 Hi, everybody. We are going to get started right on time. Maybe we'll wait for a second. We'll just get started. Okay. Welcome to our October webinar, Visible Light Communication and Applications in Smart Grids with Dr. Xiao from New Mexico Tech. I'm Brittany Vanworth, the Communication and Outreach Specialist for New Mexico EPSCORE, and that's the established program to stimulate competitive research. EPSCORE is a nationwide program funded by the National Science Foundation, and I'll be your host for today's webinar along with Dustin Allen, our systems and network analyst who will be behind the scenes making sure everything goes smoothly. All right. Oh, no, not yet. Okay. So a few housekeeping things before I begin. If you have any questions at any point, please type them into the Q&A box and Dustin will politely but firmly interrupt Dr. Xiao and read them out loud. I also want to let you know this will be the last webinar of our 2021 series. We will be back with more fabulous webinars in January 2022 and information about those and that lineup will be available in late December probably on our website and in the monthly New Mexico EPSCORE newsletter. All right. With that, I'd like to introduce our presenter for today, Dr. Xiao. Dr. Xiao received his BS degree in electrical engineering from South China University of Technology in 2011, an MS degree in electrical engineering from Hong Kong Polytechnic Institute in 2012, and a PhD degree in electrical engineering from New Jersey Institute of Technology in 2018. He obtained the Hashimoto Prize for best doctoral dissertation and he's currently an assistant professor in the Department of Electrical Engineering at New Mexico Tech. He is also a faculty hire with the New Mexico's Margaret Center. His research areas involve wireless communication and networking with primary interest in visible light communication and positioning. His current research efforts focus on retro reflective visible light communication, reinforcement and deep learning and intelligent reflecting service aided wireless network and ultra low power backscatter communication. I'm so glad you're here to explain what all of that means. Thank you so much for your time and please begin whenever you're ready. So thank you very much Brittany for introducing me and good afternoon everybody. Let me now share my screen and start the presentation. So can you see the full screen of my powerpoint? Okay and my sound is also clear right? Yes it is. Okay so good afternoon everyone. Today I'm going to talk about a pretty new term probably new to everybody the visible light communication and its applications in the smart grid project. Here is the outline. First of all I would like to talk about why smart grids need new wireless access technologies. Without new wireless access technologies what problem it will encounter? And as a new wireless access technologies the visible light communication can offload the data traffic from the conventional radio access. For example your home Wi-Fi router, the cellular network 4G 5G and also the visible light communication can secure the wireless communication between the smart appliances, the IoT sensors and the gateway. Compared to a conventional visible light communication the retro visible light communication is actually a further step for the VLC. Use some reflection instead of generating the optical signal and could be a better solution in some case. And also this retro VLC supports accurate real-time tracking that can probably will be very beneficial in the future automation system. When the automation system is included in the smart grid control then you would better know the real-time position of those like the robots the UAVs. Okay first let's look at what are smart grids or smart micro grids supposed to do. This is one sentence from the smart grid book. As a subset of smart grids smart micro grids operate in grid connected mode and offer the benefits of distributed computing and communications to deliver real-time information and enable instantaneous balancing of electrical supply and demand at the level required for each discrete device. So real-time instantaneous balancing and each discrete device are the essential features in the smart micro grid. For example your laptop requires a hundred watt your refrigerator requires a thousand watt. When you have an issue with the power supply which one you want to turn it off you don't want to turn the refrigerator off right you want to turn your laptop off or turn your desktop off. So this instantaneous balancing needs the real-time information collection to help the energy management operation to make the instantaneous decision in a smart way. In the home area network the smart grid can deliver the electricity to loads on a targeted as needed basis and the micro grids will do the custom diagnostic to do the load shedding and the level demand in real-time. You have many many devices in your home like smart appliances iot sensors and are the electrical devices like the electrical vehicles you want them to adjust their run schedule to reduce the electricity demand on the grid at critical times and that can significantly reduce your energy bill. The refrigerator and the desktop is one very essential example i think to show the importance of the load shedding. Typically the home smart appliances can be characterized in three categories tier one tier two and tier three. Tier one is the most sensitive one and you don't want to the tier one load to be disconnected or to lose the power at any time like the elevator like the emergency light. Part of the appliances you might consider the disconnection sometime even for a refrigerator like disconnected for an hour will not make your life much harder. Some devices we can disconnect it for a long time for example the fans and some appliances their tier level may depend on their depend on the season for example thermostats AC conditioner. These type of devices they are not that severe to be disconnected in let's say early or mid spring or mid autumn but they will give