The Experts below are selected from a list of 1047 Experts worldwide ranked by ideXlab platform

Christos Verikoukis - One of the best experts on this subject based on the ideXlab platform.

  • VTC Fall - Adaptive Generalized Space Shift Keying (GSSK) Modulation for MISO Channels: A New Method for High Diversity and Coding Gains
    2012 IEEE Vehicular Technology Conference (VTC Fall), 2012
    Co-Authors: Konstantinos Ntontin, Ana Perez-neira, Marco Di Renzo, Christos Verikoukis
    Abstract:

    Generalized Space Shift Keying (GSSK) modulation is a recently proposed low-complexity concept for Multiple-Input- Multiple-Output (MIMO) wireless systems. GSSK modulation is a generalized version of Space Shift Keying (SSK) modulation, which provides a better spectral efficiency through multiple active antennas at the transmitter. An apparent weakness of GSSK modulation is that it does not exploit the transmit-antennas to achieve transmit-diversity. In this paper, we propose a precoding method for GSSK modulation, which simultaneously achieves high diversity and coding gains. The solution is based on: i) \emph{co-phasing} the active antennas of each spatial-Constellation Point; and ii) properly \emph{rotating} the phases among spatial-Constellation Points. The new scheme requires Channel State Information at the Transmitter (CSIT), i.e., the channel phases of each wireless link, which can be obtained through a feedback channel. For the case of a perfect feedback channel, we analytically show that for three and four antennas at the transmitter a full transmit diversity can be achieved without reducing the achievable rate. Furthermore, for various MISO configurations and achievable rates we show through Monte Carlo simulations that our proposed scheme outperforms state-of-the-art open- loop GSSK schemes, in terms of both diversity and coding gain, when the number of bits allocated for the quantization of each channel phase is between 2 and 4.

  • Adaptive generalized space shift keying (GSSK) modulation for MISO channels: A new method for high diversity and coding gains
    IEEE Vehicular Technology Conference, 2012
    Co-Authors: Konstantinos Ntontin, Ana Perez-neira, Marco Di Renzo, Christos Verikoukis
    Abstract:

    Generalized Space Shift Keying (GSSK) modulation is a recently proposed low-complexity concept for Multiple-Input Multiple-Output (MIMO) wireless systems. GSSK modulation is a generalized version of Space Shift Keying (SSK) modulation, which provides a better spectral efficiency through multiple active antennas at the transmitter. An apparent weakness of GSSK modulation is that it does not exploit the transmit-antennas to achieve transmit-diversity. In this paper, we propose a precoding method for GSSK modulation, which simultaneously achieves high diversity and coding gains. The solution is based on: i) cophasing the active antennas of each spatial-Constellation Point; and ii) properly rotating the phases among spatial-Constellation Points. The new scheme requires Channel State Information at the Transmitter (CSIT), i.e., the channel phases of each wireless link, which can be obtained through a feedback channel. For the case of a perfect feedback channel, we analytically show that for three and four antennas at the transmitter a full transmit diversity can be achieved without reducing the achievable rate. Furthermore, for various MISO configurations and achievable rates we show through Monte Carlo simulations that our proposed scheme outperforms state-of-the-art open-loop GSSK schemes, in terms of both diversity and coding gain, when the number of bits allocated for the quantization of each channel phase is between 2 and 4.

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

  • Spatial Modulation -- OFDM
    2020
    Co-Authors: Raed Mesleh, Harald Haas
    Abstract:

    Abstract—In this paper, a novel multiple antenna-OFDM transmission approach, called spatial modu-lation (SM)-OFDM is presented. SM entirely avoidsinter-channel interference (ICI) at the receiver input,requires no synchronization between the transmittingantennas, and avoids correlation between them whilemaintaining high spectral efficiency. SM maps a blockof information bits into a Constellation Point in thesignal as well as the spatial domain. The spatialdomain corresponds to a particular antenna location.Hence, for OFDM transmission, each subcarrier ismapped to one of the transmitting antennas. Onlythe corresponding antenna will be sending poweron that subcarrier at an instant of time while allother antennas are transmitting zero power on thisparticular subcarrier. The receiver estimates the trans-mitted signal and the transmit antenna number anduses the two information to de-map the block ofinformation bits. A comparison between SM-OFDMand V-BLAST-OFDM using optimum ordering (OR)and successive interference cancelation (SIC) in termsof system performance is presented in this paper.Index Terms—MIMO, OFDM, V-BLAST, SpatialModulation, ZF, ICI.

