The Experts below are selected from a list of 5772 Experts worldwide ranked by ideXlab platform
Martin Bossert - One of the best experts on this subject based on the ideXlab platform.
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VTC Fall - Resulting Channel Characteristics from Time-Varying Cyclic Delay Diversity in OFDM
2007 IEEE 66th Vehicular Technology Conference, 2007Co-Authors: Simon Plass, Armin Dammann, Gerd Richter, Martin BossertAbstract:The influence of time-varying Cyclic Delay diversity (TV-CDD) on the channel fading correlation properties is analyzed in this paper. TV-CDD is an attractive transmit diversity technique which increases not only the frequency diversity like pure CDD but also the time diversity in orthogonal frequency division multiplexing (OFDM) based systems. These transmit diversity schemes are characterized by no need of additional complexity at the receiver to exploit the increased transmit diversity. This paper gives first investigations regarding the resulting channel characteristics from TV-CDD and the impact on the system performance. Due to the increased frequency and time selectivity and a larger channel Delay, an unintended higher channel estimation effort is possible. Therefore, we analyze the choice of the maximum Cyclic Delay. We show that the resulting channel for TV-CDD can be seen as an uncorrelated Rayleigh channel (except for the first sub-carrier) for a large maximum Cyclic Delay. Furthermore, analysis and simulation results demonstrate a feasible choice of small time-varying Cyclic Delays for guaranteeing the standard conformability of the TV- CDD technique at the receiver without significant performance degradations.
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On time-varying Cyclic Delay diversity
2006Co-Authors: Gerd Richter, Martin Bossert, Elena Costa, Martin WeckerleAbstract: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.
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On Time-Varying Cyclic Delay Diversity
European Transactions on Telecommunications, 2006Co-Authors: Gerd Richter, Martin Bossert, Elena Costa, Martin WeckerleAbstract: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
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A simple space-frequency coding scheme with Cyclic Delay diversity for OFDM
5th European Personal Mobile Communications Conference 2003, 2003Co-Authors: Axel Huebner, Martin Bossert, Elena Costa, F. Schuehlein, Harald HaasAbstract:Cyclic Delay diversity (CDD) is a simple approach to increase the frequency selectivity of the channel in an orthogonal frequency division multiplexing (OFDM) based transmission scheme. The reason for this is that CDD inserts virtual echoes. Due to these virtual multipath components carriers experience different channels if the antenna specific Cyclic Delays are chosen properly. Without any additional effort this increased frequency selectivity can be exploited by using a forward error correction (FEC) code, e.g., a convolutional code that benefits from an altered error distribution after demodulation. In this paper we investigate a simple multiple antenna transmission scheme that exploits the frequency selectivity of the channel even without FEC coding. On each antenna a shifted version of the signal is sent which enables the receiver to apply optimum demodulation. We analyze the choice of the Cyclic Delay and present a comparison with the well-known Alamouti scheme.
Simon Plass - One of the best experts on this subject based on the ideXlab platform.
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an overview of Cyclic Delay diversity and its applications
Vehicular Technology Conference, 2008Co-Authors: Simon Plass, Armin Dammann, Stephan SandAbstract: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.
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Benefits, variants and applications of Cyclic Delay diversity
European Transactions on Telecommunications, 2008Co-Authors: Armin Dammann, Simon Plass, Stephan Sand, Ronald RaulefsAbstract: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.
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VTC Fall - An Overview of Cyclic Delay Diversity and its Applications
2008 IEEE 68th Vehicular Technology Conference, 2008Co-Authors: Simon Plass, Armin Dammann, Stephan SandAbstract: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.
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Cyclic Delay Diversity - A Simple, Flexible and Effective Multi-Antenna Technology for OFDM
2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications, 2008Co-Authors: Armin Dammann, Simon Plass, Stephan SandAbstract: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 in- troduced 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.
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VTC Fall - Resulting Channel Characteristics from Time-Varying Cyclic Delay Diversity in OFDM
2007 IEEE 66th Vehicular Technology Conference, 2007Co-Authors: Simon Plass, Armin Dammann, Gerd Richter, Martin BossertAbstract:The influence of time-varying Cyclic Delay diversity (TV-CDD) on the channel fading correlation properties is analyzed in this paper. TV-CDD is an attractive transmit diversity technique which increases not only the frequency diversity like pure CDD but also the time diversity in orthogonal frequency division multiplexing (OFDM) based systems. These transmit diversity schemes are characterized by no need of additional complexity at the receiver to exploit the increased transmit diversity. This paper gives first investigations regarding the resulting channel characteristics from TV-CDD and the impact on the system performance. Due to the increased frequency and time selectivity and a larger channel Delay, an unintended higher channel estimation effort is possible. Therefore, we analyze the choice of the maximum Cyclic Delay. We show that the resulting channel for TV-CDD can be seen as an uncorrelated Rayleigh channel (except for the first sub-carrier) for a large maximum Cyclic Delay. Furthermore, analysis and simulation results demonstrate a feasible choice of small time-varying Cyclic Delays for guaranteeing the standard conformability of the TV- CDD technique at the receiver without significant performance degradations.
Armin Dammann - One of the best experts on this subject based on the ideXlab platform.
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an overview of Cyclic Delay diversity and its applications
Vehicular Technology Conference, 2008Co-Authors: Simon Plass, Armin Dammann, Stephan SandAbstract: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.
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Benefits, variants and applications of Cyclic Delay diversity
European Transactions on Telecommunications, 2008Co-Authors: Armin Dammann, Simon Plass, Stephan Sand, Ronald RaulefsAbstract: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.
