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Wireless Future
Sweden
Приєднався 1 кві 2016
Wireless Future is a channel by Emil Björnson (Professor at KTH Royal Institute of Technology) and Erik G. Larsson (Professor at Linköping University), both IEEE Fellows and Clarivate Highly Cited Researchers. The channel focuses on wireless communications and its applications. It contains a combination of podcast episodes, popular science material, tutorial videos, lecture material from university courses, and technical presentations related to recent research. Some recurring themes are Cellular and Cell-free Massive MIMO, reconfigurable intelligent surfaces (a.k.a. intelligent reflecting surfaces), 5G, and 6G.
6G in the Upper Mid-Band: The Rise of Gigantic MIMO
For the last five years, most of the research into wireless communications has been motivated by its potential role in 6G. After this exploratory phase, it is time to identify which new technology components will make it into the standard and eventually into practical networks. It has recently become clear that 6G networks will operate in the upper mid-band from 7 to 25 GHz, which has been called the "golden band" since it offers more spectrum than current 5G networks in the 3.5 GHz band and much better propagation conditions than at mmWave frequencies. The most interesting new frequency range is around 7.8 GHz, where 650-1275 MHz of spectrum might become available, depending on the country. This might seem like a lot, but it is far from enough to reach the ambitious 6G requirements defined by the International Telecommunications Union.
For 6G to deliver on its promises, we also need a leap in the antenna technology - from "Massive MIMO" in 5G to "Gigantic MIMO" in 6G. In this video, Professor Emil Björnson explains the anticipated development with a focus on how many antenna elements we need to overcome the pathloss challenge, how to reach the theoretical peak bit rates, how to achieve impressive typical rates using spatial multiplexing, and how to utilize radiative near-field propagation effects for more precise communication, localization, and sensing. He also identifies four open research areas where new contributions have good prospects to affect the actual 6G technology implementation.
This talk was first delivered at the NGMA-ETI 2nd QMUL ‘6G’ Workshop, Queen Mary University of London, July 11, 2024.
The slides are available here: github.com/emilbjornson/presentation_slides/blob/master/6G_gigantic_MIMO.pdf
If you want to learn more, we recommend the following article:
Emil Björnson, Ferdi Kara, Nikolaos Kolomvakis, Alva Kosasih, Parisa Ramezani, and Murat Babek Salman, “Enabling 6G Performance in the Upper Mid-Band Through Gigantic MIMO,” arXiv:2407.05630.
arxiv.org/pdf/2407.05630
For 6G to deliver on its promises, we also need a leap in the antenna technology - from "Massive MIMO" in 5G to "Gigantic MIMO" in 6G. In this video, Professor Emil Björnson explains the anticipated development with a focus on how many antenna elements we need to overcome the pathloss challenge, how to reach the theoretical peak bit rates, how to achieve impressive typical rates using spatial multiplexing, and how to utilize radiative near-field propagation effects for more precise communication, localization, and sensing. He also identifies four open research areas where new contributions have good prospects to affect the actual 6G technology implementation.
This talk was first delivered at the NGMA-ETI 2nd QMUL ‘6G’ Workshop, Queen Mary University of London, July 11, 2024.
The slides are available here: github.com/emilbjornson/presentation_slides/blob/master/6G_gigantic_MIMO.pdf
If you want to learn more, we recommend the following article:
Emil Björnson, Ferdi Kara, Nikolaos Kolomvakis, Alva Kosasih, Parisa Ramezani, and Murat Babek Salman, “Enabling 6G Performance in the Upper Mid-Band Through Gigantic MIMO,” arXiv:2407.05630.
arxiv.org/pdf/2407.05630
Переглядів: 3 039
Відео
6G: What, why, and how?
Переглядів 4,4 тис.Місяць тому
Professor Emil Björnson (KTH Royal Institute of Technology) overviews the 6G technology development. He begins by explaining what cellular/mobile communication networks are and how their characteristics and services have evolved over the last five generations. He then describes why we need 6G and what it might be used for during the next decade. Next, he explains how the 6G standard is develope...
Reconfigurable Intelligent Surfaces Through the Lens of Array Signal Processing
Переглядів 3,5 тис.2 місяці тому
Recording of the keynote speech that Prof. Emil Björnson delivered at the IEEE CAMSAP 2023 (camsap23.ig.umons.ac.be) and IEEE SITB 2024 (sites.google.com/view/sitb2024/). Abstract: Wireless communication systems have traditionally been designed to operate under the channel conditions provided by nature, with the Shannon capacity being the ultimate limit. The advent of reconfigurable intelligent...
Three Misconceptions in Near-Field Communications
Переглядів 2,9 тис.3 місяці тому
This is a recording of Professor Emil Björnson's invited talk in the "Special Forum: Theory and Technology of 6G Near-Field Communications" at the 17th China Electronics & Information Conference. This hybrid event took place at the Pan Pacific Hotel, Ningbo, on April 27, 2024. Abstract: The attempts to use mmWave bands in cellular networks have largely failed. The latest example is South Korea,...
