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Vehicular Technology, IEEE Transactions on

Issue 3 • Date May 2008

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Displaying Results 1 - 25 of 69
  • Table of contents

    Page(s): C1 - C4
    Save to Project icon | Request Permissions | PDF file iconPDF (58 KB)  
    Freely Available from IEEE
  • IEEE Transactions on Vehicular Technology publication information

    Page(s): C2
    Save to Project icon | Request Permissions | PDF file iconPDF (39 KB)  
    Freely Available from IEEE
  • Fading Channel Modeling via Variable-Length Markov Chain Technique

    Page(s): 1338 - 1358
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1796 KB) |  | HTML iconHTML  

    Channel characterization and modeling are essential to the wireless communication system design. A model that optimally represents a fading channel with a variable-length Markov chain (VLMC) is proposed in this paper. A VLMC offers a general class of Markov chains whose structure has a variable order and a parsimonious number of transition probabilities. The proposed model consists of two main components: 1) the optimal fading partition under the constraint of a transmission policy and 2) the derivation of the best VLMC representation with respect to the Kullback-Leibler (K-L) distance of fading samples. The fading partition is used to discretize a continuous fading channel gain. The optimal discretization criterion is developed based on the cost function of fading channel statistics and the transmission policy used in the system. Once a continuous fading channel gain is discretized, a VLMC is then used to model the channel. To obtain the optimal VLMC representation, we use the K-L distance of the discretized fading samples as the optimization criterion. The K-L distance of the discretized fading samples is used to determine the appropriate transition probabilities characterizing the optimal VLMC. Last, we show simulation results that demonstrate the accuracy and the effectiveness of the proposed fading channel representation in modeling the Rayleigh fading as well as the lognormal fading. View full abstract»

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  • Statistical Analysis of UWB Channel Correlation Functions

    Page(s): 1359 - 1373
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1889 KB) |  | HTML iconHTML  

    Various performance metrics of impulse-radio (IR) ultrawideband (UWB) receivers are closely connected to the correlation functions of the multipath channel responses to UWB pulses. Interpulse interference is related to the autocorrelation function (ACF) of the received pulse (RP), the RP energy and its fading correspond to the ACF at zero lag, and multiple access interference is connected to the cross-correlation function (CCF) between two channel pulse responses. Each realization of the multipath channel shows different correlation functions due to the ldquorandomnessrdquo of the UWB propagation environment. This paper derives the first- and second-order statistics of the ACF and CCF, capturing this randomness. Such results are useful for incorporating the multipath channel into the performance and design optimization studies of UWB systems. The analysis is based on a model of the received UWB pulse. The model describes the random channel response by two continuous functions of the excess delay time-one expresses the power, the other expresses power variations-and by a prototype pulse shape representing all linear system components including the band limitation of the RP and antenna effects. The analytical results are validated through the analysis of simulated and measured channel responses. View full abstract»

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  • Outdoor-to-Indoor Office MIMO Measurements and Analysis at 5.2 GHz

    Page(s): 1374 - 1386
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1057 KB) |  | HTML iconHTML  

    The outdoor-to-indoor wireless propagation channel is of interest for cellular and wireless local area network applications. This paper presents the measurement results and analysis based on our multiple-input-multiple-output (MIMO) measurement campaign, which is one of the first to characterize the outdoor-to-indoor channel. The measurements were performed at 5.2 GHz; the receiver was placed indoors at 53 different locations in an office building, and the transmitter was placed at three "base station" positions on a nearby rooftop. We report on the root-mean-square (RMS) angular spread, building penetration, and other statistical parameters that characterize the channel. Our analysis is focused on three MIMO channel assumptions often used in stochastic models. 1) It is commonly assumed that the channel matrix can be represented as a sum of a line-of-sight (LOS) contribution and a zero-mean complex Gaussian distribution. Our investigation shows that this model does not adequately represent our measurement data. 2) It is often assumed that the Rician if-factor is equal to the power ratio of the LOS component and the other multipath components (MPCs). We show that this is not the case, and we highlight the difference between the Rician if-factor often associated with LOS channels and a similar power ratio for the estimated LOS MPC. 3) A widespread assumption is that the full correlation matrix of the channel can be decomposed into a Kronecker product of the correlation matrices at the transmit and receive array. Our investigations show that the direction-of-arrival (DOA) spectrum noticeably depends on the direction-of-departure (DOD); therefore, the Kronecker model is not applicable, and models with less-restrictive assumptions on the channel, e.g., the Weichselberger model or the full correlation model, should be used. View full abstract»

