ultra massive mimo - 6g channel
Post on 20-Dec-2021
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Ultra Massive MIMOVision and different embodiments
Emil Björnson
Visiting professor, KTH Royal Institute of Technology, Sweden
Associate professor, Linköping University, Sweden
Massive MIMO versus Ultra Massive MIMO
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5G in 3.5 GHz band64 antenna-integrated radios
1 m x 0.5 m
Beamforming gainSpatial multiplexing gain
Massive MIMO arrayMany antennasElectrically small
Ultra Massive MIMOEven more antennas
Electrically large
Ways to Increase the Capacity Towards 1 Terabit/s
• Capacity of a communication system:
• Three ways to increase it:
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Multiplexed layers . Bandwidth . log! 1 +Signal power . Beamforming gain . Pathloss
𝑁" . Bandwidth
Multiplexed more layersTo one or multiple users
Use more bandwidthMust be associated with higher
power or beamforming gain
Reduce rangeImprove pathloss
Scoring the Terabit/s Goal in Different Bands
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50 MHz bandwidth, 3 GHz band 1 GHz bandwidth, 60 GHz band
Low bandsMultiplex 10000 signals per site
Good channel coherence
High bandsMultiplex fewer signalsUse more bandwidth
E. Björnson, L. Van der Perre, S. Buzzi, E. G. Larsson, “Massive MIMO in Sub-6 GHz and mmWave: Physical, Practical,
and Use-Case Differences,” IEEE Wireless Communications, 2019
Fundamental Limit: Spatial Degrees-of-Freedom
• Determines how many signals an array can separate• Like sampling of a band-limited signal, but we have a space-limited signal
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Definition:Number of layers 𝜂 that can spatially multiplexed, while controlling the interference
Ultra Massive MIMO𝐿 = 10 m, 𝐻 = 30 m𝜂 ≈
𝜋𝜆! 𝐿𝐻 ≈ 100000
Planar array (length 𝐿, height 𝐻):
𝜂 ≈𝜋𝜆!𝐿𝐻
We are very far from the limits!The richness of the channels is key
Three Potential Embodiments of 6G MIMO Technology
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2) Intelligent reflecting surface
1) Cell-free Massive MIMO
3) Ultra MassiveMIMO
Holographic Radio: A New Paradigm in Array Design
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Passive patch
Diod to varyimpedance
Radio unit
Arrays with ultra many elementsRadio units at the same order asdesired spatial degree-of-freedom
MetasurfaceWhy “holographic”?
Phase-shift pattern is the hologramRecord it from uplink pilots
What about Orbital Angular Momentum (OAM)?Generate wavefronts that spin in different ways Special case of MIMO: No extra degrees-of-freedom
E-karimi, Wikimedia Commons
FOR MORE INFORMATION
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Listen to my podcast: Check out my YouTube channel:
Blog: https://ma-mimo.ellintech.se
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