We have proposed a novel radio-over-fiber architecture to reduce the system cost at both central office (CO) and base station (BS). In this architecture, by incorporating the proper dc bias and ...optical filtering techniques in CO, the optical millimeter- wave (mm-wave) carriers are generated with four times frequency of the local oscillator signal. The BS is simplified by using the separated optical carrier along with downlink mm-wave signals to carry the upstream data. We have experimentally demonstrated optical mm-wave carrier generation up to 64-GHz, and both down- and upstream signal delivery over 20 km fiber with 1-dB power penalty.
We experimentally demonstrate a hardwareand spectral-efficient large-capacity single-carrier radio-overfiber system at Q-band (33-50 GHz), employing high-level polarization-division-multiplexing ...64-ary quadrature-amplitudemodulation (PDM-64QAM) modulation and heterodyne coherent detection. In our demonstrated system, up to 10-GBd (120-Gb/s) PDM-64QAM vector millimeter-wave (mm-wave) signal at 37.5 GHz can be generated and delivered over 1-m wireless distance, with a bit-error ratio (BER) less than the hard-decision forward-error-correction (FEC) threshold of 3.8 × 10 -3 . Our demonstrated system can also generate up to 16-GBd (192-Gb/s) PDM-64QAM vector mm-wave signal at 37.5 GHz, with a BER less than the soft-decision FEC threshold of 1 × 10 -2 . During the receiver digital signal processing, the employment of largetap decision-directed least-mean-square equalization after carrier recovery significantly improves the system performance. To the best of our knowledge, this is the first time to demonstrate single-carrier PDM-64QAM modulated wireless mm-wave signal delivery.
Metro network, as a medium distance transmission system, poses a special challenge of transmission capacity and cost. In this paper, we present a detailed comparison of applying three advanced ...modulation formats including pulse amplitude modulation-4 (PAM-4), carrierless amplitude and phase modulation-16 QAM (CAP-16), and discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S OFDM) with low-cost direct detection for 100-Gb/s/λ metro optical transmission systems. These modulation formats are all experimentally demonstrated with similar digital signal processing algorithms. Three kinds of chromatic dispersion (CD) compensation ways named CD precompensation method, single sideband (SSB), and dispersion compensating fiber (DCF) are also compared. Two types of modulators including an IQ modulator and a dual-drive Mach-Zehnder modulator are employed to generate SSB or CD precompensated signals in this experiment and their transmission performance is also evaluated. To the best of our knowledge, this is the first time that the performance of single-wavelength 100-G signal transmission based on direct detection is evaluated over 480 km of standard single mode fiber with PAM-4, CAP-16, and DFT-S OFDM modulation formats.
The wavelength-division-multiplexed passive optical network (WDM-PON) is considered to be the next evolutionary solution for a simplified and future-proofed access system that can accommodate ...exponential traffic growth and bandwidth-hungry new applications. WDM-PON mitigates the complicated time-sharing and power budget issues in time-division-multiplexed PON (TDM-PON) by providing virtual point-to-point optical connectivity to multiple end users through a dedicated pair of wavelengths. There are a few hurdles to overcome before WDM-PON sees widespread deployment. Several key enabling technologies for converged WDM-PON systems are demonstrated, including the techniques for longer reach, higher data rate, and higher spectral efficiency. The cost-efficient architectures are designed for single-source systems and resilient protection for traffic restoration. We also develop the integrated schemes with radio-over-fiber (RoF)-based optical-wireless access systems to serve both fixed and mobile users in the converged optical platform.
A 12-bit Vernier ring time-to-digital converter (TDC) with time resolution of 8 ps for digital-phase-locked-loops (DPLL) is presented. This novel Vernier ring TDC places the Vernier delay cells and ...arbiters in a ring format and reuses them for the measurement of the input time interval. The proposed TDC thus achieves large detectable range, fine time resolution, small die size and low power consumption simultaneously. A pre-logic unit is developed to measure both positive and negative phase errors for DPLL applications. The TDC achieves a large detectable range of 12 bits with core area of 0.75 × 0.35 mm 2 in a 0.13 μm CMOS technology. The total power consumption for the entire TDC chip is only 7.5 mW with a 1.5 V power supply, while operating at a clock frequency of 15 MSPS.