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  • Analysis and Architecture Design of a Downlink M -Modification MC-CDMA System Using the Tomlinson–Harashima Precoding Technique

    Page(s): 1387 - 1397
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1535 KB) |  | HTML iconHTML  

    This paper investigates the feasibility of applying Tomlinson-Harashima precoding (THP) to multicarrier code-division multiple-access (MC-CDMA) system downlinks, in which multiple-access interference and possible complexity in the mobile terminal (MT) are major burdens. A THP based on the minimum mean-square error (MMSE) criterion is also presented, making it possible to realize a low-complexity receiver at the MT. The hardware architecture of the MMSE THP with modified QR decomposition at the transmitter is presented, along with the required word length analyzed. Pipeline and parallel schemes are adopted to reduce the execution time. For a generic square matrix of order for RQ decomposition, the required latency is time units, which is based on the modified Gram-Schmidt algorithm. View full abstract»

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  • Design of a Shape-Constrained Dual-Band Polygonal Monopole for Car Roof Mounting

    Page(s): 1398 - 1403
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (624 KB) |  | HTML iconHTML  

    This paper describes the design of a new compact dual-band roof antenna (which is capable of operating in both U.S. and European mobile telephone bands) for automotive applications. The flipper shape of the antenna and its dimensional constrains are chosen according to prevailing automotive market trends. The chosen basic geometry of the radiating element is a planar printed monopole structured as a vertical fan with two narrow strips folding toward the ground plane and etched on a low-cost, medium-permittivity thin substrate. The geometrical variations of the basic radiating structure are introduced afterward to constrain the antenna shape under the assigned profile and to allow easy integration of a small Global Positioning System patch antenna without affecting radiation and bandwidth performances. The integration of a matching network directly over the etched monopole trace allows a good input matching over the lower and upper operative bands to be obtained, slightly affecting the radiation efficiency of the whole antenna. View full abstract»

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  • A Simulation Tool to Predict the Impact of Soil Topologies on Coupling Between a Light Rail System and Buried Third-Party Infrastructure

    Page(s): 1404 - 1416
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1806 KB) |  | HTML iconHTML  

    The production of stray currents by DC light rail systems leads to the corrosion of the supporting and third-party infrastructure in close proximity to the rail system. This paper simulates two parallel tracks that are occupied by two trains: one on each track. This type of modeling constitutes a case study that is utilized to investigate the effect of soil topologies on the corrosion performance of a floating DC light rail system focusing on the supporting and third-party infrastructure. The modeling technique used involves the accurate computation of the shunt and series parameters for use in a resistive-type model using a commercially available software package. The results demonstrate the importance that soil resistivity has on the corrosion risk to traction system and third-party infrastructure. Such information could ultimately be used to vary the level of stray current protection across a light rail system to ensure a consistent lifetime across the whole system. View full abstract»

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  • License Plate Localization and Character Segmentation With Feedback Self-Learning and Hybrid Binarization Techniques

    Page(s): 1417 - 1424
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (689 KB) |  | HTML iconHTML  

    License plate localization (LPL) and character segmentation (CS) play key roles in the license plate (LP) recognition system. In this paper, we dedicate ourselves to these two issues. In LPL, histogram equalization is employed to solve the low-contrast and dynamic-range problems; the texture properties, e.g., aspect ratio, and color similarity are used to locate the LP; and the Hough transform is adopted to correct the rotation problem. In CS, the hybrid binarization technique is proposed to effectively segment the characters in the dirt LP. The feedback self-learning procedure is also employed to adjust the parameters in the system. As documented in the experiments, good localization and segmentation results are achieved with the proposed algorithms. View full abstract»

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  • Battery Management System Based on Battery Nonlinear Dynamics Modeling

    Page(s): 1425 - 1432
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (937 KB) |  | HTML iconHTML  

