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Vehicular Technology Conference, 2002. VTC Spring 2002. IEEE 55th

Date 6-9 May 2002

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  • IEEE 55th Vehicular Technology Conference VTC Spring 2002 [front matter]

    Page(s): 0_1 - 0_25
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  • Author's index

    Page(s): 18 - 23
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  • SAMU project: tests and improvement of UMTS for users in a car

    Page(s): 1839 - 1843 vol.4
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    This paper gives an overview of the French collaborative project SAMU, Advanced Services by Mastering UMTS, dedicated to developing enhanced services for users in a car. For that purpose, complementary research domains have been investigated such as radio resource management, IP over UMTS and the use of software agents. While field trials were planned in the project to validate the outputs of the abovementioned research areas over a UMTS experimental network, the general delay encountered by UMTS manufacturers led the project to investigate alternative experimentation. Hence, a UMTS-TDD software radio platform has been built to show IP based telematics applications over UMTS. View full abstract»

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  • Call admission control in hierarchical cell structure

    Page(s): 1955 - 1959 vol.4
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    In interference limited CDMA systems, call admission control plays a very important role because it directly controls the number of users. We introduce a interference-based CAC algorithm according to the characteristics of HCS. This algorithm adopts a global strategy in macro layer, while using a local strategy in the micro layer. Meanwhile, in order to make full use of resources in the macro layer, different threshold values in the two layers are used. Simulation results show that the performance has been greatly improved. View full abstract»

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  • Performance trade-offs of different RAKE receivers

    Page(s): 1665 - 1669 vol.4
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    We determine the effects of different diversity schemes on the behavior of a direct-sequence spread spectrum RAKE receiver which operates with random spreading sequences, in a multipath channel with arbitrary power delay profile. Two different receiver architectures, the former employing the L instantaneously strongest paths out of the Nr resolved ones, and the latter simply the L first paths out of the received Nr, are confronted in terms of symbol error probability, when an M-level PSK system is assumed. The analytical approach devised for assessing such comparison gives the symbol error probability in terms of simple elementary integrals, and immediately evidences the influence on system behavior of the number of resolved paths, bandwidth occupancy of the signal and power delay profile, with a remarkably moderate computational effort. View full abstract»

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  • Adaptive resolution control scheme for RAKE receiver using delay profile conversion technique in DS/CDMA systems

    Page(s): 2033 - 2037 vol.4
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    This paper proposes an adaptive resolution control scheme for a RAKE receiver in direct sequence/code division multiple access (DS/CDMA) systems to effectively resolve and combine multipaths for high-bit-rate wireless multimedia services. In the proposed scheme, the receiver measures a delay profile for the received signal with its resolution equal to the highest chip rate, estimates delay profiles for lower chip rates using a delay profile conversion technique, and selects a chip rate that maximizes the received signal to noise plus interference power ratio (SNIR) under a condition that the number of RAKE fingers is limited by a certain number. Computer simulation confirms that the proposed scheme with a 3-finger RAKE receiver can reduce the average transmit power by about 5 dB without degrading the transmission quality under a 30-ray Rayleigh fading channel. View full abstract»

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  • Space-time coding-assisted double-spread RAKE receiver-based CDMA for dispersive Rayleigh fading environments

    Page(s): 1670 - 1674 vol.4
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    We propose a novel space-time coding-assisted double-spread RAKE receiver (STC-DS-RR) based CDMA scheme for downlink (base to mobile) transmissions over dispersive Rayleigh fading channels. The STC-DS-RR scheme invokes turbo convolutional (TC) channel coding and space-time block coding (STBC) for achieving both time and space diversity gains in addition to the path diversity gain provided by the dispersive Rayleigh fading environments. The double-spreading mechanism of the STC-DS-RR scheme is capable of detecting the wanted user's channel-impaired wideband signals with the aid of a low-complexity RAKE receiver, without resorting to complex multi-user detection. The performance of the proposed scheme was investigated using quadrature-phase-shift-keying (QPSK), when communicating over dispersive channels. It was shown that the wideband scheme advocated is capable of achieving Eb/N0 gains up to 35 dB in comparison to an uncoded narrowband single-transmitter scheme. View full abstract»

