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Unitary SpaceTime Modulation for MultipleAntenna Communications in Rayleigh Flat Fading
 IEEE Trans. Inform. Theory
, 1998
"... Motivated by informationtheoretic considerations, we propose a signalling scheme, unitary spacetime modulation, for multipleantenna communication links. This modulation is ideally suited for Rayleigh fastfading environments, since it does not require the receiver to know or learn the propagation ..."
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Cited by 307 (19 self)
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Motivated by informationtheoretic considerations, we propose a signalling scheme, unitary spacetime modulation, for multipleantenna communication links. This modulation is ideally suited for Rayleigh fastfading environments, since it does not require the receiver to know or learn the propagation coefficients. Unitary spacetime modulation uses constellations of T \cross M spacetime signals {\Phi_l, l= 1,...L},where T represents the coherence interval during which the fading is approximately constant, and M > M . We design some multipleantenna signal constellations and simulate their effectiveness as measured by bit error probability with maximum likelihood decoding. We demonstrate that two antennas have a 6dB diversity gain over one antenna at 15db SNR.
A framework for spectrally efficient noncoherent communication
, 2000
"... Abstract—This paper considers noncoherent communication over a frequencynonselective channel in which the timevarying channel gain is unknown a priori, but is approximately constant over a coherence interval. Unless the coherence interval is large, coherent communication, which requires explicit c ..."
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Cited by 32 (6 self)
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Abstract—This paper considers noncoherent communication over a frequencynonselective channel in which the timevarying channel gain is unknown a priori, but is approximately constant over a coherence interval. Unless the coherence interval is large, coherent communication, which requires explicit channel estimation and tracking prior to detection, incurs training overhead which may be excessive, especially for multipleantenna communication. In contrast, noncoherent detection may be viewed as a generalized likelihood ratio test (GLRT) which jointly estimates the channel and the data, and hence does not require separate training. The main results in this paper are as follows 1) We develop a “signal space ” criterion for signal and code design for noncoherent communication, in terms of the distances of signal points from the decision boundaries. 2) The noncoherent metric thus obtained is used to guide the design of signals for noncoherent communication that are based on amplitude/phase constellations. These are significantly more efficient than conventional differential phaseshift keying (PSK), especially at high signaltonoise ratio (SNR). Also, known results on the highSNR performance of multiplesymbol demodulation of differential PSK are easily inferred from the noncoherent metric. 3) The GLRT interpretation is used to obtain nearoptimal lowcomplexity implementations of noncoherent block demodulation. In particular, this gives an implementation of multiple symbol demodulation of differential PSK, which is of linear complexity (in the block length) and whose degradation from the exact, exponential complexity, implementation can be made as small as desired. Index Terms—Differential phaseshift keying (PSK), differential quadrature amplitude modulation (QAM), generalized likelihood ratio test (GLRT), noncoherent communication, noncoherent distance. I.
From Watermarks to Fuzzy Extractors: a Practical Construction
"... Abstract. Fuzzy extractors are a powerful tool to extract randomness from noisy data. A fuzzy extractor can extract randomness only if the source data is discrete while in practice source data is continuous. Using quantizers to transform continuous data into discrete data is a commonly used solution ..."
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Abstract. Fuzzy extractors are a powerful tool to extract randomness from noisy data. A fuzzy extractor can extract randomness only if the source data is discrete while in practice source data is continuous. Using quantizers to transform continuous data into discrete data is a commonly used solution. However, as far as we know no study has been made of the effect of the quantization strategy on the performance of fuzzy extractors. We use an unexplored parallel between watermarking theory and fuzzy extractors to study the effects of quantization. We construct the encoder and the decoder function of a fuzzy extractor using quantization index modulation (QIM) and we express performance properties of a fuzzy extractor in terms of geometric properties of the usedQIM. In the end we present and analyze, as an exercise, two constructions in the two dimensional space. Our 6hexagonal tiling construction offers ( log2 6 − 1) ≈ 0.3 extra bits per dimension of the space compared to the known square quantization based 2 fuzzy extractor. The other construction turns out to be optimal from resilience to noise perspective. 1
Griesmer:
"... For systematic encoding matrices we have the corresponding bounds [3] ..."
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