Wireless Future

The NYU Wireless Workshop this year was a lively scientific event, where the future of wireless technology was debated. Erik G. Larsson was among the invited speakers, and the main theme was “Twenty Years of Massive MIMO: What’s Next?”. In this episode, he discusses the main insights with Emil Björnson. They first dissect the practical challenges that still hinder multi-antenna technology from reaching its full potential. It ranges from unfavorable traffic patterns to channel characteristics and channel state information, and how to circumvent these issues. The conversation also covers wireless sensing, AI data aggregation over the air, near-field communications, and common misconceptions around mutual coupling. The most thought-provoking question is: Is the demand for wireless connectivity saturating, or is there still a wireless future ahead? Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39and Emil’s website https://ebjornson.com/

Antenna arrays are used everywhere to enhance the wireless signal quality through beamforming and aperture gains. A common practice is to arrange antennas uniformly along a line or in a rectangle, but this is not necessarily the preferred arrangement. In this episode, Emil Björnson and Erik G. Larsson discuss how the geometry of an antenna array affects the shape of the beams it can transmit and the ability to spatially multiplex many users. They uncover how uniform arrays excel at packing many antennas into a compact space, while adjacent antennas collect redundant information about the world around us. In future systems operating above 6 GHz, we might not be able to afford to fill the aperture with antennas and can instead place them in a sparse non-uniform pattern. The vision is to optimize the arrangement at each base station site to maximize its communication and/or sensing performance. The conversation covers grating lobes, minimum redundancy arrays, preoptimized irregular arrays, and movable/fluid antenna systems. Further details can be found in “From Antenna Abundance to Antenna Intelligence in 6G Gigantic MIMO Systems”, https://arxiv.org/abs/2601.08326 Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

Almost every 6G-related keynote speech at scientific conferences focuses on ISAC: Integrated sensing and communications. In this episode, Erik G. Larsson and Emil Björnson discuss how sensing and communication technologies have been developed separately in the past but are built on similar yet distinctly different principles. The conversation covers different integration levels, beamforming implementations, fundamental tradeoffs, alternative waveforms, and the most important question: What would ISAC be used for if it becomes widely available in 6G networks? Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

One of the first topics covered in this podcast was reconfigurable intelligent surfaces (RIS). Five years later, Erik G. Larsson and Emil Björnson return to this topic to reflect on what has happened since then. The conversation covers how these surfaces can improve wave propagation between transmitters and receivers, and identifies the most convincing practical use cases. Core challenges overcome in recent years are discussed, and Emil describes the RIS used in his lab and the lessons learned from his measurements. They also go through new forms of RIS, known as Beyond-Diagonal RIS, STAR-RIS, and Stacked Intelligent Metasurfaces. To learn more, you can read the paper “Reconfigurable Intelligent Surfaces in Upper Mid-Band 6G Networks: Gain or Pain?” (https://doi.org/10.1109/MWC.2025.3616979). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

“6G should be for the many, not the few” is the final sentence of a recent book by William Webb. In this episode, Erik G. Larsson and Emil Björnson use this book as the starting point for a conversation on why and how wireless technology can improve its coverage. The end goal is to deliver ubiquitous connectivity, so we can use any wirelessly connected application anywhere at any time. The discussion starts at the conceptual level: Why do cellular networks have generations? How are visions for future generations created, and can they be trusted? Different ways to enhance future networks are then covered, from making optimal use of existing network resources to adding different kinds of new infrastructure where it is most needed. The episode was inspired by the book “The 6G Manifesto”, ISBN 9798338481936. Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

Coverage holes exist in cellular networks despite decades of wireless technology evolution, but new potential solutions are on the horizon. In this episode, Emil Björnson and Erik G. Larsson discuss network-controlled repeaters, reconfigurable intelligent surfaces, and half-duplex relays. Network-controlled repeaters have attracted particular attention from 3GPP in recent years; the conversation focuses on how these can create strong propagation paths through signal amplification. Implementation challenges related to synchronization, band selectivity, and stability are also covered. A detailed overview is provided in “Achieving Distributed MIMO Performance with Repeater-Assisted Cellular Massive MIMO” (https://arxiv.org/abs/2406.00142). Technical details can be found in: https://arxiv.org/pdf/2405.01074 and https://arxiv.org/pdf/2403.17908  Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

