The Experts below are selected from a list of 50895 Experts worldwide ranked by ideXlab platform
B L Hughes - One of the best experts on this subject based on the ideXlab platform.
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double differential space time block coding for time selective Fading Channels
IEEE Transactions on Communications, 2001Co-Authors: Zhiqiang Liu, Georgios B Giannakis, B L HughesAbstract:Most existing space-time coding schemes assume time-invariant Fading Channels and offer antenna diversity gains relying on accurate channel estimates at the receiver. Other single differential space-time block coding schemes forego channel estimation but are less effective in rapidly Fading environments. Based on a diagonal unitary matrix group, a novel double differential space-time block coding approach is derived in this paper for time-selective Fading Channels. Without estimating the Channels at the receiver, information symbols are recovered with antenna diversity gains regardless of frequency offsets. The resulting transceiver has very low complexity and is applicable to an arbitrary number of transmit and receive antennas. Approximately optimal space-time codes are also designed to minimize bit error rate. System performance is evaluated both analytically and with simulations.
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double differential space time block coding for time selective Fading Channels
Wireless Communications and Networking Conference, 2000Co-Authors: Zhiqiang Liu, Georgios B Giannakis, B L HughesAbstract:Most existing space-time coding schemes assume time-invariant Fading Channels and offer antenna diversity gains relying on accurate channel estimates at the receiver. Based on a diagonal unitary matrix group, a novel double differential space-time block coding approach is derived for time-selective Fading Channels. Without estimating the Channels at the receiver, information symbols are recovered with antenna diversity gains regardless of the frequency offsets. The resulting transceiver has very low complexity and is applicable to an arbitrary number of transmit and receive antennas. Approximately optimal space-time codes are also designed to minimize the bit error rate. System performance is evaluated both analytically and with simulations.
Murat Uysal - One of the best experts on this subject based on the ideXlab platform.
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cooperative diversity over log normal Fading Channels performance analysis and optimization
IEEE Transactions on Wireless Communications, 2008Co-Authors: Majid Safari, Murat UysalAbstract:Although there has been a growing interest on cooperative diversity, the current literature is mainly limited to the results obtained for Rayleigh, Rician, or Nakagami Fading Channels. In this paper, we investigate the performance of cooperative diversity schemes over log-normal Fading Channels which provide an accurate channel model for indoor wireless environments. We focus on single-relay cooperative networks with amplify-and-forward relaying and consider three TDMA-based cooperation protocols: which correspond to distributed implementations of MIMO (multi-input multi-output), SIMO (single-input multi-output), and MISO (multi-input single-output) schemes. For each protocol under consideration, we derive upper bounds on pairwise error probability over log-normal Channels and quantify the diversify advantages. Based on the minimization of a union bound on the bit error rate performance, we further formulate optimal power allocation schemes which demonstrate significant performance gains over their counterparts with equal power allocation.
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a space time block coded ofdm scheme for unknown frequency selective Fading Channels
IEEE Communications Letters, 2001Co-Authors: Murat Uysal, Naofal Aldhahir, C N GeorghiadesAbstract:We introduce a space-time block-coded orthogonal frequency-division multiplexing (STBC-OFDM) selective Fading Channels which does not require channel knowledge either at the transmitter or at the receiver. The decoding algorithm is based on generalized maximum-likelihood sequence estimation. We investigate the performance of the proposed scheme over two-tap Rayleigh Fading Channels. Simulation results show the performance to be near optimum.
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a space time block coded ofdm scheme for unknown frequency selective Fading Channels
Personal Indoor and Mobile Radio Communications, 2001Co-Authors: Murat Uysal, Naofal Aldhahir, C N GeorghiadesAbstract:We introduce a space-time block-coded orthogonal frequency-division multiplexing (MC-OFDM) scheme for frequency-selective Fading Channels which does not require channel knowledge either at the transmitter or at the receiver. The decoding algorithm is based on generalized maximum-likelihood sequence estimation. Due to the assumed orthogonality structure of STBC, the decoding rule reduces to a single step. Its form also allows the derivation of a recursive expression, which can be easily implemented by a Viterbi-type algorithm. We investigate the performance of the proposed scheme over two-tap Rayleigh Fading Channels. Simulation results show the performance of the proposed recursive-type receiver to be near optimum.
Jeehwan Ahn - One of the best experts on this subject based on the ideXlab platform.
