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Microwave Theory and Techniques, IEEE Transactions on

Issue 4  Part 2 • Date April 2006

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Displaying Results 1 - 25 of 36
  • Table of contents

    Publication Year: 2006 , Page(s): c1 - c4
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  • IEEE Transactions on Microwave Theory and Techniques publication information

    Publication Year: 2006 , Page(s): c2
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  • Guest Editorial

    Publication Year: 2006 , Page(s): 1633 - 1636
    Cited by:  Papers (1)
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  • A low-complexity noncoherent IR-UWB transceiver architecture with TOA estimation

    Publication Year: 2006 , Page(s): 1637 - 1646
    Cited by:  Papers (49)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (864 KB)  

    Impulse-radio (IR)-based ultra-wideband (UWB) technology is a strong candidate for short-range data communication and positioning systems. This paper examines the performance of time-of-arrival (TOA) position estimation techniques as well as the simulated and measured performances of an IR-UWB noncoherent energy-collection receiver. The noncoherent IR-UWB transceiver has been designed for operation over the frequency range 3.1-4.1 GHz and implemented in 0.35-μm SiGe BiCMOS technology. The performance of two different algorithms, namely, the threshold-crossing and the maximum selection (MAX) algorithms, are compared in terms of TOA estimation error in Saleh Valenzuela channel model 3 and channel model 4. The implemented structure of the TOA MAX algorithm suitable for IR-UWB-based noncoherent receivers is presented. A UWB testbed has been constructed in order to test and measure the transmitted waveform as well the receiver performances. The simulated receiver noise figure is 7.3 dB while the receiver gain is 34 dB. The TOA MAX algorithm can achieve ±5-ns positioning accuracy for 95% of cases. Constant transconductance tuning circuits for improved TOA estimation reliability are also presented. View full abstract»

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  • Gaussian pulse Generators for subbanded ultra-wideband transmitters

    Publication Year: 2006 , Page(s): 1647 - 1655
    Cited by:  Papers (64)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1040 KB)  

    This paper presents calculations for approximating the measured spectrum of pulsed signals in the high and low pulse-repetition-frequency (PRF) region. Experimentally verified peak and average power calculations are presented for pulse trains with no modulation and when modulated by random data using binary phase-shift keying (BPSK). A pulse generator is presented that is built using commercially available discrete components. BPSK pulses are generated at a PRF of 50 MHz. The output spectrum has a center frequency of 5.355 GHz and a -10-dB bandwidth of 550 MHz. A technique for pulse shaping is presented that approximates a Gaussian pulse by exploiting the exponential behavior of a bipolar junction transistor. This technique is demonstrated by a pulse generator fabricated in a 0.18-μm SiGe BiCMOS process. BPSK pulses are generated by inverting a local oscillator signal as opposed to the reference pulse, improving matching. Pulses are transmitted at a PRF of 100 MHz and centered in 528-MHz-wide channels equally spaced within the 3.1-10.6-GHz ultra-wideband band. Measurement results for both transmitters match well with calculated values. View full abstract»

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  • Codesign of an impulse generator and miniaturized antennas for IR-UWB

    Publication Year: 2006 , Page(s): 1656 - 1666
    Cited by:  Papers (29)
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    The codesign of an impulse generator and miniaturized antennas for ultra-wideband impulse radio is described. The impulse generator, discussed by Bragga in 2004, is designed with differential outputs that are fed to the antenna, producing an optimum match of the generator to the antenna, an improved magnitude response, and reduced ringing of the radiated pulse. The impulse generator is preceded by a programmable pulse-position modulator and consists of a triangular pulse generator and a cascade of complex first-order systems, which, in turn, are made up of differential pairs employing partial positive feedback to approximate a Gaussian monocycle waveform. The complete pulse generator is fabricated in IBM 0.18-μm Bi-CMOS IC technology. Measurements show the correct operation of the circuit for supply voltages of 1.8 V and a power consumption of 45 mW. The output pulse approximates the Gaussian monocycle having a pulse duration of about 375 ps. Proper modulation of the pulse in time is confirmed. A number of antennas with differentially fed baluns and input impedances of 100 Ω have been designed. From measurements, it can be seen that ringing is considerably smaller as compared to conventionally fed antennas. View full abstract»

