如果无线互联网都能够依靠灯泡运行将会怎样?WiFi 走开, LiFi 过来!

Wi-Fi技术已经越来越普及,不过抱怨无线信号不稳定、上网速度慢、WiFi热点太少而用的人也越来越多。由于电灯泡一直以来被视作发明家梦寐以求的灵感闪现的象征,2011年,爱丁堡大学的哈拉尔德·哈斯(Harald Haas)教授在苏格兰的一次TED演讲上提出了一个革命性的理念:如果全世界的无线互联网系统都能够依靠LED灯泡运行将会怎样?

这项新的技术LiFi,即光通讯技术。通过特质LED发出的光信号就可以传输数据,提供低成本的高速无线网络。在实验室中,数据的传输速度可以达到近10Gb/s,是现有WiFi网络的十倍以上。

这5年来,这项技术一直在爱沙尼亚塔林的实验室中进行测试,以应用于现实世界。在科学家们的不懈努力下,终于在实验室中实现了224GB/s的惊人传输速率!

原理:有光就有网络

Li-Fi的工作原理是将可见光源作为信号的发射源,通过控制安装有特制微芯片的LED灯的亮、灭,来与终端接收器之间进行通讯,把光信号转译成普通电信号。简单说,就是用光来传输网络,有光就有网络。

Li-Fi原型产品依赖太阳能作为电力来源,所以LED光源配合着太阳能面板就可以成为一套功能齐全的高速、安全数据收发系统。

不过,Li-Fi也并非那么完美。

上面提到的安全性也正成为它的弱点,如果你想在家里通过Li-Fi进行无死角上网,那就得确保每个房间里都有安有带芯片的LED灯泡。

正如你猜到的,如果把灯关了是不是就没有网络了?答案是对的,不过你可以把灯光调到最暗,这样人眼不会感受到光的存在,而接收器依然可以接收信号。

目前,这种技术已经在航空公司当中试用,他们希望这可以帮助建立更好的飞机内通信系统。

而在前不久,有细心的网友就在iOS 9.1的系统库缓存文件中发现了“LiFi兼容”的功能陈述。也许,在新一代iPhone 7或未来下一代手机的无线传输标准上,苹果将采用Li-Fi可见光天线通讯技术替代WiFi技术,最起码会共存一段时间。

Li-Fi优势:可以避免被“蹭网”

Li-Fi技术最大的优势是不同于Wi-Fi,它并不会和其他无线电信号发生干扰,所以能够用在飞机上以及其他需要考虑到电磁兼容问题的场合。

另一大优势是,相对频段频谱有限的无线电,可见光的频段频谱要比前者大10000倍,这意味着在Li-Fi网络里单个数据信道的带宽就可以做得很大,也可以容纳更多的信道做并行传输,从而让整个传输速度大幅提升。

最后就是其高安全性。首先光的特性决定了它无法穿墙传输信号,这也就意味着不同设备之间“干扰”将更少,也就意味着它的安全性很强,Wi-Fi使用中常出现的“蹭网”现象,就可以有效避免。同时 LiFi的上行和下行信道是独立的,黑客必须处在同一个房间之中,并侵入两个信道才能完成一次真正意义上的攻击。

但这一技术的缺点也很明显,最大的问题就是由于信号会被阳光干扰,导致它无法在有阳光的室外使用,这一点对广大移动端用户来说显然很不友好。

Li-Fi未来:利用灯泡来接入互联网

Li-Fi可能在短期内还无法彻底取代WiFi技术,这两项技术可能会同时存在,从而创建一种更有效的网络。

如果测试成功,Li-Fi网络将在未来3-5年时间推向大众消费市场,让普通消费者能够利用其家用灯泡来接入互联网。

在Li-Fi大规模应用之前,这项技术需要做进一步的改善,使其能够兼容目前的设备。“创建一种Li-Fi全新的基础设施是非常困难的,需要与现有系统相整合。”Harald Haas说,未来每一盏LED灯泡都可以充当WiFi的替代品,目前的基础设施适合对Li-Fi做整合。

Harald Haas还表示:“我们所需要做的就是,在每一个照明设备中加入一个微型芯片,这样它就能够具备两个基本功能:照明和无线数据传输。在未来,我们不光将拥有140亿盏灯泡,我们可能还将以一种更环保的方式搭建140亿个Li-Fi网络。”

近日,由Haas教授创立的公司PureLiFi获得了150万英镑的融资,约合225万美元,公司的估值也增长至2100万美元。PureLiFi的研究大部分还处在实验室之中,已经推出的少部分商业化产品大多还处在闭门内测的阶段。

