Path Loss Modeling Based on Field Measurements Using Deployed 3.5 GHz WiMAX Network

WiMAX technology carries the promise of broadband access and wireless coverage. Developing countries throughout the world have been fast at adopting and employing the new technology to bridge the digital divide. The deployment of WiMAX networks enables the validation and testing of the technology. It is imperative that the technology be tested in different environments and the results shared and compared. Jordan provides a unique environment in its architecture, building construction materials, usage model, topology and vegetation. This work considers a mobile WiMAX network operating at 3.5 GHz deployed in Amman, Jordan. The work presents a new model for predicting path loss based on the results of field measurements of signals power and it compares proposed model and measured data to different propagation models.     

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.     

SMART： A Strengthened Model of Access Router Tree for Multihoming in Nested Mobile Network

Load balance and failure tolerance are thecrucial issues for multihomed mobile network. However,existing solutions are still far away from our expectation.In this paper, we first analyze the problems of multihoming in a nested mobile network and review their existingschemes in the eye of load balance and failure tolerance.Then we give a strengthened model of access router tree,where a novel and comprehensive metric for best pathrecognition is proposed to realize the load balance. In order to enhance the failure tolerance of the system, we further propose fast handover algorithms which can be usedwhen burst access failure appears. We perform extensivesimulations to evaluate the proposed scheme. Results indicate that comprehensive load balance and failure tolerance can be achieved. Moreover, our proposed handoveralgorithm achieves least latency of package transmissioncompared with its existing counterparts.     

Design of a 30.5 GHz Transition for Gyro-TWT

A 30.5 GHz circular transition used to transmit TE₀₁ mode is proposed because of no suitable one available. Calculations and simulations indicate that it can transmit TE₀₁ mode with transmission efficiency over 0.99 (within a bandwidth of 3 GHz). At the same time, the good performance of it has been demonstrated in experiment. Furthermore, the transition has only a length of 80 mm much shorter than linear or the other nonlinear ones. Such short length is very helpful for construction of a compact microwave device.     

Estimation of Path Length Reduction Factor by Using One Year Rain Attenuation Statistics over a Line of Sight Link Operating at 28.75 GHz in Amritsar (INDIA)

The effect of environmental factors in general and rain droplets in particular, on microwave propagation is a very well known fact now. If the rain droplets are present in an inhomogeneous way across the path length of the microwave communication system then, a new concept of path length reduction factor is introduced which accounts for the inhomogeneous nature of the rain droplets along the path length of the microwave signal. The present paper presents results of path length reduction factor using data on attenuation levels obtained on a LOS link operating at 28.75 GHz in Amritsar region and its comparison with Crane’s and ITU-R’s model.     

An Indoor Propagation Model Based on a Novel Multi Wall Attenuation Loss Formula at Frequencies 900 MHz and 2.4 GHz

This paper describes an indoor propagation model pertaining to a sample of six different multi-floor building structures that have a stone block type outer wall and are generally described as university, hospital and office type buildings. Those flat roofed, stone built, multi floor buildings are very common, not only in Palestine, but probably in vast areas in the Middle East region. The goal is to come up with a relatively general model that would be both reliable and representative to a wider sample of multi-floor buildings, falling under a similar building structure classification. The improved model; we name the AMATA model, lends itself to its generalization for the GSM and wireless LAN frequencies as well as the developed multiwall effective attenuation fourth power nonlinear equation that solely relies on the number of wall separations within the floor. A clear improvement in the standard deviation of the mean path loss resulted in comparison to the well known indoor ITU path loss model. Our model can be applied with a high confidence level to the wider range of buildings similar to the classification type of the building structure sample, we conducted measurements upon.     

A Study of Equilibrium Points and Stability in a Nonlinear Model of a Phase-Compensated Operational Amplifier

A nonlinear model is derived for a phase-compensated operational amplifier. Instead of well-known s-domain small-signal analysis, which linearizes the system equations with respect to an operating point, we locate all equilibrium points and study the stability of important ones. Two important conclusions incorporating novel, yet simple, design equations to improve stability and linearity are stated.     

Modeling and characterization of a 5.2 GHz VCO for UWB applications in 0.13 μm CMOS process

This paper describes a 5.2 GHz voltage-controlled oscillator (VCO) as a key component in RF transceivers. The circuit includes a complementary cross-coupled MOSFET as a negative conductance, beside a tank circuit which consists of an optimal on-chip spiral inductor (L), and an accumulation mode MOS varactor (C(V)). A model for phase noise and figure merit is introduced and verified through simulation in a standard 0.13 μm CMOS process. The VCO core drew a 4.2 mA of current from a 1.2 V power supply and a phase noise of −98.5 dBc/Hz at 1 MHz offset from the 5.2 GHz carrier was calculated. The whole performance of the circuit specifically the tuning range was found to be 26%.     

