Development of a Submillimeter Double-Ridged Waveguide Ortho-Mode Transducer (OMT) for the 385–500 GHz Band

We present design and evaluations of a submillimeter double-ridged waveguide ortho-mode transducer (OMT) for ALMA Band 8 (385–500 GHz) cartridge receiver. The measured transmission loss of the OMT at 4 K was 0.4–0.5 dB according to noise measurements with an SIS mixer. The polarization isolation was measured to be larger than 29 dB from quasioptical measurements. The OMT consists of a Bϕifot junction and a double-ridged guide. A robust design with allowable mechanical errors of 20 μm has been demonstrated.     

Optimization of the UTC-PD Epitaxy for Photomixing at 340 GHz

We present a method to optimize the epitaxial layer structure of an InGaAs/InP uni-traveling-carrier photo-diode (UTC-PD) for continuous THz-wave generation. The design approach used is general in that it can be applied for any target frequency while this study focuses on 340 GHz. The photodiode epitaxy is modeled and optimized using a TCAD software implementing the hydrodynamic semiconductor equations. This physical device model was found to be in good agreement with reported experimental results. It is shown that the UTC-PD can generate ~1 mW at 340 GHz by choosing the optimum absorption layer and collection layer thicknesses.     

A New Method for the Computation of the Error Probability of Differentially Detected Modulation Formats in Mobile Radio Channels – The Case of Minimum Shift Keying

We show a new approach to analytically compute the error probability BER in mobile radio channels. The method is applicable to a variety of differentially detected modulation formats; here we use minimum shift keying (MSK) as an example. We include the following effects: (i) fading and (ii) time dispersion of the mobile radio channel (iii) noise, and (iv) filtering both of the data sequence and the received signal. Sampling is at a fixed but arbitrary instant. We develop a new mathematical formalism, which we call the two-path equivalent-matrix (TPEM) method. In this method, we reduce the general channel (including noise) exactly to a two-path fading channel without noise, whose BER can be easily computed. With this method, we can find analytically the BER for both filtered and unfiltered (G)MSK if the BER is small; for large BER a single well-behaved integral must be solved numerically. Asymptotic equations for unfiltered MSK and small BERs are also given. To a first approximation, the BER is 0.5· [(S/T)²+1/SNR] for pure MSK, where S/T is the delay spread normalized to the bit duration and SNR is the signal-to-noise ratio. The BER is increased by less than 50% for Gaussian filtering of the data sequence and receiver filtering with a time-bandwidth product larger than 0.3.     

A Swept-Frequency Wideband Channel Sounding System at the 63.4–64.4 GHz Band with 1 ns Time-Resolution

A Versatile channel sounding impulse response identification system using the swept-frequency method is designed at the 63.4–64.4 GHz band. The swept-frequency channel sounder offers high time and frequency resolution of 1 ns and 625 KHz respectively. The high dynamic range (70 dB) and constant power enable non-linearities to be overcome in the measurement areas lying with the coverage range of the order of a picocell.     

Review of Wireless Personal Communications Radio Propagation Models in High Altitude Mountainous Areas at 2.6 GHz

This paper presents five commonly used radio propagation models (RPMs) which are suitable for the prediction of path loss in macrocell environments of LTE wireless communication systems. These RPMs’ application in high altitude mountainous areas networks (HAMANETs) environment requires further validation and studies. Through using the measured path loss in the HAMANETs at 2.6 GHz to calculate the predicted value of the five RPMs and the measured value’s mean error (ME), root mean square error, and error standard deviation (ESTD), we verified the predicted value of the SPM model that is closer to the actual measurement. On this basis, the empirical propagation model in HAMANETs environment is corrected. When correcting, a method to calculate base station’s effective antenna height and propagation distance is provided by using the altitude above sea level data. This method can reduce the error that the mountainous areas are simplified to the flat-terrain in the existed propagation models. A linear least square method is used to calculate the optimal propagation model. Finally, the ME is the smallest, and the ESTD is less than 8 dB, which indicate that the corrected propagation model is more suitable for the actual environmental path loss’s prediction. The results show that the path loss factor of the test area is about 65 dB, including the influence of the high altitude, mountains, vegetation, and air humidity in HAMANETs environment. The study results can provide useful advice to the evaluation and verification of personal wireless communications in the HAMANETs. Furthermore, using the correction method proposed in this paper can correct propagation models suitable for the different propagation environments to improve the accuracy and efficiency of wireless network optimization.     

