to move into—and often create—the 5G industry is very high, and few tools are available to test and validate any individual approach early enough in the process to be useful, according to Frank Schirrmeister, senior group director for product management at Cadence.

机器翻译(仅供参考):散热只是5G世界中出现的众多问题之一。 这是一种完全不同的无线技术,特别是涉及毫米波时。 根据弗兰克的说法,技术和服务提供商试图进入并立足5G行业的压力非常大,很少有可以在过程中尽早测试和验证的方法。 Cadence产品管理高级组主任Schirrmeister表示。

This is particularly important for dealing with heat, which can impact the lifespan of components. Thermal effects can speed up electromigration, impact performance, and create noise that can impact quality. But engineers are just starting to work with these technologies, and it’s not clear what else might crop up.

机器翻译(仅供参考):这对于处理热量尤其重要,因为热量会影响组件的使用寿命。 热效应可以增大电迁移 ,影响性能,并产生可能影响质量的噪音。 但是工程师们刚刚开始使用这些技术,还不清楚还有什么可能会出现。


“If engineers are used to working at lower frequencies on these earlier cellular applications, and then they transition to working on 5G at higher frequencies, all of sudden all the rules are more stringent, all the rules of thumb go out the door, and you have to do a more thorough design,” said Mike Leffel, an application engineer at Rohde & Schwarz. “It is a more challenging design. Components don’t work as well at the higher frequencies as they used to in lower frequencies, so you really have to retrain yourself on how to make a well-functioning product. Everything gets smaller. Wavelengths get smaller. The ability to adjust the phase of a path is more difficult because now the wavelength is so small so a small change in a wavelength might be 10 degrees instead of 1 degree at lower frequencies.”

机器翻译(仅供参考):“如果工程师习惯于在这些早期的蜂窝应用中以较低的频率工作,然后他们过渡到更高频率的5G工作,突然所有的规则都更严格,所有的经验法则都不再适用,你必须做更彻底的设计,“Rohde&Schwarz的应用工程师Mike Leffel说。 “这是一个更具挑战性的设计。 组件在频率较高的情况下不能像以前那样在较低频率下工作,因此必须重新学习如何制作功能良好的产品。 一切都变小了。 波长变小。 调整路径相位的能力更加困难,因为现在波长很小,波长的微小变化可能是10度,而不是低频率的1度。“

Rhode & Schwarz recently started one-day educational conferences to help engineers understand the issues. But for Leffel, preparing engineers for the 5G universe is “one of the biggest challenges for the customers that we have. They have to rethink how things work at higher frequencies. What I see is somebody saying ‘I used to do this at 6GHz, I didn’t even have to calibrate the cable. I would just hook it on and it was good enough. Now when I’m at 40GHz, when I do that, it fails. Everything fails and I have to do this calibration. And when I calibrate, it still doesn’t work right. And the guy came in from Rohde & Schwarz and said you have to use a torque wrench to do this. I never had to use a torque wrench before.’ Yes, but you never worked at 40GHz before. Now everything is touchy. And this is a more expensive, better quality cable at 40GHz. You can’t use that cheap cable anymore. You have to calibrate maybe every day instead of once a week. You have to worry about the length of that line and the insertion loss, so there’s an extra trace on this board, so you can measure how much loss is in that line and then subtract it from the results so that when you measure a path on here, you can correct for that trace. At low frequency you don’t have to do that. At high frequency, that trace is critical to know exactly. So all of these things you didn’t have to do before are suddenly important, and if nobody told you this, then how would you know?”

机器翻译(仅供参考):罗德与施瓦茨最近开始为期一天的教育会议,来帮助工程师了解这些问题。 但对于Leffel来说,为5G领域准备工程师是“我们拥有的客户面临的最大挑战之一。 他们必须重新考虑事物在更高频率下的工作方式。 我所看到的是有人说''''''''我曾经在6GHz做过这个,我甚至不需要校准电缆。 我会把它挂钩,这已经足够了。 现在,当我在40GHz时,我这样做一定会失败。 一切都会失败,我必须做这个校准。 当我校准时,它仍然无法正常工作。 那个人从Rohde&Schwarz进来说你必须使用扭矩扳手才能做到这一点。 我之前从未使用扭矩扳手。 是的,但你以前从未在40GHz工作过。 现在一切都很敏感。 这是一款价格更高,质量更好的40GHz电缆。 你不能再使用那种便宜的电缆了。 你必须每天校准一次而不是每周校准一次。 您必须担心该线的长度和插入损耗,因此在该板上有一个额外的迹线,您可以测量该线的损耗量,然后从结果中减去它,以便在测量路径时,你可以纠正那条标记。 在低频率下,您不必这样做。 在高频率下,该跟踪对于准确了解至关重要。 因此,以前你不必做的所有这些事情突然变得很重要,如果没有人告诉你这个,那么你怎么会知道呢?“