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  • Analysis of equal-gain diversity receiver in correlated fading channels

    Page(s): 2038 - 2041 vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (428 KB) |  | HTML iconHTML  

    Performance evaluation of equal-gain combining (EGC) diversity receivers are known to be a much more difficult task in comparison with other diversity combining techniques such as the selection diversity or the maximal-ratio combining method. The difficulty of the above mathematical problem is compounded when the diversity branches are correlated. This paper presents a novel mathematical framework for analyzing a dual-branch EGC receiver performance over nonidentical Rayleigh and Nakagami-m fading channels when the diversity branches are correlated. It is also shown that the average bit error rate (ABER) formula for coherent BPSK and BFSK schemes reduces to the familiar expressions in the literature for the limiting case of independent diversity paths by setting the correlation coefficient to zero. Selected numerical plots that illustrate the effect of branch correction on the ABER performance are also provided. View full abstract»

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  • New sub-optimal detection algorithm of layered space-time code

    Page(s): 1791 - 1794 vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (369 KB) |  | HTML iconHTML  

    As an important space-time code, the layered space-time (LST) code has been studying widely since it was firstly proposed by Foschini in 1996. To exploit its potential, the Bell Lab Layered Space-Time (BLAST) structure of the LST was proposed by Bell Lab. There are two types of BLAST architectures: vertical BLAST (V-BLAST) and diagonally BLAST (D-BLAST). Detection algorithms of V-BLAST were proposed by Golden (see Electronics Letters, vol.35, no.1, 1999). His detection process uses linear combination ing and successive symbol cancellation (SSC) based on inversing and ordering. However, inversing (Moore-Penrose pseudoinverse) and ordering operation for each iteration bring a huge computation complexity. To detect M transmit antenna signals, Golden's detection algorithm needs M inversing and M ordering operations. Aiming at this shortcoming, a new detection algorithm for layered space-time code is proposed. This new sub-optimal detection algorithm is based on Greville inversing process, with two inversing and one ordering process. Simulation results show us the proposed sub-optimal scheme still has a good BER performance. View full abstract»

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  • Employment of a multipath receiver structure in a combined GALILEO/UMTS receiver

    Page(s): 1844 - 1848 vol.4
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    Current navigation systems like GPS (Global Positioning System) and its Russian counterpart GLONASS (Global Navigation Satellite System) only evaluate the direct signal path. The receivers treat the reflected paths also reaching the receiver antenna as disturbance which has to be suppressed. Multipath affects the tracking accuracy by resulting in a degeneration of the S-curve of the DLL (delay locked loop). Nowadays the future European systems GALILEO and GPSIIF/III with two new signals are on the way to the market and it is time to think about new receiver structures. Therefore we investigated if it is possible to use multipath for navigation constructively. View full abstract»

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  • An adaptive modulation algorithm for multicarrier DS/CDMA systems

    Page(s): 1873 - 1876 vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB) |  | HTML iconHTML  

    An adaptive modulation algorithm is proposed in this paper to improve the performance of the multicarrier DS/CDMA system where no frequency diversity is available and no bandwidth efficiency loss meanwhile. In our algorithm only repetitive comparison operation is need to accomplish the allocation work, and no repetitive division operation needed; this feature makes it very appropriate for engineering implementation. Simulation results demonstrate that great performance improvement can be achieved in this adaptive modulated system. View full abstract»

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  • Equivalent consumption minimization strategy for parallel hybrid powertrains

    Page(s): 2076 - 2081 vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (535 KB) |  | HTML iconHTML  

    Hybrid vehicles use at least two energy sources for their propelling. Usually an electric motor is used with an IC engine. Hybrid vehicles are expected to be less polluting and to have a lower fuel consumption than conventional vehicles. This paper presents an algorithm which chooses the power split between the motor and the engine in order to minimize the fuel consumption. First of all, the prototype built at the LAMIH is presented, then the equivalent consumption minimization strategy is described. First results show that a 17.5% of fuel reduction can be achieved for the CEN speed cycle. View full abstract»