Bit Error Ratio or Channel Capacity: Which metric should I use? [Frequently Asked Questions]
Переглядів 2,9 тис.4 місяці тому
Professor Emil Björnson (KTH, Sweden) answers the question "Bit Error Ratio (BER) or Channel Capacity: Which metric should I use?", which he has received repeatedly in emails, on his blog, and in comments on this UA-cam channel. The background to the question is that the BER is often considered in basic communication textbooks, while research papers often consider the capacity metric. The short...
Ep 40. Synchronization of Massive Antenna Arrays [Wireless Future Podcast]
Переглядів 1,8 тис.4 місяці тому
Many textbook models of communication systems assume that the transmitter and receiver are synchronized in time, frequency, and phase. Achieving and maintaining such synchronization is an often-overlooked practical challenge. However, the importance of synchronization grows as we plan to use larger antenna arrays and distributed MIMO in 6G. In this episode, Emil Björnson and Erik G. Larsson dis...
Introduction to Multiple Antenna Communications and Reconfigurable Surfaces
Переглядів 3,4 тис.5 місяців тому
Professor Emil Björnson explains why he wrote the open-science book "Introduction to Multiple Antenna Communications and Reconfigurable Surfaces" together with Özlem Tuğfe Demir. In particular, he answers the questions: What is covered by the book? Who is the book written for? Where can I get the book? You can download the PDF for free from: www.nowpublishers.com/article/BookDetails/97816382831...
Ep 39. Radio Stripes at Terahertz (With Parisa Aghdam) [Wireless Future Podcast]
Переглядів 1,7 тис.5 місяців тому
Massive bandwidths are available in the sub-terahertz bands, but the coverage of a cellular network exploiting those frequencies will be spotty. The 6GTandem project tries to circumvent this issue by developing a dual-frequency system architecture that jointly uses the sub-6 GHz and sub-THz bands. In this episode, Erik G. Larsson and Emil Björnson are visited by Dr. Parisa Aghdam, Technical Lea...
How many beams can you send from a MIMO array? [Frequently Asked Questions]
Переглядів 2,9 тис.6 місяців тому
Professor Emil Björnson (KTH, Sweden) answers the question "How many beams can you send from a MIMO array?", which he has received repeatedly in emails, on his blog, and in comments on this UA-cam channel. The answer is not what you think it is, unless we reformulate the question. Emil illustrates and explains the basic concepts in an accessible manner. Intro music: Quiet Calculation by Joseph ...
Ep 38. Things We Learned at the 6G Symposium [Wireless Future Podcast]
Переглядів 3,5 тис.7 місяців тому
Many topics are studied within the 6G research community, from hardware design to algorithms, protocols, and services. Erik G. Larsson and Emil Björnson recently attended the ELLIIT 6G Symposium in Lund, Sweden. In this episode, they discuss ten things that they learned from listening to the keynote speeches. The topics span from integrated sensing, positioning, and localization via machine-lea...
Ep 37. Wireless Future Panel Discussion (Live Podcast) [Wireless Future Podcast]
Переглядів 3,2 тис.9 місяців тому
We celebrate the three-year anniversary of the podcast with a live recording from the Wireless Future Symposium that was held in September 2023. A panel of experts answered questions that we received on social media. Liesbet Van der Perre (KU Leuven) discusses the future of wireless Internet-of-Things, Fredrik Tufvesson (Lund University) explains new channel properties at higher frequencies, Ja...
6G requires many more antennas than today - this is how it will work!
Переглядів 2,7 тис.9 місяців тому
Many antennas are required to get 6G, the future technology for mobile networks, to work properly. This can be done, for example, by setting up strips with small antennas. Emil Björnson and his research group at KTH develop the technology with the help of advanced calculation algorithms. Watch the movie with one of SSF's Future Research Leaders 7! The video is recorded by the Swedish Foundation...
6G kräver många fler antenner än idag - så ska det gå till! [English version exists]
Переглядів 3169 місяців тому
There is a version with English subtitles: ua-cam.com/video/kOC0TOZmh4g/v-deo.html Beskrivning: För att 6G, framtidens teknik för mobilnäten, ska fungera krävs det många antenner. Det kan till exempel ske genom att sätta upp remsor med små antenner. Emil Björnson och hans forskargrupp på KTH utvecklar tekniken med hjälpa av avancerade beräkningsalgoritmer. Filmen är skapad av Stiftelsen för Str...
Fundamentals of Wireless Channels
Переглядів 5 тис.10 місяців тому
In this video, Professor Emil Björnson explains the basic principles of wireless communication channels, such as the impact of antennas and wave propagation. The free-space pathloss formula is derived and the impact of the antenna gains is clarified. Finally, the use of antenna arrays to create controllable antenna directivity is introduced. The slides are available here: github.com/emilbjornso...
Linear Time-Invariant Systems
Переглядів 1,7 тис.10 місяців тому
In this video, Professor Emil Björnson explains what a linear time-invariant (LTI) system is, and how such systems interact with signals. In particular, examples of linear and non-linear are provided, as well as examples of time-invariance and time-varying systems. These concepts underpin the study of communication systems, where the communication channel is a system. The slides are available h...
