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Radio and Wireless Conference, 2001. RAWCON 2001. IEEE

Date 19-22 Aug. 2001

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  • Proceedings 2001 IEEE Radio and Wireless Conference [front matter]

    Page(s): 0_1 - xv
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  • Proceedings RAWCON 2001. 2001 IEEE Radio and Wireless Conference (Cat.No.01EX514)

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  • Index of authors

    Page(s): 0_3 - 0_4
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  • Role of signal envelope distribution in predicting the performance of a multicarrier communication system

    Page(s): 245 - 248
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    The peak-to-average power ratio of a signal is often used to determine the output power backoff needed to prevent spectral regrowth due the effects of nonlinear power amplifiers. It has been suggested that a better measure of the impact of a nonlinear amplifier on the transmitted signal is the envelope power distribution function. This paper presents simulation results for a multicarrier communication system showing how the peak-to-average power ratio and the envelope power distribution function change as the number of carriers increases, these results show that the envelope power distribution function is a better figure of merit than the peak-to-average power ratio for determining the impact of a nonlinear power amplifier on a communication system's BER View full abstract»

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  • A channelized DSSS ultra-wideband receiver

    Page(s): 105 - 108
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (312 KB) |  | HTML iconHTML  

    Critical to the design of a digital ultra-wideband (UWB) receiver is the ability for the analog-to-digital converter (ADC) to efficiently sample and digitize the UWB signal of several gigahertz. Designing a single ADC to operate at such frequencies is impractical, and parallel ADC architectures with each ADC operating at a fraction of the effective sampling frequency need to be devised. A parallel receiver architecture that efficiently samples and processes the UWB signal at a fraction of the chip frequency is proposed. The received signal is channelized in the frequency domain by employing a bank of mixers and lowpass filters. After sampling at a much reduced frequency, digital filters then operate directly on the sampled signals in each subband channel to optimally estimate multiple spread codes in parallel View full abstract»

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  • Performance analysis of integrated wireless mobile networks with queueing handoff scheme

    Page(s): 69 - 72
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    We propose and analyze a handoff scheme for integrated real-time and non-real-time service in wireless mobile network. The channels are divided into three parts, one is for real-time service calls, another is for non real-time services calls, and the third part of channels are reserved for overflowed handoff requests, in which some number of channels are reserved exclusively for the real-time service handoff requests. Handoff requests also have their own queues. The system is modeled by a multidimensional Markov chain and the system performance in closed formula are obtained. The scheme is also simulated using extensive runs. Both simulation and analytical results are observed to agree fairly well. In the proposed scheme, forced termination probability of real-time service calls is seen to be significantly decreased. The probability of packet loss of non-real-time transmission is made to be negligibly small, as a non-real-time service handoff request in the queue can be transferred from the queue of the current base station to one of the target base station View full abstract»

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  • Modeling bipolar transistors using multibias S parameter sets

    Page(s): 125 - 128
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    This paper presents a technique for accurate small-signal modeling of microwave bipolar transistors. Model parameters are extracted using measured S parameters in some bias points within the forward active region and then calculated in every point of that region by using a first order interpolation algorithm. The resulting multibias model shows excellent agreement with the measured data over the entire operating region. Moreover, accurate agreement is also achieved with the measured minimum noise figure even though the parameter extraction technique does not make use of noise measurements. Although model parameters are only extracted on measured data at 1 and 5 GHz, scattering parameters are accurately predicted up to 50 GHz, i.e. at a frequency exceeding the transistor FT View full abstract»

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  • Improvement of harmonic responses of a λ/4 resonator BPF with tap-connection technique

    Page(s): 65 - 68
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB) |  | HTML iconHTML  

    Improvement of harmonic responses for a λ/4 resonator bandpass filter (BPF) using a microstrip line (MSL) is carried out. Firstly, a basic mechanism for improving the harmonic responses of the λ/4 resonator under the condition that the excitation procedure is changed. Secondly, a BPF on the basis of our proposal is presented, as an example. It is confirmed that the λ/4 resonator with the tap-connection technique is of great use for improving the harmonic responses of the microwave filters View full abstract»

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  • Linearized InGaP/GaAs HBT MMIC power amplifier with active bias circuit

