Category Archives: 5G

5G, Beyond 5G, Commentary, Podcast, Technical insights

Episode 12: Privacy and Security in Connectivity (with Panos Papadimitratos)

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We have now released the twelfth episode of the podcast Wireless Future, with the following abstract:

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.

You can watch the video podcast on YouTube:

You can listen to the audio-only podcast at the following places:

5G, Beyond 5G, Commentary, Podcast, Technical insights

Episode 11: Non-Orthogonal Multiple Access

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We have now released the eleventh episode of the podcast Wireless Future, with the following abstract:

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”.

You can watch the video podcast on YouTube:

You can listen to the audio-only podcast at the following places:

5G, Beyond 5G, Commentary, Podcast, Technical insights

Episode 10: Reaching the Terabit/s Goal

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We have now released the tenth episode of the podcast Wireless Future, with the following abstract:

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”.

You can watch the video podcast on YouTube:

You can listen to the audio-only podcast at the following places:

5G, Beyond 5G, Commentary, Podcast, Technical insights

Episode 9: Q/A on Reconfigurable Intelligent Surfaces

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We have now released the ninth episode of the podcast Wireless Future, with the following abstract:

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?

You can watch the video podcast on YouTube:

You can listen to the audio-only podcast at the following places:

5G, Beyond 5G, Commentary, Podcast, Technical insights

Episode 8: Analog versus Digital Beamforming

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We have now released the eighth episode of the podcast Wireless Future, with the following abstract:

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.

You can watch the video podcast on YouTube:

You can listen to the audio-only podcast at the following places:

5G, Beyond 5G, Commentary, Education, Technical insights

Who is Who in Massive MIMO?

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I taught a course on complex networks this fall, and one component of the course is a hands-on session where students use the SNAP C++ and Python libraries for graph analysis, and Gephi for visualization. One available dataset is DBLP, a large publication database in computer science, that actually includes a lot of electrical engineering as well.

In a small experiment I filtered DBLP for papers with both “massive” and “MIMO” in the title, and analyzed the resulting co-author graph. There are 17200 papers and some 6000 authors.  There is a large connected component, with over 400 additional much smaller connected components!

Then I looked more closely at authors who have written at least 20 papers. Each node is an author, its size is proportional to his/her number of “massive MIMO papers”, and its color represents identified communities. Edge thicknesses represent the number of co-authored papers.  Some long-standing collaborators, former students, and other friends stand out.  (Click on the figure to enlarge it.)

To remind readers of the obvious, prolificacy is not the same as impact, even though they are often correlated. Also, the study is not entirely rigorous. For one thing, it trusts that DBLP properly distinguishes authors with the same name (consider e.g., “Li Li”) and I do not know how well it really does that. Second, in a random inspection all papers I had filtered out dealt with “massive MIMO” as we know it. However, theoretically, the search criterion would also catch papers on, say, MIMO control theory for a massive power plant.  Also, the filtering does miss some papers written before the “massive MIMO” term was established, perhaps most importantly Thomas Marzetta’s seminal paper on “unlimited antennas”.  Third, the analysis is limited to publications covered by DBLP, which also means, conversely, that there is no specific quality threshold for the publication venues. Anyone interested in learning more, drop me a note. 

5G, Beyond 5G, News

Globecom Tutorial on Cell-free Massive MIMO

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I am giving a tutorial on “Beyond Massive MIMO: User-Centric Cell-Free Massive MIMO” at Globecom 2020, together with my colleagues Luca Sanguinetti and Özlem Tuğfe Demir. It is a prerecorded 3-hour tutorial that can be viewed online at any time during the conference and there will be a live Q/A session on December 11 where we are available for questions.

The tutorial is based on our upcoming book on the topic: Foundations on User-Centric Cell-free Massive MIMO.

Until December 11 (the last day of the tutorial), we are offering a free preprint of the book, which can be downloaded by creating an account at the NOW publishers’ website. By doing so, I think you will also get notified when the final version of the book is available early next year, so you can gain access to the final PDF and an offer to buy printed copies.

If you download the book and have any feedback that we can take into account when preparing the final version, we will highly appreciate to receive it! Please email me your feedback by December 15. You find the address in the PDF.

The abstract of the tutorial is as follows:

Massive MIMO (multiple-input multiple-output) is no longer a promising concept for cellular networks-in 2019 5G it became a reality, with 64-antenna fully digital base stations being commercially deployed in many countries. However, this is not the final destination in a world where ubiquitous wireless access is in demand by an increasing population. It is, therefore, time for MIMO and mmWave communication researchers to consider new multi-antenna technologies that might lay the foundations for beyond 5G networks. In particular, we need to focus on improving the uniformity of the service quality.

Suppose all the base station antennas are distributed over the coverage area instead of co-located in arrays at a few elevated locations, so that the mobile terminals are surrounded by antennas instead of having a few base stations surrounded by mobile terminals. How can we operate such a network? The ideal solution is to let each mobile terminal be served by coherent joint transmission and reception from all the antennas that can make a non-negligible impact on their performance. That effectively leads to a user-centric post-cellular network architecture, called “User-Centric Cell-Free Massive MIMO”. Recent papers have developed innovative signal processing and radio resource allocation algorithms to make this new technology possible, and the industry has taken steps towards implementation. Substantial performance gains compared to small-cell networks (where each distributed antenna operates autonomously) and cellular Massive MIMO have been demonstrated in numerical studies, particularly, when it comes to the uniformity of the achievable data rates over the coverage area.