Ep 36. 6G from an Operator Perspective [Wireless Future Podcast]
Переглядів 2,6 тис.11 місяців тому
Ep 36. 6G from an Operator Perspective [Wireless Future Podcast]
Beamwidth, beam pattern, and sensing [Part 5, Fundamentals of mmWave communication]
Переглядів 5 тис.Рік тому
Beamwidth, beam pattern, and sensing [Part 5, Fundamentals of mmWave communication]
Maximum ratio and zero-forcing beamforming [Part 4, Fundamentals of mmWave communication]
Переглядів 7 тис.Рік тому
Maximum ratio and zero-forcing beamforming [Part 4, Fundamentals of mmWave communication]
Constructive and destructive interference [Part 3, Fundamentals of mmWave communication]
Переглядів 3,3 тис.Рік тому
Constructive and destructive interference [Part 3, Fundamentals of mmWave communication]
Wireless propagation losses [Part 2, Fundamentals of mmWave communication]
Переглядів 6 тис.Рік тому
Wireless propagation losses [Part 2, Fundamentals of mmWave communication]
Beamforming directivity [Part 1, Fundamentals of mmWave communication]
Переглядів 13 тис.Рік тому
Beamforming directivity [Part 1, Fundamentals of mmWave communication]
Ep 35. Ten Challenges on the Road to 6G [Wireless Future Podcast]
Переглядів 3,5 тис.Рік тому
Ep 35. Ten Challenges on the Road to 6G [Wireless Future Podcast]
New professor: Emil Björnson, Wireless Communication
Переглядів 2 тис.Рік тому
New professor: Emil Björnson, Wireless Communication
Ep 34. How to Achieve 1 Terabit/s over Wireless? [Wireless Future Podcast]
Переглядів 2,6 тис.Рік тому
Ep 34. How to Achieve 1 Terabit/s over Wireless? [Wireless Future Podcast]
Ep 33. Reproducible Wireless Research [Wireless Future Podcast]
Переглядів 4,7 тис.Рік тому
Ep 33. Reproducible Wireless Research [Wireless Future Podcast]
Intelligent mirror on the wall, what's the best use case of them all?
Переглядів 3 тис.Рік тому
Intelligent mirror on the wall, what's the best use case of them all?
Wireless Networks With Uniform Performance: Distributed MIMO and Sequential Fronthaul
Переглядів 3,3 тис.Рік тому
Wireless Networks With Uniform Performance: Distributed MIMO and Sequential Fronthaul
Ep 32. Information-Theoretic Foundations of 6G (With Giuseppe Caire) [Wireless Future Podcast]
Переглядів 12 тис.Рік тому
Ep 32. Information-Theoretic Foundations of 6G (With Giuseppe Caire) [Wireless Future Podcast]
Cellular Networks: How will they evolve?
Переглядів 2,3 тис.Рік тому
Cellular Networks: How will they evolve?
Introduction to Mobile Networks and Services
Переглядів 8 тис.Рік тому
Introduction to Mobile Networks and Services
Hi, I remember some textbooks say that ZF will amplify the noise, how can this be interpreted geometrically like 15:05 ? Additionally, on the page 442, line 4 of your new book INTRODUCTION TO MULTIPLE ANTENNA COMMUNICATION, it seems that LMMSE will sacrifice the desired signal power, how could this be interpreted? Thanks in advance!
I’ve also seen that statements in textbooks and I’m not particularly fond of it, mostly because it only makes sense for receiver processing and not transmission. The ZF combining vector can be scaled in different ways. What I assume in the video is that we normalize the vector so it has norm/length 1. This implies that the noise variance remains constant but we sacrifice signal power to eliminate the interference. Another approach is to scale the ZF vector so that the signal power remains constant. In that case, the price to pay for removing interference is that we amplify the noise. These two interpretations are equivalent in the sense that the SNR after ZF is the same. Which option that is closest to reality depends on the hardware implementation. LMMSE tries to maximize the SINR (which is equivalent to minimizing the MSE). There are two terms in the denomination: interference and noise. To mitigate interference, we need to sacrifice parts of the desired signal - the parts that lies in the same dimensions in the vector space. To “mitigate” noise, we just need to keep the desired signal power as strong as possible. LMMSE finds a balance between these things: A balance between ZF and MR.
Thanks! It is now much clear to me.
Thank you so much for this brilliant lecture
Good video! So what problem will near field communication bring compared to far field communication? Thanks!
A lot of work on “massive MIMO” focused on making the algorithms universally applicable so they don’t require a particular propagation environment or array configuration to be used. All such results are directly applicable to both near and far field channels. New challenges arise when we want to exploit the specific channel characteristics in the algorithms to improve things like channel estimation. The broadcasting of information might also have to be done differently.
Good explanation! A small question, at around 8:15 , you mentioned that in TDD mode, the user send pilots and base station estimate the channel. Then in the downlink, should the base station send pilots and user estimate the channel? ❤ Thanks!
This is a good question that I tried to answer in a blog post a few years ago: ma-mimo.ellintech.se/2018/11/02/when-are-downlink-pilots-needed/ From a theoretical standpoint, it is sufficient to send pilots in one direction and then use it to make the effective channel predictable in the other direction. However, in practice, we often send pilots in both directions to deal with hardware impairments. Insufficient calibration between the hardware components used in uplink and downlink will lead to slightly different channels. This is particularly the case with phase drifts that are added with different signs in the uplink and downlink.
