Reconfigurable intelligent surfaces: Myths and realities

[James_Knott]

This talk about mirrors and reflective surfaces reminds me of something I came across almost 50 years ago, when I worked for a telecom company. This is "billboard reflectors", which were huge reflectors, used to extend a microwave path beyond line of sight. While this was used in Canada's far north, the one I came across was at an office I worked in, in Capreol Ontario, which connected to another office in Sudbury. Problem was Sudbury was down in a valley (created by meteor impact) and the rim of the valley was blocking line of sight. To get around this, a billboard reflector was placed on a hill north of Capreol, which was line of sight to both offices, allowing the microwave connection to be made. This dates back to the mid 1960s, when that network was set up. I expect that link has long been replaced by fibre.
BTW, that meteor is why the Sudbury basin is home to copper and nickel mines.

[anandsingh]

Thank you so much, Prof. Emil Björnson. It is an interesting one, especially the myths you have clarified.

[asmaabid]

wishes professor would you consider giving a lecture on optimization dealing with the mathematical details about this

[ferchoalmeida]

This video is awesome!! Thanks Prof. Emil Björnson

[chicagogirl]

I don't understand why we don't have pre-log factor in metasurfaces

[mathematicality]

Hi Prof. Björnson. I'm thinking of incorporating these IRSs in optical wireless communications, specifically in FSO systems. In this case, we are using lasers instead of radio waves. It's often the case that concepts in RF cannot be translated directly to optical wireless communication systems. While the generalized Snell's Law is still applicable, I'm not sure about how the 'reconfiguring' and design of these metasurfaces for optical beams would be.

[booprice]

How can I make a simple RIS using copper tape on cardboard? How do I know what the pattern should be on the unit cells? Can you post a video going over making a small (2x2 or 4x4) RIS to demonstrate redirecting a beam from a antenna to a receiver antenna?

[linhai]

study irs from a communication systerm perspective ，it really nice idea

[bh]

Question for the Professor : How does it compare to DF relays interms of complexity and power consumption in processing circuit ? Is there a win there for the intelligent surfaces ?

[usama]

Hi this article that you share in the slide in which it is mentioned that DF relay shows better energy efficiency at low data rate but what about if we compare IRS with AF relay

[MohandAlbaz]

Thank you Prof. for this valuable video. Just I need your advice if possible, I am a postdoc and I don't whether I start do my research in IRS or cell-free massive MIMO. What do you think which one would be more impactful?

[vishnuvardhan]

Dear Prof. I have a query, why the spectral efficiency is reduced to half in the case of a classical relay solution?

[ShahnazFatima-gp]

may be a trivial question. may i know how the reconfigurability is realised.
1. the fpga or microcontroller controls the pin / varactor diode switching.
2. reconfigurability in metasurfaces is due to metameterials changing their permeability and ( other properties? ).
how 1 and 2 are related. i mean how the diodes effect the metameterials?
kindly help me understand this.
thank you

[ShahnazFatima-gp]

may be a trivial question, not for the professor Emil . myth 1 : can anybody justify the spectral efficiency formulae in both cases.

[wjyspdy]

I have a question Is there any tuning time to change the element of RIS??

[MohandAlbaz]

There is a paper concludes that the the IRS-assisted system is able to provide an energy efficiency up to 300\% higher than what can be provided by an angular multiple antennas amplify-and-forward relaying. Do you think the outcomes of this paper contradicts your results. This is the paper:
Huang, Chongwen, et al. "Reconfigurable intelligent surfaces for energy efficiency in wireless communication." IEEE Transactions on Wireless Communications 18.8 (2019): 4157-4170.

[mulusewyitbarek]

nice presentation.Dear professor, is there any opportunities to study phd in communication system engineering @linkoping University, LIU.in the form of scholarship

[subhoartwork]

Hi Professor, What software you will suggest to simulate this type of metasurface? and is there any way that I can communicate with you regarding this?

[mahammadrafi]

Hi professor.. I am a Research scholar from India. Would you please suggest one area for me to work in 5g

[ericphan]

We can use electrodynamic and ether to influence surface mirror different appearance over time occurence by changing surface voltage and temperature and space density over its surface and so we can make handsome look ugly or ugly look beautiful girls