Multiantenna communications have a long and winding history, starting with how Guglielmo Marconi used an array of phase-aligned antennas to communicate over the Atlantic and Karl Ferdinand Braun used a triangular array to transmit phase-shifted signal copies to beamform in a controlled direction. The use of antenna arrays for spatial diversity and multiplexing has since appeared. The cellular network pioneer Martin Cooper tried to launch multi-user MIMO in the 1990s but concluded in 1996 that “computers weren’t powerful enough to operate it”.
During the last 25 years, multiantenna communications have changed from being a technology only used for beamforming and diversity, to becoming a mainstream enabler of high-capacity communication in 5G. It is used for both single-user and multi-user MIMO when connecting any modern mobile phone to the Internet, in both the 3 GHz and mmWave bands.
The IEEE Signal Processing Society is celebrating its 75 years anniversary and, therefore, the Signal Processing Magazine publishes a special issue focusing on the last 25 years of research developments. I have written a paper for this issue called “25 Years of Signal Processing Advances for Multiantenna Communications“. It is now available on arXiv, and it is co-authored by Yonina Eldar, Erik G. Larsson, Angel Lozano, and H. Vincent Poor. I hope you will like it!
The Wireless Future podcast is back with a new season. We have released the 32nd episode, which has the following abstract:
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”, “Joint Spatial Division and Multiplexing”, and “Massive MIMO has Unlimited Capacity”.
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We have now released the 30th episode of the podcast Wireless Future. It has the following abstract:
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.
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We have now released the 28th episode of the podcast Wireless Future. It has the following abstract:
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)” and its companion video.
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We have now released the 27th episode of the podcast Wireless Future. It has the following abstract:
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”.
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We have now released the 26th episode of the podcast Wireless Future. It has the following abstract:
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.
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We have now released the 24nd episode of the podcast Wireless Future, which is a New Year’s special! It has the following abstract:
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.
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