  • WCNC - Coded spatial modulation applied to optical wireless communications in indoor environments
    2012 IEEE Wireless Communications and Networking Conference (WCNC), 2012
    Co-Authors: Thilo Fath, Jirka Klaue, Harald Haas
    Abstract:

    Spatial Modulation (SM) is a combined multiple-input-multiple-output (MIMO) and digital modulation technique which besides common signal modulation conveys additional information bits in the spatial domain. To this end, only one transmitter is active at any time instance. The actual index of each emitter represents a unique spatial Constellation Point and thus conveys additional information. As a consequence, SM completely avoids inter-channel interference (ICI) and provides low detection complexity. Like for any MIMO scheme, the performance of SM is degraded in the presence of high channel correlation. Therefore, Trellis Coded Spatial Modulation (TCSM) applies coding techniques to the bits conveyed in the spatial domain to assist the detection of the active transmitter. As optical wireless communications (OWC) in indoor environments is subject to high spatial correlation and low channel distinctness, we evaluate the performance of coded SM applied to indoor OWC. For this purpose, we propose an enhanced coded SM technique which jointly encodes the bits conveyed in the signal and spatial domains. It is found in this paper that our enhanced coded SM technique can achieve gains in signal to noise ratio (SNR) of about 1–3 dB compared to the originally proposed TCSM scheme.

  • Coded spatial modulation applied to optical wireless communications in indoor environments
    IEEE Wireless Communications and Networking Conference WCNC, 2012
    Co-Authors: Thilo Fath, Jirka Klaue, Harald Haas
    Abstract:

    Spatial Modulation (SM) is a combined multiple-input-multiple-output (MIMO) and digital modulation technique which besides common signal modulation conveys additional information bits in the spatial domain. To this end, only one transmitter is active at any time instance. The actual index of each emitter represents a unique spatial Constellation Point and thus conveys additional information. As a consequence, SM completely avoids inter-channel interference (ICI) and provides low detection complexity. Like for any MIMO scheme, the performance of SM is degraded in the presence of high channel correlation. Therefore, Trellis Coded Spatial Modulation (TCSM) applies coding techniques to the bits conveyed in the spatial domain to assist the detection of the active transmitter. As optical wireless communications (OWC) in indoor environments is subject to high spatial correlation and low channel distinctness, we evaluate the performance of coded SM applied to indoor OWC. For this purpose, we propose an enhanced coded SM technique which jointly encodes the bits conveyed in the signal and spatial domains. It is found in this paper that our enhanced coded SM technique can achieve gains in signal to noise ratio (SNR) of about 1-3 dB compared to the originally proposed TCSM scheme.

  • ICC - Indoor MIMO Optical Wireless Communication Using Spatial Modulation
    2010 IEEE International Conference on Communications, 2010
    Co-Authors: Raed Y. Mesleh, Hany Elgala, Rashid Mehmood, Harald Haas
    Abstract:

    In this paper, a multiple-input multiple-output (MIMO) technique for indoor optical wireless (OW) communication is proposed. The technique is referred to as \emph{optical spatial modulation (OSM)}. The key concept is based on spatial modulation (SM). At any given time instant, only one transmitter is active and the others are inactive. A transmitter in space is considered as a spatial Constellation Point which is assigned a unique bit sequence. Consequently, transmitters are turned on and off depending on the incoming data bits, similar to the activation of Constellation Points in traditional digital modulation schemes. Hence, a data rate of the base two logarithm of the number of transmit units is achieved. The active transmitter radiates a certain intensity level at a particular time instant. At the receiver side, the optimal SM detector is slightly modified and used to estimate the spatial Constellation Point. The estimated spatial Constellation Point is used to arrive at the original bit stream via de-mapping. The upper bound bit-error-ratio (BER) of OSM is analyzed for a MIMO configuration consisting of four transmit units (light emitting diodes (LEDs)) and four receive units (photo diodes (PDs)) in a room. The BER performance is determined for different transmitter and receiver separation distances and different transmitter half power semiangles. It is shown that the proposed OSM technique achieves twice and four times the data rate as compared to OOK (on-off keying) and PPM (pulse-position modulation), respectively.