There are many textbooks to choose between when learning the basics of wireless communications. In this episode, Erik G. Larsson and Emil Björnson discuss the recent book “Introduction to Multiple Antenna Communications and Reconfigurable Surfaces” that Emil has written together with Özlem Tugfe Demir. The conversation focuses on ten subtopics that are covered by the book and differentiates it from many previous textbooks. These are related to the dimensionality of physical constants, the choice of performance metrics, and the motivation behind OFDM signaling. Various system modeling characteristics are discussed, including how the antenna array geometry impacts the channel, dual-polarized signals, carrier frequency dependencies, and the connection between models for small-scale fading and radar cross-sections. The role of non-orthogonal multiple access, hybrid beamforming, and reconfigurable intelligent surfaces are also covered. The textbook is meant for teaching an introductory course on the topic and can be freely downloaded from https://www.nowpublishers.com/NowOpen Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

Even if the 6G standardization is just beginning, the last five years of intensive research have illuminated the contours of the next-generation technology. In this episode, Emil Björnson and Erik G. Larsson discuss the recent paper “6G takes shape” written by leading researchers at UT Austin and Qualcomm. The conversation covers lessons learned from 5G, the potential role of new frequency bands and waveforms, and new coding schemes and forms of MIMO. The roles of machine learning and generative AI, as well as satellite integration and Open RAN, are also discussed. The original paper by Jeffrey G. Andrews, Todd E. Humphreys, and Tingfang Ji will appear in the IEEE BITS magazine, and the preprint is openly available: https://arxiv.org/abs/2411.18435 Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

New cellular network deployments are often associated with new frequency bands. 6G will likely use the upper mid-band from 7-24 GHz. It is called the “golden band” since it provides more spectrum than in current 5G networks and features decent propagation conditions. In this episode, Erik G. Larsson and Emil Björnson discuss the coexistence issues that must be overcome when operating in this band and how much spectrum we can expect to utilize. The future role of multi-antenna technology and its associated challenges are detailed, including the emerging “Gigantic MIMO” term. The prospects of exploiting near-field propagation effects in 6G and the road towards distributed cell-free MIMO are also covered. You can read Emil’s paper about Gigantic MIMO here: https://arxiv.org/pdf/2407.05630 Nokia has a white paper about coverage evaluation: https://onestore.nokia.com/asset/213702 Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

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 discuss some fundamental principles of synchronization, including the underlying physical phenomena, pilot signaling for phase synchronization, and reciprocity calibration. We especially discuss how the seemingly simplest angular beamforming can be among the hardest features to support from a synchronization perspective, with a digital array. More technical details in the papers https://arxiv.org/abs/2304.05144 and https://arxiv.org/abs/2401.11730 Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

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 Lead of 6GTandem and Research Manager at Ericsson. The discussion starts with potential use cases, such as extended reality services in stadiums and connected factories. The conversation then focuses on hardware aspects, such as how to build a distributed antenna system using plastic microwave fibers and amplifiers so that sub-THz signals can be transmitted from many different locations. You can read more about the EU-funded project and its partners at https://horizon-6gtandem.eu/ Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

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-learning applications in communications to fundamental communication theory, such as circuits for universal channel decoding and jamming protection. The expected 6G spectrum ranges, energy efficiency in base stations, and new use cases for electromagnetic materials are also covered. You can find slides from the symposium at https://elliit.se/news-and-events/focus-period-lund-2023/ Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

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, Jakob Hoydis (NVIDIA) describes differentiable ray-tracing and its connection to machine learning, Deniz Gündüz (Imperial College London) presents his vision for how artificial intelligence will affect future wireless networks, Henk Wymeersch (Chalmers University of Technology) elaborates on the similarities and differences between communication and positioning, and Luca Sanguinetti (University of Pisa) demystifies holographic MIMO and its relation to near-field communications. Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

It is easy to get carried away by futuristic 6G visions, but what matters in the end is what technology and services the telecom operators will deploy. In this episode, Erik G. Larsson and Emil Björnson discuss a new white paper from SK Telecom that describes the lessons learned from 5G and how these experiences can be utilized to make 6G more successful. The paper and conversation cover network evolution, commercial use cases, virtualization, artificial intelligence, and frequency spectrum. The latest developments in defining official 6G requirements are also discussed. The white paper can be found here:https://www.sktelecom.com/en/press/press_detail.do?idx=1575 The following news article about mmWave licenses is mentioned: https://telecoms.com/521670/south-korea-cancels-skts-28-ghz-5g-licence/ The IMT-2030 Framework for 6G can be found here: https://www.itu.int/en/ITU-R/study-groups/rsg5/rwp5d/imt-2030/Pages/default.aspx Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

