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MIMO

About: MIMO is a(n) research topic. Over the lifetime, 62743 publication(s) have been published within this topic receiving 959118 citation(s). The topic is also known as: multiple-input and multiple-output & Multi-input Multi-output.

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Open accessBook
David Tse1, Pramod Viswanath2Institutions (2)
01 Jan 2005-
Abstract: 1. Introduction 2. The wireless channel 3. Point-to-point communication: detection, diversity and channel uncertainty 4. Cellular systems: multiple access and interference management 5. Capacity of wireless channels 6. Multiuser capacity and opportunistic communication 7. MIMO I: spatial multiplexing and channel modeling 8. MIMO II: capacity and multiplexing architectures 9. MIMO III: diversity-multiplexing tradeoff and universal space-time codes 10. MIMO IV: multiuser communication A. Detection and estimation in additive Gaussian noise B. Information theory background.

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Topics: Multi-user MIMO (72%), Spatial multiplexing (72%), MIMO (71%) ...read more

7,400 Citations


Journal ArticleDOI: 10.1109/TWC.2010.092810.091092
Thomas L. Marzetta1Institutions (1)
Abstract: A cellular base station serves a multiplicity of single-antenna terminals over the same time-frequency interval. Time-division duplex operation combined with reverse-link pilots enables the base station to estimate the reciprocal forward- and reverse-link channels. The conjugate-transpose of the channel estimates are used as a linear precoder and combiner respectively on the forward and reverse links. Propagation, unknown to both terminals and base station, comprises fast fading, log-normal shadow fading, and geometric attenuation. In the limit of an infinite number of antennas a complete multi-cellular analysis, which accounts for inter-cellular interference and the overhead and errors associated with channel-state information, yields a number of mathematically exact conclusions and points to a desirable direction towards which cellular wireless could evolve. In particular the effects of uncorrelated noise and fast fading vanish, throughput and the number of terminals are independent of the size of the cells, spectral efficiency is independent of bandwidth, and the required transmitted energy per bit vanishes. The only remaining impairment is inter-cellular interference caused by re-use of the pilot sequences in other cells (pilot contamination) which does not vanish with unlimited number of antennas.

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Topics: Fading (61%), Channel state information (58%), Many antennas (57%) ...read more

5,634 Citations


Open accessJournal ArticleDOI: 10.1109/MCOM.2014.6736761
Abstract: Multi-user MIMO offers big advantages over conventional point-to-point MIMO: it works with cheap single-antenna terminals, a rich scattering environment is not required, and resource allocation is simplified because every active terminal utilizes all of the time-frequency bins. However, multi-user MIMO, as originally envisioned, with roughly equal numbers of service antennas and terminals and frequency-division duplex operation, is not a scalable technology. Massive MIMO (also known as large-scale antenna systems, very large MIMO, hyper MIMO, full-dimension MIMO, and ARGOS) makes a clean break with current practice through the use of a large excess of service antennas over active terminals and time-division duplex operation. Extra antennas help by focusing energy into ever smaller regions of space to bring huge improvements in throughput and radiated energy efficiency. Other benefits of massive MIMO include extensive use of inexpensive low-power components, reduced latency, simplification of the MAC layer, and robustness against intentional jamming. The anticipated throughput depends on the propagation environment providing asymptotically orthogonal channels to the terminals, but so far experiments have not disclosed any limitations in this regard. While massive MIMO renders many traditional research problems irrelevant, it uncovers entirely new problems that urgently need attention: the challenge of making many low-cost low-precision components that work effectively together, acquisition and synchronization for newly joined terminals, the exploitation of extra degrees of freedom provided by the excess of service antennas, reducing internal power consumption to achieve total energy efficiency reductions, and finding new deployment scenarios. This article presents an overview of the massive MIMO concept and contemporary research on the topic.