2013年,美国的一家医疗服务提供商成为了它的第一个客户。2014年,Li-1st问世,可以实现双向的数据传输,只对合作客户开放购买。

2014年年底,PureLiFi发布Li-Flame,同样是面向行业合作伙伴,但它的意义远大于前两款产品,可以将在现有的照明装置改装成LiFi AP。整个装置包括一款USB接收器,连接至LiFi AP 后便可接入网络。

在LiFi领域, 除了PureLiFi之外,上海复旦大学也已研发出相关的技术,并在2013年亮相上海工博会。基本原理是将光源像淋浴喷头那样进行分流,然后通过控制开光让LED在一毫秒内开关数百万次,传输大量0和1组成的二进制数据。

以下是演讲全文

I would like to demonstrate for the first time in public that it is possible to transmit a video from a standard off-the-shelf LED lamp to a solar cell with a laptop acting as a receiver. There is no Wi-Fi involved, it's just light.
我想要第一次向公众证明视频可以由一台LED台灯传送至太阳能电池板上,并由一台手提电脑接收。没有Wi-Fi介入,只是光。

And you may wonder, what's the point? And the point is this: There will be a massive extension of the Internet to close the digital divide, and also to allow for what we call "The Internet of Things" -- tens of billions of devices connected to the Internet.
那么你可能想知道, 这样做有什么意义? 意义就是: 将来互联网会大规模覆盖 “数字鸿沟“将不复存在,并且让我们所说的“物联网”变为可能—— 数以亿计的设备连接到互联网。

In my view, such an extension of the Internet can only work if it's almost energy-neutral. This means we need to use existing infrastructure as much as possible. And this is where the solar cell and the LED come in.
在我看来,互联网的大程度扩张的前提是需要基本保证“能源中性化”(指尽量减少能源消耗)。这就是说,我们需要尽可能的多用现存的基础设施,这就是为什么前面提到太阳能电池和LED。

I demonstrated for the first time, at TED in 2011, Li-Fi, or Light Fidelity. Li-Fi uses off-the-shelf LEDs to transmit data incredibly fast, and also in a safe and secure manner. Data is transported by the light, encoded in subtle changes of the brightness. If we look around, we have many LEDs around us, so there's a rich infrastructure of Li-Fi transmitters around us. But so far, we have been using special devices -- small photo detectors, to receive the information encoded in the data. I wanted to find a way to also use existing infrastructure to receive data from our Li-Fi lights. And this is why I have been looking into solar cells and solar panels.
我之前第一次证明这件事是2011年在TED演讲,我称它为Li-Fi,即光保真。用现存的LED灯可以极快地传递Li-Fi数据,并且这种方式安全可靠。数据由光传输,由亮度的细微变化解码。如果我们环视四周,在我们身边有很多的LED灯,因此在我们周围有着非常丰富的Li-Fi发射装置。但是目前,我们通常使用一个特别的设备——小型照片探测器来接收由数据解码出来的信息。我想要找到一种方法,利用现有的基础设施来接收Li-Fi灯发出的数据,这也是为什么我一直研究太阳能电池和太阳能电板。

A solar cell absorbs light and converts it into electrical energy. This is why we can use a solar cell to charge our mobile phone. But now we need to remember that the data is encoded in subtle changes of the brightness of the LED, so if the incoming light fluctuates, so does the energy harvested from the solar cell. This means we have a principal mechanism in place to receive information from the light and by the solar cell, because the fluctuations of the energy harvested correspond to the data transmitted.
太阳能电池吸收光并转化成电能,这就是为什么我们能用太阳能电池给我们的手机充电。但我们知道数据是由LED亮度的微妙变化来编码的,所以如果入射的光有波动,那么太阳能电池收集的能量也有波动。这就意味着我们具备了一项基本原理:信息通过光的传导,由太阳能电池板接收。因为收集的能量波动与传输的数据相对应。

Of course the question is: can we receive very fast and subtle changes of the brightness, such as the ones transmitted by our LED lights? And the answer to that is yes, we can. We have shown in the lab that we can receive up to 50 megabytes per second from a standard, off-the-shelf solar cell. And this is faster than most broadband connections these days.
当然问题就在:我们是否能够收集到非常迅速和微小的亮度变化?比如通过我们的LED灯传递的那种?答案是:是的,我们可以。我们在实验室已经展示我们能够接收达到每秒50MB的数据,通过一个标准的,现有的太阳能电池,这比目前最高速的宽带连接还要快。

Now let me show you in practice. In this box is a standard, off-the-shelf LED lamp. This is a standard, off-the-shelf solar cell; it is connected to the laptop. And also we have an instrument here to visualize the energy we harvest from the solar cell. And this instrument shows something at the moment. This is because the solar cell already harvests light from the ambient light.
现在让我来实践展示一下,在这个盒子里是一个现有的标准LED灯,这是一个现有的标准太阳能电池,它连接到笔记本电脑上,这儿我们还有一个测量仪,用来显示我们从太阳能电池收集的能量,现在这个仪表上有读数,这是因为太阳能电池已经开始从周围环境收集光了。

