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Armin Dammann - One of the best experts on this subject based on the ideXlab platform.

  • an overview of cyclic Delay Diversity and its applications
    Vehicular Technology Conference, 2008
    Co-Authors: Simon Plass, Armin Dammann, Stephan Sand
    Abstract:

    We recall the principles of cyclic Delay Diversity (CDD) and discuss the properties and impact of this transmit antenna Diversity technology. Different applications motivate variations of the CDD principle. This variants are briefly introduced and discussed. We show the application to several types of wireless systems, in particular terrestrial digital video broadcasting, cellular mobile radio communications systems and a wireless communications system using adaptive bit loading. Simulation results show the benefits of CDD for these kind of systems.

  • Benefits, variants and applications of cyclic Delay Diversity
    European Transactions on Telecommunications, 2008
    Co-Authors: Armin Dammann, Simon Plass, Stephan Sand, Ronald Raulefs
    Abstract:

    Cyclic Delay Diversity (CDDx) is a simple multiple antenna technologyxs which provides additional Diversity in Rayleigh fading channels, and therefore, improves the system performance. We recall the principles of CDD and discuss the properties and impact of this transmit (TX) antenna Diversity technology. Different applications motivate variations of the CDD principle. This variants are briefly introduced and discussed. We show the application to several types of wireless systems, in particular terrestrial digital video broadcasting, cellular mobile radio communications systems and a wireless communications system using adaptive bit loading (ABL). Simulation results highlight the benefits of CDD for these kind of systems.

  • VTC Fall - An Overview of Cyclic Delay Diversity and its Applications
    2008 IEEE 68th Vehicular Technology Conference, 2008
    Co-Authors: Simon Plass, Armin Dammann, Stephan Sand
    Abstract:

    We recall the principles of cyclic Delay Diversity (CDD) and discuss the properties and impact of this transmit antenna Diversity technology. Different applications motivate variations of the CDD principle. This variants are briefly introduced and discussed. We show the application to several types of wireless systems, in particular terrestrial digital video broadcasting, cellular mobile radio communications systems and a wireless communications system using adaptive bit loading. Simulation results show the benefits of CDD for these kind of systems.

  • Cyclic Delay Diversity: Effective Channel Properties and Applications
    2006
    Co-Authors: Armin Dammann, Simon Plass
    Abstract:

    We briefly explain the concept of cyclic Delay Diversity (CDD) as a variant of standard conformable Delay Diversity techniques. Usually being implemented at the transmitter side of an OFDM based system, the application of CDD is recognized at the receiver side only by observing modified channel propagation conditions. Therefore, we analyze the effect of CDD on the channel fading properties observed by a receiver in terms of the effective channel transfer function and the effective subcarrier fading correlation function. These modified properties provide the possibility for optimizing Diversity and coding gain of mobile radio communications systems. Simulations show the performance improvement capabilities of CDD for the terrestrial digital video broadcasting system (DVB-T) and to a cellular mobile radio communications system.

  • cellular cyclic Delay Diversity for next generation mobile systems
    Vehicular Technology Conference, 2006
    Co-Authors: Simon Plass, Armin Dammann
    Abstract:

    In this paper, we address a new method called cellular cyclic Delay Diversity (C-CDD) to a cellular mobile radio communications system. A promising candidate for a next generation mobile downlink is multi-carrier code division multiple access (MC-CDMA). The C-CDD technique is exemplarily applied to MC-CDMA. The cyclic Delay Diversity technique increases the Diversity in a system by cyclically shifted replicas of the transmitted signal over several transmit antennas. For improving the performance at the cell border in a cellular system, we introduce the cyclic Delay Diversity principle by sending replicas of the desired signal including a cyclic shift from adjacent base stations. The resulting C-CDD scheme is standard conformable. Therefore, no additional change in the mobile terminal is needed to exploit the C-CDD. The influence of the cyclic Delay to a cellular MC-CDMA system is investigated. Furthermore, simulation results show the significant improvement of the performance at the cell border by using C-CDD in an MC-CDMA cellular system for different transmission scenarios.

Martin Weckerle - One of the best experts on this subject based on the ideXlab platform.

