In order to estimate the signal parameters accurately for mobile systems, it is necessary to estimate a system's propagation characteristics through a medium. Propagation analysis provides a good initial estimate of the signal characteristics. The ability to accurately predict radio-propagation behavior for wireless personal communication systems, such as cellular mobile radio, is becoming crucial to system design. Since site measurements are costly, propagation models have been developed as a suitable, low-cost, and convenient alternative. Channel modeling is required to predict path, loss and to characterize the impulse response of the propagating channel. The path loss is associated with the design of base stations, as this tells us how much a transmitter needs to radiate to service a given region. Channel characterization, on the other hand, deals with the fidelity of the received signals, and has to do with the nature of the waveform received at a receiver. The objective here is to design a suitable receiver that will receive the transmitted signal, distorted due to the multipath and dispersion effects of the channel, and that will decode the transmitted signal. An understanding of the various propagation models can actually address both problems. This paper begins with a review of the information available on the various propagation models for both indoor and outdoor environments. The existing models can be classified into two major classes: statistical models and site-specific models. The main characteristics of the radio channel - such as path loss, fading, and time-delay spread - are discussed. Currently, a third alternative, which includes many new numerical methods, is being introduced to propagation prediction. The advantages and disadvantages of some of these methods are summarized. In addition, an impulse-response characterization for the propagation path is also presented, including models for small-scale fading, Finally, it is shown that when two-way communication ports can be defined for a mobile system, it is possible to use reciprocity to focus the energy along the direction of an intended user without any explicit knowledge of the electromagnetic environment in which the system is operating, or knowledge of the spatial locations of the transmitter and the receiver.

A survey of various propagation models for mobile communication

In general, Micropower Impulse Radar (MIR) depends on Ultra-Wideband (UWB) transmission systems. UWB technology can supply innovative new systems and products that have an obvious value for radar and communications uses. Important applications include bridge-deck inspection systems, ground penetrating radar, mine detection, and precise distance resolution for such things as liquid level measurement. Most of these UWB inspection and measurement methods have some unique qualities, which need to be pursued. Therefore, in considering changes to Part 15 the FCC needs to take into account the unique features of UWB technology. MIR is applicable to two general types of UWB systems: radar systems and communications systems. Currently LLNL and its licensees are focusing on radar or radar type systems. LLNL is evaluating MIR for specialized communication systems. MIR is a relatively low power technology. Therefore, MIR systems seem to have a low potential for causing harmful interference to other users of the spectrum since the transmitted signal is spread over a wide bandwidth, which results in a relatively low spectral power density.

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Response to FCC 98-208 notice of inquiry in the matter of revision of part 15 of the commission's rules regarding ultra-wideband transmission systems

Inter-vehicle communication (IVC) systems (i.e., systems not relying on roadside infrastructure) have the potential to radically improve the safety, efficiency, and comfort of everyday road travel. Their main advantage is that they bypass the need for expensive infrastructure; their major drawback is the comparatively complex networking protocols and the need for significant penetration before their applications can become effective. In this article we present several major classes of applications and the types of services they require from an underlying network. We then proceed to analyze existing networking protocols in a bottom-up fashion, from the physical to the transport layers, as well as security aspects related to IVC systems. We conclude the article by presenting several projects related to IVC as well as a review of common performance evaluation techniques for IVC systems.

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Inter-vehicle communication systems: a survey

Sound transmission through a fluctuating ocean

Understanding ultra-wide-band (UWB) propagation channels is a prerequisite for UWB system design as well as communication-theoretic and information-theoretic investigations. This paper surveys the fundamental properties of UWB channels, pointing out the differences to conventional channels. If the relative bandwidth is large, the propagation processes, and therefore path loss and shadowing, become frequency-dependent, and the well-known wide-sense stationary uncorrelated scattering model is not applicable anymore. If the absolute bandwidth is large, the shape of the impulse responses as well as the fading statistics change. This paper also describes methods for measuring UWB channels and extracing channel parameters. Throughout this paper, the relationship between channel properties and other areas of UWB research are pointed out.

