MMW System Research Articles

A new scheme for adding a pilot at direct current component location in photonics-assisted OFDM MMW system

This paper proposes a new scheme, that is, a constant is added to the real part or imaginary part of the signal at the transmitting end, and the constant becomes a pilot at the location of DC component, thereby replacing the scheme of traditional manual bias IQ modulator to generate a pilot. By adopting this scheme, the purpose of frequency offset estimation can be achieved, and the performance can be improved by quantitatively optimizing the magnitude of the constant at the same time. Using this technology and combined probability shaping technology, a 3.4Gbaud 256QAM OFDM signal can be transmitted 700 m wireless distance, achieving the normalized general mutual information (NGMI) threshold of 0.83 with 25% soft-decision forward-error correction (SD-FEC) overhead.

Scheme for optimizing a direct current component in a photonics-assisted OFDM MMW system.

This Letter proposes a new scheme for optimizing a direct current (DC) component to enable both the frequency offset estimation and system performance improvement by controlling the IQ modulator to adjust the DC component in a photonics-assisted OFDM MMW system. Compared with the traditional method, a large DC component is used as the pilot frequency for frequency offset estimation. When a small DC component is used, the system performance is better. A 3 Gbaud 16QAM OFDM signal is delivered over 70 m wireless, enabling a 3.5 dB sensitivity improvement at the bit error rate threshold of 1×10-2 in the E-band.

Bidirectional OFDM Based MMW/THzW Over Fiber System for Next Generation Communication

The modern world and modern technology want 5G communication to satiate their urgent need of multi-gigabits data transmission in small cells. For this aspiration, a bidirectional orthogonal frequency division multiplexing (OFDM) based millimeter wave over and terahertz wave over fiber system is proposed and demonstrated for 5G access fronthaul. A comparative study between millimeter-wave (MMW) and terahertz wave (THzW) regarding 5G communication is also analyzed. With the assistance of L and C band quantum dash laser diode, MMW and THzW are generated. For downstream (DS), 10 Gbps/12.5Gbps (for MMW/THzW) OFDM data in L band is transmitted over 50-km/25-km single mode fiber (SMF) and 100-m free space optics (FSO) distance, on the other side for upstream (US) transmission, 6.5 Gbps/10 Gbps OFDM data in C band is communicated over 50-km/25-km SMF plus 100-m FSO link. The selection of L and C band for DS and US transmission provide the advantages to reduce the Rayleigh back scattering effect in our bidirectional system not only that it also helps to mitigate the intensity-noise as compared to the conventional amplified spontaneous emission source. This research work gives an overview for the reliability of MMW and THzW system regarding 5G communication. The capability of our system becomes build up by obtaining low bit error rate (under FEC limit), proper error vector magnitude (<10.2%), and clear constellation diagram.

A 2-D Radon Transformation for Enhancing the Detection and Imaging of Embedded Defects in Layered Composite Structures Using Millimeter-Wave System

This paper aims to tackle the challenge of detecting the presence of embedded defects in layered composite structures using imaging techniques including a 2D Radon transformation. The proposed technique aims at enhancing the detection and imaging of embedded defects in layered composite structures that is captured using a millimeterwave (MMW) radar system. A 94 GHz MMW system is used in the near field to detect defects such as disbond and delamination embedded in complex glass fiber composite structures. In order to simplify the detection in glass fibers, measurement data attained using a MMW radar are plotted as images using MATLAB. A stable detection and identification of these defects from the collected images is proposed using a robust two-stage algorithm. The Weiner filter-based deconvolution technique is used for the reflectivity deconstruction in the image and a two-dimensional Radon transformation called back-projection is used to as an additional filtering step enhance the detection of the embedded defects. The proposed method allows defects that are embedded 24mm below the surface of the scanning probe to be detected and identified in terms of location. Our results show potential in the proposed method to be employed in accurately imaging defects in composites that are used in the aerospace and civil infrastructure industries.

Polar Coded OFDM Signal Transmission at the W-Band in Millimeter-Wave System

We experimentally demonstrate the transmission of orthogonal frequency division multiplexing (OFDM) signals with polar codes FEC in a W-band MMW system. The BER performances of the M-QAM OFDM signal with FEC and without FEC are investigated, respectively. The experimental results show that the polar codes have a net gain of 7.9 dB compare with that of the LDPC code (7.4 dB). To the best of our knowledge, this is the first demonstration that the polar codes FEC are used in a W-band MMW system with OFDM modulation.

Frequency-demultiplication OEO for stable millimeter-wave signal generation utilizing phase-locked frequency-quadrupling.

A novel scheme for the generation and stabilization of the millimeter-wave (mmW) signal employing a frequency-demultiplication optoelectronic oscillator (FD-OEO) has been theoretically analyzed and experimentally demonstrated. The FD-OEO can keep sustaining without optical first-order sidebands, which would help to simplify the photonic-assisted frequency multiplication process and provide a wide frequency compensation range for the mmW system simultaneously. The stability of the generated 40-GHz mmW signal reaches 1.38 × 10-12 at the average time of 100s. Besides, the measured single-sideband phase noise of the generated mmW signal exhibits as low as -103 dBc/Hz at 10-kHz offset frequency, maintaining a spurious level of -97 dBc.