you very hard time if you disconnect your AC conditioner in the mid summer. So in order to collect this information in real time and have the best control over all this energy usage we want a new wireless technology that can give these five features simultaneously. They need to be reliable even though they need to be reliable they need to be secure protect your data exchange between you between the smart appliances and the energy management management operator and they need to be ubiquitous because you have the appliances everywhere they need to have low latency to guarantee the real time data collection and they also want to be energy efficient because you don't want to create something that is costing you a much additional energy to do some energy management right. Okay so giving this all these five features let's look at how our wireless technology evolved from the 20 years ago to the current one. 20 years ago we are using the gprs that's supporting the basic phone call short message services multimedia message services and it takes 36 hours to download a one gigabyte hd video. Back to now in the 5g communication network it only takes 0.8 second and in the 5g network we have three highlighted features the massive connections we want to satisfy the iot the internet of things requirement to connect everything of course in the smart grid we cares more about the electrical devices and we want to achieve ultra low latency the specification is lower than five milliseconds between the communication of a device and the cellular power the third one is the ultra high speed that's something around 10 gigabit per second although this is we know that even though for the Verizon the 5g network provided by the Verizon t-mobile they cannot go to that high speed right so actually the current 5g is not from my understanding it's not a complete 5g yet it utilize some additional bandwidth like in this figure it utilize some additional bandwidth in the 5g primary band but it's still lower than six gigahertz the very challenging part in 5g is the green part which is here why it's challenging because this type of signal that here is really fast and it's very hard for them to penetrate like the concrete wall therefore the indoor communication becomes a huge challenge to the cellular power if they are going to apply the signal here which we call it millimeter width this is the trend of the wireless technology evolution we keep exploring the higher frequency spectrum to allow more connection to provide lower latency to provide higher speed then what's next after the 5g maybe visible light could be a solution which is happening at the terahertz level what can actually visible light provide us there are many advantages for it high security you can only sense the signal inside your room no rfe mi the electromagnetic interference so it can be applied in some places for example the hospital it has no interference to the clinic equipment or some places like very sensitive to the rf signals like the underground mining and also vlc is ubiquitous where you have illumination you can utilize the light to do the visible light communication it can achieve the high data rate once it applied the mimo technique and it's a green technology because in addition to the power you cost to do the illumination it only costs you a little bit amount more to enable the communication and finally the high location accuracy is a benefit result from the dominant line of sight of the visible light signal you have some reflection from the wall from the objects from the obstacles but compared to the link between the light source and your optical sensor those reflections are probably the very accurate estimation three percent of the line of sight so they are not even strong enough to create interference that's the reason why we get the very high location accuracy so here we show a typical vlc system diagram to better understand what is the visible light communication instead of just showing a light bulb there so the light bulb is a emitter the led emitter then behind the emitter we have the deeming control that satisfy the illumination required level a data control send the zero one zero one bit sequence into the driver circuit and finally the driver circuit including the deeming control and the data you are going to transmit and generate a raw signal a current signal driving the led so the led transform the electrical signal into an optic signal and send into the air in the air your signal is fluctuating very quickly and this very quickly fluctuating signal is imperceptible to human eyes so that eliminates the concern that you are turning the light on and off and it will cause the blinking any blinking that has the frequency higher than 60 giga or 60 hertz 60 hertz means you turn on and off the light at a frequency above 60 hertz you typically cannot see the blinking at all that's that is done by experiment i test it and this optical signal once it's received by the photodiode the PD it will include some noise in it the noise comes from the circuit comes from the ambient light and this noise will accumulate with the signal and got amplified by this tia a trans impedance amplifier typically used to amplify the optical signal and transform into an electrical signal so that's the entire typical way how we use a light bulb to transmit signal and the carry data where we integrate the vlc into the smart grid home area network there are two fold benefits let's consider now we have some appliances like the washing machine the electrical vehicle a desktop we want to connect these devices all to a same gateway a wireless gateway it can be a wi-fi and this gateway is interfaced with the am i the advanced metering infrastructure to control the power to control the energy usage this because you are connecting all the appliances to just a single gateway therefore the latest the the the wireless channel is pretty congested and in such a way the latency goes up in the worst case the connection will not even be able to maintain means that you send the data the