The main directions for 6G research have been established and include pushing the communication to higher frequency bands, creating smart radio environments, and removing the conventional cell structure. There are many engineering issues to address on the way to realizing these visions. In this episode, Emil Björnson and Erik G. Larsson discuss the article “The Road to 6G: Ten Physical Layer Challenges for Communications Engineers” from 2021. What specific research challenges did the authors identify, and what remains to be done? The conversation covers system modeling complexity, hardware implementation issues, and signal processing scalability. The article can be found here: https://arxiv.org/pdf/2004.07130 The following papers were also mentioned: https://arxiv.org/pdf/2111.15568 and https://arxiv.org/pdf/2104.15027 Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

The speed of wired optical fiber technology is soon reaching 1 million megabits per second, also known as 1 terabit/s. Wireless technology is improving at the same pace but is 10 years behind in speed, thus we can expect to reach 1 terabit/s over wireless during the next decade. In this episode, Erik G. Larsson and Emil Björnson discuss these expected developments with a focus on the potential use cases and how to reach these immense speeds in different frequency bands – from 1 GHz to 200 GHz. Their own thoughts are mixed with insights gathered at a recent workshop at TU Berlin. Major research challenges remain, particularly related to algorithms, transceiver hardware, and decoding complexity. Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

Research is carried out to obtain new knowledge, find solutions to pertinent problems, and challenge the researchers’ abilities. Two key aspects of the scientific process are reproducibility and replicability, which sound similar but are distinctly different. In this episode, Erik G. Larsson and Emil Björnson discuss these principles and their impact on wireless communication research. The conversation covers the replication crisis, Monte Carlo simulations, best practices, pitfalls that new researchers should avoid, and what the community can become better at. The following article is mentioned: “Reproducible Research: Best Practices and Potential Misuse” (https://arxiv.org/pdf/1905.00645.pdf). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

Information theory is the research discipline that establishes the fundamental limits for information transfer, storage, and processing. Major advances in wireless communications have often been a combination of information-theoretic predictions and engineering efforts that turn them into mainstream technology. Erik G. Larsson and Emil Björnson invited the information-theorist Giuseppe Caire, Professor at TU Berlin, to discuss how the discipline is shaping current and future wireless networks. The conversation first covers the journey from classical multiuser information theory to Massive MIMO technology in 5G. The rest of the episode goes through potential future developments that can be assessed through information theory: distributed MIMO, orthogonal time-frequency-space (OTFS) modulation, coded caching, reconfigurable intelligent surfaces, terahertz bands, and the use of ever larger numbers of antennas. The following papers are mentioned: “OTFS vs. OFDM in the Presence of Sparsity: A Fair Comparison” (https://doi.org/10.1109/TWC.2021.3129975) , “Joint Spatial Division and Multiplexing”(https://arxiv.org/pdf/1209.1402.pdf), and “Massive MIMO has Unlimited Capacity” (https://arxiv.org/pdf/1705.00538.pdf). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

A wave of digitalization is sweeping over the world, but not everything benefits from a transformation from analog to digital methods. In this episode, Emil Björnson and Erik G. Larsson discuss the fundamentals of analog modulation techniques to pinpoint their key advantages. Particular attention is given to how analog modulation enables over-the-air aggregation of data, which can be used for computations, efficient federated training of machine learning models, and distributed hypothesis testing. The conversation covers the need for coherent operation and power control and outlines the challenges that researchers are now facing when extending the methods to multi-antenna systems. Towards the end, the following paper is mentioned: “Optimal MIMO Combining for Blind Federated Edge Learning with Gradient Sparsification” (https://arxiv.org/pdf/2203.12957.pdf). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

Many assumptions must be made when simulating a communication link, including the modulation format, channel coding, multi-antenna transmission scheme, receiver processing, and channel modeling. In this episode, Emil Björnson and Erik G. Larsson are visited by Jakob Hoydis, Principal Research Scientist at NVIDIA, to discuss the fundamentals of link-level simulations. Jakob has led the development of the new open-source simulator Sionna, which is particularly well suited for machine learning research. The conversation covers the needs and means for making accurate simulations, channel modeling, reproducibility, and how machine learning can be used to improve standard algorithms. Other topics that are discussed are MIMO decoding and technical debt. Sionna can be downloaded from https://nvlabs.github.io/sionna/ and the white paper that is mentioned in the episode is found here: https://arxiv.org/pdf/2203.11854.pdf Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