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  • Iterative detection for space-time coded synchronous CDMA communication systems

    Page(s): 2013 - 2017 vol.4
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    An iterative receiver is proposed for the downlink of CDMA communication systems that employ both a convolutional channel code and a space-time trellis code to achieve transmit diversity in the presence of channel fading. The proposed iterative receiver operates by exchanging extrinsic information between the channel and space-time decoders in each iteration. Comparison of performance results, obtained via simulations, with a similar system using Alamouti space-time codes (space-time block codes) shows that the proposed turbo decoder outperforms a concatenated system consisting of channel and Alamouti codes and that the performance gap increases with fast fading. View full abstract»

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  • Security equipment in ad hoc networks

    Page(s): 1819 - 1823 vol.4
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    Due to the inherent quality of wireless mobile networks and the lack of center control units, the security is always a weak point for ad hoc networks. We propose a new concept, that is, the security equipment in ad hoc networks. We consider that a user can use an infrastructure ad hoc without completely putting his resources to the network. He can become invisible at the routing level without loss his abilities of receiving and sending. Thus he well be protected at the equipment level. View full abstract»

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  • A new scalable decoder for linear space-time block codes with intersymbol interference

    Page(s): 1795 - 1799 vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (447 KB) |  | HTML iconHTML  

    Space-time codes represent a key technology for future broadband wireless communication systems. A class of space-time block codes according to Wittneben and Kuhn (see VTC 2002 - Spring) is used which can lead to intersymbol interference (ISI) due to an optimized diversity performance. Therefore ISI compensation is an important task of the decoding process of these codes. Several known ISI compensation methods can be applied for example MMSE equalization or parallel or serial ISI cancellation. In this paper a new scalable ISI cancellation method is presented, that by using a posteriori information achieves almost the performance of the maximum likelihood decoder but with a much lower complexity. The key idea is to use estimated a posteriori probabilities to determine the order of the cancellation process. In each iteration the decoder jointly decodes a variable number of symbols, which meet a specified probability threshold. By varying the threshold, the decoder is scalable in such a way that the complexity of the decoder - and consequently the available data flow rate - can be adapted in a wide range to the requests of the transmission, to a given node complexity or a required quality of service. View full abstract»

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  • Basic access network assisted IP mobility and AAA in MIRAI architecture

    Page(s): 1660 - 1664 vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (661 KB) |  | HTML iconHTML  

    A novel architecture for future integrated wireless network is proposed in MIRAI (Multimedia Integrated network by Radio Access Innovation) where a dedicated network takes care of the mobility functionalities of the participant wireless networks in the integration. The dedicated network, called basic access network (BAN) is used for paging whenever a call arrives for the mobile user for any of the wireless interfaces of the user's multiservice terminal. We analyze a scheme for using the BAN channel, and associated network to aid the AAA (authentication, authorization and accounting) and IP mobility functionalities of the integrated network environment in a seamless fashion. View full abstract»

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  • A time-scale decomposition approach for efficient wireless resource utilization with minimum performance guarantees

    Page(s): 1613 - 1617 vol.4
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    Wireless channels are error-prone and susceptible to several kinds of interference from different time scales, causing difficulties in the support of real-time multimedia services. This paper investigates the resource optimization and scheduling of wireless networks through a time-scale decomposition approach. We decompose the dynamics of time-varying wireless channel conditions into random processes in two different time scales and deal with the two time scales by two different algorithms: the resource optimizer optimizes the sum of utilities in the slowly changing time scale, and the slot scheduler exploits the efficiency in the highly variable time scale. Our scheme can obtain high system utilization and provide a minimum service guarantee simultaneously. Simulation results show that our scheme can improve substantially the performance and efficiency. View full abstract»

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  • A recursive filtering technique for mobile terminal positioning in dynamic satellite systems

    Page(s): 1849 - 1853 vol.4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (541 KB) |  | HTML iconHTML  