Continuously Tunable 250 GHz Gyrotron with a Double Disk Window for DNP-NMR Spectroscopy

In this paper, we describe the design and experimental results from the rebuild of a 250 GHz gyrotron used for Dynamic Nuclear Polarization enhanced Nuclear Magnetic Resonance spectroscopy on a 380 MHz spectrometer. Tuning bandwidth of approximately 2 GHz is easily achieved at a fixed magnetic field of 9.24 T and a beam current of 95 mA producing an average output power of >10 W over the entire tuning band. This tube incorporates a double disk output sapphire window in order to maximize the transmission at 250.58 GHz. DNP Signal enhancement of >125 is achieved on a ¹³C-Urea sample using this gyrotron.     

Design of a 300 GHz Band TWT with a Folded Waveguide Fabricated by Microelectromechanical Systems

For future broadband wireless links, we have designed a 300 GHz band traveling wave tube (TWT) with a folded waveguide fabricated by microelectromechanical systems (MEMS). The TWT operates at a beam voltage of 12 kV and a beam current of 8.3 mA. The classical large signal simulation code predicts the output power greater than 1 W and gain larger than 20 dB over the bandwidth from 280 to 300 GHz.     

Numerical Simulation of a Double-anode Magnetron Injection Gun for 110 GHz, 1 MW Gyrotron

A 40 A double-anode magnetron injection gun for a 1 MW, 110 GHz gyrotron has been designed. The preliminary design has been obtained by using some trade-off equations. The electron beam analysis has been performed by using the commercially available code EGUN and the in-house developed code MIGANS. The operating mode of the gyrotron is TE_22,6 and it is operated in the fundamental harmonic. The electron beam with a low transverse velocity spread (db _^max = 2.26% \delta {\beta_{ \bot \max }} = 2.26\% ) and the transverse-to-axial velocity ratio of the electron beam (α) = 1.37 is obtained. The simulated results of the MIG obtained with the EGUN code have been validated with another trajectory code TRAK. The results on the design output parameters obtained by both the codes are in good agreement. The sensitivity analysis has been carried out by changing the different gun parameters to decide the fabrication tolerance.     

Estimation of the Non-Measurable State Variables of a Transcutaneous Energy Transmission System for Artificial Human Implants Using Extended Kalman Filters

Due to the separation of the two sides of the coupling network, the acquisition of data on the operating state variables of a transcutaneous energy transmission system (TETS) inside the human body is difficult. A non-measurable state estimation approach is used in this work to facilitate the estimation of non-measurable variables on the secondary side of the TETS, including the current of the secondary coil and the output voltage of the secondary side. The estimation algorithm is based on a discrete dynamic mathematical model of the TETS. Following this model, using the extended Kalman filter (EKF) algorithm, the complexity of the TETS for artificial human implants can be reduced, while the reliability is simultaneously enhanced. Additionally, as an adaptive filter, the EKF can also successfully filter out processing noise during energy transmission. All of the results are verified by simulation using MATLAB.     

Design and implementation of a 94 GHz CMOS down-conversion mixer with integrated miniature planar baluns for image radar sensors

A 94 GHz down-conversion mixer for image radar sensors using standard 90 nm CMOS technology is reported. The down-conversion mixer comprises a double-balanced Gilbert cell with peaking inductors between RF transconductance stage and LO switching transistors for conversion gain (CG) enhancement and noise figure suppression, a miniature planar balun for converting the single RF input signals to differential signals, another miniature planar balun for converting the single LO input signals to differential signals, and an IF amplifier. The mixer consumes 22.5 mW and achieves excellent RF-port input reflection coefficient of ?10 to ?35.9 dB for frequencies of 87.6–104.4 GHz, and LO-port input reflection coefficient of ?10 to ?31.9 dB for frequencies of 88.2–110 GHz. In addition, the mixer achieves CG of 4.9–7.9 dB for frequencies of 81.8–105.8 GHz (the corresponding 3-dB CG bandwidth is 24 GHz) and LO–RF isolation of 37.7–47.5 dB for frequencies of 80–110 GHz, one of the best CG and LO–RF isolation results ever reported for a down-conversion mixer with operation frequency around 94 GHz. Furthermore, the mixer achieves an excellent input third-order intercept point of ?3 dBm at 94 GHz. These results demonstrate the proposed down-conversion mixer architecture is promising for 94 GHz image radar sensors.     