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  • System-on-package ultra-wideband transmitter using CMOS impulse generator

    Publication Year: 2006 , Page(s): 1667 - 1674
    Cited by:  Papers (33)
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    In this paper, a low-cost CMOS ultra-wideband (UWB) impulse transmitter module with a compact form factor is proposed for impulse-radio communications. The module consists of a CMOS impulse generator, a compact bandpass filter (BPF), and a printed planar UWB antenna. The impulse generator is designed using a Samsung 0.35-μm CMOS process for low-cost and low-power fabrication. The measurement shows the fabricated chip makes a train of sharp triangular pulses with a peak voltage of about 2.8 V under the supply voltage of 3.3 V. To make an impulse fit the Federal Communications Commission (FCC) spectrum mask, the compact BPF is developed using a coupled strip line and a tapered stub. Also, the compact planar UWB antenna is developed. All of the components of the UWB transmitter module are fabricated on a single package using system-on-package technology for miniaturization. The proposed UWB transmitter is tested in an office environment. The measured results show that the generated UWB signal meets the FCC regulation, and the peak-to-peak amplitude of received UWB signal at 1-m distance on line of sight is 16 mVpp with a 10-dB-gain low-noise amplifier in the receiver. View full abstract»

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  • The discone antenna in a BPSK direct-sequence indoor UWB communication system

    Publication Year: 2006 , Page(s): 1675 - 1680
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    The current ultra-wideband (UWB) channel models proposed by different research groups are generally based on measurements in which the effect of the antennas used are inevitably embedded. There is potentially significant waveform distortion by UWB antennas, and it is difficult to distinguish between antenna and real propagation path effects in many of the reported channel measurements. However, understanding these effects is important for overall system performance prediction. The discone antenna is known for its broadband characteristics and has been widely used for channel measurements. In this paper, we address the importance of the antenna and indoor propagation effects as applied to a UWB system analysis. This is achieved by use of a true time-domain three-dimensional ray-tracing propagation model coupled with accurate simulation of the time-domain performance of the discone antenna. A DS-UWB system approach was adopted for detailed study and its performance is evaluated under the channel model with and without considering the antenna pattern effect. Both line-of-sight and non-line-of-sight cases are considered. The antenna effect can be seen to be significant, leading to the conclusion that interpretation of practical system measurements must allow for the antennas being used in the measurement system. View full abstract»

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  • Compensation of the effects of antenna dispersion on UWB waveforms via optical pulse-shaping techniques

    Publication Year: 2006 , Page(s): 1681 - 1686
    Cited by:  Papers (27)
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    To our knowledge, we present the first experimental demonstration of compensation of antenna dispersion effects on impulsive ultra-wideband (UWB) signals. By extracting the RF spectral phase from a time-domain impulse response measurement of a pair of ridged TEM horn antennas, we utilize a photonic-synthesis technique for arbitrary electromagnetic signal waveforms to generate a signal ''matched'' to the antenna pair. We demonstrate that the received waveform is compressed and exhibits reduced ringing levels, as compared to the impulse response of the system. Our technique is reprogrammable and we believe the technique will be applicable to a variety of antennas operating in the UWB communications band of 3.1-10.6 GHz. View full abstract»

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  • The analysis of UWB SiGe HBT LNA for its noise, linearity, and minimum group delay variation

    Publication Year: 2006 , Page(s): 1687 - 1697
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (744 KB)  