  • On time-varying cyclic Delay Diversity
    2006
    Co-Authors: Gerd Richter, Martin Bossert, Elena Costa, Martin Weckerle
    Abstract:

    Cyclic Delay Diversity (CDD) was introduced in 2001 to obtain spatial Diversity in an orthogonal frequency division multiplexing (OFDM) based transmission system. In contrast to space-time codes, CDD introduces no additional effort at the receiver side, since CDD changes only the channel impulse response seen by the receiver by increasing the frequency selectivity. Furthermore, CDD has the advantage that there is no rate loss even for more than two transmit antennas. In this paper, we analyse CDD for an orthogonal frequency division multiple access (OFDMA) based transmission system. To increase not only the frequency selectivity but also the time selectivity, we introduce time-varying cyclic Delay Diversity (TV-CDD), which changes the cyclic shift with each OFDM symbol. Especially in systems, where each user can only allocate a few subcarriers for data transmission, TV-CDD improves the performance of the OFDMA-based transmission system significantly.

  • On Time-Varying Cyclic Delay Diversity
    European Transactions on Telecommunications, 2006
    Co-Authors: Gerd Richter, Martin Bossert, Elena Costa, Martin Weckerle
    Abstract:

    Cyclic Delay Diversity (CDD) was introduced in 2001 to obtain spatial Diversity in an orthogonal frequency division multiplexing (OFDM) based transmission system. In contrast to space-time codes, CDD introduces no additional effort at the receiver side, since CDD changes only the channel impulse response seen by the receiver by increasing the frequency selectivity. Furthermore, CDD has the advantage that there is no rate loss even for more than two transmit antennas. In this paper, we analyse CDD for an orthogonal frequency division multiple access (OFDMA) based transmission system. To increase not only the frequency selectivity but also the time selectivity, we introduce time-varying cyclic Delay Diversity (TV-CDD), which changes the cyclic shift with each OFDM symbol. Especially in systems, where each user can only allocate a few subcarriers for data transmission, TV-CDD improves the performance of the OFDMA-based transmission system significantly. Copyright © 2006 AEIT

Simon Plass - One of the best experts on this subject based on the ideXlab platform.

  • an overview of cyclic Delay Diversity and its applications
    Vehicular Technology Conference, 2008
    Co-Authors: Simon Plass, Armin Dammann, Stephan Sand
    Abstract:

    We recall the principles of cyclic Delay Diversity (CDD) and discuss the properties and impact of this transmit antenna Diversity technology. Different applications motivate variations of the CDD principle. This variants are briefly introduced and discussed. We show the application to several types of wireless systems, in particular terrestrial digital video broadcasting, cellular mobile radio communications systems and a wireless communications system using adaptive bit loading. Simulation results show the benefits of CDD for these kind of systems.

  • Benefits, variants and applications of cyclic Delay Diversity
    European Transactions on Telecommunications, 2008
    Co-Authors: Armin Dammann, Simon Plass, Stephan Sand, Ronald Raulefs
    Abstract:

    Cyclic Delay Diversity (CDDx) is a simple multiple antenna technologyxs which provides additional Diversity in Rayleigh fading channels, and therefore, improves the system performance. We recall the principles of CDD and discuss the properties and impact of this transmit (TX) antenna Diversity technology. Different applications motivate variations of the CDD principle. This variants are briefly introduced and discussed. We show the application to several types of wireless systems, in particular terrestrial digital video broadcasting, cellular mobile radio communications systems and a wireless communications system using adaptive bit loading (ABL). Simulation results highlight the benefits of CDD for these kind of systems.

  • VTC Fall - An Overview of Cyclic Delay Diversity and its Applications
    2008 IEEE 68th Vehicular Technology Conference, 2008
    Co-Authors: Simon Plass, Armin Dammann, Stephan Sand
    Abstract:

    We recall the principles of cyclic Delay Diversity (CDD) and discuss the properties and impact of this transmit antenna Diversity technology. Different applications motivate variations of the CDD principle. This variants are briefly introduced and discussed. We show the application to several types of wireless systems, in particular terrestrial digital video broadcasting, cellular mobile radio communications systems and a wireless communications system using adaptive bit loading. Simulation results show the benefits of CDD for these kind of systems.

