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Asymptotic analysis of downlink MISO systems over Rician fading channels,” in
 Proc. IEEE ICASSP,
, 2016
"... ABSTRACT In this work, we focus on the ergodic sum rate in the downlink of a singlecell largescale multiuser MIMO system in which the base station employs N antennas to communicate with K singleantenna user equipments. A regularized zeroforcing (RZF) scheme is used for precoding under the assu ..."
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ABSTRACT In this work, we focus on the ergodic sum rate in the downlink of a singlecell largescale multiuser MIMO system in which the base station employs N antennas to communicate with K singleantenna user equipments. A regularized zeroforcing (RZF) scheme is used for precoding under the assumption that each link forms a spatially correlated MIMO Rician fading channel. The analysis is conducted assuming N and K grow large with a non trivial ratio and perfect channel state information is available at the base station. Recent results from random matrix theory and large system analysis are used to compute an asymptotic expression of the signaltointerferenceplusnoise ratio as a function of the system parameters, the spatial correlation matrix and the Rician factor. Numerical results are used to evaluate the performance gap in the finite system regime under different operating conditions.
Design, Modeling, and Performance Analysis of MultiAntenna Heterogeneous Cellular Networks
, 2016
"... Abstract This paper presents a stochastic geometrybased framework for the design and analysis of downlink multiuser multipleinput multipleoutput (MIMO) heterogeneous cellular networks (HetNets) with linear zeroforcing (ZF) transmit precoding and receive combining, assuming Rayleigh fading chann ..."
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Abstract This paper presents a stochastic geometrybased framework for the design and analysis of downlink multiuser multipleinput multipleoutput (MIMO) heterogeneous cellular networks (HetNets) with linear zeroforcing (ZF) transmit precoding and receive combining, assuming Rayleigh fading channels and perfect channel state information (CSI). The generalized tiers of base stations (BSs) may differ in terms of their Poisson point process (PPP) spatial density, number of transmit antennas, transmit power, artificialbiasing weight, and number of user equipments (UEs) served per resource block. The spectral efficiency of a typical user equipped with multiple receive antennas is characterized using a nondirect momentgeneratingfunction (MGF)based methodology with closedform expressions of the useful received signal and aggregate network interference statistics systematically derived. In addition, the area spectral efficiency is formulated under different spacedivision multipleaccess (SDMA) and singleuser beamforming (SUBF) transmission schemes. We examine the impact of different cellular network deployments, propagation conditions, antenna configurations, and MIMO setups on the achievable performance through theoretical and simulation studies. Based on stateoftheart system parameters, the results highlight the inherent limitations of baseline singleinput singleoutput (SISO) transmission and conventional sparse macrocell deployment, as well as the promising potential of multiantenna communications and smallcell solution in interferencelimited cellular environments. Index Terms Multiantenna communications, downlink heterogeneous cellular networks, stochastic geometry theory.
Achievable Rate of Rician LargeScale MIMO Channels with Transceiver Hardware Impairments
"... AbstractTransceiver hardware impairments (e.g., phase noise, inphase/quadraturephase (I/Q) imbalance, amplifier nonlinearities, and quantization errors) have obvious degradation effects on the performance of wireless communications. While prior works have improved our knowledge on the influence ..."
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AbstractTransceiver hardware impairments (e.g., phase noise, inphase/quadraturephase (I/Q) imbalance, amplifier nonlinearities, and quantization errors) have obvious degradation effects on the performance of wireless communications. While prior works have improved our knowledge on the influence of hardware impairments of singleuser multipleinput multipleoutput (MIMO) systems over Rayleigh fading channels, an analysis encompassing the Rician fading channel is not yet available. In this paper, we pursue a detailed analysis of regular and largescale (LS) MIMO systems over Rician fading channels by deriving new, closedform expressions of the achievable rate to provide several important insights for practical system design. More specifically, for regular MIMO systems with hardware impairments, there is always a finite achievable rate ceiling, which is irrespective of the transmit power and fading conditions. For LSMIMO systems, it is interesting to find that the achievable rate loss is independent of the Rician Kfactor, which reveals that the favorable propagation in LSMIMO systems cannot remove the influence of hardware impairments. However, we show that the nonideal LSMIMO system can still achieve high spectral efficiency due to its huge degrees of freedom.