    The design of ultra-wideband (UWB) low-noise amplifiers (LNAs) require additional circuit design principles, which differ from those used in conventional LNAs. The design of a low-dc-power-consumption SiGe HBT LNA covering the 2-10-GHz range is demonstrated for UWB applications. Important design factors that must be carefully considered for UWB applications are analyzed, which include power dissipation, operating bandwidth, noise figure, group delay variation, and linearity. The dominant factor for low group delay variation in UWB LNAs is identified through the theoretical analysis. The linearity behavior over the wide bandwidth is analyzed and explained using the Volterra series. Second-harmonic cancellation is determined to be the dominant degradation factor for linearity. The implemented SiGe LNA achieves a gain of 13 dB, a minimum noise figure of 3.3 dB, and an input third-order intercept point of -7.5 dBm between 2-10 GHz while consuming a dc power of only 9.6 mW. This SiGe UWB LNA exhibits less than 22 ps of uniform group delay variation over the entire band. View full abstract»

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  • A 6.5-kV ESD-protected 3-5-GHz ultra-wideband BiCMOS low-noise amplifier using interstage gain roll-off compensation

    Publication Year: 2006 , Page(s): 1698 - 1706
    Cited by:  Papers (10)
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    Design and validation of an electrostatic discharge (ESD)-protected ultra-wideband low-noise amplifier (LNA) is presented in this paper. It features an interstage matching network for gain roll-off compensation to achieve a flat gain over its passband. Evaluated with a chip-on-board approach, the amplifier demonstrates a gain of 11.8 ± 0.3 dB, minimum noise figure of 2.1 dB, and a group delay variation of ±30 ps from 3 to 5 GHz, even though it uses a less advanced 0.35-μm BiCMOS technology. The LNA is protected against human body model ESD stress up to 6.5 kV. The measured input third-order intercept point at 4.5 GHz is -5.5 dBm. The core LNA draws 3 mA from a 3-V supply. View full abstract»

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  • Multi(Six)-port impulse radio for ultra-wideband

    Publication Year: 2006 , Page(s): 1707 - 1712
    Cited by:  Papers (30)
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    Multi(six)-port impulse radio (MIR) validates the full channel (3-4 GHz) novel quaternary phase spectrum modulation (QPSM) scheme using a six-port modulator and demodulator circuits. Due to the lack of a monocycle generator, a 1-GHz spectral phase channel is generated from a rectangular pulse signal, upconverted using filters, mixer, and a local oscillator. The 3-4-GHz signal is applied to the RF input of a six-port modulator and digital data is simultaneously fed to a switch matrix terminating four ports of the modulator with either a short or open circuit. This operation produces an output signal in the QPSM scheme. One input port of the six-port demodulator is fed with the received phase-modulated signal and a second input port is fed with the reference nonmodulated signal. The demodulator's four outputs provide signals of different amplitudes used to determine the modulation states with digital signal processing (DSP) algorithms. Modulation algorithms, demodulation algorithms, and synchronization control are implemented on a field-programmable gate-array-based DSP platform fitted with four analog-to-digital converters. Measurements and simulation results are presented to validate the MIR hardware and software in an operating 1-GHz ultra-wideband channel. View full abstract»

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  • A robust front-end architecture for low-power UWB radio transceivers

    Publication Year: 2006 , Page(s): 1713 - 1723
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (792 KB)  

    In this paper, we propose a transceiver architecture and a novel modulation scheme for ultra-wideband (UWB) radio technology. The modulation uses a combination of binary-shift keying and a carrierless amplitude modulation. A demodulation method is proposed and theoretically investigated. These techniques enable the implementation of low-power although robust and reliable UWB radio transceivers intended for short ranges (below 10 m) and medium bit rates (1-10 Mb/s). This paper addresses the theoretical bit error rate performance of a demodulator/detector for data transmission over an additive white Gaussian noise channel. Additional simulation results are given to assess the performance of the proposed solution in a dense multipath environment with the help of available UWB channel models. View full abstract»

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  • Robust detection of ultra-wideband signals in non-Gaussian noise

    Publication Year: 2006 , Page(s): 1724 - 1730
    Cited by:  Papers (7)
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    A robust receiver is proposed for time-hopping pulse-position-modulation impulse radio systems transmitting over frequency-selective ultra-wideband channels, which aims to remove large-amplitude outliers that occur due to impulsive noise. The proposed system contains a rake structure for collecting the signal energy, which is dispersed over a large number of paths as a result of the wide channel bandwidth. Before the paths are merged via maximal ratio combining, they are passed through nonlinearities to trim the outlier noise components. The robust receiver so designed is shown to outperform the conventional linear rake receiver that consists of only matched filters at its fingers. View full abstract»

