In this paper, we study the capacity of multiple-antenna fading channels. We focus on the scenario where the fading coefficients vary quickly;thus an accurate estimation of the coefficients is generally not available ...
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In this paper, we study the capacity of multiple-antenna fading channels. We focus on the scenario where the fading coefficients vary quickly;thus an accurate estimation of the coefficients is generally not available to either the transmitter or the receiver. We use a noncoherent block fading model proposed by Marzetta and Hochwald. The model does not assume any channel side information at the receiver or at the transmitter, but assumes that the coefficients remain constant for a coherence interval of length T symbol periods. We compute the asymptotic capacity of this channel at high signal-to-noise ratio (SNR) in terms of the coherence time T, the number of transmit antennas M, and the number of receive antennas N. While the capacity gain of the coherent multiple antenna channel is min {M, N} bits per second per hertz for every 3-dB increase in SNR, the corresponding gain for the noncoherent channel turns out to be M* (1 - M*/T) bits per second per herz, where M* = min{M, N, [T/2]}.The capacity expression has a geometric interpretation as sphere packing in the Grassmann manifold.
We design an optimal linear precoder for a space-time coded system assuming knowledge of only the transmit antenna fading correlations. Assuming a flat fading channel and a maximum-likelihood receiver, we show that th...
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We design an optimal linear precoder for a space-time coded system assuming knowledge of only the transmit antenna fading correlations. Assuming a flat fading channel and a maximum-likelihood receiver, we show that the linear precoder transmits power on the eigenmodes of the transmit antenna correlation matrix. The power allocation on the eigenmodes is a form of waterpouring policy. Simulation results are presented to show performance improvement on a space-time coded system.
An adaptive receiver based on per-survivor processing is proposed for detecting space-time trellis codes transmitted over time-selective flat-fading channels, and its performance is examined through simulations. Resul...
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An adaptive receiver based on per-survivor processing is proposed for detecting space-time trellis codes transmitted over time-selective flat-fading channels, and its performance is examined through simulations. Results suggest that the new receiver can outperform iterative approaches based on Kalman filtering and the expectation-maximization algorithm, at the cost of increased receiver complexity.
We derive a layered space-time scheme for multi-antenna orthogonal frequency-division multiplexed transmissions over frequency-selective channels. Compared with existing alternatives. the proposed scheme can attain ve...
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We derive a layered space-time scheme for multi-antenna orthogonal frequency-division multiplexed transmissions over frequency-selective channels. Compared with existing alternatives. the proposed scheme can attain very high spectral efficiency as well as improved performance. Enhanced diversity gains document its superior performance that is also tested by simulation.
Differential space-time modulation (DSTM) schemes were recently proposed to fully exploit the transmit and receive antenna diversities without the need for channel state information. DSTM is attractive in fast flat fa...
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Differential space-time modulation (DSTM) schemes were recently proposed to fully exploit the transmit and receive antenna diversities without the need for channel state information. DSTM is attractive in fast flat fading channels since accurate channel estimation is difficult to achieve. In this paper. we propose a new modulation scheme to improve the performance of DS-CDMA systems in fast time-dispersive fading channels. This scheme is referred to as the differential space-time modulation for DS-CDMA (DST-CDMA) systems. The new modulation and demodulation schemes are especially studied for the fast fading down-link transmission in DS-CDMA systems employing multiple transmit antennas and one receive antenna. We present three demodulation schemes. referred to as the differential space-time Rake (DSTR) receiver, differential space-time deterministic (DSTD) receiver, and differential space-time deterministic de-prefix (DSTDD) receiver, respectively. The DSTD receiver exploits the known information of the spreading sequences and their delayed paths deterministically besides the Rake-type combination: consequently, it can outperform the DSTR receiver. which employs the Rake-type combination only, especially for moderate-to-high SNR. The DSTDD receiver avoids the effect of intersymbol interference and hence can offer better performance than the DSTD receiver. Copyright (C) 2001 John Wiley Sons, Ltd.
A simple method to enhance the performance of simplified decoding of block space-time Codes (STC) is proposed. The method is capable of removing the error floor observed when conventionally' decoded STC is applied...
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ISBN:
(纸本)0780375890
A simple method to enhance the performance of simplified decoding of block space-time Codes (STC) is proposed. The method is capable of removing the error floor observed when conventionally' decoded STC is applied under fast fading conditions, provided that the channel is known, or accurately enough estimated, across the block. This requirement can be reached by interpolating channel estimates from pre- and pos-posted pilot symbols, which allows several blocks to be framed together, enhancing spectral efficiency.
Antenna diversity promises to provide high data rates with low error probabilities in wireless communication. An important step for realizing these promises centers around the design of efficient space-time codes for ...
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ISBN:
(纸本)0819444669
Antenna diversity promises to provide high data rates with low error probabilities in wireless communication. An important step for realizing these promises centers around the design of efficient space-time codes for multiple-antenna links. The case of mobile communication is particularly challenging. The use of complex representations of finite algebraic groups has recently been shown by some researchers to be a promising avenue for the design of space-time codes. This paper provides some background on the interplay between group representation theory and wireless communication. Then, it examines the potential contributions of finite groups of Lie type and finite unitary geometry to space-time coding. Java technologies are used for the implementation of our numerical experimentation platform.
We provide expressions for the bit error rate of various transmit and receive diversity schemes for orthogonal frequency division multiplexing (OFDM) systems in the presence of frequency offset, phase noise, and chann...
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We provide expressions for the bit error rate of various transmit and receive diversity schemes for orthogonal frequency division multiplexing (OFDM) systems in the presence of frequency offset, phase noise, and channel estimation errors. The derivations are also applicable for a general multiplicative distortion of the received signal. Our results show that with perfect channel estimates, practical values of the phase noise do not significantly degrade the performance of the various diversity methods for binary phase-shift keying modulation. In contrast, the transmit diversity schemes for OFDM are much more sensitive to channel estimation errors than maximal ratio combining receive diversity.
Accurate channel state information (CSI) is required at the receiver in a space-time coded OFDM system. In this paper, two channel estimation methods based on,least squares (LS) criteria for space-time coded OFDM syst...
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ISBN:
(纸本)0780374673
Accurate channel state information (CSI) is required at the receiver in a space-time coded OFDM system. In this paper, two channel estimation methods based on,least squares (LS) criteria for space-time coded OFDM systems are studied and compared in detail. The channel frequency response estimator uses training sequences that rely on real orthogonal designs for acquisition, while the channel impulse response estimator exploits space-time coded sequence for both acquisition and tracking modes. Computer simulations show that both estimators work well in a Rayleigh flat-fading channel. The performance of the estimators is similar in the acquisition mode if the correlation between the subcarriers is taken into account similarly in both cases.
The exponential growth of cellular radio, WLANs and the Internet sets the context for a discussion on the role and objectives of 4G. In this paper OFDM is proposed as a leading candidate for a 4G cellular communicatio...
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ISBN:
(纸本)0780375890
The exponential growth of cellular radio, WLANs and the Internet sets the context for a discussion on the role and objectives of 4G. In this paper OFDM is proposed as a leading candidate for a 4G cellular communications standard. The key design considerations and link parameters for a 4G OFDM system are identified and initial physical layer performance results are presented for a number of transmission modes and channel scenarios. Additionally, space-time techniques are considered as a means of enhancing the performance of the coded OFDM system.
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