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72
Fading Channels: InformationTheoretic And Communications Aspects
 IEEE TRANSACTIONS ON INFORMATION THEORY
, 1998
"... In this paper we review the most peculiar and interesting informationtheoretic and communications features of fading channels. We first describe the statistical models of fading channels which are frequently used in the analysis and design of communication systems. Next, we focus on the information ..."
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Cited by 425 (3 self)
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In this paper we review the most peculiar and interesting informationtheoretic and communications features of fading channels. We first describe the statistical models of fading channels which are frequently used in the analysis and design of communication systems. Next, we focus on the information theory of fading channels, by emphasizing capacity as the most important performance measure. Both singleuser and multiuser transmission are examined. Further, we describe how the structure of fading channels impacts code design, and finally overview equalization of fading multipath channels.
Closest Point Search in Lattices
 IEEE TRANS. INFORM. THEORY
, 2000
"... In this semitutorial paper, a comprehensive survey of closestpoint search methods for lattices without a regular structure is presented. The existing search strategies are described in a unified framework, and differences between them are elucidated. An efficient closestpoint search algorithm, ba ..."
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Cited by 332 (2 self)
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In this semitutorial paper, a comprehensive survey of closestpoint search methods for lattices without a regular structure is presented. The existing search strategies are described in a unified framework, and differences between them are elucidated. An efficient closestpoint search algorithm, based on the SchnorrEuchner variation of the Pohst method, is implemented. Given an arbitrary point x 2 R m and a generator matrix for a lattice , the algorithm computes the point of that is closest to x. The algorithm is shown to be substantially faster than other known methods, by means of a theoretical comparison with the Kannan algorithm and an experimental comparison with the Pohst algorithm and its variants, such as the recent ViterboBoutros decoder. The improvement increases with the dimension of the lattice. Modifications of the algorithm are developed to solve a number of related search problems for lattices, such as finding a shortest vector, determining the kissing number, compu...
Signal Space Diversity : A Power and Bandwidth Efficient Diversity Technique for the Rayleigh Fading Channel
 IEEE Trans. on Information Theory
, 1998
"... Abstract—The increasing need for high datarate transmissions over time or frequencyselective fading channels has drawn attention to modulation schemes with high spectral efficiency such as QAM. With the aim of increasing the “diversity order” of the signal set we consider multidimensional rotated ..."
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Cited by 187 (27 self)
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Abstract—The increasing need for high datarate transmissions over time or frequencyselective fading channels has drawn attention to modulation schemes with high spectral efficiency such as QAM. With the aim of increasing the “diversity order” of the signal set we consider multidimensional rotated QAM constellations. Very high diversity orders can be achieved and this results in an almost Gaussian performance over the fading channel. This multidimensional modulation scheme is essentially uncoded and enables one to trade diversity for system complexity, at no power or bandwidth expense. Index Terms—Diversity, fading, lattices, number fields, QAM modulation, rotation.
The Golden Code: A 2 × 2 fullrate spacetime code with nonvanishing determinants
 IEEE Transactions on Information Theory
, 2005
"... Abstract — In this paper we present the Golden ..."
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SpaceTime Diversity Systems Based on Linear Constellation Precoding
 IEEE TRANS. WIRELESS COMMUN
, 2003
"... We present a unified approach to designing spacetime (ST) block codes using linear constellation precoding (LCP). Our designs are based either on parameterizations of unitary matrices, or on algebraic numbertheoretic constructions. With an arbitrary number of transmit and receiveantennas, STLCP ..."
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Cited by 128 (8 self)
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We present a unified approach to designing spacetime (ST) block codes using linear constellation precoding (LCP). Our designs are based either on parameterizations of unitary matrices, or on algebraic numbertheoretic constructions. With an arbitrary number of transmit and receiveantennas, STLCP achieves rate 1 symbol/s/Hz and enjoys diversity gain as high as over (possibly correlated) quasistatic and fast fading channels. As figures of merit, we use diversity and coding gains, as well as mutual information of the underlying multipleinputmultipleoutput system. We show that over quadratureamplitude modulation and pulseamplitude modulation, our LCP achieves the upper bound on the coding gain of all linear precoders for certain values of and comes close to this upper bound for other values of , in both correlated and independent fading channels. Compared with existing ST block codes adhering to an orthogonal design (STOD), STLCP offers not only better performance, but also higher mutual information for...
Approximately universal codes over slow fading channels
 IEEE Trans. Inform. Theory
, 2006
"... Performance of reliable communication over a coherent slow fading channel at high SNR is succinctly captured as a fundamental tradeoff between diversity and multiplexing gains. We study the problem of designing codes that optimally tradeoff the diversity and multiplexing gains. Our main contribution ..."