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  • Space-time selective RAKE receiver with finger selection strategies for UWB overlay communications

    Publication Year: 2006 , Page(s): 1731 - 1744
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (848 KB)  

    This paper proposes a space-time selective RAKE (SRAKE) receiver with maximum signal-to-interference-plus-noise ratio (MSINR) for direct-sequence ultra-wideband (UWB) communications in the presence of narrowband interference (NBI) and multiple-access interference. For effectively extracting a fixed number of the UWB signal components (fingers) from numerous resolvable paths, four finger selection strategies (FSSs) are considered for the proposed space-time SRAKE receiver, including the optimum FSS (with MSINR), which is not very computationally feasible, and three feasible FSSs: an energy-based FSS (EB-FSS), a constrained energy-based FSS (CEB-FSS), and a hybrid energy-based FSS, which is also a combination of the EB-FSS and CEB-FSS. Through a performance analysis, we show that the performance of the proposed receiver in the presence of NBI not only depends on the power ratio, bandwidth ratio, and relative spectrum location of NBI with respect to the UWB signal, but also on the FSS used. Some simulation results are then presented to show that the proposed space-time MSINR-SRAKE receiver with the preceding FSSs used can provide a larger system capacity and better immunity to strong NBI than the existing time-only SRAKE receivers and space-time SRAKE receivers. View full abstract»

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  • Frequency-domain implementation of the transmitted-reference ultra-wideband receiver

    Publication Year: 2006 , Page(s): 1745 - 1753
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    This paper presents a mixed-signal frequency-domain implementation of the autocorrelation receiver used in the detection of ultra-wideband communication signals that are modulated with transmitted-reference signaling. The digital receiver architecture is based on samples provided by an analog-to-digital converter (ADC) in the frequency domain. Among the advantages of the new receiver are the relaxation of the conversion speed achieved by the inherent parallel architecture of the frequency-domain ADC and the flexibility and simplicity of an all-digital receiver architecture that follows the mixed-signal ADC radio front-end. The paper provides the symbol detection formulas and the corresponding system implementation and makes comparisons with the conventional time-domain implementations. Additionally, a time synchronization technique for the new receiver structure is proposed, which makes the receiver insensitive to any time offset at the pulse level. Furthermore, as a particular case of great practical interest, we consider a single bit for the ADC implementation, and we show with experimental results that the resultant frequency-domain mono-bit digital receiver provides a performance gain that increases with the number of frequency samples, when compared with its time-domain counterpart. View full abstract»

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  • Transmitted-reference UWB systems using weighted autocorrelation receivers

    Publication Year: 2006 , Page(s): 1754 - 1761
    Cited by:  Papers (27)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (928 KB)  

    The application of a fractionally sampled autocorrelation receiver (AcR) is proposed for the demodulation of transmitted-reference (TR) signals, to simplify synchronization and suppress nonlinear intra-symbol-interference and inter-symbol-interference (ISI) by means of linear weighting. A system model is presented for the TR system and its statistical properties are derived, taking into account both noise and ISI. The weighting coefficients are computed in closed form and a method is presented to compute the bit error probability. Multiple ultra-wideband TR systems are compared, which differ with respect to correlation lag, bandwidth, sampling rate, and bit rate. In the absence of ISI, a 250-MHz bandwidth system outperforms the larger bandwidth systems. On the other hand, the larger bandwidth systems are found to be inherently less sensitive to ISI. Furthermore, increasing the fractional sampling ratio is shown to enable the AcR to equalize more (nonlinear) ISI. View full abstract»

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  • A computable formula for the average bit error probability as a function of window size for the IEEE 802.15.3a UWB channel model

    Publication Year: 2006 , Page(s): 1762 - 1768
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB)  