The research towards 6G is intense and many new technology components are being proposed by academia and industry. In this episode, Erik G. Larsson and Emil Björnson identify the key selling points of six of these 6G technologies. They discuss the potential for major breakthroughs and what the main challenges are. The episode covers: 1) Semantic communications; 2) Distributed/cell-free Massive MIMO; 3) Reconfigurable intelligent surfaces; 4) Full-duplex radios; 5) Joint communication and sensing; and 6) Orbital Angular Momentum (OAM). The following paper is mentioned: “Is Orbital Angular Momentum (OAM) Based Radio Communication an Unexploited Area?” by Edfors and Johansson (https://lup.lub.lu.se/search/ws/files/4023050/2339120.pdf). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

The reliability of an application is determined by its weakest link, which often is the wireless link. Channel coding and retransmissions are traditionally used to enhance reliability but at the cost of extra latency. 5G promises to enhance both reliability and latency in a new operational mode called ultra-reliable low-latency communication (URLLC). In this episode, Erik G. Larsson and Emil Björnson discuss URLLC with Petar Popovski, Professor at Aalborg University, Denmark. The conversation pinpoints the physical reasons for latency and unreliability, and viable solutions related to network deployment, diversity, digital vs. analog communications, non-orthogonal network slicing, and machine learning. Further details can be found in the article “Wireless Access in Ultra-Reliable Low-Latency Communication (URLLC)” (https://doi.org/10.1109/TCOMM.2019.2914652) and its companion video (https://youtu.be/XGbe_ckKKpE). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

Mobile network technology builds on open standards, but it is nevertheless a major effort to implement the required software protocols and interface them with actual hardware. Many algorithmic choices must also be made in the implementation, leading to each vendor having its proprietary solution. The OpenAirInterface Alliance wants to change the game by providing open-source software implementations of the wireless air interface and core network. In this episode, Emil Björnson and Erik G. Larsson are discussing these prospects with a Board Member of the Alliance: Florian Kaltenberger, Associate Professor at EURECOM, France. The conversation covers the fundamentals of air interfaces, how anyone can build a 5G network using their open-source software and off-the-shelf hardware, and the pros and cons of implementing everything in software. The connections to Open RAN, functional splits, and patent licenses are also discussed. Further details can be found at https://openairinterface.org and in the paper “OpenAirInterface: Democratizing innovation in the 5G Era” (https://doi.org/10.1016/j.comnet.2020.107284). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

In the near future, we will be able to deploy new wireless networks without installing new physical infrastructure. The networks will instead be virtualized on shared hardware using the new concept of network slicing. This will enable tailored wireless services for businesses, entertainment, and devices with special demands. In this episode, Erik G. Larsson and Emil Björnson discuss why we need multiple virtual networks, what the practical services might be, who will pay for it, and whether the concept might break net neutrality. The episode starts with a continued discussion on the usefulness of models, based on feedback from listeners regarding Episode 25. The network slicing topic starts after 10 minutes. Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

The statistician George Box famously said that “All models are wrong, but some are useful”. In this episode, Emil Björnson and Erik G. Larsson discuss what models are useful in the context of wireless communications, and for what purposes. The conversation covers modeling of wireless propagation, noise, hardware, and wireless traffic. A key message is that the modeling requirements are different for algorithmic development and for performance evaluation. Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

In this episode, Emil Björnson and Erik G. Larsson answer ten questions from the listeners. The common theme is predictions of how 5G will evolve and which technologies will be important in 6G. The specific questions: Will Moore’s law or Edholm’s law break down first? How important will integrated communication and sensing become? When will private 5G networks start to appear? Will reconfigurable intelligent surfaces be a key enabler of 6G? How can we manage the computational complexity in large-aperture Massive MIMO? Will machine learning be the game-changer in 6G? What is 5G Dynamic Spectrum Sharing? What does the convergence of the Shannon and Maxwell theories imply? What happened to device-to-device communications, is it an upcoming 5G feature? Will full-duplex radios be adopted in the future? If you have a question or idea for a future topic, please share it as a comment to the YouTube version of this episode. Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

