The Experts below are selected from a list of 9747 Experts worldwide ranked by ideXlab platform

Hamid Jafarkhani - One of the best experts on this subject based on the ideXlab platform.

  • Quasi-Orthogonal Space-Time-Frequency Trellis Codes for Two Transmit Antennas
    IEEE Transactions on Wireless Communications, 2010
    Co-Authors: Jorge Flores, Jaime Sánchez, Hamid Jafarkhani
    Abstract:

    In this letter, we propose two full-rate space-time-frequency trellis code (STFTC) designs for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. The first proposal based on rotating constellation is called extended super-orthogonal STFTC (Ex-SOSTFTC). The second proposal, called Quasi-Orthogonal STFTCs (QOSTFTCs), combines set partitioning and the structure of quasi-orthogonal space-frequency designs in a systematic way. In addition to spatial diversity, the proposed codes provide multipath diversity and achieve High-Coding Gain over a frequency selective fading channel. Simulation results show the proposed codes significantly outperform the existing STFTC designs.

  • Differential Quasi-Orthogonal Space-Frequency Trellis Codes
    IEEE Transactions on Wireless Communications, 2010
    Co-Authors: Jorge Flores, Jaime Sánchez, Hamid Jafarkhani
    Abstract:

    Two rate-one differential quasi-orthogonal space-frequency trellis codes (DQOSFTCs) for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) channels are proposed. The DQOSFTCs are systematically constructed within an OFDM symbol period, by combining unitary quasi-orthogonal trellis codes and differential modulation over the frequency domain (DF-QOSFTC) or time domain (DT-QOSFTCs). Besides multipath diversity, our DQOSFTCs achieve High-Coding Gain and simple deCoding when the channel state information is not available at both the transmitter and the receiver. Simulation results show that our proposed codes significantly outperform the existing differential space-frequency trellis codes.

  • Super-quasi-orthogonal space-time trellis codes for four transmit antennas
    IEEE Transactions on Wireless Communications, 2005
    Co-Authors: Hamid Jafarkhani, Navid Hassanpour
    Abstract:

    We introduce a new family of space-time trellis codes that extends the powerful characteristics of super-orthogonal space-time trellis codes to four transmit antennas. We consider a family of quasi-orthogonal space-time block codes as building blocks in our new trellis codes. These codes combine set partitioning and a super set of quasi-orthogonal space-time block codes in a systematic way to provide full diversity and improved Coding Gain. The result is a powerful code that provides full rate, full diversity, and High Coding Gain. It is also possible to maintain a tradeoff between Coding Gain and rate. Simulation results demonstrate the good performance of our new super-quasi-orthogonal space-time trellis codes.

  • GLOBECOM - A class of full diversity space-time codes
    GLOBECOM '03. IEEE Global Telecommunications Conference (IEEE Cat. No.03CH37489), 1
    Co-Authors: Navid Hassanpour, Hamid Jafarkhani
    Abstract:

    We propose a new class of space-time trellis codes for 4 transmit antennas. These codes combine set-partitioning and a super set of quasi-orthogonal space-time block codes in a systematic way to provide full diversity and improved Coding Gain. The result is a very powerful non full-rate code that provides full diversity and High Coding Gain for different number of states and at different rates. Also, it is possible to maintain a tradeoff between Coding Gain and rate. The deCoding complexity of the new codes is very low because the symbols can be decoupled at the decoder. Simulation results demonstrate the good performance of our new space-time trellis codes. We provide a study of Coding Gain and different code examples.

Trac D. Tran - One of the best experts on this subject based on the ideXlab platform.

  • fast approximations of the orthogonal dual tree wavelet bases
    International Conference on Acoustics Speech and Signal Processing, 2005
    Co-Authors: A. Abbas, Trac D. Tran
    Abstract:

    Recently, there has been a significant interest in the design of iterated filter banks in which the resulting wavelet bases form an approximate Hilbert transform pair. In this work, we propose three approximations of such dual-tree wavelet bases that satisfy Hilbert transform conditions. Our designs are derived from Selesnick's and Kingsbury's orthogonal wavelet filter solutions, and meet other desirable properties such as High Coding Gain, reduced computational complexity and sufficient regularity. The quantization is performed in the lattice domain using sum-of-power-of-two (SOPOT) coefficients. Several performance comparisons are presented. Furthermore, this paper introduces a proposition that lattice coefficients of filters that are time-reversals of each other are closely related.

  • ICASSP (4) - Fast approximations of the orthogonal dual-tree wavelet bases
    Proceedings. (ICASSP '05). IEEE International Conference on Acoustics Speech and Signal Processing 2005., 1
    Co-Authors: A. Abbas, Trac D. Tran
    Abstract:

    Recently, there has been a significant interest in the design of iterated filter banks in which the resulting wavelet bases form an approximate Hilbert transform pair. In this work, we propose three approximations of such dual-tree wavelet bases that satisfy Hilbert transform conditions. Our designs are derived from Selesnick's and Kingsbury's orthogonal wavelet filter solutions, and meet other desirable properties such as High Coding Gain, reduced computational complexity and sufficient regularity. The quantization is performed in the lattice domain using sum-of-power-of-two (SOPOT) coefficients. Several performance comparisons are presented. Furthermore, this paper introduces a proposition that lattice coefficients of filters that are time-reversals of each other are closely related.