Multi-Fractal Characteristics of Mobile Node’s Traffic in Wireless Mesh Network with AODV and DSDV Routing Protocols

The analysis of traffic characteristics can be used for performance evaluation, design and implementation of routing protocols in WMNs (Wireless Mesh Networks). Higher bursty traffic will cause larger queue size, which means more dropping packets, and thus affects other metrics. Because burstiness can be modeled by multi-fractal characteristics effectively, multi-fractal characteristics of mobile node’s traffic in WMNs are analyzed with typical proactive and reactive routing protocols, which are DSDV (Destination Sequenced Distance Vector) and AODV (Ad hoc On-demand Distance Vector), respectively. Three types of traffic models are used to generate traffic at application level, which corresponding to open-loop and closed-loop scenarios. With different configurations, the probability distribution of inter-arrival time and multi-fractal characteristics of traffic at mobile node and gateway are analyzed with DSDV and AODV protocols. Results show that inter-arrival time with AODV and DSDV protocols possesses heavy-tailed property. And traffic with DSDV protocol exhibits more multi-fractal characteristics than that with AODV protocol, which can explain the higher routing performance of AODV.     

Demonstration of using multi-band 16-QAM OFDM modulation with direct-detection in 10 GHz bandwidth for 37.3-Gb/s PON

We propose and experimentally demonstrate a 37.3 Gb/s passive optical network using four-band orthogonal-frequency-division-multiplexing (OFDM) channels within 10 GHz bandwidth. Here, the required sampling rate and resolution of digital-to-analog/analog-to-digital (DA/AD) converter are only 5 GS/s and 8 bits to accomplish the 40 Gb/s OFDM downstream rate. Moreover, to reduce the power fading and fiber chromatic dispersion issues, a $-$ 0.7 chirp parameter Mach-Zehnder modulator is used for the four-band OFDM modulation scheme. Downstream negative power penalty of $-$ 0.37 dB can be obtained at the bit error rate of $3.8\times 10^{-3}$ after 20 km standard single mode fiber transmission without dispersion compensation.     

Design of a Low Voltage Highly Linear 2.4 GHz Up-Conversion Mixer in 0.18 μm CMOS Technology

This paper presents a low voltage highly linear up-conversion mixer for 2.4 GHz IEEE 802.11b WLAN transmitter applications based on a Chartered 0.18 μm CMOS technology. In the proposed mixer, the double balanced Gilbert cell topology was adopted and the dual resistive current-reuse and current-bleeding techniques in both the driver and switching stages with a capacitive cross-coupling technique were used. The up-conversion mixer can convert a 10 MHz intermediate frequency signal to a 2.4 GHz radio frequency signal, with a local oscillator power of 0 dBm at 2.39 GHz. A comparison with conventional CMOS mixer shows that this up-conversion mixer has advantages of low voltage, low power consumption and high performance. The post-layout simulation results demonstrate that at 2.4 GHz, the circuit provides 7.1 dB of conversion gain and the input-referred third-order intercept point of 11.3 dBm, while drawing only 5 mA for the mixer core under a supply voltage of 1.2 V. The chip area including testing pads is only 0.65 × 0.75 mm.     

Comparison of Free Space Measurement Using a Vector Network Analyzer and Low-Cost-Type THz-TDS Measurement Methods Between 75 and 325 GHz

Specifications of two measurement systems, free space measurement using a vector network analyzer and low-cost-type terahertz time-domain spectroscopy using a multimode laser diode, have been compared in the frequency region of millimeter/sub-THz waves. In the comparison, accuracy, cost, measurement time, calculation time, etc. were considered. Four samples (Rexolite, RO3003, Ultralam 3850HT-design, and L1000HF) were selected for the comparison of the specifications of the two methods. The acquired data was used to compute the complex permittivity of measured materials. The extracted results by free space measurement agreed well to the ones obtained by low-cost-type terahertz time-domain spectroscopy. This result proves free space measurement that can be assessed as a new method of material characterization in the sub-THz region successfully worked. Furthermore, free space measurement was proved to be suitable for a measurement in a narrow frequency range. On the other hand, low-cost-type terahertz time-domain spectroscopy has features not only low cost but also measurement capability in wide frequency range.