The good side of the social distancing that is currently taking place is that I have spent more time recording video material than usual. For example, I was supposed to give a tutorial entitled “Signal Processing for MIMO Communications Beyond 5G” at ICASSP 2020 in Barcelona in the beginning of May. This conference has now turned into an online event with free registration. Hence, anyone can attend the tutorial that I am giving together with Jiayi Zhang from Beijing Jiaotong University. We have prerecorded the presentations, which will be broadcasted to the conference attendees on May 4, but will be available for live discussions in between each video segment.
As a teaser for this tutorial, I have uploaded the 30 minute introduction to YouTube:
In this video, I explain what Massive MIMO is, what role it plays in 5G, why there will be a large gap between the theoretical performance and what is achieved in practice, and what might come next. In particular, I explain my philosophy regarding 6G research.
The remaining 2.5 hours of the tutorial will only be available from ICASSP. I hope to meet you online on May 4!
8 thoughts on “Towards 6G: Massive MIMO is a Reality—What is Next?”
To some extent, you believe in implementing cell-free massive MIMO in beyond 5G wireless communication?
Yes, I think that is one most likely things to be included in beyond 5G systems. It might even appear in future releases of 5G, 4-5 years from now. Since the data and control plane are decoupled in 5G, cell-free operation is to some extent already supported, if someone can just implement it properly.
Hi Prof. Björnson,
Thanks for the post. I’m confused about your above comments. You said that “It might even appear in future releases of 5G, 4-5 years from now” – what is missing in current 5G specifications to enable cell-free massive MIMO?
Then you commented that “Since the data and control plane are decoupled in 5G, cell-free operation is to some extent already supported, if someone can just implement it properly” – does it mean 5G spec already supports cell-free massive MIMO?
I feel two above comments are conflicting. Could you please clarify them. Thank you.
Hi Henry, thank you for noticing this inconsistency. I don’t know the 5G spec in sufficient detail to give a precise answer, but I’ve been told that cell-free operation is supported, even if it takes a lot of engineering work to implement it. It might not be identical to what is described in the academic literature, but it should be implementable in some form.
With the statement “It might even appear in future releases of 5G, 4-5 years from now”, I meant that I think that cell-free-like products might appear 4-5 years from now, if the vendors decide to develop them. Those products will of course support the newest releases of 5G, but might not require any particular new features to be operational.
I would like to know few key points of the research gap on massive MIMO till date.
You can read my thoughts about this in the following paper:
Emil Björnson, Luca Sanguinetti, Henk Wymeersch, Jakob Hoydis, Thomas L. Marzetta, “Massive MIMO is a Reality – What is Next? Five Promising Research Directions for Antenna Arrays,” Digital Signal Processing, vol. 94, pp. 3-20, November 2019.
You suggested me a paper which states that the limitation due to pilot contamination is resolved and methods to achieve unprecedented spectral efficiency has been developed. Can you please suggest me a few good papers which clearly and easily proves or show this concept.
The paper were we proved this is called “Massive MIMO has Unlimited Capacity” (https://arxiv.org/pdf/1705.00538.pdf). The paper also contains references to other related papers.