@@WirelessFuture Thanks for your explanation! In this blog, it is assumed that uses are equipped with single antenna and downlink pilots are not needed theoretically. For the case where multiple antennas are equipped, should we send downlink pilots? I think users must know h to combine signals ( MRC et al.) and hence downlink pilots are needed. Is that true? Additionally, if downlink pilots are needed, the number of downlink pilots is proportional to the number of antennas at the base station M, which may incur high signaling cost in massive MIMO, right?
You are right that downlink pilots will be needed whenever the user device has multiple antennas. In that case, one should transmit one pilot per downlink beam, and beamform/precode it as one will do what the downlink signal. The number of downlink pilot is then equal to the number of beams, which is typically much lower than the number of base station antennas. So the signaling code is not overly high - typically the same as the uplink pilot signaling.
@@WirelessFuture clear explanation, thanks for ur patient response!
Thank you! A small suggestion: could u please summarize what has been talked at the end of the video? Hence, we can get a hole picture of today’s talk. ❤
I have a question to an exercise. It is about that capacity expression (OFDM MIMO - 7.10). The solution is C=2S*ld(1+2*q*beta/N0). It is just about the SNR expression. It is surely from the equation...(1+(q_opt*s^2)/N0). The s is 2 for both H (just one sing. value) So 2^2 is 4, but we have 2 in the nominator. I assume q_opt is q/2. But I don't know why? Because we have 2 transmit antennas? But we have just one sing. value, with (7.49), I don't get to q_opt=q/2 with that equation. Thanks a lot.
We didn’t even need 5G
The fact that one third of the worldwide mobile data traffic is transferred over 5G is an example of why 5G is very useful.
Hi, when we say fast fading or slow fading, should we always assume that transmitter does not know CSI? For a close loop system, should we consider fast fading or slow fading?
Yes, these traditional terminologies were defined for open-loop systems, which remains relevant for broadcasting of information. The main data transmission is often done in closed-loop mode nowadays and such systems are usually designed for fast fading and uses frequent pilot signal transmission to estimate/track the channels. We discuss this later in the course when we reach the “Massive MIMO” part.
@@WirelessFuturethanks for your explanation ❤
sir here mmse estimation is carried out for Gaussian distributed variables. however, if we are interested for rician distributed variables mmse estimation then what will be change in to the derivation provided in to the video or where I will find it . kindly provide link or details of it.
The general formula for the MMSE estimator (Slide 4) holds regardless of the distribution, but it is considerably more complicated to compute the estimate. I'm not aware of a general closed-form expression of it, but there are two special cases that have been treated in the prior literature: "Phase-aware MMSE estimator" and "Phase-unaware linear MMSE estimator". We cover these things in the following paper: arxiv.org/pdf/1903.07335
I want to know details about spatial layers and sub antenna array formation. how do these impact the capacity?
Spatial layers are data signals sent at the same time and frequency, but with different spatial directivity. It is like listening to two songs at same time - one with each ear. The capacity increases almost proportionally to the number of spatial layers. The word “almost” refers to that we need to divide the signal power between the layers and that there might be interference between the layers. With subarrays, we can reduce the latter losses since the spatial resolution of the transmission improves.
Thanks and one curious question, Is it possible to create orthogonal beams and send to same user so that separate streams can be transmitted on those beams and increase the data rate for that user ?
Yes, this is known as single-user MIMO or point-to-point MIMO. The number of beams that can be sent in this way is equal to the number of distinguishable paths between the transmitter and receiver. If you begin with sending one beam directly between them, then the next beam needs to be aimed toward a reflecting object that is located outside the first beam, from both the transmitter’s and receiver’s viewpoint.
@@WirelessFuture thanks for the answer, but what if there is no reflection path, it is simply LoS scenario
In a far-field free-space LOS channel, one can only transmit one beam since there is only one path. In practical LOS scenarios on earth, there are usually some reflected paths as well but they can be so much weaker than the LOS path that they doesn’t help much in boosting the data rate. This is why multi-user MIMO is particularly important in current and future systems because one can always send beams to multiple users, even in LOS scenarios.
@@WirelessFuture thanks for your very good explanation :)
Nice overview 😊
amazing talk
very informative lecture; thank you so much.
I am about exercise 6.11 from your great book. Can you give me an approach how we get to that result in a) (P*beta_k/4.....), please? I am struggeling there. Thank you.
In the past each new generation used to bring more bandwidth, more antennas, and more base stations per unit geographical area. 6G seems to continue with the trend of more bandwidth and more antennas but what about network densification? Is their any juice left in that idea or have we pretty much squeezed out every single drop out of that?
When there is a need for more capacity, network operators have a choice between adding more base station sites or using a higher MIMO dimension at existing sites. The latter was not a real option until 4G LTE Advanced, and network densification has become less attractive since then. The fact that 5G mmWave networks have failed to become economically sustainable is an example of how further densification is unattractive. So yes, we have squeezed out the most we can from that. What remains is the battle between WiFi and 5G/6G in private networks, where the telecom industry hopes to make money from guaranteeing better performance than in WiFi.