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  • Figure 7: Achieved downlink sum-rates, using MRT precoding, with four single-antenna terminals and between 4 and 128 base station antennas.
    Figure 7: Achieved downlink sum-rates, using MRT precoding, with four single-antenna terminals and between 4 and 128 base station antennas.
  • Figure 2: Relative field strength around a target terminal in a scattering environment of size 800λ×800λ, when the base station is placed 1600λ to the left. Average field strengths are calculated over 10000 random placements of 400 scatterers, when two different linear precoders are used: a) MRT precoders and b) ZF precoders. Left: pseudo-color plots of average field strengths, with target user positions at the center (?), and four other users nearby (◦). Right: average field strengths as surface plots, allowing an alternate view of the spatial focusing.
    Figure 2: Relative field strength around a target terminal in a scattering environment of size 800λ×800λ, when the base station is placed 1600λ to the left. Average field strengths are calculated over 10000 random placements of 400 scatterers, when two different linear precoders are used: a) MRT precoders and b) ZF precoders. Left: pseudo-color plots of average field strengths, with target user positions at the center (?), and four other users nearby (◦). Right: average field strengths as surface plots, allowing an alternate view of the spatial focusing.
  • Figure 6: CDF of the singular value spread for MIMO systems with 4 terminals and three different numbers of BS antennas: 4, 32, and 128. The theoretical i.i.d. channel is shown as a reference, while the other two cases are measured channels with linear and cylindrical array structures at the BS. Note: The curve for the linear array coincides with that of the i.i.d. channel for 4 BS.
    Figure 6: CDF of the singular value spread for MIMO systems with 4 terminals and three different numbers of BS antennas: 4, 32, and 128. The theoretical i.i.d. channel is shown as a reference, while the other two cases are measured channels with linear and cylindrical array structures at the BS. Note: The curve for the linear array coincides with that of the i.i.d. channel for 4 BS.
  • Figure 5: Massive MIMO antenna arrays used for the measurements.
    Figure 5: Massive MIMO antenna arrays used for the measurements.
  • Figure 3: Half the power—twice the force (from [6]): Improving uplink spectral efficiency 10 times and simultaneously increasing the radiated-power efficiency 100 times with massive MIMO technology, using extremely simple signal processing—taking into account the energy and bandwidth costs of obtaining channel state information.
    Figure 3: Half the power—twice the force (from [6]): Improving uplink spectral efficiency 10 times and simultaneously increasing the radiated-power efficiency 100 times with massive MIMO technology, using extremely simple signal processing—taking into account the energy and bandwidth costs of obtaining channel state information.
  • + 2

Topics: 3G MIMO (72%), Multi-user MIMO (66%), Spatial multiplexing (63%) ...read more

5,302 Citations


Open accessJournal ArticleDOI: 10.1109/MSP.2011.2178495
Fredrik Rusek1, Daniel Persson1, Buon Kiong Lau1, Erik G. Larsson1  +2 moreInstitutions (1)
Abstract: Multiple-input multiple-output (MIMO) technology is maturing and is being incorporated into emerging wireless broadband standards like long-term evolution (LTE) [1]. For example, the LTE standard allows for up to eight antenna ports at the base station. Basically, the more antennas the transmitter/receiver is equipped with, and the more degrees of freedom that the propagation channel can provide, the better the performance in terms of data rate or link reliability. More precisely, on a quasi static channel where a code word spans across only one time and frequency coherence interval, the reliability of a point-to-point MIMO link scales according to Prob(link outage) ` SNR-ntnr where nt and nr are the numbers of transmit and receive antennas, respectively, and signal-to-noise ratio is denoted by SNR. On a channel that varies rapidly as a function of time and frequency, and where circumstances permit coding across many channel coherence intervals, the achievable rate scales as min(nt, nr) log(1 + SNR). The gains in multiuser systems are even more impressive, because such systems offer the possibility to transmit simultaneously to several users and the flexibility to select what users to schedule for reception at any given point in time [2].

