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Results of recent measurement campaigns demonstrate a significant increase in the degrees of freedom introduced by the elevation domain, and consequently, a large capacity gap as predicted by 3D and 2D MIMO channel models. To gain further insight into the effects of the elevation domain on MIMO system performance, we derive new spatial correlation (SC) expressions for 3D and 2D channel models, given...
In this paper, we take a proposed low-complexity Vertical Bell Laboratories Layered Space Time receiver based on maximal ratio combining and further simplify the algorithm by replacing the channel norm ordering by a power based ordering. The receiver operates in an uplink massive multiple-input-multiple-output deployment with distributed single-antenna users and a large base station (BS) array. The...
This paper investigates the achievable spectral efficiency (SE) of millimeter wave downlink cellular systems accounting for both small and large-scale fading effects. The base station (BS) employs a uniform linear array (ULA) and maximal ratio transmission. We derive the expectation of the squared inner product for different channel links under the assumption that the users are randomly distributed...
In this paper we examine a number of deployment issues which arise from practical considerations in massive multiple-input-multiple-output (MIMO) systems. We show both spatial correlation and line-of-sight (LOS) introduce an interference component to the system which causes non-orthogonality between user channels. Distributing the antennas into multiple clusters is shown to reduce spatial correlation...
We consider the performance of a low complexity Vertical Bell Laboratories Layered Space Time system with a maximum ratio combining receiver (LC-VBLAST) in an uplink massive multiple-input-multiple-output (MIMO) deployment with single antenna users. This receiver is known to give a similar error rate performance to zero forcing (ZF) for simple systems while reducing complexity. In this paper, we show...
In an uplink massive multiple-input-multiple-output (MIMO) deployment with distributed single-antenna users and a large base-station array, we consider the performance of Vertical Bell Laboratories Layered Space Time (V-BLAST) with maximum ratio combining (MRC) and V-BLAST with zero forcing (ZF). In the performance evaluation, we include the effects of imperfect channel state information (CSI) and...
In this paper we examine convergence properties of massive MIMO systems with the aim of determining the number of antennas required for massive MIMO gains. We consider three characteristics of a channel matrix and study their asymptotic behaviour. Furthermore, we derive ZF SNR and MF SINR for a scenario of unequal receive powers. In our results we include the effects of spatial correlation. We show...
In an uplink massive multiple-input-multiple-output deployment with distributed single-antenna users and a large base-station array, we consider several combinations of receivers using linear combiners (maximum ratio combining (MRC) and zero forcing (ZF)) in conjunction with Vertical Bell Laboratories Layered Space Time (V-BLAST). We show that the performance loss of MRC relative to ZF can be removed...
In this paper, we present a differential codebook design by modifying the Grassmannian codebook for a single-cell multiuser (MU) multiple-input single-output (MISO) system operating under spatially and temporally correlated channels. The differential codebook design involves scaling and rotation methods that help a codebook to track the slow varying channel. We propose an adaptive scaling technique...
In limited feedback multiple-input multiple-output (MIMO) systems, it is important that the codebooks used provide a good approximation to the channel. Any mismatch between the codebook entries and the actual channel creates a non zero chordal distance (or subspace angle) between the codebook element and the corresponding columns of the right singular matrix of the channel. As a result, the system...
Limited feedback precoding is part of the LTE standard. Despite standardization, important fundamental questions, especially relating to the performance due to the use of codebooks and receiver processing techniques, remain to be explored. In order to understand these questions, we consider a single user in a single cell employing single or multi-stream transmission using a variety of codebooks and...
The standard condition number (SCN) is a fundamental metric in the context of multiple-input multiple-output communication systems, linear detection and classical linear algebra. Hence, in this paper we propose a novel generic framework for the SCN distribution of three different classes of Wishart matrices which leads to new results and insights. In particular, our analysis covers both central and...
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