8,278 research outputs found
Two-phase Unsourced Random Access in Massive MIMO: Performance Analysis and Approximate Message Passing Decoder
In this paper, we design a novel two-phase unsourced random access (URA)
scheme in massive multiple input multiple output (MIMO). In the first phase, we
collect a sequence of information bits to jointly acquire the user channel
state information (CSI) and the associated information bits. In the second
phase, the residual information bits of all the users are partitioned into
sub-blocks with a very short length to exhibit a higher spectral efficiency and
a lower computational complexity than the existing transmission schemes in
massive MIMO URA. By using the acquired CSI in the first phase, the sub-block
recovery in the second phase is cast as a compressed sensing (CS) problem. From
the perspective of the statistical physics, we provide a theoretical framework
for our proposed URA scheme to analyze the induced problem based on the replica
method.
The analytical results show that the performance metrics of our URA scheme
can be linked to the system parameters by a single-valued free entropy
function. An AMP-based recovery algorithm is designed to achieve the
performance indicated by the proposed theoretical framework. Simulations verify
that our scheme outperforms the most recent counterparts.Comment: 16pages,7 figure
A Fully Bayesian Approach for Massive MIMO Unsourced Random Access
In this paper, we propose a novel fully Bayesian approach for the massive
multiple-input multiple-output (MIMO) massive unsourced random access (URA).
The payload of each user device is coded by the sparse regression codes
(SPARCs) without redundant parity bits. A Bayesian model is established to
capture the probabilistic characteristics of the overall system. Particularly,
we adopt the core idea of the model-based learning approach to establish a
flexible Bayesian channel model to adapt the complex environments. Different
from the traditional divide-and-conquer or pilot-based massive MIMO URA
strategies, we propose a three-layer message passing (TLMP) algorithm to
jointly decode all the information blocks, as well as acquire the massive MIMO
channel, which adopts the core idea of the variational message passing and
approximate message passing. We verify that our proposed TLMP significantly
enhances the spectral efficiency compared with the state-of-the-arts baselines,
and is more robust to the possible codeword collisions
Adam29 expression in human breast cancer and its effects on breast cancer cells in vitro
Background: A Disintegrin and Metalloprotease Domain 29 (ADAM29) is involved in many important physiological processes. Recent studies have demonstrated that ADAM29 is a susceptibility locus showing traits as a risk factor for breast cancer under genome-wide significance, however, the clinical relevance and cellular function of ADAM29 in breast cancer have not been reported. Materials and Methods: In this study, we assessed the expression levels of ADAM29 in a cohort of human breast cancer specimens. We also used MDA-MB-231 cells with differing ADAM29 expression and assessed the influence of ADAM29 and its mutations on the MDA-MB-231 cell line. Results: Increased transcript expression of ADAM29 was observed in breast cancer tissues compared to normal ones. The expression of ADAM29 and its mutations in different domains significantly influenced proliferation, migration and invasion of breast cancer cells in vitro. Conclusion: ADAM29 may represent a prognostic factor in human breast cancer, as well as a novel molecular candidate to be used as a therapeutic target
Type I critical dynamical scalarization and descalarization in Einstein-Maxwell-scalar theory
We investigated the critical dynamical scalarization and descalarization of
black holes within the framework of the Einstein-Maxwell-scalar theory
featuring higher-order coupling functions. Both the critical scalarization and
descalarization displayed first-order phase transitions. When examining the
nonlinear dynamics near the threshold, we always observed critical solutions
that are linearly unstable static scalarized black holes. The critical
dynamical scalarization and descalarization share certain similarities with the
type I critical gravitational collapse. However, their initial configurations,
critical solutions, and final outcomes differ significantly. To provide further
insights into the dynamical results, we conducted a comparative analysis
involving static solutions and perturbative analysis.Comment: 38 pages, 12 figure
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Uplift, Climate and Biotic Changes at the Eocene-Oligocene Transition in Southeast Tibet
The uplift history of southeastern Tibet is crucial to understanding processes driving the tectonic evolution of the Tibetan Plateau and surrounding areas. Underpinning existing palaeoaltimetric studies has been regional mapping based in large part on biostratigraphy that assumes a Neogene modernisation of the highly diverse, but threatened, Asian biota. Here, with new radiometric dating and newly-collected plant fossil archives, we quantify the surface height of part of Tibet’s southeastern margin of Tibet in the latest Eocene (~34 Ma) to be ~3 km and rising, possibly attaining its present elevation (3.9 km) in the early Oligocene. We also find that the Eocene-Oligocene transition in southeastern Tibet witnessed leaf size diminution and a floral composition change from sub-tropical/warm temperate to cool temperate, likely reflective of both uplift and secular climate change, and that by the latest Eocene floral modernization on Tibet had already taken place implying modernization was deeply-rooted in the Paleogene
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