• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.281-288
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• 2004

In this paper, we consider the diversity combining method for multiple symbol differential detection (MSDD) over the slow fading diversity channel. Though the performance of the optimum maximum-likelihood sequence estimator for MSDD approaches the performance of maximal-ratio combining with differential encoding, the complexity increases exponentially as the size of MSDD block is increased. This new pre-combining method can make use of the efficient MSDD algorithm that has a complexity increasing linearly with the block length or MSDD. Thus, in many wireless scenarios where it is not possible to perform coherent detection. this pre-combined diversity MSDD can be applied to obtain substantial gain compare to conventional differential detection.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.4
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• pp.59-64
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• 2007

In this paper, we propose a new decoding method for differentially biorthogonal chirp spread spectrum (DBO-CSS). In DBO-CSS, the information is carried on the differential phase not between the adjacent sub-chirp symbols but between the sub-chirp symbols in the same position of adjacent full-chirp symbol. So, the conventional multiple symbol differential detection (MSDD) algorithms to enhance the BER performance can not be applied to the DBO-CSS directly. In this paper, we propose a new differential detection algorithm based on a partial MSD(multiple symbol detection) and a viterbi algorithm. It is shown that the performance gain of the proposed algorithm when compared with that of the conventional detection algorithm is around 2.5dB at BER = 10-5.

• Journal of Navigation and Port Research
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• v.30 no.2
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• pp.167-172
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• 2006

In this paper, the issue of blind detection of Alamouti-type differential space-time (ST) ${\pi}/2$-shifted BPSK modulation in static Rayleigh fading channels is considered. We introduce a novel transformation to the received signal from each receiver antenna such that this binary ST modulation, which has a second-order transmit-diversity, is equivalent to QPSK modulation with second-order receive-diversity. The pre-detection combining of the result of transformation allows us to apply a low complexity detection technique specifically designed for receive-diversity, namely, scalar multiple-symbol differential detection (MSDD). With receiver complexity proportional to the observation window length, our receiver can achieve the performance 1.5dB better than that of conventional differential detection ST and 0.5dB worse than that qf a coherent maximum ratio combining receiver (with differential decoding) approximately.