We experimentally demonstrate W-band vector millimeter-wave (mm-wave) signal generation and its air space transmission, from constant-modulus quadrature phase shift keying modulation to multimodulus ...8-ary quadrature amplitude modulation/16-ary quadrature amplitude modulation (8QAM/16QAM) modulation, employing a photonic frequency-quadrupling scheme enabled by a single phase modulator and precoding technique. As far as we know, it is the first time to realize W-band 8QAM/16QAM vector mm-wave signal generation based on a single phase modulator with photonic frequency multiplication. We also investigate by numerical simulation and experiment the effect of the radio-frequency (RF) driving peak-to-peak voltage of the phase modulator on the performance of the generated vector mm-wave signal, and find that there exists an optimal RF driving peak-to-peak voltage for the best performance of the generated vector mm-wave signal, which agrees well with our theoretical analysis.
Tactile sensors of comprehensive functions are urgently needed for the advanced robot to co-exist and co-operate with human beings. Pneumatic tactile sensors based on air bladder possess some ...noticeable advantages for human-robot interaction application. In this paper, we construct a pneumatic tactile sensor and apply it on the fingertip of robot hand to realize the sensing of force, vibration and slippage via the change of the pressure of the air bladder, and we utilize the sensor to perceive the object's features such as softness and roughness. The pneumatic tactile sensor has good linearity, repeatability and low hysteresis and both its size and sensing range can be customized by using different material as well as different thicknesses of the air bladder. It is also simple and cheap to fabricate. Therefore, the pneumatic tactile sensor is suitable for the application of co-operative robots and can be widely utilized to improve the performance of service robots. We can apply it to the fingertip of the robot to endow the robotic hand with the ability to co-operate with humans and handle the fragile objects because of the inherent compliance of the air bladder.
This paper presents taphonomic and zooarchaeological analysis of the late Middle Paleolithic occupation layers at Tongtian cave in Xinjiang, northwestern China. The taphonomic history reflects that ...human and animals shared the cave and human occupations were short in duration. Hominids subsisted mainly on large game, but hunting target was comparatively broader with inclusion of small fauna. The subsistence strategy was suitable for small populations living with a higher mobility in the high-elevation mountainous environment. This work suggests a “broader-diet” strategy in the Middle Paleolithic before the emergence of modern humans, which is yet different with the broad-spectrum economy in the (late) Upper Paleolithic, and reveals an adaptive variety in northwestern China.
In this paper, we experimentally demonstrated a four-channel wavelength-division-multiplex (WDM) 560 Gbit/s 128 quadrature amplitude modulation (128QAM)-Discrete MultiTone (DMT) signal transmission ...in a short reach interconnect. Coordinated discrete Fourier transform-spread and preequalization are jointly used to simultaneously overcome serious frequency domain power attenuation and reduce the peak-to-average power ratio of the DMT signal. An additional postdecision-directed least mean square equalizer is used afterward to further compensate the channel response and mitigate the devices' implementation penalty. These proposed algorithms and equalizer are validated through experiment in this paper, we achieved the highest capacity signal transmission in the four-channel WDM transmission system using intensitymodulation and directdetection over a 2.4-km single mode fiber with a bit-error-ratio under the hard-decision forward error correction limit of 3.8 × 10 -3 .
The YAP transcription coactivator has been implicated as an oncogene and is amplified in human cancers. Recent studies have established that YAP is phosphorylated and inhibited by the Hippo tumor ...suppressor pathway. Here we demonstrate that the TEAD family transcription factors are essential in mediating YAP-dependent gene expression. TEAD is also required for YAP-induced cell growth, oncogenic transformation, and epithelial-mesenchymal transition. CTGF is identified as a direct YAP target gene important for cell growth. Moreover, the functional relationship between YAP and TEAD is conserved in Drosophila Yki (the YAP homolog) and Scalloped (the TEAD homolog). Our study reveals TEAD as a new component in the Hippo pathway playing essential roles in mediating biological functions of YAP.
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