Smart metasurfaces promise to double wireless network capacity
研究人员说，这一新实现的属性称为“全双工非交易”，可以使现有无线网络的能力增加一倍。
“This is happening,” says George Eleftheriades, a professor in the Edward S. Rogers Sr. department of electrical and computer engineering in the Faculty of Applied Science & Engineering. “Within the next three to five years this technology will be adopted.”
Metamaterials are synthetic structures composed of building blocks that are smaller than the wavelengths they are designed to manipulate. The material used by the researchers is composed of repeating unit cells about 20 millimeters in size. These appear to form one homogenous object – a metasurface – for larger electromagnetic waves such as microwaves, which are used to carry cell phone signals and reflect off the metasurface exhibiting a property known as nonreciprocity.
An example to illustrate this using light is a car’s rear-view mirror, say the researchers.
“当您开车并看一下后视镜时，您会看到背后的驾驶员，” Eleftheriades说。“该驾驶员也可以看到您，因为光线从镜子上弹起并沿着同样的路径向后沿着相同的路径弹跳。非次数不寻常的是入射角和反射角不相等。具体而言，波浪的后路是不同的。基本上，您可以看到某人，但是您无法看到。”
此外，元信息可用于引导和放大传入的光束，这在许多应用中很有用，从医疗成像和太阳能电池板到卫星通信甚至新生的覆贴技术。研究人员说，通过添加引导反射光束的能力，新的智能元信息可以在无线通信上留下很大的印记。
“在日常经验,microwave emitted from a tower reaches its intended terminal point, like a modem, and then goes back to the telecommunication station,” says Eleftheriades. “That’s why when you have a conversation on your cellphone, you do not talk and listen on the same channel. If you did, the signals would interfere and you wouldn’t be able to separate your own voice from the voice of your partner.”
Today’s 5G networks feature only “half-duplex” links – essentially, the 5G signal uses slightly different frequencies, or the same frequency but at a slightly different time, to avoid interference. The time delay is imperceptible to the user.
By contrast, the full-duplex architecture developed by the researchers means that one can talk and listen on the same channel at the same time. Unlike other metamaterial technology, say the researchers, it spatially separates the forward and backward paths within the one frequency – doubling the system capacity.
While full-duplex functionality exists in a limited capacity in military-grade radars, it’s currently unsuitable for consumer applications such as mobile devices. For example, current full-duplex transceivers are made of bulky and expensive structures comprising ferrite materials and biasing magnets to manipulate the beam.
“我们提出了一种完全不同的机制，” Elefthreriades说。“没有磁铁或铁氧体。一切都是使用印刷电路板和硅电子组件（例如晶体管）完成的。”
研究人员说，这些智能的元信息的广泛适用性令人兴奋。他们的概念证明的知识产权最近被转移到蒙特利尔的初创企业Latys Intelligence Inc.，该公司由T Engineering Alumnus Gursimran Singh Sethi共同创立。
“Tunable, asymmetric radiation beams in both the reception and transmission states have incredible potential to address some of the most pressing and major challenges in the wireless communication industry,” says Sethi. “By spatially decoupling the receive and transmit paths, we can create ‘true full-duplex systems’ that can support bidirectional communication at the same time and the same frequency.
Sethi说：“这将使Latys产品和原型能够在竞争和牵引力方面获得优势，尤其是在诸如工业自动化，IIOT（IIOT IOTICT INTIFERIAL INTERPER INTERT INTERT INTERT）和5G应用程序之类的无线电托管环境中。”
For more, see “Full-duplex reflective beamsteering metasurface featuring magnetless nonreciprocal amplification。“
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