  • Cyclic Delay Diversity: Effective Channel Properties and Applications
    2006
    Co-Authors: Armin Dammann, Simon Plass
    Abstract:

    We briefly explain the concept of cyclic Delay Diversity (CDD) as a variant of standard conformable Delay Diversity techniques. Usually being implemented at the transmitter side of an OFDM based system, the application of CDD is recognized at the receiver side only by observing modified channel propagation conditions. Therefore, we analyze the effect of CDD on the channel fading properties observed by a receiver in terms of the effective channel transfer function and the effective subcarrier fading correlation function. These modified properties provide the possibility for optimizing Diversity and coding gain of mobile radio communications systems. Simulations show the performance improvement capabilities of CDD for the terrestrial digital video broadcasting system (DVB-T) and to a cellular mobile radio communications system.

  • cellular cyclic Delay Diversity for next generation mobile systems
    Vehicular Technology Conference, 2006
    Co-Authors: Simon Plass, Armin Dammann
    Abstract:

    In this paper, we address a new method called cellular cyclic Delay Diversity (C-CDD) to a cellular mobile radio communications system. A promising candidate for a next generation mobile downlink is multi-carrier code division multiple access (MC-CDMA). The C-CDD technique is exemplarily applied to MC-CDMA. The cyclic Delay Diversity technique increases the Diversity in a system by cyclically shifted replicas of the transmitted signal over several transmit antennas. For improving the performance at the cell border in a cellular system, we introduce the cyclic Delay Diversity principle by sending replicas of the desired signal including a cyclic shift from adjacent base stations. The resulting C-CDD scheme is standard conformable. Therefore, no additional change in the mobile terminal is needed to exploit the C-CDD. The influence of the cyclic Delay to a cellular MC-CDMA system is investigated. Furthermore, simulation results show the significant improvement of the performance at the cell border by using C-CDD in an MC-CDMA cellular system for different transmission scenarios.

Gerhard Bauch - One of the best experts on this subject based on the ideXlab platform.

  • differential modulation and cyclic Delay Diversity in orthogonal frequency division multiplex
    IEEE Transactions on Communications, 2006
    Co-Authors: Gerhard Bauch
    Abstract:

    We propose a new scheme for differential modulation in orthogonal frequency-division multiplexing (OFDM) with cyclic Delay Diversity. Delay Diversity is done in a cyclic manner in order not to exceed the guard interval. However, the increased frequency selectivity, and consequently, reduced coherence bandwidth, causes problems for noncoherent detection of differential modulation in frequency direction. Our proposal is able to cope with the increased frequency selectivity,and enables picking up the spatial Diversity in frequency-selective channels with unknown Delay spread in combination with standard differential modulation techniques. The new scheme is less complex than differential unitary space-time modulation. The overhead due to reference symbols is minimized and the detection Delay is reduced, compared with differential modulation in time direction.

  • Aspects of Delay Diversity in OFDM
    African Journal of Information & Communication Technology, 2006
    Co-Authors: Gerhard Bauch
    Abstract:

    We consider several aspects of Delay Diversity in coded OFDM. The cyclic properties of the FFT allow to do Delay Diversity in a cyclic manner without exceeding the guard interval. We investigate the impact of different cyclic Delays in terms of achievable Diversity level, information theory and BER performance. Furthermore, we propose an interleaving and user assignment strategy which allows multiple users to exploit the full spatial Diversity in an OFDMA system with appropriately chosen cyclic Delays. Finally, we introduce a scheme with low Delay and low reference symbol overhead for differential modulation in frequency direction which can be detected non-coherently and is able to cope with the increased frequency-selectivity which is caused by the cyclic Delays.

  • Cyclic Delay Diversity with bit-interleaved coded modulation in orthogonal frequency division multiple access
    IEEE Transactions on Wireless Communications, 2006
    Co-Authors: Gerhard Bauch, J S Malik
    Abstract:

    We consider cyclic Delay Diversity in OFDMA. Cyclic Delay Diversity is an elegant way to obtain spatial Diversity in an FEC coded OFDM system without exceeding the guard interval. We first address the problem of choosing the cyclic Delays and propose a new robust design rule which enables to pick up the full spatial and frequency Diversity which is inherent in a frequency-selective MIMO channel. Our choice of cyclic Delays has consequences for the interleaving and multiple access scheme since the spatial Diversity appears to be transformed into frequency Diversity between neighbouring subcarriers. Therefore, a system with a conventional block frequency interleaver will fail to exploit the spatial Diversity. We propose an interleaving and multiple access strategy which guarantees that all users obtain the maximum possible Diversity advantage using FEC codes with a limited constraint length. Furthermore, we provide a performance comparison to transmit Diversity from orthogonal designs