  • Indoor MIMO Optical Wireless Communication Using Spatial Modulation
    Communications (ICC) 2010 IEEE International Conference on, 2010
    Co-Authors: Raed Y. Mesleh, Hany Elgala, Rashid Mehmood, Harald Haas
    Abstract:

    In this paper, a multiple-input multiple-output (MIMO) technique for indoor optical wireless (OW) communication is proposed. The technique is referred to as optical spatial modulation (OSM). The key concept is based on spatial modulation (SM). At any given time instant, only one transmitter is active and the others are inactive. A transmitter in space is considered as a spatial Constellation Point which is assigned a unique bit sequence. Consequently, transmitters are turned on and off depending on the incoming data bits, similar to the activation of Constellation Points in traditional digital modulation schemes. Hence, a data rate of the base two logarithm of the number of transmit units is achieved. The active transmitter radiates a certain intensity level at a particular time instant. At the receiver side, the optimal SM detector is slightly modified and used to estimate the spatial Constellation Point. The estimated spatial Constellation Point is used to arrive at the original bit stream via de-mapping. The upper bound bit-error-ratio (BER) of OSM is analyzed for a MIMO configuration consisting of four transmit units (light emitting diodes (LEDs)) and four receive units (photo diodes (PDs)) in a room. The BER performance is determined for different transmitter and receiver separation distances and different transmitter half power semiangles (Φ1/2). It is shown that the proposed OSM technique achieves twice and four times the data rate as compared to OOK (on-off keying) and PPM (pulse-position modulation), respectively.

Konstantinos Ntontin - One of the best experts on this subject based on the ideXlab platform.

  • VTC Fall - Adaptive Generalized Space Shift Keying (GSSK) Modulation for MISO Channels: A New Method for High Diversity and Coding Gains
    2012 IEEE Vehicular Technology Conference (VTC Fall), 2012
    Co-Authors: Konstantinos Ntontin, Ana Perez-neira, Marco Di Renzo, Christos Verikoukis
    Abstract:

    Generalized Space Shift Keying (GSSK) modulation is a recently proposed low-complexity concept for Multiple-Input- Multiple-Output (MIMO) wireless systems. GSSK modulation is a generalized version of Space Shift Keying (SSK) modulation, which provides a better spectral efficiency through multiple active antennas at the transmitter. An apparent weakness of GSSK modulation is that it does not exploit the transmit-antennas to achieve transmit-diversity. In this paper, we propose a precoding method for GSSK modulation, which simultaneously achieves high diversity and coding gains. The solution is based on: i) \emph{co-phasing} the active antennas of each spatial-Constellation Point; and ii) properly \emph{rotating} the phases among spatial-Constellation Points. The new scheme requires Channel State Information at the Transmitter (CSIT), i.e., the channel phases of each wireless link, which can be obtained through a feedback channel. For the case of a perfect feedback channel, we analytically show that for three and four antennas at the transmitter a full transmit diversity can be achieved without reducing the achievable rate. Furthermore, for various MISO configurations and achievable rates we show through Monte Carlo simulations that our proposed scheme outperforms state-of-the-art open- loop GSSK schemes, in terms of both diversity and coding gain, when the number of bits allocated for the quantization of each channel phase is between 2 and 4.

  • Adaptive generalized space shift keying (GSSK) modulation for MISO channels: A new method for high diversity and coding gains
    IEEE Vehicular Technology Conference, 2012
    Co-Authors: Konstantinos Ntontin, Ana Perez-neira, Marco Di Renzo, Christos Verikoukis
    Abstract:

    Generalized Space Shift Keying (GSSK) modulation is a recently proposed low-complexity concept for Multiple-Input Multiple-Output (MIMO) wireless systems. GSSK modulation is a generalized version of Space Shift Keying (SSK) modulation, which provides a better spectral efficiency through multiple active antennas at the transmitter. An apparent weakness of GSSK modulation is that it does not exploit the transmit-antennas to achieve transmit-diversity. In this paper, we propose a precoding method for GSSK modulation, which simultaneously achieves high diversity and coding gains. The solution is based on: i) cophasing the active antennas of each spatial-Constellation Point; and ii) properly rotating the phases among spatial-Constellation Points. The new scheme requires Channel State Information at the Transmitter (CSIT), i.e., the channel phases of each wireless link, which can be obtained through a feedback channel. For the case of a perfect feedback channel, we analytically show that for three and four antennas at the transmitter a full transmit diversity can be achieved without reducing the achievable rate. Furthermore, for various MISO configurations and achievable rates we show through Monte Carlo simulations that our proposed scheme outperforms state-of-the-art open-loop GSSK schemes, in terms of both diversity and coding gain, when the number of bits allocated for the quantization of each channel phase is between 2 and 4.

