The Experts below are selected from a list of 36618 Experts worldwide ranked by ideXlab platform

Ye Li - One of the best experts on this subject based on the ideXlab platform.

  • Iterative and Diversity Techniques for Uplink MC-CDMA Mobile Systems With Full Load
    IEEE Transactions on Vehicular Technology, 2008
    Co-Authors: Y. Yuan, Ye Li
    Abstract:

    Iterative and diversity techniques are two of the most effective techniques for uplink multicarrier code-division multiple-access (MC-CDMA) systems. However, there is still no knowledge on how to efficiently combine these techniques to design high-performance uplink Receivers when there is a complexity constraint. In this paper, we compare the performance and the complexity of MC-CDMA systems with and without iterative detectors and multiple-receive-Antenna arrays. Through extensive simulation, we demonstrate that the following four combinations are good tradeoffs between complexity and performance: a single-Antenna Receiver with an iterative parallel-interference-cancellation (PIC) detector initialized by a matched filter (MF) with three iterations, a two-Antenna Receiver with a minimum-mean-square-error multiuser detector or an iterative PIC detector initialized by an MF with two iterations, and a four-Antenna Receiver with a simple MF detector. Therefore, noniterative detectors with multiple-receive-Antenna arrays can be used to replace iterative detectors and reduce complexity, which is a promising solution for fourth-generation (4G) uplink MC-CDMA systems, where multiple-receive Antennas are available at the base stations. In this paper, we also briefly discuss pilot-aided channel estimation using the weighted-delay-profile technique and investigate the impact of channel-estimation error in different environments.

  • VTC Spring - How to obtain good performance by iterative and diversity techniques for uplink MC-CDMA systems
    2006 IEEE 63rd Vehicular Technology Conference, 2006
    Co-Authors: Y. Yuan, Mireille Sarkiss, Ye Li
    Abstract:

    This paper aims at the system design on the MC-CDMA uplink. In this paper, we compare the performance and the complexity of MC-CDMIA systems with and without iterative detectors and multiple receive Antenna arrays. Through extensive computer simulation, we demonstrate that the following four combinations are good solutions: a single-Antenna Receiver with an iterative PIC detector initialized by the MF and with 3 iterations, a two-Antenna Receiver with MMSE-MUD or an iterative PIC detector initialized by the MF and with 2 iterations, and a four-Antenna Receiver with a simple MF detector. Therefore, non-iterative detectors can be used with multiple receive Antenna arrays to substitute complicated iterative detectors and it is a promising solution for the 4G up-link MC-CDMA systems where multiple receive Antennas are available. In this paper, we have also considered pilot-aided channel estimation with weighted delay profile technique and investigated the impact of channel estimation error on different systems.

Harald Haas - One of the best experts on this subject based on the ideXlab platform.

  • on space frequency coding using cyclic delay diversity for ofdm based transmission systems
    European Transactions on Telecommunications, 2003
    Co-Authors: Axel Huebner, Frank Schuehlein, Martin Bossert, Elena Costa, Harald Haas
    Abstract:

    We present a space-frequency coding scheme using cyclic delay diversity (CDD) for an orthogonal frequency division multiplexing (OFDM)-based transmission system. CDD is a simple multiple transmit Antenna approach for increasing the frequency selectivity of the channel seen at a single Antenna Receiver. This is due to the insertion of virtual echoes caused by Antenna specific cyclic delays in the time domain at the transmitter. On each Antenna a shifted version of the signal is sent, with these shifts being performed in the frequency domain. This allows the Receiver to apply optimum demodulation, and thus exploit the diversity introduced by CDD. We optimize the selection of the time domain cyclic delays in the CDD so as to get full spatial diversity with the proposed space-frequency codes with CDD (SFC-CDDs) scheme. Moreover, we show simulation results for SFC-CDD, which confirm theoretical results with respect to the achieved spatial diversity, and present a comparison with the well-known Alamouti scheme implemented as SFC.

  • On space‐frequency coding using cyclic delay diversity for OFDM‐based transmission systems
    European Transactions on Telecommunications, 2003
    Co-Authors: Axel Huebner, Frank Schuehlein, Martin Bossert, Elena Costa, Harald Haas
    Abstract:

    We present a space-frequency coding scheme using cyclic delay diversity (CDD) for an orthogonal frequency division multiplexing (OFDM)-based transmission system. CDD is a simple multiple transmit Antenna approach for increasing the frequency selectivity of the channel seen at a single Antenna Receiver. This is due to the insertion of virtual echoes caused by Antenna specific cyclic delays in the time domain at the transmitter. On each Antenna a shifted version of the signal is sent, with these shifts being performed in the frequency domain. This allows the Receiver to apply optimum demodulation, and thus exploit the diversity introduced by CDD. We optimize the selection of the time domain cyclic delays in the CDD so as to get full spatial diversity with the proposed space-frequency codes with CDD (SFC-CDDs) scheme. Moreover, we show simulation results for SFC-CDD, which confirm theoretical results with respect to the achieved spatial diversity, and present a comparison with the well-known Alamouti scheme implemented as SFC.