Electrical models of through silicon Vias and silicon‐based devices for millimeter‐wave application

As the short vertical interconnections can significantly shorten the interconnect length between different circuits, three-dimensional integrated circuits (3D ICs) based on the through-silicon via (TSV) technology are considered as one of the most promising alternatives to overcome the scaling limits of Moore's low. Moreover, as the silicon technologies have been progressively expanded into the millimeter-wave (mmW) realm, the TSV technology also provides a promising option to realize a compact system with high performance and operating frequencies. This article provides an overview of recent advances in the development of TSV technologies and silicon-based passive devices for mmW applications. As various kinds of TSV losses are detrimental to the electrical performance of 3D ICs, especially in mmW systems, TSVs exploiting novel structures and materials still needs much more research, making it possible to integrate the passive device on 3D ICs and providing a promising option to realize a compact mmW system with excellent electrical performance and system reliability.

Performance evaluation of TOA estimation for 60 GHz MMW system based on IEEE 802.15.3c channel model

Performance evaluation of TOA estimation for 60 GHz MMW system based on IEEE 802.15.3c channel model

WDM RoF-MMW and linearly located distributed antenna system for future high-speed railway communications

In this article, we propose dual-hop network architecture capable of providing high-speed communications to high-speed trains (HSTs). The system uses a seamless fiber-millimeterwave system for backhaul transmission from a central station to antennas on trains, and a highspeed in-train Wi-Fi network. The system can be combined with signal processing and network control technologies to compensate for interference and the Doppler effect, and to reduce the number of handovers. It can realize seamless connectivity between the inside and outside of trains to avoid penetration loss and help organize the in-train network optimally to increase coverage and data rate. We present and discuss the possible network architecture and technologies that can help realize the proposed network. We also present a proof-of-concept demonstration on a high-performance seamless fiber- MMW system that can be applied for applications in backhaul networks. The proposed network can be an attractive solution to provide broadband services such as video on demand and high-speed mobile signals to users on HSTs.

Advances in Silicon Based Millimeter-Wave Monolithic Integrated Circuits

In this paper, the advances of the silicon-based millimeter-wave (MMW) monolithic integrated circuits (MMICs) are reported. The silicon-based technologies for MMW MMICs are briefly introduced. In addition, the current status of the MMW MMICs is surveyed and novel circuit topologies are summarized. Some representative MMW MMICs are illustrated as design examples in the categories of their functions in a MMW system. Finally, there is a conclusion and description of the future trend of the development of the MMW ICs.

Nuclear Radiation-Induced Atmospheric Air Breakdown in a Spark Gap

We have investigated the effect of pre-ionization by a radioactive -ray source on the atmospheric air breakdown conditions in a high-voltage spark gap. A standoff millimeter-wave (mmW) system was used to monitor the breakdown properties. A decrease in breakdown threshold was observed with an increase of radiation dose. We attribute this to a space charge-controlled electron diffusion process in a cloud of radiation-induced ion species of both polarities. The space charge-dependent diffusion coefficient was determined from the measurement data. In addition, we found that the breakdown process shows random spikes with Poisson-like statistical feature. These findings portend the feasibility of remote detection of nuclear radiation using high-power mmWs.

Compact Millimeter-Wave Sensor for Remote Monitoring of Vital Signs

A compact millimeter-wave (MMW) sensor has been developed for remote monitoring of human vital signs (heart and respiration rate). The low-power homodyne transceiver operating at 94 GHz was assembled by using solid-state active and passive block-type components and can be battery operated. A description of the MMW system front end and the back-end acquisition hardware and software is presented. Representative test case results on the application of various signal processing and data analysis algorithms developed to extract faint physiological signals of interest in presence of strong background interference are provided. Although the laboratory experiments so far have been limited to standoff distances of up to 15 m, the upper limit of the detection range is expected to be higher. In comparison with its microwave counterparts, the MMW system described here provides higher directivity, increased sensitivity, and longer detection range for measuring subtle mechanical displacements associated with heart and respiration functions. The system may be adapted for use in a wide range of standoff sensing applications including for patient health care, structural health monitoring, nondestructive testing, biometric sensing, and remote vibrometry in general.

MMW system trade-offs

A brief review is given of the current state of knowledge of millimeter-wave atmospheric propagation and clutter characteristics and the detection performance of two air-to-ground fire-control systems evaluated in terms of their ability to detect a 40-m/sup 2/ target in the presence of atmospheric attenuation and three types of clutter. Generally, the 35-GHz system considered performed better in terms of signal-to-noise ratio performance and in signal-to-clutter ratio performance for light clutter. In heavy clutter, the 95-GHz system performed significantly better than the 35-GHz system. For 300-m altitude with refrozen snow clutter background, neither system developed a large enough signal-to-clutter radio to detect the target reliably.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>