Alister Burr - One of the best experts on this subject based on the ideXlab platform.

  • Hierarchical Alphabet and Parametric Channel Constrained Capacity Regions for HDF Strategy in Parametric Wireless 2-WRC
    2010 IEEE Wireless Communication and Networking Conference, 2010
    Co-Authors: Jan Sykora, Alister Burr
    Abstract:

    The paper addresses wireless the 2-Way Relay Channel (2-WRC) system with a Hierarchical Decode and Forward strategy. This strategy uses a Hierarchical eXclusive Code (HXC) that allows full decoding of the hierarchical symbols at the relay. The HXC represents two data sources only through the exclusive law and requires side information on the complementary data at the destination (which naturally holds for the 2-WRC). The HDF strategy has the advantage over classical MAC stage relaying with joint decoding that its rate region extends beyond the classical MAC region. We evaluate the hierarchical MAC capacity regions for various alphabets, Constellation Point indexing and various channel parametrization and compare that to the alphabet limited and unconstrained cut-set bounds.

Kazuhiko Fukawa - One of the best experts on this subject based on the ideXlab platform.

  • VTC-Fall - Phase Rotated Non-Orthogonal Multiple Access for 3-User Superposition Signals
    2019 IEEE 90th Vehicular Technology Conference (VTC2019-Fall), 2019
    Co-Authors: Yuyuan Chang, Kazuhiko Fukawa
    Abstract:

    Non-orthogonal multiple access (NOMA) is one of the most promising techniques to achieve high spectral efficiency for 5G. In the NOMA downlink, a transmitter allocates different power levels to users and linearly combines user signals using the square roots of the power levels. A Constellation Point of the combined signal can be very close to other Points, which degrades bit error rate (BER) performance severely. To overcome such degradation, the proposed NOMA system rotates phases of the user signals and then linearly combines the resultant signals. On the receiver side, multiuser detection (MUD) is introduced so as to improve BER performance more than successive interference cancellation (SIC), which the conventional scheme employs. Since the proposed scheme with phase rotation (PR) for 2-user signal transmission has been thoroughly investigated, this paper considers 3-user transmission in the proposed NOMA scheme and proposes one method to optimize two angles of PR, whereas another method previously proposed by the authors can control only one angle. Computer simulations under the 3-user condition demonstrate that the proposed scheme employing PR and joint MUD and SIC for signal detection is much superior to other schemes in downlink BER performance and that the two optimization methods bring about almost the same BER.

  • Phase Rotated Non-Orthogonal Multiple Access for 3-User Superposition Signals
    2019 IEEE 90th Vehicular Technology Conference (VTC2019-Fall), 2019
    Co-Authors: Yuyuan Chang, Kazuhiko Fukawa
    Abstract:

    Non-orthogonal multiple access (NOMA) is one of the most promising techniques to achieve high spectral efficiency for 5G. In the NOMA downlink, a transmitter allocates different power levels to users and linearly combines user signals using the square roots of the power levels. A Constellation Point of the combined signal can be very close to other Points, which degrades bit error rate (BER) performance severely. To overcome such degradation, the proposed NOMA system rotates phases of the user signals and then linearly combines the resultant signals. On the receiver side, multiuser detection (MUD) is introduced so as to improve BER performance more than successive interference cancellation (SIC), which the conventional scheme employs. Since the proposed scheme with phase rotation (PR) for 2-user signal transmission has been thoroughly investigated, this paper considers 3-user transmission in the proposed NOMA scheme and proposes one method to optimize two angles of PR, whereas another method previously proposed by the authors can control only one angle. Computer simulations under the 3-user condition demonstrate that the proposed scheme employing PR and joint MUD and SIC for signal detection is much superior to other schemes in downlink BER performance and that the two optimization methods bring about almost the same BER.