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symbol error probability for space time block codes over spatially correlated rayleigh Fading Channels
Vehicular Technology Conference, 2006Co-Authors: Juphil Cho, Kyung Seung Ahn, Heung Ki Baik, Youngjin Kim, Jeehwan AhnAbstract:In general, multi-input multi-output (MIMO) channel is correlated by an amount that depends on the propagation environment as well as the polarization of the antenna elements and the spacing between them. In this paper, an exact error probability of orthogonal space-time block codes is considered in spatially correlated Rayleigh Fading Channels. We derive a general formula for the symbol error probability (SEP) of orthogonal space-time block codes for general PSK/PAM/QAM over spatially correlated Rayleigh Fading Channels.
Jamie Evans - One of the best experts on this subject based on the ideXlab platform.
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transactions letters outage capacity and optimal power allocation for multiple time scale parallel Fading Channels
IEEE Transactions on Wireless Communications, 2007Co-Authors: Jamie EvansAbstract:In this paper, we address the optimal power allocation problem for minimizing capacity outage probability in multiple time-scale parallel Fading Channels. Extending ideas from the work of Dey and Evans (2005), we derive the optimal power allocation scheme for parallel Fading Channels with fast Rayleigh Fading, as a function of the slow Fading gains. Numerical results are presented to demonstrate the outage performance of this scheme for lognormal slow Fading on two parallel Channels.
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outage capacity and optimal power allocation for multiple time scale parallel Fading Channels
Wireless Conference 2006 - Enabling Technologies for Wireless Multimedia Communications (European Wireless) 12th European, 2007Co-Authors: Jamie EvansAbstract:In this paper, we address the optimal power alloca- tion problem for minimizing capacity outage probability in mul- tiple time-scale parallel Fading Channels. Extending ideas from (1), we derive the optimal power allocation scheme for parallel Fading Channels with fast Rayleigh Fading, as a function of the slow Fading gains. Numerical results are presented to demonstrate the outage performance of this scheme for lognormal slow Fading on two parallel Channels.
K J R Liu - One of the best experts on this subject based on the ideXlab platform.
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diversity analysis of space time modulation over time correlated rayleigh Fading Channels
IEEE Transactions on Information Theory, 2004Co-Authors: Zoltan Safar, K J R LiuAbstract:Most space-time codes in the literature were proposed based on two ideal channel conditions: either quasistatic or rapid Fading. However, these codes may suffer performance degradation due to temporal correlation caused by the movement of the mobile terminal or imperfect interleaving. In this correspondence, we provide a novel analytical framework for the diversity analysis of space-time modulation in time-correlated Fading environment. We show that the space-time signals of square size achieving full diversity in quasistatic Fading Channels also achieve full diversity in time-correlated Fading Channels, independently of the time correlation matrix. Consequently, various classes of space-time signals designed for quasistatic Fading Channels can also be used for full-diversity transmission over time-correlated Fading Channels. Moreover, we show that if the time correlation matrix is of full rank, the design criteria for time-correlated Fading Channels are the same as those for rapid Fading Channels. To illustrate the theoretical results, some simulations were also performed under various temporal Fading conditions.
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space time signal design for time correlated rayleigh Fading Channels
International Conference on Communications, 2003Co-Authors: Zoltan Safar, K J R LiuAbstract:The existing construction of space-time codes or modulation has mainly focused on two ideal situations: either quasi-static or rapid Fading Channels. In this paper, we consider the design of robust space-time modulation for time-correlated Rayleigh Fading Channels. We show that the space-time signals of square size achieving full diversity in quasi-static Fading Channels can also achieve the full diversity in time-correlated Fading Channels irrespectively of the time correlation matrix. Moreover, we propose a space-time signal construction method by combining orthogonal designs with sphere packings. The simulation results show that our scheme outperforms the previously existing methods. For example, we observe a coding gain of about 1.5 dB over the conventional orthogonal design, about 2 dB over the parametric code, and about 4 dB over the cyclic code under certain Fading conditions.
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performance analysis of space time codes over correlated rayleigh Fading Channels
International Conference on Communications, 2003Co-Authors: Zoltan Safar, K J R LiuAbstract:The potential for capacity increase in multiantenna wireless communication systems has drawn considerable attention to space-time codes. However, most of the existing space-time code construction methods have assumed ideal channel models: either quasi-static Fading of fast Fading. In this work, we derive the performance criteria for space-time coded wireless communications systems taking into account both spatial and temporal channel correlation. We show that if the space-time correlation matrix is of full rank, the space-time code design problem for fast Fading Channels can be reduced to the code design problem for fast Fading Channels. Some simulation results are also presented to support the theory.