@@WirelessFuture Thanks for taking time to answer this. Glad you clarified this aspect.
from massive MIMO to gigantic MIMO. The whole telco world is starting to look like a farse. Do we have any realistic use cases that people are actually interested in or is it going to be another 5G fiasco?
The telecom world mainly creates “bit pipes” and has managed to sustain an exponential capacity growth in their networks without increasing the prices at the same pace, so the mobile broadband business is quite successful. Other potential new use cases, focused on machine-to-machine communications, are growing slower than the telecom world has hoped for. But there is much investments into that right now so it might take off during the next five years. This is further discussed in the following video: 6G: What, why, and how? ua-cam.com/video/70BOKA0PmdE/v-deo.html
@@WirelessFuture I worked in the development of 5G back in 2017, I've heard it all before. Machine type communications, haptic communications, VR, robotic surgeries, etc. I was the first to demonstrate many of these on a fully virtualised prototype 5G system with function splits and ultra-low latency and jitter. Most of them are scenarios that either don't require the bandwidth/latency or they are likely to have access to fibre, or have no element of mobility so little reason to do over radio. I was vocal that it is BS but I was surrounded by celebrity professors and vendors who wanted to pump the BS hype, so I was hushed in favour of people who played the game and who took all the credit for my work in the end. As for the reason that prices have been the same is not because the telcos managed to keep the prices low but because connectivity is commoditised and nobody wants to pay a lot of money for it. Operators had tried to push prices a few decades ago and the churn went through the roof. They are attempting it again now by trying to monetise QoS with QoD. I'd love to see how that scales, considering that they are effectively proposing intserv as a solution to QoD. I guess all the decent network engineers have gone to hyperscalers and the telco is left with people who don't understand scalability of the control plane. They also don't understand traffic flows judging by the state of the CAMARA Project. The telco world has become a version of Boeing with business people at the helm instead of engineers. Anyway, rant over, thanks for your time and good luck.
@@WirelessFuture I was part of the 5G bandwagon back in 2017 and developed testbeds for it and showcased several world first use cases. I was vocal that most of the use cases are not based on reality, they do not consider whether enabling and supporting technologies are likely to reach the required maturity, and most importantly, they never investigate the cost/benefit over having a wired connection. Many of them do not even require mobility, and yet they were used to showcase low latency in 5G. But nobody listened to me because people were making careers out of selling snake oil in the hype. Over half a decade later and practically nobody cares about the ultra low latency or VR or the metaverse, or robotic telesurgeries. 6G is going the be a failure of even bigger magnitude than 5G. We are trying to invent convoluted ways to manage spectrum efficiently instead of investing on fibre and letting the radio handle cases of mobility. Fibre will always beat radio in performance and yet we are focused on mobile communications for use cases that don't need it, we spend millions over millions to solve spectrum management problems, and in the end we end up with a solution inferior to the performance of fibre. Is the whole telco world asleep at the wheel?
How will power consumption be affected in the carrier network between 5G and 6G, at least estimated? I guess it will increase roughly about the level of bandwidth, is that correct?
Yes, the transmit power at base stations is proportional to the bandwidth. The total power consumption also contains digital computations and losses in radio circuits. The latter things can also increase with the bandwidth and/or number of antennas, but are also improved by the gradual hardware improvements that happen all the time. I think the general goal of 6G will be to deliver much more data and better services with roughly the same total power consumption.
Thanks for sharing your wonderful technical wireless home surveillance project. ❤
Thanks for the insightful video. One of the issue of catering demands is the bandwidth of arrays (operational). What if we have massive bandwidths to operate using the same array (saying a few tens of gigs) ? Theoretically we can get this by connected linear arrays but they are susceptible to high mutual coupling. Why can’t we use connected arrays in base stations?
To my understanding, base stations are unlikely to have contiguous bandwidths that are larger than the operational bandwidth of an array. The problem rather arises due to carrier aggregation of multiple bands that are too far apart to use the same array. The industry has started to make products with so-called "interleaved arrays" where arrays for low and mid bands are integrated into the same box. As you pointed out, their design is intricate due to mutual coupling and other non-ideal electromagnetic effects, but it can apparently be done. Ericsson mentions one of its products on this page: www.ericsson.com/en/portfolio/networks/ericsson-radio-system/antenna-system/antenna/passive-antenna
@@WirelessFuture In the USA, the 6705 Ericsson radio is used for the 28 GHz band (considered mmWave), which can use up to 8 continuous 100 MHz carriers. Regarding interleaved arrays, a passive antenna with multiple ports is used, using the 4449 (new version 4490) low band radios and the 8843 (new version 4890 Ericsson) mid band radios. These configurations are widely used, using NR in 850 MHz and LTE in midband. For antennas, many brands are used, such as Commscope, JMA, etc. For C-band (NR), there are other antennas or radios from Ericsson considered, but they depend on which can be used, but there are like 3 options (2 antennas and 1 radio). I hope this helps.
