This work describes the diffuse scattering response of a terahertz data stream on metallic rough surfaces to investigate its influence on wireless channels. The measurements are performed using a wireless link with carrier frequencies operating from 100-400 GHz with transmitter and receiver modules mounted on separate rotatable rails. The acquired data are analyzed to determine the dependence of scattering pattern on surface roughness parameters, including rms height and correlation length. Fundamentals of scattering and reflections are explained and integral equation method (IEM) with an exponential correlation function is verified for theoretical predictions. The implications of surface roughness for non-line-of-sight (NLOS) paths in non-specular directions are discussed for the first time.
With increasing interest in wireless communications at terahertz (THz) frequencies, investigations on the link performance in indoor and outdoor environments are required. In order to analyze the signal impairments caused by outdoor weathers and indoor surface reflections, wireless channels are employed using a continuous wave (CW) signal at five discrete frequencies (100, 200, 300, 400 and 625 GHz) with a data rate of several Gb/sec. The link performance in rainy, snowy, and atmospheric turbulence weathers is analyzed by measuring the power and bit-errorratios (BERs). Scattering effects due to reflection by indoor rough surfaces are investigated. Predictions for power attenuation and link performance in these scenarios are conducted and compared with experimental results.
We first compare different polarization mode dispersion (PMD) models for evaluating PMD impairments. We show that, compared with the all-order PMD model, most of the known first- and second-order PMD models overestimate the PMD induced distortions. Then we discuss various PMD mitigation techniques. We show that modulation formats have a big impact on choosing the most effective PMD compensation techniques. Not only do the benefits of using PMD compensators (PMDCs) depend on modulation formats, but the designing of a PMDC is largely affected by modulation formats as well. Some multi-channel PMD mitigation techniques for wavelength division multiplexing (WDM) systems are also discussed.
OOK signals with certain phase modulations can show improved performance without incurring much complexity and cost. In this paper we report recent progress on the performance study of high-speed OOK data signals with different phase-modulation schemes.
We discuss recent progress on ultra-high-speed modulation formats for next-generation optical transport networks at 160 Gb/s and beyond. In particular, we demonstrate CSRZ, PAP-CSRZ, GAP-CSRZ, RZ-VSB, and DPSK signals at ultra-high data rates.
We demonstrate a method to generate ultra-high-speed phase correlated optical signals using a Kerr shutter. Two examples are provided: 160-Gb/s CSRZ with pair-wise alternating phase, and 320-Gb/s CSRZ signals. We also discuss other phase correlated data signals including RZ-VSB, DPSK, and CSRZ with alternating phases in groups.
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