data will be just keep failing keep failing keep failing and then your channel is disconnected how we can solve this issue we can apply a visible light communication to offload some of the data to the light access point and then the wireless channel for the radio will be less congested and the latency will go down so that's the first benefit the second benefit consider a hacker that is outside of your room trying to intercept your wireless signal they can intercept the wire the wi-fi one or the radio frequency one but they cannot intercept the visible light one so that is a protection that enabled by the visible light communication channel off the data communication so based on this feature we can consider using the vlc link to do sensitive data exchange for example the key exchange and the mutual authentication while leave the conventional radio frequency link to do the encrypted data communication that is more bulky for example the video data segment the audio data segment so next we will explain this twofold benefit separately the first one we are going to introduce is the offloading how vlc offloads the data if we want to offload the data using the vlc link we first needs to connect the vlc to the internet right and one essential problem of the conventional vlc is the uplink your desktop does not have a light bulb to transmit the optical signal back to the ceiling light your printer also does not have a led emitter to shoot a uplink optical signal so how can we resolve this uplink challenge of the duplex vlc incorporating a conventional radio frequency uplink could be a solution so this schematic way we can use a duplex wi-fi link to connect your wi-fi access point with your laptop and the visible light will only provides the unidirectional downlink now we use a diagram to explain the traffic flow of this setting we call it asymmetric wi-fi wi-fi system wi-fi is another term for visible light communication is coming from the university of edinberg doctor has he proposed this wi-fi term back to 2012 in the td in a td presentation so asymmetric wi-fi wi-fi system we have a client which is the pc2 that this one is going to connect to the internet pc1 is the one that is driving the light source we use a software to to drive the light source and the package first of all the package going is going out from the pc2 the client which is the this blue one and then the package will pass through the access point and reach to the remote server located in the internet the remote server replied from the internet goes back to the wi-fi router and here now the tricky part occurs this package should be going to the pc2 based on your conventional setting however we change the routing table in the wireless access point to reroute the package to the pc1 which is the relay machine and then the package will flow through the wireless vlc channel and finally arrives the pc2 client so in such a way we can use the downlink vlc and the downlink vlc and the uplink wi-fi in an asymmetric way next i'm going to show you the testbed based on this design this diagram design so we have this desktop as a client we have this laptop as the controller for the software defined vlc and we have this led board as the light source we have this solar photo detector as the receiver next please watch a video here is the experiment devices of the sdvlc software defined visible light communication and you can see here is two computers this one acts as the client and this one acts as the relaying machine here is two peripheral devices which is the us rp this device is the photo detector which is the vc receiver in the vlc channel and this board will generate the led light carry the signal okay and now let's open a website in the client for example we type in the youtube.com and then click on the enter button okay you see the website show up here and now what i'm going to do is shade the light use this hand to shade the light and at the same time i try to open the google website here click on the button and we see there is no reflect no response okay now i move my hand away and let's see the client now the website show up yeah and that's the visible light communication connect to internet thank you very much so in this uh video we see that we use the unidirectional vlc to connect to the internet and the uplink is actually using a wi-fi from the client so it can actually uh implement such a system now we are looking at a broad view of how we integrate this uh hybrid wi-fi wi-fi into a heterogeneous network the coexistence of wi-fi wi-fi leverage ubiquitous the wi-fi illuminars to alleviate the wireless radio channel congestion and provide a better quality of experience to the end users looking in this room this lady is holding a phone very close to the wi-fi his signal her signal is very good so he she can use actually the wi-fi to communicate very well while this lady here using this laptop has a very low signal stress over the wi-fi if she also wants to use the wi-fi to transmit like the same amount of data used with same amount of latency that will cause a huge effort in the wireless channel which is not quite beneficial so in such a case we probably we want to use the wi-fi illuminars to offload some of the data that this lady this lady want through the optical channel okay so based on this broad view concept we consider two configurations the first configuration is what we have introduced we use a unidirectional vlc channel and the duplex wi-fi to send the uplink the second one we assume in some case that we have a duplex vlc and then the device can utilize two channels simultaneously to boost the data rate and we call the second case as the aggregated system based on experimental results we evaluate the average throughput for the end user when the number of user increases first of all let's look at what wi-fi only performs you don't need to worry that much about like the initial value like the 36.6 you may think like why wi-fi is so slow it shouldn't be that slow the reason here is the wi-fi router we connect to is actually the the