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VTC Fall - An Overview of Cyclic Delay Diversity and its Applications
2008 IEEE 68th Vehicular Technology Conference, 2008Co-Authors: Simon Plass, Armin Dammann, Stephan SandAbstract: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.
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Cyclic Delay Diversity - A Simple, Flexible and Effective Multi-Antenna Technology for OFDM
2008 IEEE 10th International Symposium on Spread Spectrum Techniques and Applications, 2008Co-Authors: Armin Dammann, Simon Plass, Stephan SandAbstract: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 in- troduced 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.
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VTC Fall - Resulting Channel Characteristics from Time-Varying Cyclic Delay Diversity in OFDM
2007 IEEE 66th Vehicular Technology Conference, 2007Co-Authors: Simon Plass, Armin Dammann, Gerd Richter, Martin BossertAbstract:The influence of time-varying Cyclic Delay diversity (TV-CDD) on the channel fading correlation properties is analyzed in this paper. TV-CDD is an attractive transmit diversity technique which increases not only the frequency diversity like pure CDD but also the time diversity in orthogonal frequency division multiplexing (OFDM) based systems. These transmit diversity schemes are characterized by no need of additional complexity at the receiver to exploit the increased transmit diversity. This paper gives first investigations regarding the resulting channel characteristics from TV-CDD and the impact on the system performance. Due to the increased frequency and time selectivity and a larger channel Delay, an unintended higher channel estimation effort is possible. Therefore, we analyze the choice of the maximum Cyclic Delay. We show that the resulting channel for TV-CDD can be seen as an uncorrelated Rayleigh channel (except for the first sub-carrier) for a large maximum Cyclic Delay. Furthermore, analysis and simulation results demonstrate a feasible choice of small time-varying Cyclic Delays for guaranteeing the standard conformability of the TV- CDD technique at the receiver without significant performance degradations.
Gerd Richter - One of the best experts on this subject based on the ideXlab platform.
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VTC Fall - Resulting Channel Characteristics from Time-Varying Cyclic Delay Diversity in OFDM
2007 IEEE 66th Vehicular Technology Conference, 2007Co-Authors: Simon Plass, Armin Dammann, Gerd Richter, Martin BossertAbstract:The influence of time-varying Cyclic Delay diversity (TV-CDD) on the channel fading correlation properties is analyzed in this paper. TV-CDD is an attractive transmit diversity technique which increases not only the frequency diversity like pure CDD but also the time diversity in orthogonal frequency division multiplexing (OFDM) based systems. These transmit diversity schemes are characterized by no need of additional complexity at the receiver to exploit the increased transmit diversity. This paper gives first investigations regarding the resulting channel characteristics from TV-CDD and the impact on the system performance. Due to the increased frequency and time selectivity and a larger channel Delay, an unintended higher channel estimation effort is possible. Therefore, we analyze the choice of the maximum Cyclic Delay. We show that the resulting channel for TV-CDD can be seen as an uncorrelated Rayleigh channel (except for the first sub-carrier) for a large maximum Cyclic Delay. Furthermore, analysis and simulation results demonstrate a feasible choice of small time-varying Cyclic Delays for guaranteeing the standard conformability of the TV- CDD technique at the receiver without significant performance degradations.
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On time-varying Cyclic Delay diversity
2006Co-Authors: Gerd Richter, Martin Bossert, Elena Costa, Martin WeckerleAbstract: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.
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On Time-Varying Cyclic Delay Diversity
European Transactions on Telecommunications, 2006Co-Authors: Gerd Richter, Martin Bossert, Elena Costa, Martin WeckerleAbstract: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
Wei Zou - One of the best experts on this subject based on the ideXlab platform.
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selective random Cyclic Delay diversity for harq in cooperative relay
Wireless Communications and Networking Conference, 2010Co-Authors: Haifeng Wang, Wei ZouAbstract:In the next generation cellular system, relay has been considered to increase coverage extension and cell-edge throughput. Cooperative relay can provide transmission diversity gain to improve outage probability, overall throughput and energy efficiency. Cooperative beamforming has been considered as one of the cooperative relay if the relay nodes can get the feedback information from the destination. In this paper, a new cooperative relay scheme is proposed for hop-by-hop HARQ in cooperative relay. The scheme is to adopt selective random Cyclic Delay diversity (CDD) to the retransmission in HARQ, which can get rid of the relative bad relay nodes and form a better frequency selective channel to exploit diversity gain when channel coding is used. Performance evaluation and analysis have shown that the selective random CDD can achieve higher throughput and lower transmission Delay than the conventional cooperative beamforming.
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WCNC - Selective Random Cyclic Delay Diversity for HARQ in Cooperative Relay
2010 IEEE Wireless Communication and Networking Conference, 2010Co-Authors: Haifeng Wang, Wei ZouAbstract:In the next generation cellular system, relay has been considered to increase coverage extension and cell-edge throughput. Cooperative relay can provide transmission diversity gain to improve outage probability, overall throughput and energy efficiency. Cooperative beamforming has been considered as one of the cooperative relay if the relay nodes can get the feedback information from the destination. In this paper, a new cooperative relay scheme is proposed for hop-by-hop HARQ in cooperative relay. The scheme is to adopt selective random Cyclic Delay diversity (CDD) to the retransmission in HARQ, which can get rid of the relative bad relay nodes and form a better frequency selective channel to exploit diversity gain when channel coding is used. Performance evaluation and analysis have shown that the selective random CDD can achieve higher throughput and lower transmission Delay than the conventional cooperative beamforming.