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  • Fig. 6. CDFs of ordered eigenvalues for a measured6×128 large array system, a measured6×6 MIMO system and simulated IID6 × 6 and 6 × 128 MIMO systems. Note that for the simulated IID cases, only theCDFs of the largest and smallest eigenvalues are shown for clarity.
    Fig. 6. CDFs of ordered eigenvalues for a measured6×128 large array system, a measured6×6 MIMO system and simulated IID6 × 6 and 6 × 128 MIMO systems. Note that for the simulated IID cases, only theCDFs of the largest and smallest eigenvalues are shown for clarity.
  • TABLE II ROUGH COMPLEXITY ESTIMATES FOR DETECTORS IN TERMS OF FLOATING POINT OPERATIONS. IF A SIGNIFICANT AMOUNT OF THE COMPUTATIONS IN QUESTION CAN BE PRE-PROCESSED FOR EACHG IN SLOW FADING, THE PRE-PROCESSING COMPLEXITY IS GIVEN IN THE RIGHT COLUMN.
    TABLE II ROUGH COMPLEXITY ESTIMATES FOR DETECTORS IN TERMS OF FLOATING POINT OPERATIONS. IF A SIGNIFICANT AMOUNT OF THE COMPUTATIONS IN QUESTION CAN BE PRE-PROCESSED FOR EACHG IN SLOW FADING, THE PRE-PROCESSING COMPLEXITY IS GIVEN IN THE RIGHT COLUMN.
  • Fig. 1. Geometry of the simulated dense scattering environment, with 400 uniformly distributed scatterers in a 800× 800 λ area. The transmitM -element ULA is placed at a distance of 1600λ from the edge of the scatterer area with its broadside pointing towards the center. Two single scattering paths from the first ULA element to an intended receiver in the center of the scatterer area are shown.
    Fig. 1. Geometry of the simulated dense scattering environment, with 400 uniformly distributed scatterers in a 800× 800 λ area. The transmitM -element ULA is placed at a distance of 1600λ from the edge of the scatterer area with its broadside pointing towards the center. Two single scattering paths from the first ULA element to an intended receiver in the center of the scatterer area are shown.
  • Fig. 4. Impact of correlation and coupling on capacity per anten a over different adjacent antenna spacing for autonomous transmitters.M = K and the apertures of ULA and USA are5λ and5λ × 5λ, respectively.
    Fig. 4. Impact of correlation and coupling on capacity per anten a over different adjacent antenna spacing for autonomous transmitters.M = K and the apertures of ULA and USA are5λ and5λ × 5λ, respectively.
  • Fig. 3. Diagram of a MIMO system with antenna impedance matrices and matching networks at both link ends (freely reproduced from [23]).
    Fig. 3. Diagram of a MIMO system with antenna impedance matrices and matching networks at both link ends (freely reproduced from [23]).
  • + 11

Topics: MIMO (61%), Many antennas (56%), Bell Laboratories Layered Space-Time (53%) ...read more

4,913 Citations


Journal ArticleDOI: 10.1109/TIT.2003.810646
Lizhong Zheng1, David Tse1Institutions (1)
Abstract: Multiple antennas can be used for increasing the amount of diversity or the number of degrees of freedom in wireless communication systems. We propose the point of view that both types of gains can be simultaneously obtained for a given multiple-antenna channel, but there is a fundamental tradeoff between how much of each any coding scheme can get. For the richly scattered Rayleigh-fading channel, we give a simple characterization of the optimal tradeoff curve and use it to evaluate the performance of existing multiple antenna schemes.

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Topics: Antenna diversity (64%), MIMO (56%), Multiplexing (55%) ...read more

4,264 Citations


Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202246
20212,996
20203,734
20194,118
20184,018
20174,291

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Topic's top 5 most impactful authors

Robert W. Heath

345 papers, 34K citations

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Emil Björnson

281 papers, 10.8K citations

Erik G. Larsson

271 papers, 22.6K citations

Shi Jin

248 papers, 8K citations

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