Achievable Downlink Rates of MRC and ZF Precoders in Massive MIMO With Uplink and Downlink Pilot Contamination
"... AbstractMassive multiinput multioutput (MIMO) systems require channel state information (CSI) at base stations. In multicell environments, adjacent cells using the same spectrum cause a pilot contamination problem and degrade CSI quality. Under such practical environments, it is important to ass ..."
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AbstractMassive multiinput multioutput (MIMO) systems require channel state information (CSI) at base stations. In multicell environments, adjacent cells using the same spectrum cause a pilot contamination problem and degrade CSI quality. Under such practical environments, it is important to assess achievable rate of the system for a proper system design. There exist achievable rate bounds of uplink (UL) systems in the literature, but general closedform rate bounds for downlink (DL) systems are not available yet. This paper studies a practical massive MIMO DL system with or without pilotaided coherent detection under the scenario of pilot contamination, and derives closedform approximate achievable DL rate expressions for both maximum ratio combining (MRC) and zero forcing (ZF) precoders. For the case with DL pilot, a corresponding DL effective channel estimator is also developed. Numerical simulation results corroborate accuracy of the closedform rate expressions and they also show performance characteristics of pilotcontaminated massive MIMO DL systems with MRC and ZF precoders. Index TermsMassive MIMO, downlink achievable rate, pilot contamination, channel estimation, imperfect CSI.
ASYMPTOTIC ANALYSIS OF DOWNLINKMISO SYSTEMS OVER RICIAN FADING CHANNELS
"... In this work, we focus on the ergodic sum rate in the downlink of a singlecell largescale multiuser MIMO system in which the base station employs N antennas to communicate withK singleantenna user equipments. A regularized zeroforcing (RZF) scheme is used for precoding under the assumption that ..."
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In this work, we focus on the ergodic sum rate in the downlink of a singlecell largescale multiuser MIMO system in which the base station employs N antennas to communicate withK singleantenna user equipments. A regularized zeroforcing (RZF) scheme is used for precoding under the assumption that each link forms a homogeneous spatially correlated MIMO Rician fading channel. The analysis is conducted assuming N and K grow large with a non trivial ratio and perfect channel state information is available at the base station. Recent results from random matrix theory and large system analysis are used to compute an asymptotic expression of the signaltointerferenceplusnoise ratio as a function of the system parameters, the spatial correlation matrix and the Rician factor. Numerical results are used to evaluate the performance gap in the finite system regime under different operating conditions. 1.
Exact ZF Analysis and ComputerAlgebra Aided Evaluation in Rank1 LoS Rician Fading
"... We propose a new exact analysis and evaluation of zeroforcing detection (ZF) for multiple– input/multiple–output (MIMO) spatial multiplexing under transmitcorrelated Rician fading for an NR× NT channel matrix with rank1 lineofsight (LoS) component. First, an analysis based on several matrix tra ..."
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We propose a new exact analysis and evaluation of zeroforcing detection (ZF) for multiple– input/multiple–output (MIMO) spatial multiplexing under transmitcorrelated Rician fading for an NR× NT channel matrix with rank1 lineofsight (LoS) component. First, an analysis based on several matrix transformations yields the exact signaltonoise ratio (SNR) moment generating function (m.g.f.) as an infinite series of gamma distribution m.g.f.’s. This produces analogous series for the SNR probability density function and for ZF performance measures. However, their numerical convergence is inherently problematic with increasing Rician Kfactor, NR, and NT. Therefore, we additionally derive corresponding differential equations by using computer algebra. Finally, we apply the holonomic gradient method (HGM), i.e., we solve the differential equations by starting from suitable initial conditions computed with the infinite series. HGM yields more reliable performance evaluation than by infinite series alone and more expeditious than by simulation, for realistic values of K, and even for NR and NT relevant to large MIMO systems. We anticipate that future MIMO analyses for Rician fading will produce even more involved series that may benefit from the proposed computeralgebraaided evaluation approach. Index Terms