    This paper presents a method of determining electromotive force and battery internal resistance as time functions, which are depicted as functions of state of charge (SOC) because . The model is based on battery discharge and charge characteristics under different constant currents that are tested by a laboratory experiment. This paper further presents the method of determining the battery SOC according to a battery modeling result. The influence of temperature on battery performance is analyzed according to laboratory-tested data, and the theoretical background for calculating the SOC is obtained. The algorithm of battery SOC indication is depicted in detail. The algorithm of the battery SOC ldquoonlinerdquo indication considering the influence of temperature can be easily used in practice by a microprocessor. An NiMH battery is used in this paper to depict the modeling method. In fact, the method can also be used for different types of contemporary batteries, as well as Li-ion batteries, if the required test data are available. View full abstract»

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  • A General Approach to Energy Optimization of Hybrid Electric Vehicles

    Page(s): 1433 - 1441
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (582 KB) |  | HTML iconHTML  

    This paper approaches the problem of optimizing energy consumption onboard hybrid vehicles in a general way, considering the main issues to be solved in their conceptuality and, therefore, that are often abstracted from the actual structure of the particular drive train that the authors considered. The methods that were described are a harmonization of those used by the authors over the last several years; therefore, although being rather general, they are far from describing the state of the art of scientific literature on this topic. Both parallel and series structures are covered; for either structure, the effect of different functions on management strategies (e.g., pure-electric drive and plug-in recharge capabilities) are discussed. Some more details are supplied in the Case Studies section of this paper, where some of the authors' past experiences are reconsidered in terms of the general approach proposed in this paper. View full abstract»

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  • Efficient Drive Cycle Simulation

    Page(s): 1442 - 1453
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (717 KB) |  | HTML iconHTML  

    Drive cycle simulations of longitudinal vehicle models are important aids for the design and analysis of power trains, and tools currently on the market mainly use two different methods for such simulations: the forward dynamic and quasi-static inverse simulations. Here, a known theory for the stable inversion of nonlinear systems is used to combine the fast simulation times of the quasi-static inverse simulation with the ability of the forward dynamic simulation to include transient dynamics. The stable inversion technique and a new implicit driver model together form a new concept: inverse dynamic simulation. This technique is demonstrated to be feasible for vehicle propulsion simulation and specifically for three power train applications that include important dynamics that cannot be handled using quasi-static inverse simulation. The extensions are engine dynamics, driveline dynamics, and gas flow dynamics for diesel engines, which are also selected to represent important properties, such as zero dynamics, resonances, and nonminimum-phase systems. It is shown that inverse dynamic simulation is easy to set up, gives short simulation times, and gives consistent results for design space exploration. This makes inverse dynamic simulation a suitable method to use for drive cycle simulation, particularly in situations requiring many simulations, such as optimization over design space, power train configuration optimization, or the development of power train control strategies. View full abstract»

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  • An Integrated Starter–Alternator and Low-Cost High-Performance Drive for Vehicular Applications

    Page(s): 1454 - 1465
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1520 KB) |  | HTML iconHTML  

    This paper designs and implements an electromechanical propulsion system for a 42-V battery-sourced integrated starter-alternator (ISA) using an indirect-field-oriented (IFO) controller with a speed sensor on the shaft of the machine. The design aspects of the ISA energy conversion system are discussed, with emphasis on the motor selection and comparison of various candidate machines, power electronics, motor controller development and its integration with the engine controller, and a strategy for charging and discharging the energy source. A boost converter powered by the 42-V battery charges three 1-F ultracapacitors to 300 V, thus running the motor drive system at 300 V. The designed 300-V motor drive system is compared with the 42-V drive system directly powered by the 42-V battery. To improve the performance of the propulsion system, two modifications are proposed in this paper. First, terminal-quantities-based accurate voltage and current model flux observers (CMFOs) are designed, which can be used for any off-the-shelf machine. Second, a current model flux-observer-based sensorless controller is presented, which eliminates the need for the speed sensor on the rotor shaft, thus reducing the cost as well as the maintenance of the drive system. The proposed terminal-quantities-based flux observers and sensorless controller form the core of direct and IFO controllers commonly used in any alternative energy vehicular application including the ISA. The designed voltage model flux observer is insensitive to the stator resistance, and the CMFO is insensitive to the rotor resistance and speed, thus overcoming the long-standing problems in the area of flux observer design. The experimental results obtained while driving the vehicle are presented to demonstrate the effectiveness of the prototype ISA and to investigate its performance requirements as a sensorless drive system. Finally, the performance of the proposed flux observers and sensorless controller is evaluated - - through experimental results on a prototype induction machine to evaluate their potential for implementing a sensorless ISA drive system. View full abstract»