school internet which has a restriction on the internet port so that's how restrict the initial value but typically a wi-fi router goes above 100 megabits per second has no problem but the main idea here is that as the number of users increase what happens to the wi-fi almost nothing ends up with when you connect six users to it so that's the problem of the current wireless gateway if you connect all your devices to the wi-fi router you will end up with nothing or even a disconnection for some of the devices and then let's look at what VLC end up with it does not change at all almost and that's reasonable because we don't have any contention among each spot your laptop user one illumination spot your refrigerator use another illumination spot so they don't have cost any confliction they don't cost any collision among each other where you aggregate these two channels you will have a boosted bandwidth so key notes for this experimental result the wi-fi performs badly for more access devices vlc performance is stable even though you increase the number of devices and the aggregation boosts the data rate by combining these two channels now you may think that aggregation is always better right then why we still need to consider the wi-fi only or vlc only we just combine all of this technology together and build us fuse the communication system use the bluetooth use thickb use wi-fi use everything that will give us the best performance the answer is no why no let's look at the experiment for a loading time in web browsing we try to connect to let's say yahoo go google youtube apple using these three configurations of course wi-fi is the worst when you connect multiple users to the internet and test the loading time wi-fi takes much longer time than the vlc like here wi-fi takes 6.3 seconds while vlc only takes 1.9 seconds to load the yahoo page but the reason why aggregation performs worse here why aggregation performs worse than the vlc only the reason is that you're of traffic some of them goes to the wi-fi some of them goes to the vlc but finally you need to assemble them right you cannot receive your wheel your front wheel without your frame to assemble your your bicycle you need everything to be there to finally show you the webpage so if the wi-fi is something that hold back your performance then aggregating them may not give you a better better outcome for this type of applications and this type of application is very similar to the smart grid remote control because you want the real-time information from every devices so keynotes here wi-fi performs the worst vlc performs the best and the aggregation system is held back by the high wi-fi latency now we complete everything regarding the vlc off loading system next we are looking at the second benefit secure the wireless communication before we look at the secure wireless communication we first need to understand what the vulnerability currently we have let's say you bring a mobile phone close to your wi-fi router if it's your first time you click on the ss id you enter your password you are connected to it the second time or the third time you might not need to enter the password you just go close by your mobile phone will be directly connected to the wi-fi because the password is stored in your mobile phone but no matter its first time or second time or third time authentication every time the authorize the user will communicate with the authenticator which can be the wi-fi router through a key exchange process this key exchange process will involve a four-way handshake which will create a key that encrypt the data exchange later on the vulnerability of the current most commonly used encryption method check your home wi-fi check your office wi-fi they all use this wpa to personal settings probably a university wide in the show wide we'll use some other but small units small business unit like the home office they typically use wpa to personal and if they are using wpa to personal what happens is this key exchange can be intercepted passively via interceptor and then this interceptor do some reverse engineering method to find out the password of your wi-fi and decrypt the data exchange so finally your data exchange between your mobile device or between your other electrical consumption device and the authenticator becomes plain tax to the interceptor next let's use a video to show how actually your passive interceptor can steal your wi-fi login password we have used this wi-fi router and we use this white usb device as the wireless adapter which is actually a hacking device that passively intercept your wi-fi signal and then the result will be displayed on this screen show the captured packets and decrypted wi-fi password next let's look at a video hello this video is going to demonstrate the vulnerability of the standard security protocol for wi-fi routers known as wpa to the router needs to be compatible with this protocol the method i'm going to use to expose this vulnerability is intercepting data that is being communicated between a device and the router the device being used for this is a wireless adapter shown here this device is used normally to give access to wi-fi to the device that is plugged into this device has another capability it's called monitor mode monitor mode allows the device to monitor the data moving over wi-fi the device can be put into monitor mode with a software called air crack dash ng then information for all the nearby routers can be displayed once we have found our router and use a simple command then we could capture the data by connecting a device to the wi-fi after the device is connected the software called wire shark can display the authorization packets in real time so as you could see this phone is connecting to the router in real time and you could see the packets showing up on wire shark these lines in wire shark will give us all of the information needed to recover the password then with one command the password can be found this is done by matching the data found with over 14 million common passwords