For each wireless generation, we are using more bandwidth and more antennas. While the primary reason is to increase the communication capacity, it also increases the network’s ability to localize objects and sense changes in the wireless environment. The localization and sensing applications impose entirely different requirements on the desired signal and channel properties than communications. To learn more about this, Emil Björnson and Erik G. Larsson have invited Henk Wymeersch, Professor at Chalmers University of Technology, Sweden. The conversation covers the fundamentals of wireless localization, the historical evolution, and future developments that might involve machine learning, terahertz bands, and reconfigurable intelligent surfaces. Further details can be found in the articles “Collaborative sensor network localization” (https://doi.org/10.1109/JPROC.2018.2829439) and “Integration of communication and sensing in 6G” (https://arxiv.org/pdf/2106.13023). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

Wireless signals look different when observed near to versus far from the transmitter. The notions of near and far also depend on the physical size of the transmitter and receiver, as well as on the wavelength. In this episode, Erik G. Larsson and Emil Björnson discuss these fundamental phenomena and how they can be utilized when designing future communication systems. Concept such as near-field communications, finite-depth beamforming, mutual coupling, and new spatial multiplexing methods such as orbital angular momentum (OAM) are covered. To get more technical details, you can read the paper “A Primer on Near-Field Beamforming for Arrays and Reconfigurable Intelligent Surfaces” (https://arxiv.org/pdf/2110.06661.pdf). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

The latest wireless technologies rely heavily on beamformed data transmissions, implemented using antenna arrays. Since the signals are spatially directed towards the location of the receiver, the transmitter needs to know where to point the beam. Before the wireless link has been established, the transmitter will not have such knowledge. Hence, the geographical coverage of a network is determined by how we can transmit in the absence of beamforming gains. In this episode, Emil Björnson and Erik G. Larsson discuss how to achieve wide-area coverage in wireless networks without beamforming. The conversation covers deployment fundamentals, pathloss characteristics, beam sweeping, spatial diversity, and space-time codes. To learn more, you can read the textbook “Space-Time Block Coding for Wireless Communications” (https://doi.org/10.1017/CBO9780511550065). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

Many objects around us are embedded with sensors and processors to create the Internet of Things (IoT). Wireless connectivity is an essential component for enabling these devices to exchange data without human interaction. To learn more about this development, Erik G. Larsson and Emil Björnson have invited Liesbet Van der Perre, Professor at KU Leuven, Belgium. The conversation covers IoT applications, connectivity solutions, powering, security, sustainability, and e-waste. Further details can be found in the article “The Art of Designing Remote IoT Devices—Technologies and Strategies for a Long Battery Life” (https://doi.org/10.3390/s21030913). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

How far is the capacity of wireless networks from the limits imposed by nature? To seek an answer to this question, Erik G. Larsson and Emil Björnson invited Thomas Marzetta, Distinguished Industry Professor and originator of Massive MIMO, to this first episode of the second season. The conversation covers the history of that technology and the fundamental aspects that will always dictate the capacity of wireless networks: antenna technology, channel state information, spectral efficiency, bandwidth, spectrum bands, and link budgets. To learn more, you can read the article “Massive MIMO is a Reality – What is Next? Five Promising Research Directions for Antenna Arrays” (https://arxiv.org/pdf/1902.07678). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

Many individuals are speculating about 6G, but in this episode, you will hear the joint vision of 700+ researchers at Ericsson. Erik G. Larsson and Emil Björnson are visited by Magnus Frodigh, Vice-President and Head of Ericsson Research. His team has recently published the white paper “Ever-present intelligent communication: A research outlook towards 6G”. The conversation covers emerging applications, new requirements, and research challenges that might define the 6G era. How can we achieve limitless connectivity? Which frequency bands will become important? What is a network compute fabric? What should students learn to take part in the 6G development? These are just some of the questions that are answered. We suggest that you also read Ericsson’s white paper (https://www.ericsson.com/en/reports-and-papers/white-papers/a-research-outlook-towards-6g). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

The wireless data traffic grows by 50% per year which implies that the energy consumption in the network equipment is also growing steadily. This raises both environmental and economic concerns. In this episode, Erik G. Larsson and Emil Björnson discuss how the wireless infrastructure can be made more energy-efficient. The conversation covers the basic data traffic characteristics and definition of energy efficiency, as well as what can be done when designing future network infrastructure, planning deployments, and developing efficient algorithms. To learn more, they recommend the IEEE 5G and Beyond Technology Roadmap article “Energy Efficiency” (https://futurenetworks.ieee.org/roadmap) and also “Deploying Dense Networks for Maximal Energy Efficiency: Small Cells Meet Massive MIMO” (http://arxiv.org/pdf/1505.01181). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

