… investigate beamdomain channel estimation and feedback for FDD massive MIMO
systems. … to exploit the common support among all beam-domain channels. For threshold-based …

… and (27) give important insights when assessing the impact of beamforming/combining
techniques on the spectral efficiency of the proposed FDD-based cell-free massive MIMO system. …

… digital domain, the selection of the beams may be performed individually for each subcarrier.
b) In contrast, if implemented in the analog domain, the same set of beams … beams in FDD …

… FDD-based massive MIMO schemes by using measured channels from a test-bed in Lund,
Sweden. It concludes that FDD massive MIMO grid of beam (GoB) systems … spatial domain. …

… on the bottom layer covers an area of ∆θ = 90◦/6 = 15◦ over the elevation angle domain, and
∆φ = 360◦/12 = 30◦ over the azimuth angle domain. The hierarchical factor Q is set as 2 or 3 …

… In FDD massive MIMO, the downlink training and … One attempt of practical FDD massive
MIMO is called joint spatial … Another scheme that enables FDD massive MIMO is called beam …

… For time division duplexing (TDD) massive MIMO systems, … frequency division duplexing
(FDD) massive MIMO systems [19]–[… beam becomes smaller while the number of the orthogonal …

… In FDD massive MIMO, the downlink training and … One attempt of practical FDD massive
MIMO is called joint spatial … Another scheme that enables FDD massive MIMO is called beam …

… beam selection in FDD mMIMO involves an interesting trade-off between i) selecting the
beams … In this paper, we have shown that beam-domain coordination between the UEs offers a …

… performs better than the feedback-based FDD massive MIMO with predetermined grid of
beams, especially in the non-line-of-sight (NLOS) cases, based on channel measurements at …