Great video! This is a very neat summary of 6G in the Upper Mid-Band. However, to my knowledge, the identified candidate bands for IMT are primarily for 4G/5G, as the ITU-R is still developing and evaluating RITs and SRITs for IMT-2030. By the time a decision is made regarding these bands at WRC-27, IMT-2030 will still be under study. Am I missing something?
WRC-27 is the last WRC before the product development and deployment of 6G will begin, so it is the last chance to assign new bands to IMT before that. In principle, any IMT band could be used for 4G, 5G, or 6G. But it is natural that a new generation uses a new band so it will not collide with legacy networks and will have access to substantially more bandwidth. When the ITU has finished the IMT-2030 requirements, there will be a submission period in 2027-2029 for RITs. We describe the timelines for 6G development in 3GPP and ITU in the following video: ua-cam.com/video/70BOKA0PmdE/v-deo.htmlsi=kqzkvrVkk9ZlbSBm
Good video!
As one who studied Electrical Engineering, with a focus on telecommunications systems, along with a long career in telecom, it's nice to see proper technical videos such as this.
So, you like the video, yeah?
Thank you, when changing an equation, we calculate often with matrices and vectors. When I multilply with vector h2, I must then take h2^H because of the dimensions. Is that right h1=.../h2. |*h2 h2^H*h1=..... otherwise it would not fit the dimensions (h1*h2=...). Thank you
Yes, h2^H h1 is called the inner product or dot product between two vectors, and it is a measure of how similar they are. I don’t know what equations you are analyzing, but the basic matrix and vector equations for MIMO communications can be found in my open access book: www.nowpublishers.com/article/BookDetails/9781638283140
5g is basically useless, everyone complains about just how useless it is even if you have a station across the road. Personally no one wants stations and routers up their ass just to use a phone. I am finding more and more people who are having health issues from wifi and wireless, it clearly is getting worse the more frequencies and power these devices use.
Commercial 5G networks are mostly supporting enhanced mobile broadband so far, which means delivering 4G-like performance but to many more users simultaneuosly and at a lower price per GB. Hence, most users might not experience a big difference compared to 4G. User devices such as mobile phones are not using more power as we improve the technology, but keep following the specific absorption rate (SAR) limits set by the regulatory bodies in each country. However, thanks to the beamforming enabled by having multiple antennas in the device, the signal can be focused toward the base station so that less reaches the user.
Don't you just love the way they never bother rolling out one generation to everyone before leapfrogging it with another one we don't need yet. Governments should force service providers to guarantee a minimum rollout before they're allowed to even begin rolling out the next one.
A cellular generation is first developed under 10 years and then deployed a refined under another 10-15 years. That is why 6G is being developed now even if 5G has only been partially deployed. You are right that many of the new anticipated 5G services remain to be commercialized, particularly those that go beyond “faster speeds” and “capacity for more users”.
It takes many years to roll out a new G, with significantly more advanced tech. Also, you're not forced to drop an existing G and then jump to a new one. My carrier still has 2G and 3G available, in addition to 5G. So not a lot of people are forced to run out and get a new phone. Even when that happens, carriers around here will offer a free replacement, though it won't be the latest and greatest. The older tech will be gradually phased out, until it's time to pull the plug on it.
Thank you for the excellent video. The content was truly insightful. I have a question regarding the MUSIC algorithm example. With the increase of four separated subarrays, the Fraunhofer distance now becomes quite large. Will the same effect be observed in the near-field reactive zone? If so, will the users in that example be positioned within this zone? Thank you in advance for your clarification. Best regards,
The reactive near-field zone of an array of half-wavelength-spaced antennas is larger than the reactive near-field of an individual antenna. However, the considered subarrays are far outside each others’ reactive near-field zones so they will not affect each other or grow with the number of subarrays.
Hi! Thanks for the nice explanation! (btw, there is a tiny typo on slide 9 2403 -> 2304 :)
Thanks for watching and for noticing the typo!
@@WirelessFuture Why is your reply 5 hours earlier than the post you're replying to? Proactive? 🙂
Concerning your new book, I am struggeling with exercice 6.3. I know we must build the derivative. My approach: the term behind the LAGRANGE multipl. becomes 0 because the sum is 1 and we get 1-1, so the term is canceled. The term behind the first sum: I use the product rule for the derivative. But I get a complicated expression: Sum(B/log(2)*[log(1+(P*beta_k)/(xi_k*B*N))-(P*beta_k)/(B*N+P*beta_k*xi_k^-1)]=0. The expression in the squated brackets must be 0. Perhaps you have a little time. Thanks.
If you write up the Lagrangian and compute the derivative with respect to \xi_k, you will get something of the kind: log2(1+(P*beta_k)/(xi_k*B*N0)) - log2(e)(P*beta_k/xi_k)/(B*N0+P*beta_k/xi_k) - Lagrange multiplier. This should be equal to zero for all k. Since the Lagrange multiplier doesn't depend on k, the expression can only be zero for all k if beta_k/xi_k=constant. It then remains to identify the right value of the constant.
Thanks a lot for this information. Really interesting
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?
The easiest thing is to use a normal mirror and rotate it so it reflects the signal in the right direction. I don’t know how to build something more RIS-like with such basic components. You can possible have multiple small mirrors and rotate them individually.
