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We developed a positioning system using impulse radio UWB. The system consists of tags equipped only with transmitters and nodes provided with both transmitters and receivers. The system calculates the position of the tags using the TDOA method, whereby some nodes receive the UWB pulses sent from a tag. The tag is operated with a coin battery, and sends UWB pulses intermittently. The node sends the...
SAW/ceramic resonators are renowned for their ability to generate high spectral purity signal at RF/microwave frequencies. Unfortunately, SAW/ceramic resonators based oscillators have several disadvantages, including a limiting temperature range, limited tuning range, not amenable for fabrication by current integrated circuit (IC) technology, and also sensitive to phase hits. These resonators are...
Fixed and mobile communications convergence scenario under the user perspective is being depicted as combination of wireless and cellular networks. This is possible by the use of multimode terminals, and application servers located in the core network, that facilitates the handover between the different base stations whatever the wireless or cellular standard is used in the convergent network. Since...
In this paper, genetic algorithm (GA) was applied to orthogonal variable spreading factor (OVSF) code tree reassignment problem with adaptive population size, which is constructed according to existing OVSF code tree density. In order to improve the ability of GA, we employ so-called "dominance & diploidy" structure to adapt to changing traffic conditions. Simulation results show that...
This paper investigates the impact of technological scaling and minimization of flicker (1/f) noise on SiGe HBTs in coupled mode N-push oscillator/VCO configuration, which have recently emerged as a strong contender for RF and mixed-signal applications. 1/f noise in SiGe HBTs is sensitive with technological scaling and upconverted in coupled mode oscillators due to the presence of asymmetrical output...
The dynamics of phase locked loops (PLLs) are heavily influenced by the right choice of the loop filter parameters. A new approach for determining these parameters to meet the specification of telecommunications standards optimally is presented in this paper. The most common optimization criterium is to minimize the integral error over time of the step response. In a telecommunications system, it...
Notice of Violation of IEEE Publication Principles??A Fully-Integrated Single-Conversion SiGe BiCMOS Satellite LNB Front-End Using a Constant-Gain Full-Rate Oscillator??by Maxim, A.; Turinici, C.; Gheorghe, M.;in the Proceedings of the 2007 IEEE Radio and Wireless Symposium,After careful and considered review, it has been determined that the above paper is in violation of IEEE's Publication Principles...
This paper addresses the issue of advanced multiuser detection and equalization for multiuser space-time transmission over multipath multiple input multiple output (MIMO) fading channel. Instead of resorting to the straightforward analogy between users and antennas, we introduce a low-complexity approach where multiuser interference (MUI) cancellation and intersymbol interference (ISI) suppression...
4G evolution includes improvements beyond 3G as well as nomadic and mobile versions of fixed broadband wireless access (BWA) systems, such as WiFi and WiMAX. The resulting trend is technological and application convergence in an increasingly competitive marketplace. This introductory paper to the Focused Session "Convergence and Competition on the Way to 4G" concentrates on three key contributing...
In recent mobile communication systems, impairments in analog circuits cannot be disregarded due to achieving high performance. Errors in analog circuits consist of a distortion of a power amplifier(PA), gain and phase imbalance in a quadrature modulator (QMOD) and a quadrature demodulator (QDEMOD), dc offset, frequency offset, and so on. Because of high accuracy of compensation, many techniques of...
Significant capacity improvements are possible when the multiple antennas are employed at both the transmitter and receiver. However, the application of multiple antenna systems is restricted by increasing of the cost and complexity of radio frequency (RF) subsystem. The authors in J. Ahmadi-Shokouh et al. (2006) presented a novel structure which not only overcomes the aforementioned limitation but...
A software tool for planning and sizing wireless networks based on standard 802.16 is presented in this paper. Due to the deployment of communication systems based on this standard, it is necessary a tool which allows an easy implementation and sizing of this type of networks. With this tool the user will be able to define technical specifications of transmitters and receivers, design parameters of...
In this paper, an analysis of the output load mismatch effects on the operation of Doherty power amplifiers is presented. A load-pull based LDMOS transistor model is used to investigate the effects of the load mismatch on the load modulation seen by the carrier and peaking amplifiers of a Doherty scheme. Then, the power added efficiency and the gain of the Doherty amplifier are evaluated for various...
In this paper, we address two important issues in OPNET-based modeling and simulation for range wireless communications. The first issue is to model the fading effect in wireless communications. The present OPNET wireless suite views all wireless channels as Gaussian channels and ignores the fading effect. We add a Rayleigh fading channel model to OPNET and implement the fading effect in simulation...
This paper introduces the design and the implementation of the 60 GHz amplifier MMICs and the module for the 60 GHz WPAN system with a RoF (radio-over-fiber) link. The MMICs were designed using ETRI's 0.12 mum GaAs PHEMT 4-inch process. The MCLFs (microstrip coupled line filters) compared with the MIM (metal-insulator-metal) capacitors have greater stability and less effect by the variation of fabrication...
Orthogonal frequency division multiplexing system is known to be sensitive to nonlinear distortion due to its high peak-to-average power ratio (PAPR). Without proper linearization techniques, power efficiency is often compromised to control the nonlinear distortion caused by power amplifiers. The nonlinear distortion caused by a power amplifier is due to clipping distortion and compressive gain distortion...
Two Doherty amplifiers are designed in MMIC form, which are fabricated using a commercial InGaP/GaAs HBT foundry process. The one is classical Doherty type amplifier with the size ratio of the main device and auxiliary device of 1(N = 1), and the other is an extended Doherty with the size ratio of 3(N = 3). The input and output circuits are made using a hybrid circuit, forming power amplifier modules...
Recent technological advances have led to the emergence of small battery-powered sensors with considerable, albeit limited, processing and communication capabilities. Wireless sensor networks have gained considerable attention in applications where spatially distributed events are to be monitored with minimal delay. We present and analyze a hierarchical wireless sensor network with mobile overlays,...
This paper reviews realization concepts and achievements of wireless sensor nodes and focuses on new developments in the 24 GHz frequency range. The higher frequency offers the advantage of ultra miniaturization and therefore opens new application fields. On the other hand power consumption of the RF-front-end becomes still more challenging than at lower frequencies. It is shown that by applying very...
An extension to the positive feedback pilot generation and detection system, described previously in [1], is proposed to improve convergence of the second loop alignment search used in an adaptive feedforward compensated power amplifier (PA). The original pilot system uses frequency-selective nonlinear positive feedback to generate a pilot tone and IF detection to measure the residual pilot power...
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