Payam Heydari - One of the best experts on this subject based on the ideXlab platform.

  • A CMOS Code-Modulated Path-Sharing Multi-Antenna Receiver Front-End
    IEEE Journal of Solid-State Circuits, 2009
    Co-Authors: Fred Tzeng, A. Jahanian, Payam Heydari
    Abstract:

    This paper presents the design and implementation of a novel multi-Antenna Receiver front-end, which is capable of accommodating various multi-Antenna schemes including spatial multiplexing (SM), spatial diversity (SD), and beamforming (BF). The use of orthogonal code-modulation at the RF stage of multi-Antenna signal paths enables linear combination of all mutually orthogonal code-modulated RF received signals. The combined signal is then fed to a single RF/baseband/ADC chain. In the digital domain, all Antenna signals are fully recovered using matched filters. Primary advantages of this architecture include a significant reduction in area and power consumption. Moreover, the path-sharing of multiple RF signals mitigates the issues of LO routing/distribution and cross-talk between receive chains. System-level analyses of variable gain/dynamic range, bandwidth/area/power trade-off, and interferers are presented. Designed for the 5-GHz frequency and fabricated in 0.18 mum CMOS, the 76 mW 2.3 mm2 two-Antenna Receiver front-end prototype achieves a 10-2 symbol error rate (SER) at 64, 77, and 78 dBm of input power for SM, SD, and BF, respectively, while providing 21-85 dB gain, 6.2 dB NF, and 10.6 dBm IIP3.

  • A CMOS code-modulated path-sharing multi-Antenna Receiver front-end for spatial multiplexing, spatial diversity and beamforming
    2008 IEEE Radio Frequency Integrated Circuits Symposium, 2008
    Co-Authors: Fred Tzeng, A. Jahanian, Payam Heydari
    Abstract:

    This paper presents the design of a novel 5 GHz multi-Antenna RF front-end, which is capable of performing spatial multiplexing, spatial diversity, and beamforming. The use of a unique code-modulation scheme at the RF stages of the signal paths enables linear combination of all mutually orthogonal code-modulated received signals. The combined signal is then fed to a single RF/baseband/ADC chain, resulting in a significant reduction of power consumption and area, as well as mitigating the issue of LO routing/distribution. In the digital domain, all Antenna signals are fully recovered. Fabricated in 0.18 mum CMOS, the 76 mW 2.3 mm2 two-Antenna Receiver front-end achieves a 10-2 SER at -64, -77, and -78 dBm of input power for SM, SD, and BF, respectively, while providing 85 dB gain, 6.2 dB NF, and -10.6 dBm IIP3.

Y. Yuan - One of the best experts on this subject based on the ideXlab platform.

  • Iterative and Diversity Techniques for Uplink MC-CDMA Mobile Systems With Full Load
    IEEE Transactions on Vehicular Technology, 2008
    Co-Authors: Y. Yuan, Ye Li
    Abstract:

    Iterative and diversity techniques are two of the most effective techniques for uplink multicarrier code-division multiple-access (MC-CDMA) systems. However, there is still no knowledge on how to efficiently combine these techniques to design high-performance uplink Receivers when there is a complexity constraint. In this paper, we compare the performance and the complexity of MC-CDMA systems with and without iterative detectors and multiple-receive-Antenna arrays. Through extensive simulation, we demonstrate that the following four combinations are good tradeoffs between complexity and performance: a single-Antenna Receiver with an iterative parallel-interference-cancellation (PIC) detector initialized by a matched filter (MF) with three iterations, a two-Antenna Receiver with a minimum-mean-square-error multiuser detector or an iterative PIC detector initialized by an MF with two iterations, and a four-Antenna Receiver with a simple MF detector. Therefore, noniterative detectors with multiple-receive-Antenna arrays can be used to replace iterative detectors and reduce complexity, which is a promising solution for fourth-generation (4G) uplink MC-CDMA systems, where multiple-receive Antennas are available at the base stations. In this paper, we also briefly discuss pilot-aided channel estimation using the weighted-delay-profile technique and investigate the impact of channel-estimation error in different environments.