A New Approach to Observer-Based Fault-Tolerant Controller Design for Takagi-Sugeno Fuzzy Systems with State Delay

This paper deals with the problem of active fault-tolerant control (FTC) for time-delay Takagi-Sugeno (T-S) fuzzy systems based on a fuzzy adaptive fault diagnosis observer (AFDO). A novel fuzzy fast adaptive fault estimation (FAFE) algorithm for T-S fuzzy models is proposed to enhance the performance of fault estimation, and sufficient conditions for the existence of the fault estimator are given in terms of linear matrix inequalities (LMIs). Using the obtained on-line fault estimation information, an observer-based fast active fault-tolerant controller is designed to compensate for the effect of faults by stabilizing the closed-loop system. Simulation results of a track trail system and a nonlinear numerical example are presented to illustrate the effectiveness of the proposed method.     

The Studies of Millimeter Waves at 60 GHz in Outdoor Environments for IMT Applications: A State of Art

As the growth of mobile technology network increasing exponentially due to which radio frequency becomes more valuable natural resources. Shortage of bandwidth creates an enormous opportunities for researchers and engineers for exploration of underutilize millimeter wave spectrum in order to design and develop future technologies. It is a need of an hour to do extensive studies on the impact of millimeter wave technologies as both indoor and outdoor environments. This paper describes the various studies carried out earlier in the field of radio wave propagation at 60 GHz in different outdoor environments.     

On the Use of Radiometric Measurements to Estimate Atmospheric Attenuation at 100 and 300 GHz

At frequencies of between 100 GHz and 30 THz, propagation conditions are severely affected by the influence of the composition and phenomena of the troposphere. This paper focuses on the use of radiometric measurements to estimate attenuation at 100 and 300 GHz, considering non-scattering scenarios, in which the main contributions are given by atmospheric gases and non-rainy clouds. These techniques allow the estimation of the absorption loss through the entire atmosphere, without the need for a signal source situated in a satellite or a high altitude aircraft. On the basis of well-accepted absorption models, the results of calculating gaseous, cloud, and total attenuation using 3-year meteorological data from Madrid, Spain, are detailed, as well as estimates of the expected values of the sky brightness temperature as measured by the radiometer. Finally, based on the results obtained, a discussion on the use of radiometric measurements at both frequencies is presented, in connection with an experimental campaign currently under preparation.     

Joint Frequency Offset and Channel Estimation for MIMO Systems in the Presence of Timing Error

This paper deals with the problem of joint frequency offset (FO) and channel estimation for multi-input multi-output (MIMO) systems in the presence of a timing error. Two equivalent signal models with FO and a timing error are given, and then a joint estimation method is derived. The proposed estimation method consists of two steps. Firstly, a maximum likelihood (ML) FO estimator is proposed based on the second signal model. Secondly, based on the FO estimate, we formulate the timing error and channel estimation as a problem of composite hypothesis testing according to the first signal model, and then solve the problem using a composite hypothesis testing approach. Simulation results are performed to show the effectiveness of the proposed method.     

Propagation Path Loss and Materials Insertion Loss in Indoor Environment at WiMAX Band of 3.3 to 3.6?GHz

The purpose of this study is to characterize the indoor channel for IEEE 802.16 (WiMAX) at 3.3?C3.6?GHz frequency. This work presents a channel model based on measurements conducted in commonly found scenarios in buildings. These scenarios include closed corridor, wide corridor and semi open corridor. Path loss equations are determined using log-distance path loss model and a Rayleigh multipath induced fading, Normal multipath induced fading or a combination of both. A numerical analysis of measurements in each scenario was conducted and the study determined equations that describe path loss for each scenario. Propagation loss is given for 300?MHz bandwidth. This work also represents the insertion loss of different materials and the obstruction loss due the existence of human beings between the transmitting antenna and the receiving one.     

Parent–Daughter Confusion Component: A New Approach for the Construction of Nonlinear Confusion Component

The nonlinear confusion component is one of an integral part of any modern block cipher. This nonlinear confusion component is used to hides the relationship between the ciphertext and the key. The primary objective of this article is to formulate a new mechanism for the construction this confusion component. Usually substitution box (S-box) is used to achieve this kind of characteristics in block ciphers. We have utilized deoxyribonucleic acid (DNA) sequences for the construction of new S-boxes with optimized cryptographic characteristics. The projected technique fundamentally optimized the DNA sequences along with traditional confusion component to generate a completely new S-box. The obtained S-boxes have the same cryptographic strength as a parent S-box have.