as you can see the password is password then it could be demonstrated on another device logging into the wi-fi and the password is p-a-s-s-w-o-r-d password joining we are connected so that actually shows us so that actually shows us the vulnerability of the current wi-fi communication and we need to solve it right we are not going to connect our like smart appliances to this type of vulnerable although we can apply some other settings for example the radius server we can apply wpa3 which is not a commonly used one yet they are pretty much using a remote server to do an not a tier authentication but how can you prepare a remote server for every home that becomes a question so for the small unit for the small energy consumption unit probably you want to consider some other low cost and flexible solution vlc could be this solution how we can use vlc to do that we exchange the sensitive data on the vlc link for example authentication request and response association request and response key management like the ea-pa-l messages you show we show on the wire shark and after we have done all this key exchange process once the key is already known by the supplicants which are the mobile devices or other electrical devices and the indicator which could be the wi-fi router the key are known at both end or both entities we now use the key to do the x data exchange on wi-fi so the interceptor will not be able to get your key in such a way it cannot decrypt your data exchange over the radio there are many different ways to implement such uh like a traffic redirection one way is to implement it in the data link layer using different interface like one interface card is used for optical communication one interface card is used for the radio communication and then we aggregate this traffic to the network layer and upper layer like the tcp layer application layer based on this requirement we only need to exchange the sensitive data over the vlc do we need a one gigabit link probably not right the sensitive data exchange probably only cost you 10k 100 kilobits per second during that awake time so in from this thinking logic probably we can utilize something else other than only vlc to compromise our data rate while solving some other issues like the size the weight the energy consumption the cost all the other concerns and also very important alignment so based on this thinking logic retro vlc probably will be a better solution the left hand side which is the conventional symmetric vlc will send a downlink from a light bulb to a light sensor the uplink from another bulb to another light sensor in this case you need the very high power you need very high power uh at the device side you probably need some uplink alignment because if you missed alignment your signal will be very bad and you also have the potential uplink glaring because you are shooting a light from your desk to your ceiling and also the light bulb putting on a mobile phone is very bulky so there are some about these advantages of this uh conventional symmetric vlc setting but it can achieve better throughput no doubt but do we need that we don't in this specific application therefore retro vlc which is at the right hand side the ultra low power asymmetric retro vlc will just place this retro tag which only costs you hundreds of micro watt you probably does not have an idea what does hundreds of micro watt mean your current uh mobile phone consumes hundreds of milliwatts to transmit a signal your wi-fi router taking the heat uh heating effect into account will can goes up to six watt to ten watt power consumption to support the wireless communication so you see how low the power consumption is for this retro tag and then this retro tag will receive the downlink signal from the light bulb to a light sensor and the important part the new the new concept is uplink the uplink will be reflected by a retro reflector similar material to the stop sign you see in the uh in your uh highway as well highway sorry the cross uh the crossway and then uh this retro reflected material reflect the light and pass through something called lcd shutter the lcd shutter is just a single pixel on your mobile phone screen on your desktop screen on your laptop screen your screen has so many such pixels and we can make this pixel larger to turn on and off that selectively block and transmit the optical signal through it and this reflected signal will be received by the light sensor and finally create the duplex link in the meantime the light can also uh one second i don't know what happens but let me just reshare this slide in the meantime the led can support the power consumption of the retro tag by providing the energy for it so it's a there are many advantages for it like the ultra low power consumption the uplink alignment is already done because it's retro reflection reflect the light back to its source and there's no diffused uplink reflect glaring light you are not going to look at the tag beside the light bulb if you if you are moving a little bit away from the light you will not see any light from the retro reflected tag so it's a there's no uplink glaring and it's small size and lightweight one issue for this retro vlc is the bandwidth is limited two commonly used lcd shutters are currently in the market the twisted pneumatic and the pie cell shutters each of them associated with different driving voltage uh tn has a lower one but lower frequency pie cell has a higher voltage but higher frequency let's do some experiment now we transmit the uh we put an led light bulb at the one side of this uh shutter and the shutter will turn on and off so it becomes a signal goes to the photodiode and the photodiode will be connected to an oscilloscope and the signal will be displayed on the oscilloscope and what we do in this experiment we change the frequency of this on and off of the lcd shutter and check the frequency and check the waveform on the oscilloscope first we check the two hertz two hertz give us a very nice look square wave what happens 10 hertz still square