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• Tarek Tarek El-safrani

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Massive MIMO Omar Abu-Ella

Outlines • What is Massive MIMO • Types of MIMO Systems • Advantages of Massive MIMO • Implementation • Capacity Analysis • Practical Constraints and Challenges

How to realize 5G? • Key requirement of 5G: 1000-fold capacity

How to Increase Capacity?

Solution is Massive MIMO

What is Massive MIMO? Tens to hundreds, maybe more, physically small, low power antennas. Massive MIMO Characteristics • Many fully digital steerable antennas • Massive in numbers – NOT massive in size • Aggressive spatial multiplexing • Utilize channel

Massive Antenna Arrangement

General Purposes of Multi-antenna System

Why MIMO?

Types of MIMO Systems

Single-User MIMO (1993-1998) • unfavorable propagation • time required for training grows with system size • disappointing multiplexing gains at cell edges

Multi-User MIMO (2003) • Splitting the multi-antenna user into separate single-antenna users doesn’t decrease the sum-throughput! • • • •

Only single-antenna terminals required Propagation is almost always favorable But not scalable in its original form Both ends of link have to know channel

Massive MIMO (2010) • Add many more base station antennas • Channel state information (CSI) only available to the base station • Use linear pre-coding/de-coding instead of dirty-paper • Users don’t do any signal processing

Massive MIMO Spatial Multiplexing pushed to an extreme Massive MIMO serves all users over the same time/frequency resources The large number of antennas paradoxically makes the problem simpler

Advantages of Massive MIMO Scalability

Energy efficiency

Spectral efficiency

QoS

Simplicity

Implementation

Downlink Data Transmission: Conjugate Beamforming • ANTENNAS TRANSMIT THE WEIGHTED MESSAGE-BEARING SYMBOLS TO ARRIVE INPHASE AT THE INTENDED USER & OUT-OFPHASE ELSEWHERE.

• Information-bearing symbols combined with measured channel characteristics to create transmitted signals.

Uplink Data Transmission: Matched Filtering • BASE STATION WEIGHTS AND ADDS RECEIVED SIGNALS FOR CONSTRUCTIVE REINFORCEMENT OF THE TRANSMISSION FROM EACH USER.

• For high SINRs, zero-forcing may outperform conjugate beamforming/matched-filtering.

Capacity Analysis

LOS:

Full rank:

Practical Constraints and Challenges Hardware impairments

Space constrained

TDD or FDD Operating Mode

Overview and Research Papers: (https://massivemimo.eu/research-library) 1. T. L. Marzetta, “Noncooperative Cellular Wireless with Unlimited Numbers of Base Station Antennas,” IEEE Trans. Wireless Communications, 2010. IEEE W.R.G. Baker Prize Paper Award 2. J. Hoydis, S. ten Brink, M. Debbah, “Massive MIMO in the UL/DL of Cellular Networks: How Many Antennas Do We Need?,” IEEE Journal on Selected Areas in Communications, 2013. IEEE Leonard G. Abraham Prize 3. H. Q. Ngo, E. G. Larsson, and T. L. Marzetta, “Energy and Spectral Efficiency of Very Large Multiuser MIMO Systems,” IEEE Trans. Communication, 2013. IEEE Stephen O. Rrice Prize 4. F. Rusek, D. Persson, B. K. Lau, E. G. Larsson, T. L. Marzetta, O. Edfors, and F. Tufvesson, “Scaling up MIMO: Opportunities and Challenges with Very Large Arrays,” IEEE Signal Proces. Mag., 2013. 5. J. Hoydis, K. Hosseini, S. ten Brink, and M. Debbah, “Making Smart Use of Excess Antennas: Massive MIMO, Small Cells, and TDD,” Bell Labs Technical Journal, 2013. 6. E. G. Larsson, F. Tufvesson, O. Edfors, and T. L. Marzetta, “Massive MIMO for Next Generation Wireless Systems,” IEEE Communacation. Mag., 2014. 7. E. Bjِ rnson, E. Jorswieck, M. Debbah, B. Ottersten, “Multi-Objective Signal Processing Optimization: The Way to Balance Conflicting Metrics in 5G Systems,” IEEE Signal Processing Magazine, 2014. 8. T. L. Marzetta, “Massive MIMO: An Introduction,” Bell Labs Technical Journal, 2015 9. E. Bjِ rnson, E. G. Larsson, T. L. Marzetta, “Massive MIMO: 10 Myths and One Grand Question,” IEEE Communications Magazine, 2015.

References • Massive MIMO: Fundamentals and System Issues, Thomas L. Marzetta, Bell Labs, 2015. • Massive MIMO for 5G: From Theory to Practice, Linglong Dai, Tsinghua University, 2015. • Massive MIMO Wireless Networks: An Overview, Noha Hassan and Xavier Fernando, Ryerson University, Electronics, 2017.