  • VTC Spring - How to obtain good performance by iterative and diversity techniques for uplink MC-CDMA systems
    2006 IEEE 63rd Vehicular Technology Conference, 2006
    Co-Authors: Y. Yuan, Mireille Sarkiss, Ye Li
    Abstract:

    This paper aims at the system design on the MC-CDMA uplink. In this paper, we compare the performance and the complexity of MC-CDMIA systems with and without iterative detectors and multiple receive Antenna arrays. Through extensive computer simulation, we demonstrate that the following four combinations are good solutions: a single-Antenna Receiver with an iterative PIC detector initialized by the MF and with 3 iterations, a two-Antenna Receiver with MMSE-MUD or an iterative PIC detector initialized by the MF and with 2 iterations, and a four-Antenna Receiver with a simple MF detector. Therefore, non-iterative detectors can be used with multiple receive Antenna arrays to substitute complicated iterative detectors and it is a promising solution for the 4G up-link MC-CDMA systems where multiple receive Antennas are available. In this paper, we have also considered pilot-aided channel estimation with weighted delay profile technique and investigated the impact of channel estimation error on different systems.

Gonzalo Seco-granados - One of the best experts on this subject based on the ideXlab platform.

  • Downlink Single-Snapshot Localization and Mapping with a Single-Antenna Receiver
    arXiv: Signal Processing, 2020
    Co-Authors: Alessio Fascista, Angelo Coluccia, Henk Wymeersch, Gonzalo Seco-granados
    Abstract:

    5G mmWave MIMO systems enable accurate estimation of the user position and mapping of the radio environment using a single snapshot when both the base station (BS) and user are equipped with large Antenna arrays. However, massive arrays are initially expected only at the BS side, likely leaving users with one or very few Antennas. In this paper, we propose a novel method for single-snapshot localization and mapping in the more challenging case of a user equipped with a single-Antenna Receiver. The joint maximum likelihood (ML) estimation problem is formulated and its solution formally derived. To avoid the burden of a full-dimensional search over the space of the unknown parameters, we present a novel practical approach that exploits the sparsity of mmWave channels to compute an approximate joint ML estimate. A thorough analysis, including the derivation of the Cramer-Rao lower bounds, reveals that accurate localization and mapping can be achieved also in a MISO setup even when the direct line-of-sight path between the BS and the user is severely attenuated.

  • PIMRC - 5G multi-BS Positioning with a Single-Antenna Receiver
    2020 IEEE 31st Annual International Symposium on Personal Indoor and Mobile Radio Communications, 2020
    Co-Authors: Philip Gertzell, Alessio Fascista, Angelo Coluccia, Gonzalo Seco-granados, Jacob Landelius, Hanna Nyqvist, Nil Garcia, Henk Wymeersch
    Abstract:

    Cellular localization generally relies on timedifference-of-arrival (TDOA) measurements. In this paper, we investigate a novel scenario where the mobile user estimates its own position by jointly exploiting TDOA and angle of departure (AOD) measurements, which are estimated from downlink transmissions in a millimeter-wave (mmWave) multiple-input singleoutput (MISO) setup. We first perform a Fisher information analysis to derive the lower bounds on the estimation accuracy, and then propose a novel localization algorithm, which is able to provide improved performance also with few transmit Antennas and limited bandwidth.

  • Millimeter-Wave Downlink Positioning With a Single-Antenna Receiver
    IEEE Transactions on Wireless Communications, 2019
    Co-Authors: Alessio Fascista, Angelo Coluccia, Henk Wymeersch, Gonzalo Seco-granados
    Abstract:

    This paper addresses the problem of determining the unknown position of a mobile station for a mmWave multiple-input single-output (MISO) system. This setup is motivated by the fact that massive arrays will be initially implemented only on 5G base stations, likely leaving mobile stations with one Antenna. The maximum likelihood solution to this problem is devised based on the time of flight and angle of departure of received downlink signals. While positioning in the uplink would rely on angle of arrival, it presents scalability limitations that are avoided in the downlink. To circumvent the multidimensional optimization of the optimal joint estimator, we propose two novel approaches amenable to practical implementation thanks to their reduced complexity. A thorough analysis, which includes the derivation of relevant Cramer–Rao lower bounds, shows that it is possible to achieve quasi-optimal performance even in presence of few transmissions, low signal-to-noise ratio (SNRs), and multipath propagation effects.

  • Millimeter-Wave Downlink Positioning with a Single-Antenna Receiver
    arXiv: Signal Processing, 2018
    Co-Authors: Alessio Fascista, Angelo Coluccia, Henk Wymeersch, Gonzalo Seco-granados
    Abstract:

    The paper addresses the problem of determining the unknown position of a mobile station for a mmWave MISO system. This setup is motivated by the fact that massive arrays will be initially implemented only on 5G base stations, likely leaving mobile stations with one Antenna. The maximum likelihood solution to this problem is devised based on the time of flight and angle of departure of received downlink signals. While positioning in the uplink would rely on angle of arrival, it presents scalability limitations that are avoided in the downlink. To circumvent the multidimensional optimization of the optimal joint estimator, we propose two novel approaches amenable to practical implementation thanks to their reduced complexity. A thorough analysis, which includes the derivation of relevant Cram\'er-Rao lower bounds, shows that it is possible to achieve quasi-optimal performance even in presence of few transmissions, low SNRs, and multipath propagation effects.