wave 40 hertz probably not 100 hertz kind of a sinusoidal 140 hertz close to a saw tooth 200 hertz pretty much a saw tooth 300 hertz a saw tooth and it's fluctuating this saw tooth is not even stable when it goes to 400 800 1600 you can see that not only the square wave becomes a saw tooth this entire signal is superimposed on a low frequency signal which is something we don't want at all we say that this signal is completely distorted and cannot be utilized unless we really figure out like the low frequency signal how much it is and also the signal amplitude getting much lower getting much lower so that's the what do we mean by increasing the frequency is cannot be achieved cannot be achieved by these lcd shutters then based on this limitation we propose another concept the pixelated retro vlc tag instead of using one shutter we can actually aggregate or integrate many different shutters the band one of the benefit is that the smaller size of the shutter will have the faster switching speed that's a manufacturing concept when you manufacture small lcd shutter this capacitance we call it junction capacitance is less and then your lcd shutters can turn on and off faster then when you integrate many many pixels you can turn on and off each pixels individually to create a multi-level optical signal and up on that we can include we can develop more advanced modulation schemes rather than just the simply on and off key this is a current testbed that we have developed from the new mexico tech on the trail we have a retro vlc tag that have multiple pixels on it you can see it's four times five so there are 20 pixels on it the right hand side is the light access point based on some this is currently in the preliminary setup so based on some turning on and off we can only show currently a very low amplitude square wave signal that is reflected from the retro vlc tag showing on the oscilloscope and if you're looking into the construction of the retro vlc tag and the light ap the retro vlc tag use a microcontroller to send the digital signal to control the pixels on the retro vlc tag individually and independently the light ap use a light source use three light sources and the envelope protodetector to send and receive the light signal one other prototype is developed by my collaborator which is also my phd supervisor from new jersey institute of technology this tag use the corner cube retro reflector instead of those retro reflecting material on the stop sign the corner cube will provide a stronger reflection light because it's regular shape and it includes a solar cell to harvest the energy and the harvested energy will drive the driver circuit and the driver circuit will turn on and off the lcd shutter currently is placed on top of the corner cube retro reflector so the driver circuit turn on and off this lcd shutter to send the signal up based on this corner cube actually we can include something that is very interesting the real time tracking using this retro vlc tag consider a light infrastructure we include some photodials on top of the light infrastructure and connect the photodials to a centralized controller let's say you have some devices the mobile devices the human variable devices and some instrumentation devices all cost some electricals consumptions you place the retro tag the retro vlc tag on all of them and then they will reflect the light back to the photodials based on this reflect light signal strands you can compute the 3d coordinates of this all these devices in real time and in the meantime this retro vlc tag can send the zero one zero one data back to the photodials to enable the communication so that's why we call it vlcp the visible light communication and positioning system in this positioning system the research challenge is when the retro reflector changes location and orientation the received optical power on the photodial will change the reason why it changes is because the light from the light that is going to be reflected back the area we call it effective reflecting area from the light emitted from this reflecting area will finally be reflected back to the photodial and the interesting part is when you change the corner cubrature reflector location the effective reflecting area will also change so the the the concept becomes how we correlate the effective reflecting area with the location of the retro reflector the key idea of this design is that once we look at a parallel light rays in incident on the corner cubrature reflector only partially of them will be retro reflected back and if we look at the top view of this cylinder structure of the light rays they are actually a overlap area or intersection area between two circles and the first circle is the and these two circles are the front face of that corner cubrature reflector so what we do we put these two circles on top of the light source plane which is the light source on the sailing and what we can do to figure out the era we rotate this intersection area around the p the p is the place of the photodial and the p prime is the symmetric point which will indicate the trajectory sorry indicate the boundary of that era so when we do this rotating the p prime is the boundary of the era now let's look at how the boundary looks like the boundary is actually the intersection of two larger circle and we can easily use some mathematical derivation to find out the radius of these two larger circles so finally we characterize the relationship between the effective reflecting area and the location of the retro reflector based on this closed form expression we developed a localization system and tested using the testbed it shows that the location error can be at centimeter level for different height so the first plot the location error is a centimeter level location accuracy if we include the orientation like the asthmus angle and the elevation angle of the corner cube and the location of the corner cube then it can achieve also sentiment the level location error although a little bit higher and the single digit orientation