Millimeter wave technology isn’t new, and a lot of the networking issues in millimeter wave have been addressed before in satellite communications or radar. However, the cost difference between one satellite and a few hundred thousand WLAN-scale access points changes the cost/benefit equations enough that there’s not much direct comparison, said Cadence’s Schirrmeister.

机器翻译(仅供参考):毫米波技术并不新鲜,以前在卫星通信或雷达中已经解决了毫米波中的许多网络问题。 然而,Cadence的Schirrmeister表示,一颗卫星与数十万个WLAN级接入点之间的成本差异足以改变成本/收益方程,因此没有太多的直接比较。

There also are ongoing updates to the 5G standard. “With millimeter wave we’re talking about wavelengths of about a centimeter, so the antennas are also very small and you use two for each subscriber—one upstream, one down,” Foegelle said. “But for base stations we only have a few vendors marketing them. There’s still another version of the standard coming out later this year, so there’s some uncertainty there. And we are getting carriers coming in and trying to figure out what the propagation characteristics on their networks are going to look like and what types of problems they can expect to see in the field, but the prices are still pretty high for distribution of a product that you’re going to have to put out in density more like a WiFi access point than a cell tower.”

机器翻译(仅供参考):5G标准也在不断更新。 “对于毫米波,我们谈论的是大约一厘米的波长,因此天线也非常小,每个用户使用两个 - 一个上游,一个下游,”Foegelle说。 “但对于基站,我们只有少数厂商推销它们。 今年晚些时候还有另一个版本的标准出现,所以那里存在一些不确定性。 我们正在让运营商进入并尝试弄清楚他们网络上的传播特性将会是什么样子以及他们可以期望在现场看到哪些类型的问题,但产品分销的价格仍然相当高,你不得不放弃密度更像是一个WiFi接入点,而不是一个小区塔。“

It is best to keep things simple with a technology like 5G, which is fantastically complicated to build and test even before the standards or first rounds of implementation are finished and proven, noted Susheel Tadikonda, vice president of engineering at Synopsys’ Verification Group. “The PHY layer is getting very complex. You need high bandwidth, and the latency requirement means you have to do a lot of the processing in the PHY layer itself. We used to have the luxury to send it up the chain and have it done with an algorithm. What you’re doing is moving logic form one portion to another. You still have to convert an analog radio wave. Doing it digitally may be more effective, but in 5G you have not 12 or 14 modems, but hundreds of antennas doing beamforming. It is much more complicated than 4G was, and the transition is more complicated than the transition to 4G was.”

机器翻译(仅供参考):Synopsys Verification Group的工程副总裁Susheel Tadikonda指出,最好用5G等技术保持简单,即使在标准或第一轮实施完成和验证之前构建和测试也非常复杂。 “PHY层变得非常复杂。 您需要高带宽,延迟要求意味着您必须在PHY层本身进行大量处理。 我们曾经有过奢侈品,可以通过算法将其发送出去。 你正在做的是将逻辑从一个部分移动到另一个部分。 您仍然需要转换模拟无线电波。 以数字方式进行可能更有效,但在5G中,您没有12或14个调制解调器,而是有数百个天线进行波束成形。 它比4G复杂得多,而且过渡比向4G过渡更复杂。“

Hybrid designs/混合设计
There are good reasons to stick with hybrid approaches, however. All, or nearly all, RF base stations that operate below 6GHz use digital beamforming because it is more power- and heat efficient than analog. At frequencies higher than 6GHz the filters required for conversions take up too much space for digital to be practical, according to a 2018 
presentation at MIT by Gabriel M. Rebeiz, a University of California San Diego engineering professor and an expert in high-frequency communications and phased array design.