    Binary signaling over the IEEE 802.15.3a ultra-wideband channel model is considered. For received waveforms observed during a finite time window, a formula is derived for the average bit error probability (BEP). The formula can be rapidly evaluated using Gaussian quadratures, and is used to study average BEP curves as a function of window size, which is then related to the percentage of energy captured. These techniques should be useful to system designers in assessing the performance impact of various signaling rates, guard times, etc. View full abstract»

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  • A robust signal-detection method for ultra-wideband networks with uncontrolled interference

    Publication Year: 2006 , Page(s): 1769 - 1781
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (512 KB)  

    We propose a novel detection method for noncoherent synchronization (signal acquisition) in multi-user ultra-wideband (UWB) impulse radio (IR) networks. It is designed to solve the inter-user interference (IUI) that occurs in some ad-hoc networks where concurrent transmissions are allowed with heterogeneous power levels. In such scenarios, the conventional detection method, which is based on correlating the received IR signal with a template pulse train (TPT), does not always perform well. The complexity of our proposal is similar to that of the conventional method. We evaluate its performance with the line-of-sight (LOS) and the non-LOS (NLOS) office indoor channel models proposed by the IEEE P802.15.4a study group and find that the improvement is significant. We also investigate the particular case where the concurrent transmissions have the same time-hopping code, and we show that it does not result in collision. Such scenarios appear in ad-hoc networks that employ a common code for control or broadcast purposes. View full abstract»

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  • Interference mitigation study for UWB radio using template waveform processing

    Publication Year: 2006 , Page(s): 1782 - 1792
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (832 KB)  

    Ultra-wideband (UWB) is an effective technique that enables coexistence with other radio systems using very short pulses and spread spectrum. However, there are potential interferences among those using the same frequency bands. This paper discusses the effects of interference between pulse-based UWB (p-UWB) and other systems: continuous wave, binary phase-shift keying signal, IEEE802.11a wireless LAN using a 5-GHz band, and multiband orthogonal frequency-division multiplexing (MB-OFDM). The MB-OFDM is inferentially proposed for personal area networks, as is p-UWB. The FCC has stated that both p-UWB and MB-OFDM systems will use the same band from 3.1 to 10.6 GHz. The bit-error-rate performance is shown assuming that p-UWB and the other systems are utilized at close range. To mitigate the effects of interference to p-UWB from other radio systems, a multicarrier template wave technique is proposed. The multicarrier template wave is approximated with an ordinary pulse waveform by Gabor transform formula and is composed of several subband pulses without interfering bands. The proposed UWB receiver for MB-OFDM interferences can detect their hopping pattern without a priori knowledge from the MB-OFDM transmitter. These techniques are shown to be effective for the systems to coexist. View full abstract»

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  • Statistical multiplexing-based hybrid FH-OFDMA system for OFDM-based UWB indoor radio access networks

    Publication Year: 2006 , Page(s): 1793 - 1801
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1000 KB)  

    We propose a statistical multiplexing-based hybrid frequency-hopping orthogonal frequency-division multiple-access (HFH-OFDMA) system to increase the downlink user capacity of orthogonal frequency-division multiplexing (OFDM)-based ultra-wideband (UWB) indoor radio access networks (RANs). The downlink user capacity is here defined as the maximum allowable number of users served with a given data rate in a piconet. Statistical multiplexing, as noted by Walrand and Varaiya in 2000, is a method in which multiple users with intermittent transmissions efficiently share a link. The adoption of a statistical multiplexing concept enables the HFH-OFDMA system to accommodate many more users than the conventional FH-OFDMA system can. In OFDM-based UWB indoor RANs, the downlink user capacity of the HFH-OFDMA system is limited by either the total number of available subcarriers in a piconet (resource-limited) or the FCC UWB emission limit (power-limited). We analyze the downlink user capacity of the proposed HFH-OFDMA system in both single-piconet and multipiconet environments. In the single-piconet environment, the proposed HFH-OFDMA system which operates in 3.168-3.696-GHz band accommodates 256 users with a data rate of 532.5 kb/s in an OFDM-based UWB indoor RAN, while the proposed HFH-OFDMA system in the multipiconet environment, under the same conditions of the single-piconet environment, accommodates 110 users with a data rate of 532.5 kb/s. View full abstract»