Now what I would like to do first is switch on the light, and I'll simply, only switch on the light, for a moment, and what you'll notice is that the instrument jumps to the right. So the solar cell, for a moment, is harvesting energy from this artificial light source. If I turn it off, we see it drops. I turn it on ... So we harvest energy with the solar cell.
现在,首先我将把灯打开,只是简单的打开灯,等一段时间你会注意到指针跳到了右边。所以现在,太阳能电池正在从这个人工光源接收能量,如果把它关掉,我们看到读数降回去了。再打开,所以我们用太阳能电池收集了能源。

But next I would like to activate the streaming of the video. And I've done this by pressing this button. So now this LED lamp here is streaming a video by changing the brightness of the LED in a very subtle way, and in a way that you can't recognize with your eye, because the changes are too fast to recognize. But in order to prove the point, I can block the light of the solar cell. So first you notice the energy harvesting drops and the video stops as well. If I remove the blockage, the video will restart.
接下来,我将要启动视频传导,通过按下这个按钮来实现。所以现在这个LED灯正在通过亮度的细微变化传导一个视频。这种亮度变化太快,不能用肉眼识别。为了证明这一点,我可以阻挡太阳能电池接收的光。首先你会注意到收集的能源下降了,并且视频也停止了,如果我移开阻碍物,视频会继续播放。

And I can repeat that. So we stop the transmission of the video and energy harvesting stops as well. So that is to show that the solar cell acts as a receiver.
这个操作可以重复。所以当我们阻止视频的传输,能源收集也相应停止。这说明太阳能电池可以作为一个接收器。

But now imagine that this LED lamp is a street light, and there's fog. And so I want to simulate fog, and that's why I brought a handkerchief with me.
但是现在想像一下这个LED灯是街灯,并且周围有雾。我想模拟有雾的情况,因此我随身带来一个手帕。

And let me put the handkerchief over the solar cell. First you notice the energy harvested drops, as expected, but now the video still continues. This means, despite the blockage, there's sufficient light coming through the handkerchief to the solar cell, so that the solar cell is able to decode and stream that information, in this case, a high-definition video.
让我把手帕放到太阳能电池上。首先你会注意到能源收集量降低了,和预料的一样。但是现在视频仍在继续播放,这意味着尽管有阻碍物还是有足够的光穿过手帕到太阳能电池。因此太阳能电池仍然能够解码、传导数据信息,甚至是我们现在用的高清视频信息。

What's really important here is that a solar cell has become a receiver for high-speed wireless signals encoded in light, while it maintains its primary function as an energy-harvesting device. That's why it is possible to use existing solar cells on the roof of a hut to act as a broadband receiver from a laser station on a close by hill, or indeed, lamp post.
重要的是太阳能电池在这里成为了一个接收器,接收编码成光的高速无线信号。同时也保持了它作为能源收集设备的基本功能。这就是说,屋顶上那些现有的太阳能电池可以用来作为宽带网络的接收器,信号可以来自靠近山坡的激光站,或者街边的路灯。

And It really doesn't matter where the beam hits the solar cell. And the same is true for translucent solar cells integrated into windows, solar cells integrated into street furniture, or indeed, solar cells integrated into these billions of devices that will form the Internet of Things. Because simply, we don't want to charge these devices regularly, or worse, replace the batteries every few months.
哪里的光束到达太阳能电池并不要紧。并且实际上,窗户上安装的半透明太阳能电池安装在街道设施上的太阳能电池,甚至安装在成千上万其他设备上的太阳能电池,它们将会形成物联网。这是因为我们不想经常给这些设备充电,更不想每几个月就要更换电池。

As I said to you, this is the first time I've shown this in public. It's very much a lab demonstration, a prototype. But my team and I are confident that we can take this to market within the next two to three years. And we hope we will be able to contribute to closing the digital divide, and also contribute to connecting all these billions of devices to the Internet. And all of this without causing a massive explosion of energy consumption -- because of the solar cells, quite the opposite.
我之前说这是我第一次向公众展示这些,这次展示可以说是一个实验证明,一个原型。但是我和我的团队有信心接下来两到三年,这项产品会进入市场。希望我们能够对终结“数字鸿沟”做出贡献,并且帮助成千上万的设备连接到互联网,而且所有设备不会造成巨大的能源消耗,因为我们将利用现有的太阳能电池。

(来源:Ted、爱范儿、最黑科技 编辑/海洋)

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