MODELING THE PHOTOELECTRON SPECTRA OF CeO2Bx− (x=2, 3) AND CeB6− CLUSTERS

Density functional theory calculations were used to explore the structures of Cerium oxide and boride clusters \chem{CeO_2B_2^{-}}, \chem{CeO_2B_3^{-}}-, and \chem{CeB_6^{-}}. The results show intriguing structure and bonding trends, which are dependent on the ratio of boron centers to oxygens and the oxidation state of the cerium center. Natural ionization orbital analysis was also used to determine the nature electron detachment in photoelectron spectra of these species and to probe resulting electron rearrangement upon ionization. Such analysis allows us to differentiate between one-electron detachments and shake-up/shake-off transitions

INSIGHTS ON THE ELECTRONIC AND MOLECULAR STRUCTURES OF LANTHANIDE-BASED CLUSTERS

Lanthanide-based clusters provide useful insight to the electronic structure of bulk materials with unique magnetic, electronic, and optical properties. Inspired by photoelectron spectra reported by experimental collaborators and others, we have used density functional theory calculations to explore the molecular and electronic structures of a family of small lanthanide-based clusters. In this talk, we will present our recent results showing intriguing and unique trends in the structure and bonding of these clusters. In addition, the natural ionization orbital analysis was used to determine the nature of electron detachment in photoelectron spectra of these species and to investigate resulting electron rearrangement upon ionization. Such analysis allows us to differentiate between one-electron detachments and shake-up/shake-down transitions

A High-Performance and Low-Complexity 5G LDPC Decoder: Algorithm and Implementation

5G New Radio (NR) has stringent demands on both performance and complexity for the design of low-density parity-check (LDPC) decoding algorithms and corresponding VLSI implementations. Furthermore, decoders must fully support the wide range of all 5G NR blocklengths and code rates, which is a significant challenge. In this paper, we present a high-performance and low-complexity LDPC decoder, tailor-made to fulfill the 5G requirements. First, to close the gap between belief propagation (BP) decoding and its approximations in hardware, we propose an extension of adjusted min-sum decoding, called generalized adjusted min-sum (GA-MS) decoding. This decoding algorithm flexibly truncates the incoming messages at the check node level and carefully approximates the non-linear functions of BP decoding to balance the error-rate and hardware complexity. Numerical results demonstrate that the proposed fixed-point GAMS has only a minor gap of 0.1 dB compared to floating-point BP under various scenarios of 5G standard specifications. Secondly, we present a fully reconfigurable 5G NR LDPC decoder implementation based on GA-MS decoding. Given that memory occupies a substantial portion of the decoder area, we adopt multiple data compression and approximation techniques to reduce 42.2% of the memory overhead. The corresponding 28nm FD-SOI ASIC decoder has a core area of 1.823 mm2 and operates at 895 MHz. It is compatible with all 5G NR LDPC codes and achieves a peak throughput of 24.42 Gbps and a maximum area efficiency of 13.40 Gbps/mm2 at 4 decoding iterations.Comment: 14 pages, 14 figure

Pre-sorted Forward-Backward NB-LDPC Check Node Architecture

International audienceThis paper deals with reduced-complexity NB-LDPC check node implementation based on the Extended Min-Sum algorithm. We propose to apply a recently introduced pre-sorting technique to the forward-backward architecture. The pre-sorting of the check node inputs allows for significant complexity reduction. Simulation and synthesis results showed that this approach does not introduce any performance loss and can lead to significant area reduction in FPGA implementations (up to 54% for high check node degrees)