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Cited by 107 (1 self)
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Performance of reliable communication over a coherent slow fading channel at high SNR is succinctly captured as a fundamental tradeoff between diversity and multiplexing gains. We study the problem of designing codes that optimally tradeoff the diversity and multiplexing gains. Our main contribution is a precise characterization of codes that are universally tradeoffoptimal, i.e., they optimally tradeoff the diversity and multiplexing gains for every statistical characterization of the fading channel. We denote this characterization as one of approximate universality where the approximation is in the connection between error probability and outage capacity with diversity and multiplexing gains, respectively. The characterization of approximate universality is then used to construct new coding schemes as well as to show optimality of several schemes proposed in the spacetime coding literature. 1
An optimal two transmit antenna spacetime code and its stacked extensions
 in Proc. Asilomar Conf. on Signals, Systems and Computers
, 2003
"... Abstract—A space–time code is proposed that exhibits the highest coding gain among competing fullrate full transmit diversity space–time codes for the two transmit and receive antenna coherent quasistatic fading channel. The proposed code is derived from a layered architecture with real rotation o ..."
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Cited by 73 (1 self)
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Abstract—A space–time code is proposed that exhibits the highest coding gain among competing fullrate full transmit diversity space–time codes for the two transmit and receive antenna coherent quasistatic fading channel. The proposed code is derived from a layered architecture with real rotation of quadrature amplitude modulation (QAM) information symbols in two dimensions. The existing codes of similar architecture concentrate on application of complex full modulation diversity rotations or asymmetric real rotations. An analytic evaluation illustrates the significant improvement in coding gain achieved with the proposed code. Moreover, the coding gain of the proposed code is independent of its rate. This implies that the proposed code achieves the optimal diversity–multiplexing tradeoff curve for the two transmit antenna system. A stacked extension of the proposed code offers a reduced complexity capacity optimal alternative to the full diversity codes for larger number of transmit antennas. Performance enhancement in several scenarios is verified through simulations. Index Terms—Capacity optimal codes, coding gain, diversity–multiplexing tradeoff, fading channel, real rotation, space–time coding, transmit diversity. I.
Perfect SpaceTime Codes for Any Number of Antennas
"... In a recent paper, perfect (n × n) spacetime codes were introduced as the class of linear dispersion spacetime codes having full rate, nonvanishing determinant, a signal constellation isomorphic to either the rectangular or hexagonal lattices in 2n 2 dimensions and uniform average transmitted en ..."
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Cited by 37 (3 self)
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In a recent paper, perfect (n × n) spacetime codes were introduced as the class of linear dispersion spacetime codes having full rate, nonvanishing determinant, a signal constellation isomorphic to either the rectangular or hexagonal lattices in 2n 2 dimensions and uniform average transmitted energy per antenna. Consequence of these conditions include optimality of perfect codes with respect to the ZhengTse DiversityMultiplexing Gain tradeoff (DMT), as well as excellent lowSNR performance. Yet perfect spacetime codes have been constructed only for 2, 3, 4 and 6 transmit antennas. In this paper, we construct perfect codes for all channel dimensions, present some additional attributes of this class of spacetime codes and extend the notion of a perfect code to the rectangular case.
MMSE Analysis of Certain Large Isometric Random Precoded Systems
 IEEE Transactions on Information Theory, Volume: 49 Issue: 5, Page(s): 1293 1311
, 2001
"... Linear Precoding consists in multiplying by a N K matrix a Kdimensional vector obtained by serial to parallel conversion of a symbol sequence to be transmitted. In this paper, we analyse the performance of MMSE receivers for certain large random isometric precoded systems on fading channels. Using ..."
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Cited by 24 (11 self)
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Linear Precoding consists in multiplying by a N K matrix a Kdimensional vector obtained by serial to parallel conversion of a symbol sequence to be transmitted. In this paper, we analyse the performance of MMSE receivers for certain large random isometric precoded systems on fading channels. Using new tools, borrowed from the socalled Free Probability Theory, it can be shown that the Signal to Interference plus Noise Ratio at the equalizer output converges almost surely to a deterministic value depending on the probability distribution of the channel coefficients when N 1. These asymptotic results are used to optimally balance the redundancy introduced between Linear Precoding and classical Convolutional Coding, while preserving a simple MMSE equalization scheme at the receiver.
Impact of diversity reception on fading channels with coded modulation. Part III: Cochannel interference
, 1997
"... In previous work we have studied the impact of diversity on coded digital communication systems operating over fading channels. In particular, we have shown that diversity may be thought of as a way of making the channel more similar to a Gaussian one. The present paper extends this analysis to fadi ..."
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Cited by 22 (2 self)
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In previous work we have studied the impact of diversity on coded digital communication systems operating over fading channels. In particular, we have shown that diversity may be thought of as a way of making the channel more similar to a Gaussian one. The present paper extends this analysis to fading channels affected by cochannel interference (CCI). Several receiver models are examined, namely, with ideal coherent detection and perfect channelstate information (CSI), and with differential and pilottone detection. We study the effect of diversity on the irreducible error floor caused by CCI and fading, and the asymptotic behavior of the channel as the diversity order increases. Our results show that, when perfect CSI is available, diversity is able to turn asymptotically the channel into a CCIfree additive white Gaussian noise (AWGN) channel with the same signaltonoise ratio (SNR). On the other hand, for differential and pilottone detection, diversity achieves significant gains ...