Robust MMSE Transceiver Designs for Downlink MIMO Systems with Multicell Cooperation

Jialing Li,Enoch Lu,I-Tai Lu

doi:10.1155/2010/815704

Jialing Li, Enoch Lu + Show 1 more

Open Access

https://doi.org/10.1155/2010/815704

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Abstract

Therobust-generalized iterative approach(Robust-GIA),robust-fast iterative approach(Robust-FIA), androbust-decoder covariance optimization approach(Robust-DCOA) are proposed for designing MMSE transceivers of downlink multicell multiuser MIMO systems with per-cell and per-antenna power constraints and possibly imperfect channel state information. TheRobust-DCOAis the most restrictive but is always optimum, theRobust-GIAis the most general, and theRobust-FIAis the most efficient. When theRobust-DCOAis applicable and the decoder covariance matrices are full rank, the three proposed approaches are equivalent and all provide the optimum solution. Numerical results show that the proposed robust approaches outperform their non-robust counterparts in various single-cell and multicell examples with different system configurations, channel correlations, power constraints, and cooperation scenarios. Moreover, performances of the robust approaches are insensitive to estimation errors of channel statistics (correlations and path loss). With cell-cooperation, cell edge interference problems can be remedied without reducing the number of data streams by using the proposed robust approaches.

Highlights

Joint transceiver designs with criteria such as minimum mean square error (MMSE), maximum sum capacity, and minimum bit error rate (BER), and so forth, for multipleinput-multiple-output (MIMO) systems, with both uplink and downlink configurations, have been studied intensively in recent literature
We have shown that the generalized iterative approach (GIA) and the decoder covariance optimization approach (DCOA) are equivalent and optimum when the source covariance matrices are all identity matrices multiplied by the same constant and the decoder covariance matrices are all full rank [13]
The Robust-fast iterative approach (FIA) can be developed based on the Robust-GIA when the source covariance matrices are all identity matrices multiplied by the same constant, that is, Φsi = σ2Imi, i ∈ S

Summary

Introduction

Joint transceiver designs with criteria such as minimum mean square error (MMSE), maximum sum capacity, and minimum bit error rate (BER), and so forth, for multipleinput-multiple-output (MIMO) systems, with both uplink and downlink configurations, have been studied intensively in recent literature (e.g., see [1, 2]). To cope with CSI estimation errors, closed form solutions for the robust joint MMSE transceiver design subject to the total power constraint are developed for single-user MIMO systems in [14,15,16]. For multiuser uplink MIMO problems subject to the inequality per-user and sum power constraints, the robust transmit covariance optimization approach (RobustTCOA) is developed for independent identically distributed (i.i.d.) MIMO channels with CSI estimation errors in [17]. Proposed in this paper is the robust MMSE transceiver design with respect to CSI estimation errors for downlink multicell MIMO systems subject to arbitrary linear power constraints. MMSE transceiver designs using the proposed robust approaches are performed for various single-cell and multicell examples with different system configurations, power constraints, channel correlations, and cooperation scenarios. CN(μ, σ2) denotes a complex normal random variable with mean μ and variance σ2

Formulation

Robust Iterative Approaches

Numerical Results

Computational Efficiency

Multicell

Conclusion