    User position information is an important factor for achieving efficient operation of global wireless networks. An accurate estimation of the mobile terminal (MT) location cannot be obtained if the radio signals are corrupted by noise or other sources of signal degradation. As a consequence, processing algorithms capable of generating a single point of interception from many noisy samples need to be implemented. Simulation results presented in this paper demonstrate that a simple and computational efficient recursive filtering technique is effective in reducing the uncertainty introduced by measurement noise in the user location estimate produced by CDMA-based dynamic satellite systems. View full abstract»

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  • A cumulant-based beamforming for synchronous CDMA system with decorrelator

    Page(s): 1761 - 1765 vol.4
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    In this paper a cumulant-based beamforming technique for synchronous CDMA system with decorrelator is presented. With a decorrelating detector the proposed algorithm has the advantages that the steering vector of desired user's can be estimated independently by eliminating all the other resolved signal interferences. Furthermore employing a cumulant-based signal processing technique the steering vector of the decoupled signals can be estimated blindly. Simulation results show that the cumulant-based beamformer demonstrates excellent performance. View full abstract»

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  • Blind source separation with space-time analytical constant modulus algorithm in DS-CDMA systems

    Page(s): 1877 - 1880 vol.4
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    The constant modulus property of communication signals, such as FM and phase-modulated signals, are often used in blind separation of multiple users. Because there is no training sequence needed, the system transmission efficiency is increased. However the CMA suffers from the complex iteration computation and local minimums. The analytical constant modulus algorithm (ACMA) replaces the problem of finding the weight vector blindly with the equivalent problem of blind source separation in signal subspace. Via joint diagonalization of matrices, each user's signal can be obtained analytically. Expanding the ACMA of space domain beamforming to space-time domain can improve the performance of blind signal separation of the system. The computation complexity of ST-ACMA is only related to the amount of constant modulus sources. Its performance is similar to ST-CMA algorithm, but it has less computation than ST-CMA and the faster convergence rate. Finally, numerical simulations can illustrate the effectiveness of this algorithm. View full abstract»

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  • DEAR: an extension of traffic engineering for routing and resource management in ad hoc wireless networks

    Page(s): 1603 - 1607 vol.4
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    We propose differentiated engineered adaptable routing (DEAR) for quality-of-service (QoS) routing in ad hoc mobile wireless networks. In DEAR, traffic is engineered for both its locations (as in conventional traffic engineering) and its amount according to the proposed demand-engineered QoS routing. Moreover, QoS is provisioned in a differentiated manner through the proposed differentiated QoS routing, and is adaptable to traffic and network conditions through the proposed adaptable QoS routing. DEAR is generally applicable to previous routing paradigms and QoS routing algorithms based on on-demand, table-driven, or localized routing. We also develop DEAR STAR (selective table-driven ad hoc routing) and DEAR POWER (power-aware on-demand wireless embedded routing) to enable QoS-guaranteed and power-aware routing in ad hoc networks by utilizing stationary wireless stations and/or through dynamic maintenance of virtual stationary nodes. Finally, we apply backward learning to QoS routing in ad hoc networks. View full abstract»

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  • A RAKE-DFSE equalizer for the UMTS downlink

    Page(s): 1626 - 1630 vol.4
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    The UMTS radio interface based on CDMA, has been designed to offer a wide range of data rates using variable spreading factor. It is ongoing standardization effort to include a high data rate packet mode in the downlink direction. This new mode is called high speed downlink packet access (HS-DPA) and is characterized by the giving up of closed loop power control, link adaptation using variable constellations (QPSK, MAQ16,MAQ64), and low spreading factor. The proposed receiver is particularly adapted to HSDPA mode has it gives close to optimal performance even in the case of high modulation order and low spreading factor while keeping a reasonable complexity. View full abstract»

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  • Optimal control of a parallel powertrain: from global optimization to real time control strategy

    Page(s): 2082 - 2088 vol.4
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    This paper focuses on optimal control theory applied to parallel hybrid vehicles. For simulation purpose, a global optimization algorithm has been developed allowing one to obtain optimal consumption on a given driving cycle. In comparison with other global optimization methods, the proposed one has two main advantages: its quickness and the possibility to derive a real time control strategy. A first trial in that sense is done in this paper and compared with another real time strategy. View full abstract»

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