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  • A parametric UWB propagation channel estimation and its performance validation in an anechoic chamber

    Publication Year: 2006 , Page(s): 1802 - 1811
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    This paper presents an ultrawide-band (UWB) channel sounding scheme with a parametric channel estimation to seek accurate probing of the propagation channel. The channel sounder consists of a vector network analzer and synthetic array to measure spatial transfer functions. The measured data are then applied to a maximum-likelihood (ML)-based estimator. The concepts implemented in the ML-based parametric channel estimation are: 1) to probe frequency-dependent effects in magnitude and phase of propagation paths and 2) to incorporate with robust concept of direction finding, namely, the spherical wavefront model of incident waves. The whole frequency band was divided into subbands, and the estimation of magnitude and phase was conducted in each subband. The spherical wavefront model includes a new model parameter, curvature radii, which is not covered in the conventional plane wavefront model. Performances of the proposed parametric UWB channel estimation scheme was assessed by anechoic chamber tests. The test demonstrated that: 1) the frequency-dependent magnitude and phase were accurately detected if the path was resolved and 2) the spherical wavefront outperformed the plane wavefront to model measured data given the short-range environment. Furthermore, fundamental performance of the sounding scheme, i.e., angular and time resolutions, were also evaluated in the test. View full abstract»

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  • UWB SIMO channel measurements and simulations

    Publication Year: 2006 , Page(s): 1812 - 1819
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (856 KB)  

    Ultra-wideband (UWB) technology has recently attracted the entire wireless community with its great potential for short-range and high data-rate communications. On the other hand, multiantenna (or multiple-input multiple-output) techniques are considered as an effective way to improve the link reliability and transmission rate. In this paper, both aspects are studied through a complete UWB single-input multiple-output (SIMO) channel sounding campaign. The time-domain channel sounder with its antenna array is firstly detailed. Secondly, measurement results will be used to describe interesting antenna array effects and channel behavior (like correlation results and underlying spatial diversity). Finally, in order to show the utility of spatial diversity in UWB systems, the performance of a SIMO system with a Rake receiver will be presented through bit error rate simulations based on measurement results. View full abstract»

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  • An ultra-wideband body area propagation channel Model-from statistics to implementation

    Publication Year: 2006 , Page(s): 1820 - 1826
    Cited by:  Papers (109)
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    Body worn wireless sensors for monitoring health information is a promising new application. In developing these sensors, a communication channel model is essential. However, there are currently few measurements or models describing propagation around the body. To address this problem, we have measured electromagnetic waves near the torso and derived relevant statistics. We find that components diffracting around the body are well modeled using correlated log normal variables, and a Nakagami-m distribution can be used to incorporate the influence of arm motions. We have implement this model and evaluated it in terms of important communication metrics. This paper describes body area propagation statistics and proposes a suitable computer model implementation. View full abstract»

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  • UWB on-body radio channel modeling using ray theory and subband FDTD method

    Publication Year: 2006 , Page(s): 1827 - 1835
    Cited by:  Papers (65)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (688 KB)  

    This paper presents the ultra-wideband on-body radio channel modeling using a subband finite-difference time-domain (FDTD) method and a model combining the uniform geometrical theory of diffraction (UTD) and ray tracing (RT). In the subband FDTD model, the frequency band (3-9 GHz) is uniformly divided into 12 subbands in order to take into account the material frequency dispersion. Each subband is simulated separately and then a combination technique is used to recover all simulations at the receiver. In the UTD/RT model, the RT technique is used to find the surface diffracted ray path, while the UTD is applied for calculating the received signal. Respective modeling results from two- and three-dimensional subband FDTD and UTD/RT models indicate that antenna patterns have significant impacts on the on-body radio channel. The effect of different antenna types on on-body radio channels is also investigated through the UTD/RT approach. View full abstract»

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