Aren't 'requirements' and 'specifications' imply the same things? To ask the question differently, What are the distinct roles of the ITU (requirements: you said) and the 3GPP (roles: you said) in modeling the next generation comm. system? In your video, releases of the 3GPP are mentioned. But nothing by the ITU. Thank you.
The ITU requirements refers to the performance (data rate, latency, etc.) that a technology must deliver to be called 6G. The 3GPP specifications refers to the details of the standard: How does the technology function in order to reach the performance requirements? ITU releases requirements once per decade (4G, 5G, 6G,…). 3GPP refines its standards every other year to add more functionalities, or making existing functionalities more attractive to implement in commercial products.
Sir are you planning to post more on RIS, I have just completed your playlist. Thanks for the videos.
There is nothing in the pipeline. This was my latest talk on the topic, so I will likely create a new presentation during the autumn and then give it a few times in physical meetings before I record it. Is there something particular that you are looking for content on?
Thanks Prof. Björnson. How do you think about using sub-THz wave for communications? Since the limited power of THz sources, it seems we already reach the threshold for higher generation communications, on Earth right? In my opinion, if we need higher data rate with high reliability, the base stations will be in a few meters....
I’ve heard that the 3GPP channel models are being enhanced to also capture sub-THz bands. These bands could be used for fixed wireless backhaul links (or even fixed wireless access), where one can guarantee line-of-sight conditions in the deployment. However, I think sub-THz communications to mobile users is much further into the future, and will not happen until after mmWave communications to mobile users become a commercial success (if that will ever happen).
Very valuable material, keep it up
Good job putting this together. Thank you for posting.
Dear Professor, Thank you very much for your informative videos. I have a question regarding efficiently finding relevant references in standards. For example, I am writing a thesis chapter regarding pilot assignment algorithms and would like to include a section about pilot assignment algorithms existing in practical (MIMO) networks after explaining all advanced schemes in the literature. After all my searches in textbooks and publications, I still can not find a very comprehensive summary of practical examples regarding pilot assignments. Most of them mentioned things like greedy algorithms based on a predefined set of pilot sequences, but practical examples were not cited. Could you please share some insights on how we can efficiently and precisely locate the references regarding telecom standards and real industry use cases? Many thanks!
When I worked on my thesis, I spent several days trying to understand what scheduling algorithms were used in the latest standard. I then realized that the standard does not specify such things. Most things related to resource allocation is purposely not standardized so that the vendors can compete on making the most efficient implementations. The standard is only a skeleton that specifies the most essential things related to protocols, when to transmit signals and how, etc. I believe the same applies to pilot allocation. The possible pilot sequences are standardized and how you tell the user which one is assigned, but you don’t specify how the selected is made or what kind of estimation algorithm will be used when receiving the pilot. I don’t know what practical systems use, but I would guess it is some kind of greedy algorithm that has been fine-tuned using extensive simulations.
@@WirelessFuture Thank you very much for your reply. That explains a lot! I guess I will stop searching on those standardisation websites for a precise pilot assignment protocol!
👍👍👍👍
Very good material, indeed. Professor I will ask for material on critical communications on 4G and 5G.
The governing structure of the telecommunication industry is fascinating. The first thing I noticed after entering the field is that there are so many cartoon drawings in the papers. The second thing is that there are so many conferences. The third thing is what you are presenting here, the governing structure. It is very much a system of its own. I don't think any other field has such a close-knit governing body involving industry, academia, and regulators.
There were competing cellular standards in the 1G, 2G, and 3G eras, but the telecom industry has since then realized the benefits of having only one global standard so that the same equipment can be sold everywhere. The standard is only a skeleton that enables interoperability between equipment developed by different vendors, which can still compete when it comes to the implementation details. Since standardization is done with unanimous decisions, there are many features in the standard that were added for bargaining reasons but that might never be utilized in practice.
Thank you, they mentioned clearly sensing radar application so they can see what people doing inside their homes, i think another application would be active denial and direct energy weapon using massive mimo, this is the real reason why they pushed Huawei out, one of the application is to control people on cases of riots and something similar, I don't think they will write down that openly in the specification.
The radar features in 6G will be far from military-grade radar technology because the power levels, waveforms, and deployment locations are much different. It can probably be used to detect vehicles moving along a street and their speed and direction, but it is typically limited to locations that are within line-of-sight to the base station. Typical use cases might be to help the internal communication protocols by predicting user movements, or to detect irregular movements in a factory havinga an indoor network. If an adversary wants to know what happens in a person's home, they need to hack into WiFi network or spy on data transmissions from user devices. Some countries are afraid of that equipment from some other countries might contain features that enables that, either today or in the future. By the way, the signal losses are very large in wireless communications, so massive MIMO would not be an effective "energy weapon". It is mostly the energy from your devices that effect your body, and since it is non-ionizing radiation it only transfer heat to the body. Nevertheless, there are regulations that keep the transmit power below specific thresholds that considered to be very safe.
thank you sir
Thanks for the great lecture. I just have simple question, from the derivation of channel capacity with power constrain we know the optimum probability distribution is the Gaussian and its assumed for the transmitted signal x. however also the signal is modulated as BPSK for example, or any other higher order modulation, and it is just a points on the constellation diagram not Gaussian. so what is the philosophy or the idea behind this thinking and analysis in driving the capacity of a digital communication system.
