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Massive MIMO System

Massive MIMO System. Rui WANG 14/11/2013. Outline. Introduction The Potential of Massive MIMO Limiting Factors Of Massive MIMO Research Problems. Introduction. Global exponential mobile data traffic increase More devices, higher bit rates Larger variety of traffic types. Massive

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Massive MIMO System

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  1. Massive MIMO System Rui WANG 14/11/2013

  2. Outline • Introduction • The Potential of Massive MIMO • Limiting Factors Of Massive MIMO • Research Problems

  3. Introduction • Global exponential mobile data traffic increase • More devices, higher bit rates • Larger variety of traffic types Massive MIMO

  4. Introduction M antennas (hundreds) K terminals • Large-Scale Antenna Systems • Very Large MIMO • Hyper MIMO • Full-Dimension MIMO • ARGOS • active terminals • time division duplex operation. • Massive multiuser MIMO (MISO) • (e.g. )

  5. The Potential of Massive MIMO • Increase the capacity & radiated energy-efficiency

  6. The Potential of Massive MIMO • Simulation Parameters • 400 uniformly distributed scatterers • λ: signal wavelength • MRT precoder is used • Multipath component • Large-scale + small-scale considered • Path-loss + Rayleigh fading • Conclusion from simulation results • Field strength can be focused to a point • More antennas improve the ability to focus energy to a certain point M=10  100, Improved ability to focus energy to a certain point

  7. The Potential of Massive MIMO • Uncorrelated interference and noise vanish • : small scale fading • ; zero mean;i.i.d • : path loss + shadowing

  8. The Potential of Massive MIMO • Matched-Filter

  9. The Potential of Massive MIMO • inexpensive, low-power components • 50 Watt  milli-Watt range • a significant reduction of latency • avoid fading dips • simplifies the multiple-access layer • whole bandwidth, most of the physical-layer control signaling redundant • increases the robustness • scarcity of bandwidth->use multiple antennas • offers many excess degrees of freedom (M-K), cancel signals from jammers.

  10. Limiting Factors Of Massive MIMO • Pilot Contamination • re-using pilots During the training phase, the base station in cell 1 overhears the pilot transmission from other cells. The transmitted vector from base station 1 will be partially beamformedto the terminals in cell 2.

  11. Limiting Factors Of Massive MIMO • How to deal with pilot contamination? • The allocation of pilot waveforms can be optimized. • frequency re-use : pushes mutually-contaminating cells farther apart • coordinate the use of pilots or adaptively allocate pilot sequences to the different terminals in the network • Clever channel estimation algorithms including the use of pilots • most promising direction: jointly estimate the channels and the payload data • New precoding techniques that take into account the network structure. • e.g. Pilot contamination precoding Ashikhmin A, Marzetta T. Pilot contamination precoding in multi-cell large scale antenna systems[C]//Information Theory Proceedings (ISIT), 2012 IEEE International Symposium on. IEEE, 2012: 1137-1141.

  12. Limiting Factors Of Massive MIMO • Channel Reciprocity • TDD operation relies on channel reciprocity. • The hardware chains in the base station and terminal transceivers may not be reciprocal between the uplink and the downlink.

  13. Research Problems • The challenge of low-cost hardware. • require economy of scale in manufacturing • low-cost components->hardware imperfections are larger • phase noise • Internal power consumption. • total power consumed must be considered, the cost of baseband signal processing • Channel characterization. • additional properties of the channel to consider • Pilot contamination.

  14. Research Problems small-cell and HetNet Rusek F, Persson D, Lau B K, et al. Scaling up MIMO: Opportunities and challenges with very large arrays[J]. Signal Processing Magazine, IEEE, 2013, 30(1): 40-60.

  15. References  • [1] Larsson E G, Tufvesson F, Edfors O, et al. Massive MIMO for Next Generation Wireless Systems[J]. arXiv preprint arXiv:1304.6690, 2013. • [2]Rusek F, Persson D, Lau B K, et al. Scaling up MIMO: Opportunities and challenges with very large arrays[J]. Signal Processing Magazine, IEEE, 2013, 30(1): 40-60 • [3]Hoydis J, Hosseini K, Brink S, et al. Making Smart Use of Excess Antennas: Massive MIMO, Small Cells, and TDD[J]. Bell Labs Technical Journal, 2013, 18(2): 5-21. • [4]Marzetta T L. Noncooperative cellular wireless with unlimited numbers of base station antennas[J]. Wireless Communications, IEEE Transactions on, 2010, 9(11): 3590-3600. • [5] Ngo H, Larsson E, Marzetta T. Energy and spectral efficiency of very large multiuser MIMO systems[J]. 2011. • [6]Ashikhmin A, Marzetta T. Pilot contamination precoding in multi-cell large scale antenna systems[C]//Information Theory Proceedings (ISIT), 2012 IEEE International Symposium on. IEEE, 2012: 1137-1141. • [7]Hoydis J, ten Brink S, Debbah M. Massive MIMO in the UL/DL of cellular networks: How many antennas do we need?[J]. Selected Areas in Communications, IEEE Journal on, 2013, 31(2): 160-171.

  16. Thank you

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