    Page(s): 249 - 252
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    A linearizer using a base-emitter voltage predistortion of an active bias transistor is demonstrated. It is composed of an active bias transistor, a resistor, two base-emitter diodes for temperature compensation, and a capacitor for RF signal shorting. It compensates effectively both gain compression and phase advance of the power amplifier. Using the linearizer, an InGaP/GaAs HBT MMIC power amplifier is evaluated for W-CDMA application. The linearizer improves input 1 dB compression power by 17 dB and phase distortion by 19.89° for the HPSK modulated signal at the input power of 3 dBm, and doesn't show any significant increase of RF signal loss and chip area. The linearized two-stage HBT MMIC amplifier exhibits power added efficiency of 37%, a linear power gain of 24.5 dB, and an output power of 28 dBm with an ACPR of -44.5 dBc at 5 MHz offset, under a 3 V operation voltage View full abstract»

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  • PAPR reduction by envelope stabilization using partial response signaling in OFDM systems

    Page(s): 197 - 201
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB) |  | HTML iconHTML  

    A technique is proposed to significantly reduce the peak to average power ratio (PAPR) for an OFDM system by stabilizing the signal envelope. By using partial response (PR) signaling to spread each sub-symbol over multiple subcarriers, we first compress the signal in time. The signal is then rearranged such that it is possible to stabilize the envelope, improving the PAPR by up to 5 dB without using excessive time-bandwidth resources. We quantify the improvement in PAPR and system performance in additive white Gaussian noise View full abstract»

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  • Fully integrated low phase noise VCO design in SiGe BiCMOS technology

    Page(s): 109 - 112
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    Fully integrated voltage controlled oscillator (VCO) designs with low phase noise targeted for cellular communication in SiGe (silicon germanium) BiCMOS technology are discussed. The advantages of using IBM SiGe BiCMOS technology for fully integrated VCO designs are addressed in detail. Three fully integrated VCOs for wireless handset applications are reported with design approaches and testing results View full abstract»

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  • Power amplifier back-off analysis with AM-to-PM for millimeter-wave OFDM wireless LAN

    Page(s): 189 - 192
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB) |  | HTML iconHTML  

    With a simple AM-to-PM modeling and system simulation techniques, power amplifier adjacent channel power ratio(ACPR) is calculated for millimeter-wave OFDM wireless LAN. The required amplifier back-off for specified ACPR and the ACPR degradation are predicted for the AM-to-PM nonlinearity. More than 10 dB additional back-off is required if the amplifier has 5° AM-to-PM at the 1.0 dB compression, and the required back-off increases to 1.4 dB as the AM-to-PM increases to 10° compared to the case without phase distortion View full abstract»

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  • Joint spatial and temporal characterization of the wideband wireless communication channel for MIMO applications

    Page(s): 233 - 236
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (352 KB) |  | HTML iconHTML  

    We present a joint study of the spatial and temporal behavior of the wideband wireless channel focussed on the possibility of applying multiple-input multiple-output (MIMO) techniques for achieving extremely high data rates. In particular, we address the time dependence of small-scale spatial variations in the transmitted field resulting from pulse propagation, which could be crucial for such applications. We have performed measurements of the field associated with the propagation of a pulse in a strongly scattering environment over a local area of several wavelengths at slightly different positions of the radiation source, which allowed us to simulate the performance of a multiple-antenna system over a wideband wireless channel. From the data obtained we are able to estimate the "instantaneous" achievable capacity of multiple-antenna systems, which is found to rise to within 5% of the upper theoretical bound. The results obtained for the capacity of wideband MIMO systems are in accord with the observed behavior of the field temporal and spatial autocorrelation functions View full abstract»

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  • Adaptive algorithms for calibrating a LINC amplifier

    Page(s): 241 - 244
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    We describe adaptive signal processing algorithms for balancing the channels in a LINC power amplifier. Each of the two channels used for the signal decomposition in a LINC amplifier contains an adaptive FIR equalizer. These are designed to generate a specific frequency response in each channel, and to match the two channels before the amplified signals are combined. The adaptive algorithms are derived from least-squares cost functions, and they utilize blocks of data collected digitally from various signals in the LINC system View full abstract»

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  • Highly linear low voltage GaAs pHEMT MMIC switches for multimode wireless handset applications

    Page(s): 61 - 64
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB) |  | HTML iconHTML  

