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/

February 2, 2022

26. Network Slicing

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/

January 19, 2022

25. What Models are Useful?

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/

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