Ultra-Wide-Band Propagation Channels

An exemplary example of the present disclosure proposes an electromagnetic conductor reflecting plate including a perfect electronic conductor and at least two artificial magnetic conductors, wherein the each of the artificial magnetic conductor is disposed on arbitrary one side of the perfect electronic conductor, and a boundary between the perfect electronic conductor and each of the artificial magnetic conductor forms a virtual radiation unit. In addition, an exemplary example of the present disclosure further proposes an antenna array including an antenna and the electromagnetic conductor reflecting plate, wherein the antenna is disposed on the electromagnetic conductor reflecting plate.

Electromagnetic conductor reflecting plate and antenna array thereof and radar thereof and communication apparatus thereof

A novel band-notched planar monopole ultrawideband (UWB) antenna is proposed. A notched band, located in the 5 GHz WLAN band, is created using a resonator at the center of a fork-shaped antenna. The resonator is composed of an open-looped resonator and two tapped lines. With the open-looped resonator, the antenna has a good band-notched performance and bandstop-filter-like response in the target band. A parametric study of the notched bandwidth is described that explored the antenna operating mechanism. Then, an equivalent circuit model illustrates the band-notched behaviors more clearly. The antenna input admittance calculated with the equivalent circuit model reasonably agrees with the HFSS simulated result. The proposed antenna also features flat gain frequency responses, small varied group delay and 15 to 35 dB gain suppression at the notched band. Accordingly, the band-notched antenna can effectively select target bands by adjusting these antenna parameters.

https://ir.nctu.edu.tw:443/bitstream/11536/5295/1/000278531600008.pdf

Study of an Ultrawideband Monopole Antenna With a Band-Notched Open-Looped Resonator

A novel folded ultrawideband antenna for Wireless Body Area Network (WBAN) is proposed, which can effectively reduce the backward radiation and proximity effects of human bodies. The proposed antenna has a low-profile 3D structure that consists of a bevel-edge feed structure and a metal plate with folded strip. The bevel edge feed structure achieves broadband impedance matching and the metal plate acts as the main radiator. Moreover, the folded strip not only extends the lower frequency band but also provides additional resonant frequency around 6 GHz. The final bandwidth covers from 3.1 GHz to 12 GHz. The proposed antenna shows the directional patterns with low backward radiation due to the patch-like structure and the ground plane also prevents from the proximity effects of human bodies. Furthermore, the simulated SAR values of the proposed antenna are lower than the values of omnidirectional disc planar monopole. These features demonstrate that the proposed antenna is suitable for WBAN application.

https://ir.nctu.edu.tw:443/bitstream/11536/16145/1/000302720300048.pdf

A Novel Folded UWB Antenna for Wireless Body Area Network

A three-dimensional (3-D) propagation model, combined with a patched-wall model, has been developed to predict radio loss in a corridor environment. The ray-tracing technique is used and combined with the ray-fixed coordinate system to simplify the computations of transmission, reflection, and diffraction coefficients in 3-D space. The computed path loss is compared with the measured value of 900-MHz and 2.44-GHz radio propagation along a hallway and gives a reasonable agreement. It is also found that the fields transmitted through the interior walls give the major contribution to the received field when the radio path lies around a corner.

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Three-dimensional modeling of 900-MHz and 2.44-GHz radio propagation in corridors

A low-power low-noise amplifier (LNA) implemented in 0.18 ?m CMOS technology utilizing a self-forward-body-bias (SFBB) technique is proposed for UWB low-frequency band system. By using the SFBB technique, it reduces supply voltage as well as saves additional bias circuits, which leads to low power consumption of 4.5 mW with low supply voltage of 1.06 V for two drain-to-source voltage drops. The complementary architecture and direct coupling technique between the first two stages also save bias circuits. The measurement result shows that the proposed LNA presents a maximum power gain of 16 dB with a good input impedance matching (S11 < -12 dB) and an average noise figure of 2.65 dB in the frequency range of 3-6.5 GHz.

https://ir.nctu.edu.tw:443/bitstream/11536/5942/1/000274395200014.pdf

Jenn-Hwan Tarng

Papers

Electromagnetic conductor reflecting plate and antenna array thereof and radar thereof and communication apparatus thereof

Study of an Ultrawideband Monopole Antenna With a Band-Notched Open-Looped Resonator

A Novel Folded UWB Antenna for Wireless Body Area Network

Three-dimensional modeling of 900-MHz and 2.44-GHz radio propagation in corridors

A Low-Power Self-Forward-Body-Bias CMOS LNA for 3–6.5-GHz UWB Receivers