Hierarchical coherent and non-coherent communication

[abstract not available]https://fount.aucegypt.edu/faculty_book_chapters/1213/thumbnail.jp

On the distribution of an effective channel estimator for multi-cell massive MIMO

Accurate channel estimation is of utmost importance for massive MIMO systems to provide significant improvements in spectral and energy efficiency. In this work, we present a study on the distribution of a simple but yet effective and practical channel estimator for multi-cell massive MIMO systems suffering from pilot-contamination. The proposed channel estimator performs well under moderate to aggressive pilot contamination scenarios without previous knowledge of the inter-cell large-scale channel coefficients and noise power, asymptotically approximating the performance of the linear MMSE estimator as the number of antennas increases. We prove that the distribution of the proposed channel estimator can be accurately approximated by the circularly-symmetric complex normal distribution, when the number of antennas, M, deployed at the base station is greater than 10

Hierarchical coherent and non-coherent communication

In this paper, we propose a method for simultaneous communication of coarse and detailed information over three types of layers: two nested layers to be communicated non-coherently using Grassmannian constellations and an additional layer to be communicated coherently using unitary constellations. The layered architecture gives rise to four classes of receivers: coherent and non-coherent receivers, each operating in one of two distinct SNR regions. An operational bottleneck of this architecture is the detection complexity of these layers. To overcome this difficulty, four sequential detectors are developed. These detectors enable somewhat comparable, and in some cases identical, performance to that of their optimal maximum likelihood counterparts with significantly less computational cost