     

A More Precise Empirical Formula for Estimating Normalized Fog Attenuation in the Millimeter-Wave Frequency Range 30 ~ 100 GHz

At millimeter wavelengths, normalized fog attenuation (NFA) in units of (dB/km)/ (g/m³) is generally calculated by the Rayleigh approximation when working wavelengths are much larger than the average diameter of fog droplets. The calculations of the Rayleigh approximation are much less than those of Mie scattering theory, but still complex and heavy. To solve the above problem and facilitate the engineering applications of the Rayleigh approximation, a new empirical formula is discussed to estimate NFA in the frequency range 30?~?100 GHz and the fog common temperature range ?8?~?20 °C. The simulation results of the new formula are compared with those got by other three empirical formulae: the Altshuler empirical formula, the Liebe empirical formula and the Zhao empirical formula. Maximal absolute value of the relative errors (MAVRE) and Pearson correlation coefficient (PCC) indicate the largest deviation of estimated results and the fitting performance of an empirical formula, respectively. Comparisons show that the MAVRE of the new formula is only 4.482 %, which is much smaller than those of the other three formulae. The mean value of the Pearson correlation coefficients (PCCs) of the proposed formula is 0.999943, larger than those of other methods. Additionally, relative error (RE) curves of the four empirical formulae are given at four certain temperatures ?8 °C, 0 °C, 10 °C and 20 °C.     

A New Method for the Estimation of Mass Functions in?the?Dempster�CShafer��s Evidence Theory: Application to Colour Image Segmentation

In this paper, the problem of colour image segmentation is addressed using the Dempster–Shafer (DS) theory. Examples are provided showing that this theory is able to take into account a large variety of special situations that occur and which are not well solved using classical approaches. Modelling both uncertainty and imprecision, and computing the conflict between images and introducing a priori information are the main features of this theory. Consequently, the performance of such a segmentation scheme is largely conditioned by the appropriate estimation of mass functions in the DS evidence theory. In this paper, a new method of automatically determining the mass function for colour-image segmentation problems is presented. The mass function of each pixel is determined by applying possibilistic c-means (PCM) clustering to the grey levels of the three primitive colours. A reliability criterion, associated with each pixel and the mass functions of its neighbouring pixels, is used into a fuzzy based reasoning system in order to decide on the appropriate segmentation. Experimental segmentation results on medical and textured colour images highlight the effectiveness of the proposed method.     

Performance Analysis of Tags Collection Time on A New Architecture of 2.4 GHz Embedded Active RFID System for Indoor and Outdoor Tracking and Monitoring Applications Based on IEEE 802.15.4 Standard

This paper focuses on the analysis of tags collection time of 2.4 GHz embedded active Radio Frequency Identification (RFID) system for indoor and outdoor real-time tracking and monitoring applications based on IEEE 802.15.4 standard. The main novelty of the system is the implementation of the communication method in order to provide Machine to Machine (M2M) communication and automated switching mechanism between indoor and outdoor location by utilizing active RFID, Wireless Sensor Network (WSN), Global Positioning System (GPS) and mobile communication on a single platform. In this work, GPS receiver covers outdoor location tracking, while active RFID provides identification and Receive Signal Strength Indicator (RSSI) reading for each tag holder to cover indoor location tracking especially near or inside building where location information is not detected by GPS. Several experiments were conducted on three different RFID tags which were active RFID tag embedded with GPS and GSM (ERFIDG2), active RFID tag embedded with GPS (ERFIDG) and standalone RFID tag communicating with the same active RFID reader. The experiment was done to evaluate the communication performance of the active RFID in terms of tags collection time using Transparent (AT) and Application Programming Interface (API) mode. The experiment was extended to measure tags collection time in single hop and multi hops communication for Tag Talk First (TTF) and Reader Talk First (RTF) protocols. The results show that the proposed active RFID system (ERFIDG2) is better than the standalone and ERFIDG systems. The in-depth research done in this work is to study the experience and identify the challenges that will be faced in the development and implementation of a wireless RFID-based system for tracking and monitoring applications.     

A novel algorithm to study the impact of the mismatch on analog building blocks: a case study in basic 35 nm CMOS amplifiers

In this paper, the context of modeling of the impact of mismatch and statistical variations on analogue circuit building blocks is emphasized. The aim is to develop a new algorithm which predicts the statistical behavior of important parameters of an amplifier including output resistance, voltage gain and trans-conductance. The relative error of standard deviation of statistical parameters will remain less than 5% compared with the most accurate Monte-Carlo (MC) simulations using atomistic library model-cards. In comparison with other models which are based on the normal distribution of parameters, the proposed model does not need this limiting presumption. On the other hand, the proposed algorithm is more efficient compared with time consuming MC atomistic simulations.