The research community’s hype around 5G has quickly shifted to hyping the next big thing: 6G. This raises many questions: Did 5G become as revolutionary as previously claimed? Which physical-layer aspects remain to be improved in 6G? To discuss these things, Erik G. Larsson and Emil Björnson are visited by Professor Angel Lozano, author of the seminal papers “What will 5G be?” and “Is the PHY layer dead?”. The conversation covers the practical and physical limits in communications, the role of machine learning, the relation between academia and industry, and whether we have got lost in asymptotic analysis. Angel’s website is https://www.upf.edu/web/angel-lozano. Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

Machine learning builds on the collection and processing of data. Since the data often are collected by mobile phones or internet-of-things devices, they must be transferred wirelessly to enable machine learning. In this episode, Emil Björnson and Erik G. Larsson are visited by Carlo Fischione, a Professor at the KTH Royal Institute of Technology. The conversation circles around distributed machine learning and how the wireless technology can evolve to support learning applications via network slicing, information-aware communication, and over-the-air computation. To learn more, they recommend the article “Wireless for Machine Learning” (https://arxiv.org/abs/2008.13492). Carlo’s website is https://people.kth.se/~carlofi/ and the Machine Learning for Communications ETI has the website https://mlc.committees.comsoc.org. Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

In this episode, Emil Björnson and Erik G. Larsson answer questions from the listeners on the topics of distributed MIMO, THz communications, and non-orthogonal multiple access (NOMA). Some examples are: Is cell-free massive MIMO really a game-changer? What would be its first use case? Can visible light communications be used to reach 1 terabit/s? Will Massive MIMO have a role to play in THz communications? What kind of synchronization and power constraints appear in NOMA systems? Please continue asking questions and we might answer them in later episodes! Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

Wireless devices normally connect to a single access point, deployed at one location. The access points are deployed sparsely to create large cell regions, each controlled by the nearest access point. This architecture was conceived for mobile telephony and has been inherited by today’s networks, even if those mainly transfer wireless data. However, future wireless networks might be organized entirely differently. In this episode, Erik G. Larsson and Emil Björnson discuss how one can create cell-free networks consisting of distributed massive MIMO arrays. The vision is that each user will be surrounded by small access points that cooperate to provide uniformly high service quality. The conversation covers the key benefits, how the network architecture can be evolved to support the new technology, and what the main research challenges are. To learn more, they recommend the article “Ubiquitous Cell-Free Massive MIMO Communications” (https://jwcn-eurasipjournals.springeropen.com/track/pdf/10.1186/s13638-019-1507-0) and the new book “Foundations of User-Centric Cell-Free Massive MIMO” (https://www.nowpublishers.com/article/Details/SIG-109). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

The data that flows through wireless networks are protected by encryption, but there are anyway privacy and security issues inherent in wireless technologies. In this episode, Erik G. Larsson and Emil Björnson are visited by Panos Papadimitratos, a Professor at the KTH Royal Institute of Technology. The conversation focuses on location privacy and spoofing; what the practical issues are, what countermeasures exist, and which tradeoffs must be made when building wireless technologies. Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

The wireless medium must be shared between multiple devices that want to access various services simultaneously. To avoid interference, the devices have traditionally taken turns, which is known as orthogonal multiple access. The use of non-orthogonal multiple access (NOMA) techniques, where the devices are interfering in a controlled manner, was a popular theme in the research leading up to 5G. In this episode, Emil Björnson and Erik G. Larsson discuss the different forms of NOMA, and what their benefits and weaknesses are. They discuss what role NOMA plays in 5G and might play in future wireless technologies. To learn more, they recommend the article “Is NOMA Efficient in Multi-Antenna Networks? A Critical Look at Next Generation Multiple Access Techniques” (https://arxiv.org/abs/2101.04802). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

5G promises peak data speeds above 1 gigabit per second. Looking further into the future, will wireless technology eventually deliver 1 terabit per second? How can the technology be evolved to reach that goal, and what would the potential use cases be? In this episode, Erik G. Larsson and Emil Björnson provide answers to these questions and discuss the practical challenges that must be overcome at the hardware level and in wireless propagation. To learn more, they recommend the article “Scoring the Terabit/s Goal: Broadband Connectivity in 6G” (https://arxiv.org/abs/2008.07220). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

