2,840 research outputs found
2,2-Dimethyl-5-{[(4-nitrophenyl)amino]methylidene}-1,3-dioxane-4,6-dione
In the title compound, C13H12N2O6, the dihedral angle between the benzene ring and the aminomethylene unit is 5.42 (16)°, while the angle between the aminomethylene unit and the dioxane ring is 3.06 (43)°. The dioxane ring shows a half-boat conformation, in which the C atom between the dioxane ring O atoms is 0.464 (10) Å out of the plane. An intramolecular N—H⋯O hydrogen bond stabilizes the molecular conformation. In the crystal, a three-dimensional framework is built up via intermolecular N—H⋯O hydrogen bonds
5-(4-Chloroanilinomethylene)-2,2-dimethyl-1,3-dioxane-4,6-dione
The title compound, C13H12ClNO4, is approximately planar, with a dihedral angle of 8.23 (4)° between the mean plane of the aminomethylene unit and the planar part of the dioxane ring. The dioxane ring has a half-boat conformation, in which the C atom between the dioxane O atoms is −0.464 (8) Å out of the plane of the other five atoms. In the molecule there is an intramolecular N—H⋯O hydrogen bond, involving the NH H atom and the adjacent dioxane carbonyl O atom. In the crystal, weak intermolecular C—H⋯O hydrogen-bonding contacts, result in the formation of sheets parallel to the ab plane
4-[4-(Piperidin-1-yl)piperidin-1-yl]benzonitrile
In the title compound, C17H23N3, both piperidine rings adopt chair conformations. In the crystal packing, intermolecular C—H⋯N hydrogen bonds and C—H⋯π interactions are present
5-[(2-Chloro-4-nitroanilino)methylidene]-2,2-dimethyl-1,3-dioxane-4,6-dione
In the title compound, C13H11ClN2O6, the dihedral angles between the benzene ring and the aminomethylene unit and between the aminomethylene group and the dioxane ring are 8.19 (14) and 1.39 (17)°, respectively. The dioxane ring has a half-boat conformation, in which the C atom between the dioxane O atoms is 0.662 (4)Å out of the plane through the remaining ring atoms. Intramolecular N—H⋯O and N—H⋯Cl interactions occur
3-Fluoro-4-nitrophenyl 4-methylbenzenesulfonate
In the title compound, C13H10FNO5S, the dihedral angle between the benzene rings is 47.63 (14)°. In the crystal, π–π stacking occurs between nearly parallel benzene rings of adjacent molecules, the centroid–centroid distance being 3.7806 (16) Å. Weak intermolecular C—H⋯O hydrogen bonding is also present in the crystal structure
Differential Modulation for Short Packet Transmission in URLLC
One key feature of ultra-reliable low-latency communications (URLLC) in 5G is
to support short packet transmission (SPT). However, the pilot overhead in SPT
for channel estimation is relatively high, especially in high Doppler
environments. In this paper, we advocate the adoption of differential
modulation to support ultra-low latency services, which can ease the channel
estimation burden and reduce the power and bandwidth overhead incurred in
traditional coherent modulation schemes. Specifically, we consider a
multi-connectivity (MC) scheme employing differential modulation to enable
URLLC services. The popular selection combining and maximal ratio combining
schemes are respectively applied to explore the diversity gain in the MC
scheme. A first-order autoregressive model is further utilized to characterize
the time-varying nature of the channel. Theoretically, the maximum achievable
rate and minimum achievable block error rate under ergodic fading channels with
PSK inputs and perfect CSI are first derived by using the non-asymptotic
information-theoretic bounds. The performance of SPT with differential
modulation and MC schemes is then analysed by characterizing the effect of
differential modulation and time-varying channels as a reduction in the
effective SNR. Simulation results show that differential modulation does offer
a significant advantage over the pilot-assisted coherent scheme for SPT,
especially in high Doppler environments.Comment: 15 pages, 9 figure
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