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  • Design and Implementation of Subspace-Based Speech Enhancement Under In-Car Noisy Environments

    Page(s): 1466 - 1479
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2165 KB) |  | HTML iconHTML  

    In this paper, a new subspace-based speech enhancement model is presented for in-car speech enhancement. To effectively suppress background noise, this model incorporates a perceptual filterbank and an auditory gain adaptation derived from a psychoacoustic model into a signal subspace approach. The projection approximation subspace tracking deflation (PASTd) algorithm is used to track the signal subspace. For real-time processing, a system-on-a-programmable-chip architecture and a very large scale integration design of the PASTd algorithm are proposed. To realize a pipeline computation, this paper presents a pipelined PASTd architecture without data-dependent hazards. The maximum clock rate is 9.7 MHz, and the typical clock rate, which achieves the real-time requirement, is 4.6 MHz. The corresponding architecture was experimentally verified via an ALTERA EPXA10 development board. View full abstract»

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  • Performance Analysis of Multiuser DS-CDMA in MIMO Systems Over Rayleigh Fading Channels

    Page(s): 1480 - 1493
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (651 KB) |  | HTML iconHTML  

    The performance of space-time transmit diversity is examined in a multiuser direct-sequence code-division multiple-access (DS-CDMA) system over fast- and slow-fading channels. The underlying space-time system employs transmit antennas and receive antennas at the mobile user and receiver base station, respectively. We consider the performance of the space-time multiuser system when using the linear decorrelator detector to combat the effect of multiuser interference. In our analysis, we derive a closed-form expression for the probability of bit error for both fast- and slow-fading channels. These theoretical results are shown to be very accurate when compared to system simulations. Both simulations and theoretical results prove that, regardless of the system load, the full diversity order of for fast-fading channels and for slow-fading channels is always maintained, and only a signal-to-noise ratio (SNR) loss is incurred. This SNR loss is proved to be a function of only the number of users (i.e., level of interference) and independent of the number of transmit and/or receive antennas. Using our theoretical results, we show that the loss in SNR from the single-user bound can be well approximated by , where represents the level of multiuser interference. View full abstract»

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  • Adaptive Subcarrier Allocation in Synchronous Reverse Links of a Multicarrier CDMA System with Time and Frequency Spreading

    Page(s): 1494 - 1501
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (722 KB) |  | HTML iconHTML  

    Multicarrier code-division multiple access (CDMA) with time and frequency spreading has been recently considered as a candidate for fourth-generation (4G) wireless systems. This signaling scheme simultaneously utilizes code spreading in the time and frequency domains to simultaneously improve frequency diversity and minimize multiuser access interference. As a result, it is capable of outperforming multicarrier CDMA systems that employ 1-D spreading. In this paper, a novel adaptive subcarrier allocation algorithm is developed for multicarrier CDMA with time and frequency spreading to improve the overall bit error rate (BER) performance for all spreading configurations. This algorithm assigns users to subcarrier groups that provide favorable fading characteristics while simultaneously reducing the amount of interference caused to other users. The proposed algorithm is shown to provide a performance improvement, ranging from 1.5 dB with 2times16 (time times frequency) and spreading to 7 dB with 16times2 (time times frequency) spreading. The algorithm is also shown to maintain or improve the BER floor for each spreading configuration. It is concluded that at higher and lower levels of Eb/No, a higher frequency- and time-domain spreading should be, respectively, employed to improve BER performance. Furthermore, the Eb/No threshold level to switch between time and frequency spreading for the analyzed system is found to be 2.5 dB. View full abstract»

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  • Exact Outage Probability Analysis for a Multiuser MIMO Wireless Communication System With Space–Time Block Coding

    Page(s): 1502 - 1512
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1124 KB) |  | HTML iconHTML  

