5 research outputs found
OFDM Receiver Performance Analysis with Measured Channel Model for Power Line Communication
This paper reports the results of wideband channel measurements conducted on in house outlets. Two kinds of channel
measurements were performed: impulse response measurements and noise signal measurements. In measure based channel model,
preamble assisted orthogonal frequency-division multiplexing access (OFDM) receiver scheme is proposed for differential phase
shift keying (DPSK) and quadrature amplitude modulation (QAM). Timing synchronization and channel estimation is performed
using the preamble. We provide numerical results to illustrate the performance of OFDM receiver in measure based channel model
OFDM receiver performance analysis with measured power line channel model for coded OFDM system
This paper reports the results of wideband channel
measurements conducted on in apartment environments. Two
kinds of channel measurements were performed: impulse
response measurements and noise signal measurements. In
measure based channel model, the performance degradation is
analyzed due to timing synchronization and colored noise in
orthogonal frequency division multiplexing (OFDM) based
power line communication (PLC) systems and then proceeds
to propose a new receiver scheme for channel estimation and
soft decision decoding scheme under imperfect channel
estimation. Simulation results show that the proposed
algorithm can efficiently eliminate the effects of imperfect
channel estimation and colored noise for coded OFDM system
Knowledge of HPV and Surgery among Women Who Underwent Cervical Conization: A Korean Multi-Center Study
Hard X-ray free-electron laser with femtosecond-scale timing jitter
The hard X-ray free-electron laser at the Pohang Accelerator Laboratory (PAL-XFEL) in the Republic of Korea achieved saturation of a 0.144 nm free-electron laser beam on 27 November 2016, making it the third hard X-ray free-electron laser in the world, following the demonstrations of the Linac Coherent Light Source (LCLS) and the SPring-8 Angstrom Compact Free Electron Laser (SACLA). The use of electron-beam-based alignment incorporating undulator radiation spectrum analysis has allowed reliable operation of PAL-XFEL with unprecedented temporal stability and dispersion-free orbits. In particular, a timing jitter of just 20 fs for the free-electron laser photon beam is consistently achieved due to the use of a state-of-the-art design of the electron linear accelerator and electron-beam-based alignment. The low timing jitter of the electron beam makes it possible to observe Bi(111) phonon dynamics without the need for timing-jitter correction, indicating that PAL-XFEL will be an extremely useful tool for hard X-ray time-resolved experiments.1143Nsciescopu