  • Near-Optimal Signal Detection Based on the MMSE Detection Using Multi-Dimensional Search for Correlated MIMO Channels
    IEICE Transactions on Communications, 2011
    Co-Authors: Liming Zheng, Kazuhiko Fukawa, Hiroshi Suzuki, Satoshi Suyama
    Abstract:

    This paper proposes a low-complexity signal detection algorithm for spatially correlated multiple-input multiple-output (MIMO) channels. The proposed algorithm sets a minimum mean-square error (MMSE) detection result to the starting Point, and searches for signal candidates in multi-dimensions of the noise enhancement from which the MMSE detection suffers. The multi-dimensional search is needed because the number of dominant directions of the noise enhancement is likely to be more than one over the correlated MIMO channels. To reduce the computational complexity of the multi-dimensional search, the proposed algorithm limits the number of signal candidates to O(NT) where NT is the number of transmit antennas and O() is big O notation. Specifically, the signal candidates, which are unquantized, are obtained as the solution of a minimization problem under a constraint that a stream of the candidates should be equal to a Constellation Point. Finally, the detected signal is selected from hard decisions of both the MMSE detection result and unquantized signal candidates on the basis of the log likelihood function. For reducing the complexity of this process, the proposed algorithm decreases the number of calculations of the log likelihood functions for the quantized signal candidates. Computer simulations under a correlated MIMO channel condition demonstrate that the proposed scheme provides an excellent trade-off between BER performance and complexity, and that it is superior to conventional one-dimensional search algorithms in BER performance while requiring less complexity than the conventional algorithms.

  • Low-Complexity Signal Detection by Multi-Dimensional Search for Correlated MIMO Channels
    2011 IEEE International Conference on Communications (ICC), 2011
    Co-Authors: Liming Zheng, Kazuhiko Fukawa, Hiroshi Suzuki, Satoshi Suyama
    Abstract:

    This paper proposes a low-complexity signal detection algorithm for spatially correlated multiple-input multiple-output (MIMO) channels. The proposed algorithm sets a minimum mean-square error (MMSE) detection result to a starting Point, and searches for signal candidates in multi-dimensions of the noise enhancement from which the MMSE detection suffers. The multi-dimensional search is needed because the number of dominant directions of the noise enhancement is likely to be more than one over the correlated MIMO channels. To reduce computational complexity of the multi-dimensional search, the proposed algorithm limits the number of signal candidates to O(NT) where NT is the number of transmit antennas. Specifically, the signal candidates, which are unquantized, are obtained as the solution of a minimization problem under a constraint that a stream of the candidates should be equal to a Constellation Point. Finally, the detected signal is selected from hard decisions of both the MMSE detection result and unquantized signal candidates on the basis of the log likelihood function. For reducing the complexity of this process, the proposed algorithm decreases the number of calculations of the log likelihood functions for the quantized signal candidates. Computer simulations under a correlated MIMO channel condition demonstrate that the proposed scheme provides an excellent trade-off between BER performance and complexity, and that it is superior to conventional one-dimensional search algorithms in BER performance while requiring less complexity than that of the conventional algorithms.

  • ICC - Low-Complexity Signal Detection by Multi-Dimensional Search for Correlated MIMO Channels
    2011 IEEE International Conference on Communications (ICC), 2011
    Co-Authors: Liming Zheng, Kazuhiko Fukawa, Hiroshi Suzuki, Satoshi Suyama
    Abstract:

    This paper proposes a low-complexity signal detection algorithm for spatially correlated multiple-input multiple-output (MIMO) channels. The proposed algorithm sets a minimum mean-square error (MMSE) detection result to a starting Point, and searches for signal candidates in multi-dimensions of the noise enhancement from which the MMSE detection suffers. The multi-dimensional search is needed because the number of dominant directions of the noise enhancement is likely to be more than one over the correlated MIMO channels. To reduce computational complexity of the multi-dimensional search, the proposed algorithm limits the number of signal candidates to $O(N_T)$ where $N_T$ is the number of transmit antennas. Specifically, the signal candidates, which are unquantized, are obtained as the solution of a minimization problem under a constraint that a stream of the candidates should be equal to a Constellation Point. Finally, the detected signal is selected from hard decisions of both the MMSE detection result and unquantized signal candidates on the basis of the log likelihood function. For reducing the complexity of this process, the proposed algorithm decreases the number of calculations of the log likelihood functions for the quantized signal candidates. Computer simulations under a correlated MIMO channel condition demonstrate that the proposed scheme provides an excellent trade-off between BER performance and complexity, and that it is superior to conventional one-dimensional search algorithms in BER performance while requiring less complexity than that of the conventional algorithms.