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Open AccessJournal ArticleDOI

MU-MIMO in LTE Systems

TLDR
It is shown that MU-MIMO only offers marginal performance gains with respect to single-user MIMO and calls for improved schemes for the upcoming releases.
Abstract
A relatively recent idea of extending the benefits of MIMO systems to multiuser scenarios seems promising in the context of achieving high data rates envisioned for future cellular standards after 3G (3rd Generation). Although substantial research has been done on the theoretical front, recent focus is on making Multiuser Multiple-Input Multiple-Output (MUMIMO) practically realizable. This paper presents an overview of the different MU-MIMO schemes included/being studied in 3GPP standardization from LTE (long-term evolution) to LTE Advanced. MU-MIMO system concepts and implementation aspects have been studied here. Various low-complexity receiver architectures are investigated, and their performance assessed through link-level simulations. Appealing performance offered by low-complexity interference aware (IA) receivers is notably emphasized. Furthermore, system level simulations for LTE Release 8 are provided. Interestingly, it is shown that MU-MIMO only offers marginal performance gains with respect to single-user MIMO. This arises from the limited MU-MIMO features included in Release 8 and calls for improved schemes for the upcoming releases.

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References
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Book

LTE - The UMTS Long Term Evolution: From Theory to Practice

TL;DR: Scrase et al. as discussed by the authors provide a comprehensive system-level understanding of LTE, built on explanations of the theories which underlie it, and provide a broad, balanced and reliable perspective on this important technology Lucid yet thorough, the book devotes particular effort to explaining the theoretical concepts in an accessible way.
Journal ArticleDOI

Zero-forcing methods for downlink spatial multiplexing in multiuser MIMO channels

TL;DR: While the proposed algorithms are suboptimal, they lead to simpler transmitter and receiver structures and allow for a reasonable tradeoff between performance and complexity.
Journal ArticleDOI

On the achievable throughput of a multiantenna Gaussian broadcast channel

TL;DR: Under certain mild conditions, this scheme is found to be throughput-wise asymptotically optimal for both high and low signal-to-noise ratio (SNR), and some numerical results are provided for the ergodic throughput of the simplified zero-forcing scheme in independent Rayleigh fading.
Book

Bit-Interleaved Coded Modulation

TL;DR: The goal of this paper is to present in a comprehensive fashion the theory underlying bit-interleaved coded modulation, to provide tools for evaluating its performance, and to give guidelines for its design.
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