This is a good point that we discuss in Section 2.4 of the book "Introduction to Multiple Antenna Communications and Reconfigurable Surfaces" (Download here: www.nowpublishers.com/Article/BookDetails/9781638283140) The short answer is that the channel capacity is achieved by encoding the data using codewords whose length goes to infinity. The proof builds on generating those codewords with Gaussian distributed entries. In practice, we don't do that, but instead, we create the codewords using a combination of a modulation format (e.g., BPSK or 16-QAM) and a channel code. This makes the implementation much easier, and with the right design, we can come close to the capacity.
@WirelessFuture Thank you very much for your reply. The book is great and contains everything I want to know. I have started reading it. Thank you for this contribution.
Hi there guys! I just wanted to add this to help humanity. I personally believe that 3GPP documents should include source code for simulations, as it would accelerate everyone's work. Cheers and success to everyone! Index = 0:27; Index = transpose(Index); Modulation_Format = ["4-QAM","4-QAM","4-QAM","4-QAM","4-QAM",... "16-QAM","16-QAM","16-QAM","16-QAM","16-QAM","16-QAM",... "64-QAM","64-QAM","64-QAM","64-QAM","64-QAM","64-QAM","64-QAM","64-QAM","64-QAM",... "256-QAM","256-QAM","256-QAM","256-QAM","256-QAM","256-QAM","256-QAM","256-QAM"]; Modulation_Format = transpose(Modulation_Format); Coding_rate = [0.12, 0.19, 0.30, 0.44, 0.59,... 0.37, 0.42, 0.48, 0.54, 0.60, 0.64,... 0.46, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.86,... 0.67, 0.69, 0.74, 0.78, 0.82, 0.86, 0.90, 0.93]; Coding_rate = transpose(Coding_rate); bits_per_symbol = [0.24, 0.38, 0.60, 0.88, 1.18,... 1.48, 1.70, 1.91, 2.16, 2.41, 2.57,... 2.73, 3.03, 3.32, 3.61, 3.90, 4.21, 4.52, 4.82, 5.12,... 5.33, 5.55, 5.89, 6.23, 6.57, 6.91, 7.16, 7.41]; bits_per_symbol = transpose(bits_per_symbol); SNR = 2.^(bits_per_symbol)-ones(size(bits_per_symbol)); AMC_5G_Table = table(Index,Modulation_Format,Coding_rate,bits_per_symbol,SNR); disp(AMC_5G_Table);
Thank you both for this wonderful episode. I was really shocked when listening to Prof. Larsson talking about the idle time energy consumption of base stations and how the level increases just a bit when they are active.. I remember those BCH and many other control channels from some mobile networks courses I had during my bachelor. But I did not know about the energy they had to consume while the BS is not communicating..
I have huge respect for Prof. Björnson. I learned a lot from his books and online presentations!
Thanks for your great book. I am over the exercises now. Sometimes we use that expression from (5.56) to compute the outage probability and sometimes that last factor (1/M!) in this equation got eleminated like in Exercise 5.12 c). How is that. Thanks.
When an outage probability expression has the form constant*SNR^-M, we say that the diversity order is M. It is this number that determines the slope of the curve, as illustrated in Figure 5.13. There can be multiple transmission methods that achieve the same diversity order but anyway differ in performance because the SNR-independent constant factor is different. This happens when comparing (5.56) with repetition coding. (There is no Exercise 5.12c, but I hope my answer covers what you were looking for.)
Good Video, sir! And I have a question. What is the difference between Non-orthogonal access and MU-MISO? In the 13-th page, you mentioned that MU-MISO's region is lager than Non-Orthogonal access, why? Thx!
What we refer to as non-orthogonal access is a MU-SISO scenario, so one serves multiple users but has only one antenna at the base station.
@@WirelessFuture Clear explanation,thank you! I noticed that there is a technology named 'NOMA (Non-orthogonal Multiple Access)'. Does multiple means base station has multiple antennas? If so, Does NOMA equals MU-MISO?
I have a short question about exercise 5.1 a) (central limit therom). I have the solutions but don't know whether the way is right. I Put E{a^2} into the h equation and then take the square root -> the sum can be written as a multiplication with L: h=sum(Beta/L^2....) -> h=L*Beta/L^2... Noe the srt: h=sqrt(beta)/sqrt(L).... So L->inf. : variance becomes zero and with zero variance we have no GAUSSIAN Thank you.
This is the correct result and interpretation. The point that we want to make with exercise is that the scaling factor matters when studying problems like this. (a) The scaling factor gives a zero variance asymptotically, so this is not the central limit theorem by the law of large numbers. (b) The scaling factor gives a finite variance, and this is when the random variable becomes Gaussian distributed according to the central limit theorem. (c) The scaling factor makes the variance go to infinity asymptotically, so there is no convergence to anything.
just gone through the first chapter. man, it is an awesome book full of knowledge. complex things are explained in a very simple way.