    A true 3 V highly linear low loss single pole five throw (SP5T) switch for multimode wireless handset applications is presented. By using advanced Filtronic pHEMT technology with extremely low leakage current and low channel resistance it is possible to achieve very low harmonic levels at maximum GSM power levels (P2ND<-35 dBm at PIN=34.5 dBm) by using four FETs in series and yet still achieve insertion losses of 0.5 dB at 900 MHz. Increasing the number of FETs also allows for 24 dB of isolation to be achieved at 900 MHz View full abstract»

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  • A new class of wide-band microstrip arrays

    Page(s): 211 - 214
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB) |  | HTML iconHTML  

    Wide-band microstrip antennas are still a challenge and a number of new configurations were reported. Most of these configurations are multilayer patch antennas and some of them achieving up to 40% in bandwidth. Another new geometry was reported previously, a single patch fed by a three-dimensional feed line, which in essence is a very tall patch fed by a wide-band dipole. This antenna is reported to exhibit a 90-100% bandwidth in terms of for VSWR<2:1; towards the high end of the band, however, the radiation from the wide-band dipole is too strong and interferes with the patch pattern resulting in a high cross-polarization level. In the array environment, though, the cross-polarization is reduced by the array factor. The paper analyzes the performance of an eight-element array and its scanning capabilities. To avoid grading lobes the radiating elements have to be very close to each other, so the impact of the mutual coupling is also investigated View full abstract»

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  • A proposal of millimeter-wave multi-hop mesh wireless network architecture with adaptive network control features for broadband fixed wireless access

    Page(s): 17 - 20
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB) |  | HTML iconHTML  

    This paper proposed new system architecture and its features for multi-hop mesh wireless networks using millimeter-wave bands for broadband fixed wireless access (BFWA) systems. Adopting the adaptive control of network resources such as communications routes, wireless links and radio channels, the proposed system aimed to overcome the difficulty in the deployment of millimeter-wave broadband wireless access systems. The wireless node architecture and two possible approaches are also discussed for the adaptive control in the proposed mesh wireless network. The quantitative evaluation on the overall performance is performed for the proposed adaptive network control together with the studies on the algorithms for each of the communications routing, the wireless link configuration, and the radio channel controls View full abstract»

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  • W-CDMA even harmonic type direct conversion receiver based on 3GPP definition

    Page(s): 33 - 36
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB) |  | HTML iconHTML  

    This paper is the first demonstration of the validation results on the W-CDMA direct conversion receiver, based on the 3GPP definition. For the receiver, an even harmonic type direct conversion receiver is employed to achieve a high dynamic range. The proposed receiver has unique technical features of high sensitivity and selectivity, because the even order distortion can be suppressed with the monolithic diode pair of the mixer. This paper demonstrates experimental investigations on the receiver characteristics with the RAKE receiver, based on 3GPP specifications. The evaluation results which satisfy the required specifications are described. This paper clarifies the effectiveness of the proposed techniques for the third generation radio terminal View full abstract»

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  • Development of an integrated Bluetooth RF transceiver module using multi-layer system on package technology

    Page(s): 117 - 120
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    We present the development of an integrated Bluetooth transceiver module using a commercial low temperature co-fired ceramic (LTCC) process. The developed module contains a power amplifier (PA), low noise amplifier (LNA), mixer, balun, band select filter and integrated antenna. The MMICs and passives are developed using a commercial 0.24 μm CMOS process and LTCC respectively. The power amplifier is capable of providing an output power of 20 dBm for the Bluetooth class 1 specification. To the best of our knowledge, this work presents the first report of module with integrated antennas View full abstract»

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  • FD-MC-CDMA: a frequency-based multiple access architecture for high performance wireless communication

    Page(s): 169 - 172
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB) |  | HTML iconHTML  

    MC-CDMA demonstrates good probability-of-error performances in frequency selective fading channels, a direct result of its ability to exploit the available frequency diversity benefits. However, MC-CDMA performances are limited by degradation due to large multiple-access interference (MAI). FD-MC-CDMA, a novel multiple access architecture proposed in this paper, exploits the available frequency diversity benefits while minimizing MAI. Instead of transmitting all users' information bits over all carriers, FD-MC-CDMA employs a subset of carriers to support a subset of users (maintaining the same overall system capacity and throughput as in MC-CDMA). By careful selection of each subset of carriers, the available frequency diversity benefits are fully exploited, while the MAI experienced by each user is minimized. Simulation results show FDMC-CDMA outperforming MC-CDMA and FDMA in a frequency selective fading channel View full abstract»

