Quasi-orthogonal space-time block codes on measured MIMO channels

Orthogonal space-time block codes (OSTBC) from orthogonal designs have both advantages of complex symbol-wise maximum-likelihood (ML) decoding and full diversity. However, their symbol rates are upper bounded by 3/4 for more than 2 antennas for complex symbols. To increase the symbol rates, they have been generalized to quasi-orthogonal space-time block codes (QOSTBC) in the literature but the diversity order is reduced by half and the complex symbol-wise ML decoding is significantly increased to complex symbol pair-wise (pair of complex symbols) ML decoding. The QOSTBC has been modified by rotating half of the complex symbols for achieving the full diversity while maintaining the complex symbol pair-wise ML decoding. The optimal rotation angles for any signal constellation of any finite symbols located on both square lattices and equal-literal triangular lattices have been found by Su-Xia, where the optimality means the optimal diversity product (or product distance). QOSTBC has also been modified by Yuen-Guan-Tjhung by rotating information symbols in another way such that it has full diversity and in the meantime it has real symbol pair-wise ML decoding (the same complexity as complex symbol-wise decoding) and the optimal rotation angle for square and rectangular QAM constellations has been found.In this paper, we systematically study general linear transformations of information symbols for QOSTBC to have both full diversity and real symbol pair-wise ML decoding. We present the optimal transformation matrices (among all possible linear transformations not necessarily symbol rotations) of information symbols for QOSTBC with real symbol pair-wise ML decoding such that the optimal diversity product is achieved for both general square QAM and general rectangular QAM signal constellations. Furthermore, our newly proposed optimal linear transformations for QOSTBC also work for general QAM constellations in the sense that QOSTBC have full diversity with good diversity product property and real symbol pair-wise ML decoding. Interestingly, the optimal diversity products for square QAM constellations from the optimal linear transformations of information symbols found in this paper coincide with the ones presented by Yuen-Guan-Tjhung by using their optimal rotations. However, the optimal diversity products for (non-square) rectangular QAM constellations from the optimal linear transformations of information symbols found in this paper are better than the ones presented by Yuen-Guan-Tjhung by using their optimal rotations. In this paper, we also present the optimal transformations for the co-ordinate interleaved orthogonal designs (CIOD) proposed by Khan-Rajan for rectangular QAM constellations. Index TermsComplex symbol-wise decoding, Hurwitz-Radon family, linear transformations of information symbols, optimal product diversity, quasi-orthogonal space-time block codes, real symbol pair-wise decoding.

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“…Further recent developments on fast decoding and linear transformations can be found in, for example, [41]- [44].…”

Section: Discussionmentioning

confidence: 99%

On optimal quasi-orthogonal space-time block codes with minimum decoding complexity

Wang

Xia

2005

Proceedings. International Symposium on Information Theory, 2005. ISIT 2005.

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“…There exists another class of codes known as the quasiorthogonal space-time block codes [6]- [11], sometimes abbreviated as QO-STBC. As described in Section II-B2, no orthogonal codes with full unity rate exist beyond a diversity order of two when using any modulation schemes with a complex constellation.…”

Section: B Orthogonal Space-time Block Codesmentioning

confidence: 99%

“…From the proposed definition in [6], we define a QO-STBC as follows: Definition 2: A QO-STBC of dimension N × N has a H matrix such that H H H is a sparse matrix with h 2 on its main diagonal, at least N 2 /2 zero entries on its off-diagonal, and the magnitude for the rest of the entries being some value bounded by ± h 2 .…”

Section: B Orthogonal Space-time Block Codesmentioning

confidence: 99%

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Maximizing available diversity in a MIMO fading channel

2017

2017 IEEE 7th Annual Computing and Communication Workshop and Conference (CCWC)

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Abstract-The effects of Rayleigh fading on a wireless communications link and MIMO technique to combat fading is explored in this paper. In harnessing spatial diversity, the use of QuasiOrthogonal space-time block code (QO-STBC) is proposed to combat fading. QO-STBC codes are able to achieve a unity rate with more than two antennas. The concept of constellation rotation for QO codes to maximize the available diversity is demonstrated. QO codes are shown by simulation to be able to achieve full diversity, despite the fact that the codes are nonorthogonal.

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“…On the other hand, closed-loop antenna and code selection have also been studied, see, e.g., [13,14,15]. In [16], the authors present a closed-loop design based on OSTBC, which specializes to a single feedback bit algorithm, for the case of four transmit antennas.…”

Section: Introductionmentioning

confidence: 99%

Single-bit closed-loop quasi-orthogonal space-time codes for MIMO systems

Zacarías¹,

Werner²,

Wichman³

et al. 2009

2009 IEEE 10th Workshop on Signal Processing Advances in Wireless Communications

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This paper proposes a closed-loop beamforming algorithm for MIMO systems employing quasi-orthogonal space-time block codes (QOSTCB) and low rate feedback channels over slowly fading channels. A recursion is formulated using a stochastic signed gradient approximation, where the receiver employs a single feedback bit to command the transmit antenna weights adaptation, at a frequency much lower than that of the data rate. The algorithm tracks the weight vector that optimizes a link performance measure, which takes into account both the self-interference properties of the space-time code and the channel conditions. Simulations show that the proposed algorithm can effectively exploit the channel temporal correlation, and outperform existing single-bit feedback schemes in low mobility scenarios.

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Quasi-orthogonal space-time block codes on measured MIMO channels

Cited by 10 publications

References 11 publications

On optimal quasi-orthogonal space-time block codes with minimum decoding complexity

On optimal quasi-orthogonal space-time block codes with minimum decoding complexity

Maximizing available diversity in a MIMO fading channel

Single-bit closed-loop quasi-orthogonal space-time codes for MIMO systems

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