In this episode, Emil Björnson and Erik G. Larsson answer questions from the listeners on the topic of reconfigurable intelligent surfaces. Some examples are: What kind of materials are used? When can the technology beat traditional relays? How quickly can one change the surface’s configuration? Are there any real-time experiments? How can the research community avoid misconceptions spreading around new technologies? Please continue asking questions and we might answer them in later episodes! Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

The new 5G millimeter wave systems make use of classical analog beamforming technology. It is often claimed that digital beamforming cannot be used in these bands due to its high energy consumption. In this episode, Erik G. Larsson and Emil Björnson are visited by Bengt Lindoff, Chief Systems Architect at the startup BeammWave. The conversation covers how fully digital beamforming solutions are now being made truly competitive and what this means for the future of wireless communications. To learn more about BeammWave’s hardware architecture visit https://www.beammwave.com/whitepapers. Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

What role will machine learning play in wireless communications? In this episode, Emil Björnson and Erik G. Larsson begin by discussing the fundamentals of machine learning and what it means to “learn” something. They discuss what are the good use cases for machine learning in communications, and what are less convincing use cases. To learn more, they recommend the article “Two Applications of Deep Learning in the Physical Layer of Communication Systems” (https://arxiv.org/pdf/2001.03350.pdf). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

In this New Year's special, Erik G. Larsson and Emil Björnson answer questions from the listeners on the topic of Massive MIMO. Some examples are: How are the antennas calibrated? Will digital beamforming replace analog beamforming? What is channel hardening and how is it related to power control? Can Massive MIMO interact with drones? Practical issues such as the peak-to-average-power ratio (PAPR) and effective isotropic radiated power (EIRP) are also discussed. Please continue asking questions and we might answer them in later episodes! Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

What happened to millimeter wave communications? It is often described as synonymous with 5G, but barely any of the brand new 5G networks make use of it. In this episode, Erik G. Larsson and Emil Björnson discuss the basic properties of millimeter waves, whether it is the long sought “holy grail” in wireless communications, and where the technology stands today. To learn more, they recommend the articles “Antenna Count for Massive MIMO: 1.9 GHz versus 60 GHz” (https://arxiv.org/pdf/1702.06111.pdf) and “Massive MIMO in Sub-6 GHz and mmWave: Physical, Practical, and Use-Case Differences” (https://arxiv.org/pdf/1803.11023). Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

We are creating a society that is increasingly reliant on access to wireless connectivity. In Sweden, you can barely pay for parking without a mobile phone. Will this wireless future have a negative impact on the security of our data and privacy? In this episode, Emil Björnson and Erik G. Larsson discuss security threats to wireless technology, including eavesdropping, jamming, and spoofing. What impact can these illegitimate techniques have on our lives and what do we need to be aware of? Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

The research towards 6G has already been initiated. One of the most hyped concepts in the research community is “reconfigurable intelligent surfaces”, which can be utilized to create smart walls that capture wireless signals and reflect them towards the user device. In this episode, Erik G. Larsson and Emil Björnson discuss the prospects and limitations of this new technology. Is it the next big thing in wireless? To learn more, they recommend their new overview article “Reconfigurable Intelligent Surfaces: Three Myths and Two Critical Questions”, to appear in IEEE Communications Magazine, which can be downloaded at https://arxiv.org/pdf/2006.03377. Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

There are often hypes and speculations around new wireless technologies, including “Massive MIMO”, which is the key new feature in 5G. In 2015, Emil Björnson and Erik G. Larsson wrote the article “Massive MIMO: Ten Myths and One Critical Question” together with Thomas Marzetta. It was an attempt to dispel some of the misconceptions that were floating around at the time. In this episode, they look back at the statements they claimed to be myths to see if they were right and whether the myths are still around. The article received the 2019 Fred W. Ellersick Prize from the IEEE Communications Society and can be downloaded at https://arxiv.org/pdf/1503.06854. Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/

In the first episode of “Wireless Future”, Erik G. Larsson and Emil Björnson talk about the brand new 5G networks and what role the technology component “Massive MIMO” is playing. They reflect upon whether the practical implementation of the technology became as they envisioned in their textbooks “Fundamentals of Massive MIMO” and “Massive MIMO Networks”. Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/