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  • Integrated CMOS power amplifier and down-converter for 2.4 GHz Bluetooth applications

    Page(s): 29 - 32
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB) |  | HTML iconHTML  

    This report presents a 2.4 GHz microwave power amplifier and down-converter, which were fabricated by a standard 0.35 μm 1P4M CMOS process technology. The CMOS power amplifier delivered a 17.5 dBm output power at 2.4 GHz operation, with a maximum power added efficiency of 16%. A CMOS integrated down-converter, including an oscillator and a double-balanced mixer in the 24 GHz band, was also introduced. The oscillator's working frequency is 2.36 GHz with a -3 dBm power level. The measured conversion gain and port-to-port isolation of this double-balanced mixer, were -3 dB and 25 dB, respectively View full abstract»

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  • Achieving directionality and transmit diversity via smart antenna pattern oscillation with a geometric-based stochastic channel model for coherence time evaluation

    Page(s): 223 - 226
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    We develop a smart antenna with a controlled beam pattern oscillation, capable of providing both directionality and transmit diversity. Specifically, the antenna pattern directed toward the mobile user oscillates slightly, resulting in a time varying channel with a specific (small) coherence time: this small coherence time results in an exploitable time diversity. To evaluate the channel coherence time created via the proposed beam pattern oscillation, the time varying channel impulse response is simulated using a geometric-based stochastic channel model (GSCM). Assuming a mid-sized city center, coherence times are shown to correspond to 1/7th the symbol duration, suggesting a 7-fold time diversity is available with the proposed antenna array-in addition to its directionality benefits View full abstract»

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  • Impact of front-end filters on bit error rate performances in WLAN-OFDM transceivers

    Page(s): 193 - 196
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB) |  | HTML iconHTML  

    OFDM-based WLAN standards target wireless communications in the 5 GHz band for consumer multimedia applications. Digital OFDM transceiver ICs based on frequency domain equalization have been presented. However, it is still a challenge to build a complete system including the front-end with minimum degradation of the overall performance. Focussing on the filters in a mixed-signal WLAN-OFDM front-end, careless design will lead to significant degradation of the system performance, even if the filters fulfil the spectral specifications. We developed a efficient model to analyze the impact on system performance of these filters. This model can be used for designing front-end filters with limited and controllable system performance degradation View full abstract»

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  • Wideband printed dipole antenna for multiple wireless services

    Page(s): 153 - 156
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB) |  | HTML iconHTML  

    A coax-fed printed fat dipole backed by a ground plate is presented. The printed dipole with optimum width to length ratio (W/L) of the dipole arm has a wide impedance bandwidth of 75% (VSWR<1.5) and 82% (VSWR<2). This frequency range covers the PCs, IMT-2000, and the ISM band continuously. Antenna parameters for wide bandwidth are investigated and several antenna characteristics are discussed View full abstract»

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  • Dual frequency microstrip patch antenna for WLAN/Bluetooth and HIPERLAN applications

    Page(s): 207 - 209
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (200 KB) |  | HTML iconHTML  

    The subject of this paper is a dual frequency microstrip patch antenna operating at 2.45 GHz and 5.2 GHz ISM (industrial, scientific and medical) band. The IEEE 802.11b WLAN (wireless local area network) and Bluetooth standards utilise the 2.45 GHz band and 5.2 GHz is specified as an operating frequency in HIPERLAN (High PErformance Radio Local Area Network) standard. Antenna design was based on the previously developed dual frequency microstrip patch antenna. Adjustment for the desired frequencies, 2.45 GHz and 5.2 GHz, was achieved by using two different multiplying factors and setting the gaps between the two patches so that the return loss would be under 40 dB. Although the antenna was fabricated of a high-loss FR4 substrate material, it performed well having a matching of 32 dB for the lower and 13 dB for the upper resonant frequency. The bandwidth was over 100 MHz for both of these frequencies. FR4 was chosen as a substrate material for cost savings View full abstract»

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