Navid Hassanpour - One of the best experts on this subject based on the ideXlab platform.

  • Super-quasi-orthogonal space-time trellis codes for four transmit antennas
    IEEE Transactions on Wireless Communications, 2005
    Co-Authors: Hamid Jafarkhani, Navid Hassanpour
    Abstract:

    We introduce a new family of space-time trellis codes that extends the powerful characteristics of super-orthogonal space-time trellis codes to four transmit antennas. We consider a family of quasi-orthogonal space-time block codes as building blocks in our new trellis codes. These codes combine set partitioning and a super set of quasi-orthogonal space-time block codes in a systematic way to provide full diversity and improved Coding Gain. The result is a powerful code that provides full rate, full diversity, and High Coding Gain. It is also possible to maintain a tradeoff between Coding Gain and rate. Simulation results demonstrate the good performance of our new super-quasi-orthogonal space-time trellis codes.

  • GLOBECOM - A class of full diversity space-time codes
    GLOBECOM '03. IEEE Global Telecommunications Conference (IEEE Cat. No.03CH37489), 1
    Co-Authors: Navid Hassanpour, Hamid Jafarkhani
    Abstract:

    We propose a new class of space-time trellis codes for 4 transmit antennas. These codes combine set-partitioning and a super set of quasi-orthogonal space-time block codes in a systematic way to provide full diversity and improved Coding Gain. The result is a very powerful non full-rate code that provides full diversity and High Coding Gain for different number of states and at different rates. Also, it is possible to maintain a tradeoff between Coding Gain and rate. The deCoding complexity of the new codes is very low because the symbols can be decoupled at the decoder. Simulation results demonstrate the good performance of our new space-time trellis codes. We provide a study of Coding Gain and different code examples.

Jorge Flores - One of the best experts on this subject based on the ideXlab platform.

  • Quasi-Orthogonal Space-Time-Frequency Trellis Codes for Two Transmit Antennas
    IEEE Transactions on Wireless Communications, 2010
    Co-Authors: Jorge Flores, Jaime Sánchez, Hamid Jafarkhani
    Abstract:

    In this letter, we propose two full-rate space-time-frequency trellis code (STFTC) designs for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. The first proposal based on rotating constellation is called extended super-orthogonal STFTC (Ex-SOSTFTC). The second proposal, called Quasi-Orthogonal STFTCs (QOSTFTCs), combines set partitioning and the structure of quasi-orthogonal space-frequency designs in a systematic way. In addition to spatial diversity, the proposed codes provide multipath diversity and achieve High-Coding Gain over a frequency selective fading channel. Simulation results show the proposed codes significantly outperform the existing STFTC designs.

  • Differential Quasi-Orthogonal Space-Frequency Trellis Codes
    IEEE Transactions on Wireless Communications, 2010
    Co-Authors: Jorge Flores, Jaime Sánchez, Hamid Jafarkhani
    Abstract:

    Two rate-one differential quasi-orthogonal space-frequency trellis codes (DQOSFTCs) for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) channels are proposed. The DQOSFTCs are systematically constructed within an OFDM symbol period, by combining unitary quasi-orthogonal trellis codes and differential modulation over the frequency domain (DF-QOSFTC) or time domain (DT-QOSFTCs). Besides multipath diversity, our DQOSFTCs achieve High-Coding Gain and simple deCoding when the channel state information is not available at both the transmitter and the receiver. Simulation results show that our proposed codes significantly outperform the existing differential space-frequency trellis codes.

Peter J. Smith - One of the best experts on this subject based on the ideXlab platform.

  • VTC Fall - Space Time State Trellis Codes for Reconfigurable Antenna Systems
    2013 IEEE 78th Vehicular Technology Conference (VTC Fall), 2013
    Co-Authors: Uzma Afsheen, Philippa A. Martin, Peter J. Smith
    Abstract:

    In this paper we propose a novel class of space time trellis codes based on super quasi-orthogonal space time codes for a reconfigurable antenna system. We call them Space Time State Trellis Codes (STSTCs). The proposed codes are capable of taking advantage of the additional degrees of diversity offered by reconfigurable antennas and changing propagation states. They achieve full rate, full diversity and High Coding Gain. Simulation results demonstrate their good performance. STSTCs achieve the diversity order expected for four transmit antennas while using only two reconfigurable transmit antennas. Our code out performs the existing super orthogonal space time trellis code, which fails to achieve full diversity in a reconfigurable antenna system.