机器翻译(仅供参考):但是,有充分的理由坚持使用混合方法。 所有或几乎所有工作在6GHz以下的RF基站都使用数字波束成形,因为它比模拟功率和热效率更高。 根据麻省理工学院2018年加利福尼亚大学圣地亚哥分校工程学教授兼高频通信专家Gabriel M. Rebeiz的演讲 ,在频率高于6GHz的情况下,转换所需的滤波器占用太多数字空间。和相控阵设计。

Hybrid designs that use analog signals for RF and digital for networking are among the most common topologies used in satellite communication radar and other 5G-similar applications of the last two or three decades, communication methods, according to Redeiz, who specializes in millimeter wave and primarily on those issues before the growth in demand for terrestrial demand for high-frequency bandwidth.


Hybrid models are also less computationally complex than digital, though the arrays are larger, which makes digital beamforming much more attractive as the size of the devices and antennas shrink, according to an analysis published by Mostafa Hefnawi, a researcher at the Royal Military College of Canada in Ontario.机器翻译(仅供参考):根据皇家军事学院研究员Mostafa Hefnawi发表的一项分析 ,混合模型的计算复杂程度也不如数字,但阵列更大,这使得数字波束成形更具吸引力,因为设备和天线的尺寸缩小了。加拿大安大略省。

People are talking about a lot of ways to mix and match frequencies and protocols and devices in other ways that would deliver a lot of value from 5G, especially for people who don’t necessarily need microsecond latency and 10,000 Gbit/sec wireless network connections, says Gilles Lamant, distinguished engineer at Cadence.

机器翻译(仅供参考):人们正在谈论很多方法来混合和匹配频率,协议和设备,以其他方式提供5G的大量价值,特别是对于那些不一定需要微秒延迟和10,000 Gbit / sec无线网络连接的人来说, Cadence的杰出工程师Gilles Lamant说。

“People are talking about putting RF over fiber, but to cross analog RF at high speed to digital might cause major heat problems. Still, those would be a lot less with a slower wireless interface, or even a smaller geographic area covered by 5G that allowed all that RF data to go straight onto the network digital domains,” Lamant says. “The key here is energy efficiency, so you send the RF across the fiber without converting it first and you can save money and time. You can convert it later or transport that signal straight to another RF domain. It is a little science-fiction-like to think about, and you would have to put more energy in the connection after a certain amount of distance, but if the tradeoff is in cost and energy. It is something to think about rather than sending data out over a heavy, slow coaxial cable.”

机器翻译(仅供参考):“人们正在谈论将RF放在光纤上,但是将模拟RF高速交叉到数字可能会导致严重的热量问题。 Lamant说,尽管如此,对于速度较慢的无线接口,甚至是5G所覆盖的较小地理区域,这些都可以让所有RF数据直接进入网络数字域。 “这里的关键是能源效率,因此您可以将RF发送到光纤而不先进行转换,这样可以节省资金和时间。 您可以稍后转换它或将该信号直接传输到另一个RF域。 这是一个像科幻小说一样的想法,你需要在一定距离之后将更多的能量投入到连接中,但如果权衡成本和能量。 需要考虑的是,而不是通过沉重的慢速同轴电缆发送数据。“

Relying too much on the idea of people using smartphones means ignoring a lot of other applications. Analytics providers or IoT network owners could find connecting to 5G access points as attractive a business proposition as a company needing instant high-speed access for mobile video, but companies doing two-way high-definition streaming use the physical network behind the 5G access point is much different than an IoT network sending big chunks of data in batches to the cloud.

机器翻译(仅供参考):过分依赖人们使用智能手机的想法意味着忽略了许多其他应用程序。 分析提供商或物联网网络所有者可以发现连接到5G接入点与需要即时高速访问移动视频的公司一样具有吸引力,但使用双向高清流的公司使用5G接入点背后的物理网络与物联网网络分批向云发送大块数据有很大不同。

“If all you care about is how fast you can post Instagram pictures, that’s a different set of concerns than if you have 100,000 devices spread out across a square kilometer than you want to connect,” Schirrmeister says.


At this point there are many unknowns. Heat is just one more issue, although it is an important one. But how that gets resolved may depend on a lot of other factors, from how much of the base station is digitized to the density of cells and base stations and the millimeter wave frequencies. At this point there is plenty of momentum for 5G, but there are a lot of variables in play that could have a big effect on how this wireless technology is rolled out, how well it works, and how long it lasts.

机器翻译(仅供参考):此时还有许多未知数。 热量只是一个问题,虽然它是一个重要问题。 但是如何解决这个问题可能取决于许多其他因素,从基站的数字化程度到基站和基站的密度以及毫米波频率。 在这一点上,5G有很多动力,但是有很多变量可以对这种无线技术的推出方式,工作效果以及持续时间产生重大影响。