    A multiuser multiple-input-multiple-output (MIMO) system with orthogonal space-time block coding (OSTBC) is analyzed for the uplink of a wireless communication system in a Rayleigh fading environment. In the first part of this paper, a simple and exact closed-form expression for the outage probability of the signal-to-interference-and-noise ratio (SINR) is derived at the input of the base station (BS) receiver by making the following two assumptions: 1) All the users transmit their data by using the same OSTBC; and 2) the users are power controlled by the same BS so that the interfering users are requested to transmit with the same power. In the second part of this contribution, the outage probability of the signal-to-interference ratio (SIR) is calculated at the output of the BS receiver, which, in our case, is a spatial matched filter. To be able to analytically solve the latter problem, the presented analysis is restricted to the case of a single interferer and a 2 2 MIMO system with Alamouti coding. Monte Carlo simulations are carried out to verify the proposed analytical expressions for the outage probability. View full abstract»

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  • Effects of Subcarrier Power Allocation on an Interference Avoidance Code Assignment Strategy for Multirate MC-DS-CDMA Systems

    Page(s): 1513 - 1526
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (669 KB) |  | HTML iconHTML  

    In this paper, we propose a joint subcarrier power allocation (SPA) and code assignment scheme for the synchronous multirate multicarrier direct-sequence code-division multiple-access (MC-DS-CDMA) system with time- and frequency-domain spreadings. Based on the newly defined metric multiple-access interference (MAI) coefficient, the proposed code assignment strategy can quantitatively predict the incurred MAI before assigning a spreading code. The SPA mechanism aims to maximize the received signal power. In addition to lowering the MAI, the proposed code assignment strategy further considers the compactness of the assigned codes in the entire 2-D tree structure. The simulation results show that the proposed joint SPA and code assignment strategy not only can reach a better received signal quality but can also achieve a high call admission rate. View full abstract»

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  • UWB Direct Chaotic Communication Technology for Low-Rate WPAN Applications

    Page(s): 1527 - 1536
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (715 KB) |  | HTML iconHTML  

    The goal of this paper is to describe the design of an ultrawideband (UWB) system that is optimized for low-complexity, low-power, low-cost, and low-rate wireless personal area network applications. To this aim, we propose a system based on novel direct chaotic communication (DCC) technology, in which a 2-GHz-wide chaotic signal is directly generated into the lower band of the UWB spectrum. Based on this system, two simple modulation schemes, namely, chaotic on-off keying and differential chaos-shift keying, are studied, and the performance of both noncoherent and differential-coherent transceiver architectures is evaluated. Various system design parameters and tradeoffs are discussed throughout the paper, including frequency band plans, data throughput, and system scalability. In particular, the frequency-division multiplexing technique is proposed as a low-cost alternative to achieving simultaneous operating piconets for short-distance applications. The average power consumption for various operating data rates and the technical feasibility of implementing the DCC system as a low-cost integrated circuit are also addressed. Finally, Monte Carlo simulations are performed based on the IEEE 802.15.4a standard channel models to evaluate the performance of the two modulation schemes. In general, both schemes experience little degradation under multipath environments due to the self-inherent wideband characteristic of the chaotic signal. View full abstract»

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  • Constrained Detection for Spatial-Multiplexing Multiple-Input–Multiple-Output Systems

    Page(s): 1537 - 1547
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (485 KB) |  | HTML iconHTML  

    A family of detectors that exploit signal constraints is developed for maximum-likelihood detection for multiple-input-multiple-output (MIMO) systems. Real constrained detectors and decision-feedback detectors are proposed for real constellations by forcing the relaxed solution to be real. A generalized minimum mean square error (GMMSE) and constrained least squares MIMO detectors are also developed for unitary and nonunitary signal constellations. Using these constrained detectors, we propose a new ordering scheme to achieve a tradeoff between interference suppression and noise enhancement. Moreover, to mitigate the inherent error propagation, the decision-feedback MIMO detectors are integrated with signal constraints. The simulation results show that our combined detector achieves a significant performance gain over vertical Bell Laboratories layered space-time (V-BLAST) detection. View full abstract»

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  • Performance Analysis of Transmitter-Side Cooperation–Receiver-Side-Relaying Schemes for Heterogeneous Sensor Networks

    Page(s): 1548 - 1563
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (557 KB) |  | HTML iconHTML  

