A novel geometry-based channel model (GCM) for line-of-sight (LoS) microcell scenario in dense urban areas is proposed. The proposed two dimensional scattering power distribution (SPD) is postulated on the physical phenomenon is obtained. The implementation issues are discussed and the delay-power spectrum (DPS) and azimuth-power spectrum (APS) derived from the proposed model are compared to those for conventional elliptical models as well as to the experimental results. The superior prediction of the proposed model in contrast to the conventional models is demonstrated.
A novel ultra-broadband printed monopole antenna with 10dB return loss bandwidth from 2.1-21.5GHz is proposed. This printed monopole antenna is constructed using cross-slotted modified circular patch with etched ground plane. This UWB printed monopole antenna is microstrip-fed with a triangular tapered input line for broadband matching.
A novel tunable sinusoid oscillator design using a negative polarity current feedback amplifier (CFA) and only three resistors, is presented. The design utilises the transimpedance pole of the CFA device (AD-844). Independent fo-tunability (3MHz to 40MHz) had been verified with both PSPICE macromodel simulation and hardware circuit implementation. The genreration is practically active insensitive.
The proposed wide-range digital duty cycle correction (DCC) circuit corrects an arbitrary input clock duty ratio to 50% while preserving the output clock phase even when the input clock duty ratio suddenly changes. Also, DCC control information is preserved during power-down mode. In this work, for input frequency range of 500MHz to 2GHz with ±10% duty ratio error, the output duty ratio error is corrected to be less than ±1.4%. The proposed DCC circuit is designed and verified using a 0.18um CMOS technology.
In orthogonal frequency division multiplexing (OFDM) systems, pulse-shaping contains two purposes: reducing out-of-band emission and inter-carrier interference (ICI). However, when designing the pulse construction, the two purposes have not been considered together. Usually, the major research has focused on the ICI and neglected out-of-band emission. It results in some pulses with good effect of reducing ICI having a high out-of-band emission. In fact, such pulses are not most suitable for practical OFDM systems. In this paper, we design an optimum pulse to balance the two purposes. Simulation results show that the proposed pulse has a good performance in two aspects.
In this paper, we propose a method to reduce the blind spot based on signal processing that indicates the minimum length of a cable under test in the time-frequency domain reflectometry without using an extension cable or adding a new high-speed hardware component. The time-frequency domain reflectometry adopted the proposed method can be achieved with not only a simple modification of the previous system but also a simple technique based on signal processing. The experimental results show that the proposed method allows us to estimate fault distance on the cable with high spatial resolution.
In this paper, we report an interactive color electroholography system using the field-programmable gate array (FPGA) technology and the time division switching method for color reconstruction. We implemented 30 dedicated-processors for a computer-generated hologram (CGH) into an FPGA chip, and the FPGA chip can generate full-parallax CGHs, on which we record color information for a color 3D object, faster than a personal computer. The time division switching method can reconstruct a color 3D object from the CGHs, to make use of the afterimage effect on human eyes. The system allows us to perform interactive operations for a reconstructed color 3D object using a keyboard, while viewing the reconstructed color 3D object.
This paper proposes a biometric template protection technique using Dynamic Quantization Transformation to convert biometrics into template of bitstring. The proposed method enables the authentication to take place in the transformed domain rather than original biometric feature space. We outline four requirements for a reliable template protection in the realm of fingerprint system. Several security and experimental analysis have been conducted to show the technique is feasible in practice.
Position detection services tend to be important in ubiquitous wireless communication systems. A new position detection method which utilizes an LCX (Leaky CoaXial cable) is proposed. Proposed method is based on a TOA (time of arrival) of both direct wave and reflected wave from the end of LCX. Position detection error is experimentally investigated.
In this paper, a two-layered ultra-wideband (UWB) bandpass filter has been proposed and developed. The filter consists of two-layered dielectric substrate and one metal layer, modified from our original UWB bandpass filter using a single-layer microstrip-CPW (coplanar waveguide) structure. To miniaturize the filter length, a folded CPW, short-circuited at the right end, was introduced to reduce the length of the CPW. In this two-layered structure, we discovered from our simulation and experiments that some configuration of the filter can produce transmission zeros at the low and high sides of the passband which improve the skirt performance of the filter. The transmission zero was considered due to the direct coupling between the input and output ports. Measured results demonstrated the excellent filter performance: its frequency bandwidth form 3.1GHz to 10.1GHz, good insertion loss of 0.5dB at the center frequency of passband, respectively. Parameter study of length dependence of the filter has been carried out based on EM simulator. The ratio of the filter length to the guided wavelength of the second higher transmission zero frequency keeps almost constant as 0.48.