Mats Bengtsson

TL;DR: It is proved that the QRD-based design is optimal for ZF-DPC for any performance measure under a sum power constraint, and an optimal design is proposed, using a convex optimization framework.

TL;DR: In this article, the uplink of a cellular massive MIMO network is considered and the problem of finding efficient pilot reuse patterns is addressed using coalitional game theory, where each cell has its own unique pilots and can form coalitions with other cells to gain access to more pilots.

TL;DR: This document describes the research activity in multi-node/multi-antenna technologies within METIS and positions it with respect to the state-of-the-art in the academic literature and in the standardization bodies.

TL;DR: It is shown that for a unitarily-invariant uncertainty set, the optimally robust training sequence shares its eigenvectors with the channel covariance matrix, and analytical closed-form solutions for robust training sequences are given if the spectral norm or nuclear norm are considered as constraints to bound the existing uncertainty.

TL;DR: Numerical results show that the proposed LS-MSP techniques outperform previously proposed techniques in terms of the computational burden while complying with the spectrum mask and typically needs 3 iterations to achieve similar results at the expense of a slightly increased computational complexity.