    In this paper, we present two physical layer cooperative protocols for heterogeneous sensor networks. There is one cooperator near the transmitter and a second cooperator (as a relay) near the receiver. Although the focus is on heterogeneous sensor networks, the methods can be applied to homogeneous sensor networks as well. Analytical and simulation results show that, under an additive white Gaussian noise channel assumption for the links between the transmitter and its partner and between the receiver and its partner, the proposed protocols achieve a diversity order of three or four by using the amplify-and-forward cooperation strategy and maximal ratio combining in the receiver. In addition, the proposed methods outperform the noncooperative single-hop transmission in the clustered heterogeneous sensor network and save a considerable amount of energy relative to the noncooperative transmission. View full abstract»

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  • Analytical Framework for Optimal Combining With Arbitrary-Power Interferers and Thermal Noise

    Page(s): 1564 - 1575
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1768 KB) |  | HTML iconHTML  

    The performance of multiple-input-multiple-output systems with optimum combining (OC) is studied in a Rayleigh fading environment with arbitrary-power cochannel interference and thermal noise. Based on the joint eigenvalue distributions of quadratic functions of complex Gaussian matrices, a closed-form expression for the exact distribution of the output signal-to-interference-plus-noise ratio (SINR) is derived. A closed-form expression for the exact moment-generating function (MGF) of the output SINR of single-input-multiple-output (SIMO) systems is also derived. From the exact MGF, the moments of the output SINR and the symbol error rate of various M-ary modulation schemes are obtained. We verify the accuracy of our analytical results with numerical examples. The new analytical framework provides a simple and accurate way to assess the effects of equal- and unequal-power cochannel interferers and thermal noise on the performance of OC. View full abstract»

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  • Breadth-First Signal Decoder: A Novel Maximum-Likelihood Scheme for Multi-Input–Multi-Output Systems

    Page(s): 1576 - 1584
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB) |  | HTML iconHTML  

    A number of decoding schemes have recently been proposed to perform maximum-likelihood (ML) detection for multi-input-multi-output (MIMO) systems. In this paper, employing a ldquobreadth-firstrdquo search algorithm for closet points in a lattice, we propose a novel ML decoding scheme called the breadth-first signal decoder (BSIDE). Through analysis and computer simulations, it is shown that the BSIDE has the same bit-error-rate performance as the conventional ML decoders while allowing significantly lower computational complexity. In addition, we introduce a simple tuning scheme that allows the BSIDE to have a performance-complexity tradeoff capability as necessary. View full abstract»

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  • MIMO Channel Estimation and Tracking Based on Polynomial Prediction With Application to Equalization

    Page(s): 1585 - 1595
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1125 KB) |  | HTML iconHTML  

    This paper presents a multiple-input-multiple-output (MIMO) receiver design with integrated channel estimation and tracking for a time-varying frequency-selective Rician or Rayleigh fading environment. It first extends a polynomial-predictor-based channel estimation and tracking approach to a MIMO system. The structure and complexity of the estimator are similar to that of an optimum estimator using a Kalman filter, but it does not require a priori knowledge of the channel statistics. It employs a fixed-state transition matrix using precomputed polynomial coefficients and can be used in a Rician fading environment without reconfiguration. It is integrated with a MIMO minimum-mean-squared-error decision feedback equalizer, and simulation results show that the system performance using the estimator can be made comparable to that employing a Kalman estimator under a broad range of channel conditions. View full abstract»

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  • A Communication System Based on Walsh–Hadamard Codes and Constellations for Fading Environments

    Page(s): 1596 - 1605
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (655 KB) |  | HTML iconHTML  

    In this paper, we investigate a new digital communication system based on Walsh-Hadamard codes. The modulator maps a uniformly distributed binary source to a set of symbols with a Gaussian-like distribution. These symbols are then mapped to a 2-D constellation in such a way that performance is improved when transmission occurs over Rayleigh fading channels. We assess the performance of these modulation schemes when the channel is of the nonfrequency-selective Rayleigh fading plus white Gaussian noise type and compare the results to conventional quadrature-amplitude modulation (QAM) schemes with comparable spectral efficiencies. The proposed system provides excellent robustness to fading without the use of common diversity schemes employed in M-ary signaling systems to improve bit-error-rate (BER) performance in such environments. View full abstract»

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Aims & Scope

IEEE Transactions on Vehicular Technology covers land, airborne, and maritime mobile services, vehicular electrotechnology, equipment, and systems identified with the automotive industry.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Yuguang Michael Fang
University of Florida