  • multistream differential modulation for cyclic Delay Diversity in ofdm
    International Conference on Communications, 2004
    Co-Authors: Gerhard Bauch
    Abstract:

    A cyclic Delay Diversity in OFDM with noncoherent detection is considered. Delay Diversity is done in a cyclic manner in order not to exceed the guard interval. We give a robust design criterion for the cyclic Delay which enables to pick up the full spatial Diversity in frequency selective channels with unknown Delay spread. However, the effective channel coefficients of neighbouring subcarriers appear to be uncorrelated which makes differential modulation in frequency direction impossible. Therefore, we propose a multistream scheme which allows to noncoherently exploit the full spatial Diversity in combination with standard differential modulation techniques. The new scheme is less complex than differential unitary space-time modulation. The overhead due to reference symbols is minimized and the detection Delay is reduced compared to differential modulation in time direction.

  • orthogonal frequency division multiple access with cyclic Delay Diversity
    ITG Workshop on Smart Antennas (IEEE Cat. No.04EX802), 2004
    Co-Authors: Gerhard Bauch, J S Malik
    Abstract:

    Cyclic Delay Diversity is a simple transmit Diversity technique for coded OFDM systems with multiple transmit antennas. It does neither require an extended guard interval nor modifications of the standard OFDM receiver. We discuss the problem of choosing the cyclic Delays and propose a solution which enables to exploit the full spatial Diversity in flat fading and frequency-selective channels with unknown Delay spread. As a result, the spatial Diversity is transformed into frequency Diversity between neighbouring subcarriers. This imposes certain restrictions to the channel coding and interleaving scheme. Furthermore, we address multi user aspects and propose an interleaving and multiple access strategy which guarantees that all users obtain the maximum possible Diversity advantage using FEC codes with a limited constraint length. A performance comparison shows that space-time block codes outperform cyclic Delay Diversity on the expense of higher complexity and lower flexibility.

Gerd Richter - One of the best experts on this subject based on the ideXlab platform.

  • On time-varying cyclic Delay Diversity
    2006
    Co-Authors: Gerd Richter, Martin Bossert, Elena Costa, Martin Weckerle
    Abstract:

    Cyclic Delay Diversity (CDD) was introduced in 2001 to obtain spatial Diversity in an orthogonal frequency division multiplexing (OFDM) based transmission system. In contrast to space-time codes, CDD introduces no additional effort at the receiver side, since CDD changes only the channel impulse response seen by the receiver by increasing the frequency selectivity. Furthermore, CDD has the advantage that there is no rate loss even for more than two transmit antennas. In this paper, we analyse CDD for an orthogonal frequency division multiple access (OFDMA) based transmission system. To increase not only the frequency selectivity but also the time selectivity, we introduce time-varying cyclic Delay Diversity (TV-CDD), which changes the cyclic shift with each OFDM symbol. Especially in systems, where each user can only allocate a few subcarriers for data transmission, TV-CDD improves the performance of the OFDMA-based transmission system significantly.

  • On Time-Varying Cyclic Delay Diversity
    European Transactions on Telecommunications, 2006
    Co-Authors: Gerd Richter, Martin Bossert, Elena Costa, Martin Weckerle
    Abstract:

    Cyclic Delay Diversity (CDD) was introduced in 2001 to obtain spatial Diversity in an orthogonal frequency division multiplexing (OFDM) based transmission system. In contrast to space-time codes, CDD introduces no additional effort at the receiver side, since CDD changes only the channel impulse response seen by the receiver by increasing the frequency selectivity. Furthermore, CDD has the advantage that there is no rate loss even for more than two transmit antennas. In this paper, we analyse CDD for an orthogonal frequency division multiple access (OFDMA) based transmission system. To increase not only the frequency selectivity but also the time selectivity, we introduce time-varying cyclic Delay Diversity (TV-CDD), which changes the cyclic shift with each OFDM symbol. Especially in systems, where each user can only allocate a few subcarriers for data transmission, TV-CDD improves the performance of the OFDMA-based transmission system significantly. Copyright © 2006 AEIT