error for the angle so that concludes everything for my today's presentation and now we enter the last part q and a thank you so much that was really cool I did not expect to one understand it and two be so impressed I'm gonna give people a second to ask their questions I know I have a few but I'm gonna see what people if they have any questions first or you know what maybe I'll just ask before because I can all right I have a question about um have you heard of information centric networking yes okay what are your thoughts on this technology in that space um so the informational centric uh network design is uh completely change the current ip-based routing concept and it's a very network layer uh based design uh so they are so that I can say in this way the information centric network do not really care about whether you are using radio or whether you are using optical the physical layer implementation like what the medium is is invisible to the decision making at the network layer data when it's reached to the decision uh layer at the information centric network becomes a packet so no matter what technology you use it's just a packet and the information centric network uh instead of using the identity which is the ip address of the user as to guide how these packets are going flows through the network they use the data to do these uh flow guidance and unfortunately today we don't have the expert dr jen who can give better comments on this question but that's my best understanding okay I was just wondering if they're I mean because this seems like a really cool way to distribute networking load um oh and I do have questions so I'm gonna be quiet doesn't go okay yes we do have a couple of q&a questions uh the first one is what are your predictions for when vlc will move out of the lab and into real-world applications are there any vlc applications currently in use so uh there are already some vlc companies uh one in california in europe uh the doctor has from uh university of adinburg built the very the first vlc company called pure li-fi and they all sell the vlc products to the market we originally back to eight years ago we originally expect the vlc to be one mature uh technology in 5g unfortunately the optical device has a kind of high restriction on the modulation bandwidth so currently we are turning on and off this uh uh this uh light bulb or led emitter this specific method kind of restrict the modulation bandwidth and also the you we need to also answer a question what if we do not have the light turn on what happens sometimes the light is turned off we can also transmit uh data when the light is turned off but in a very low data rate so there is some compromise there so there are still many many challenges of the vlc that needs to be uh completely solved in order to push to the market and make it as a popular and commonly used communication technology in almost uh all the prestige journal magazine top conferences they all expect that higher frequency spectrum such as vlc will be the next uh generation wireless communication method because this is the trend this is the trend but how to overcome the optical device limitation and push this communication technology to the real market is still an open research problem gotcha thank you um leading into that um but barriers to see to adoption and the greater into the technological community it seems like this is still very young and upcoming uh sort of technology but what are some of the um bar's entry into the market yes i totally agree that this is a pivot to the technology if we look at the investment and the the the gain from the the consumer if we look at the the the company that is currently uh in in in california that is selling the uh the light and the communication usb driver that you can plug in into your mobile device and communicate with the light the light bulb is costing you one thousand and seven hundred dollars just a single desktop light and that usb communication unit costs you another thousand um still currently i do not have a clear answer how to make this uh like revenue happens in a smart way to to push this technology in the market something unfortunate for the vlc researcher is that millimetre wave is too strong that's why in the 5g communication people rather than looking at like the even higher frequency like terahertz they look at the millimetre wave first something between six gigahertz and a terahertz so millimetre wave becomes the uh the hottest research topic in 5g but we definitely expect that vlc is the next step after the millimetre wave because currently based on the uh high level view of all the wireless access access access technologies in order to come in order to satisfy all the specifications in the six g standard although it's currently still under development uh but there is some specification there in order to satisfy all those specifications uh it seems that there is no other options thank you i don't think we have any other questions at this time okay um so i i'm still grasping this concept and i think i'll close this out but like in my in my mind i see this as like a pentagon thing where they go into a room and turn on a special light and then they have their encrypted conversation and no one else can can influence is that is that even like semi-realistic no maybe you you you are asking my question yeah i could could this be i wonder if this could be implemented as a defense technology um i don't know anyway uh now really question just kind of a comment and observation um i'm going to there gonna close us out uh i wanted to say thank you so much uh dr shaw one sport for being so generous with your time and expertise on behalf of everyone who is part of the new xbox market project thank you and uh before we sign off i also want to thank my partner in crime dustin alan and don't forget to visit our webpage and read the monthly newsletter to find out what great webinars and opportunities we're hosting next uh see you all in 2022 and again thank you thank you thank you dr shaw thank you also britney