5,039 research outputs found
An Adaptive Conditional Zero-Forcing Decoder with Full-diversity, Least Complexity and Essentially-ML Performance for STBCs
A low complexity, essentially-ML decoding technique for the Golden code and
the 3 antenna Perfect code was introduced by Sirianunpiboon, Howard and
Calderbank. Though no theoretical analysis of the decoder was given, the
simulations showed that this decoding technique has almost maximum-likelihood
(ML) performance. Inspired by this technique, in this paper we introduce two
new low complexity decoders for Space-Time Block Codes (STBCs) - the Adaptive
Conditional Zero-Forcing (ACZF) decoder and the ACZF decoder with successive
interference cancellation (ACZF-SIC), which include as a special case the
decoding technique of Sirianunpiboon et al. We show that both ACZF and ACZF-SIC
decoders are capable of achieving full-diversity, and we give sufficient
conditions for an STBC to give full-diversity with these decoders. We then show
that the Golden code, the 3 and 4 antenna Perfect codes, the 3 antenna Threaded
Algebraic Space-Time code and the 4 antenna rate 2 code of Srinath and Rajan
are all full-diversity ACZF/ACZF-SIC decodable with complexity strictly less
than that of their ML decoders. Simulations show that the proposed decoding
method performs identical to ML decoding for all these five codes. These STBCs
along with the proposed decoding algorithm outperform all known codes in terms
of decoding complexity and error performance for 2,3 and 4 transmit antennas.
We further provide a lower bound on the complexity of full-diversity
ACZF/ACZF-SIC decoding. All the five codes listed above achieve this lower
bound and hence are optimal in terms of minimizing the ACZF/ACZF-SIC decoding
complexity. Both ACZF and ACZF-SIC decoders are amenable to sphere decoding
implementation.Comment: 11 pages, 4 figures. Corrected a minor typographical erro
Golden Coded Multiple Beamforming
The Golden Code is a full-rate full-diversity space-time code, which achieves
maximum coding gain for Multiple-Input Multiple-Output (MIMO) systems with two
transmit and two receive antennas. Since four information symbols taken from an
M-QAM constellation are selected to construct one Golden Code codeword, a
maximum likelihood decoder using sphere decoding has the worst-case complexity
of O(M^4), when the Channel State Information (CSI) is available at the
receiver. Previously, this worst-case complexity was reduced to O(M^(2.5))
without performance degradation. When the CSI is known by the transmitter as
well as the receiver, beamforming techniques that employ singular value
decomposition are commonly used in MIMO systems. In the absence of channel
coding, when a single symbol is transmitted, these systems achieve the full
diversity order provided by the channel. Whereas this property is lost when
multiple symbols are simultaneously transmitted. However, uncoded multiple
beamforming can achieve the full diversity order by adding a properly designed
constellation precoder. For 2 \times 2 Fully Precoded Multiple Beamforming
(FPMB), the general worst-case decoding complexity is O(M). In this paper,
Golden Coded Multiple Beamforming (GCMB) is proposed, which transmits the
Golden Code through 2 \times 2 multiple beamforming. GCMB achieves the full
diversity order and its performance is similar to general MIMO systems using
the Golden Code and FPMB, whereas the worst-case decoding complexity of
O(sqrt(M)) is much lower. The extension of GCMB to larger dimensions is also
discussed.Comment: accepted to conferenc
Reduced-complexity maximum-likelihood decoding for 3D MIMO code
The 3D MIMO code is a robust and efficient space-time coding scheme for the
distributed MIMO broadcasting. However, it suffers from the high computational
complexity if the optimal maximum-likelihood (ML) decoding is used. In this
paper we first investigate the unique properties of the 3D MIMO code and
consequently propose a simplified decoding algorithm without sacrificing the ML
optimality. Analysis shows that the decoding complexity is reduced from O(M^8)
to O(M^{4.5}) in quasi-static channels when M-ary square QAM constellation is
used. Moreover, we propose an efficient implementation of the simplified ML
decoder which achieves a much lower decoding time delay compared to the
classical sphere decoder with Schnorr-Euchner enumeration.Comment: IEEE Wireless Communications and Networking Conference (WCNC 2013),
Shanghai : China (2013
A Fast Decodable Full-Rate STBC with High Coding Gain for 4x2 MIMO Systems
In this work, a new fast-decodable space-time block code (STBC) is proposed.
The code is full-rate and full-diversity for 4x2 multiple-input multiple-output
(MIMO) transmission. Due to the unique structure of the codeword, the proposed
code requires a much lower computational complexity to provide
maximum-likelihood (ML) decoding performance. It is shown that the ML decoding
complexity is only O(M^{4.5}) when M-ary square QAM constellation is used.
Finally, the proposed code has highest minimum determinant among the
fast-decodable STBCs known in the literature. Simulation results prove that the
proposed code provides the best bit error rate (BER) performance among the
state-of-the-art STBCs.Comment: 2013 IEEE 24th International Symposium on Personal Indoor and Mobile
Radio Communications (PIMRC), London : United Kingdom (2013
Achieving Low-Complexity Maximum-Likelihood Detection for the 3D MIMO Code
The 3D MIMO code is a robust and efficient space-time block code (STBC) for
the distributed MIMO broadcasting but suffers from high maximum-likelihood (ML)
decoding complexity. In this paper, we first analyze some properties of the 3D
MIMO code to show that the 3D MIMO code is fast-decodable. It is proved that
the ML decoding performance can be achieved with a complexity of O(M^{4.5})
instead of O(M^8) in quasi static channel with M-ary square QAM modulations.
Consequently, we propose a simplified ML decoder exploiting the unique
properties of 3D MIMO code. Simulation results show that the proposed
simplified ML decoder can achieve much lower processing time latency compared
to the classical sphere decoder with Schnorr-Euchner enumeration
A Low-Complexity, Full-Rate, Full-Diversity 2 X 2 STBC with Golden Code's Coding Gain
This paper presents a low-ML-decoding-complexity, full-rate, full-diversity
space-time block code (STBC) for a 2 transmit antenna, 2 receive antenna
multiple-input multiple-output (MIMO) system, with coding gain equal to that of
the best and well known Golden code for any QAM constellation. Recently, two
codes have been proposed (by Paredes, Gershman and Alkhansari and by Sezginer
and Sari), which enjoy a lower decoding complexity relative to the Golden code,
but have lesser coding gain. The STBC presented in this paper has
lesser decoding complexity for non-square QAM constellations, compared with
that of the Golden code, while having the same decoding complexity for square
QAM constellations. Compared with the Paredes-Gershman-Alkhansari and
Sezginer-Sari codes, the proposed code has the same decoding complexity for
non-rectangular QAM constellations. Simulation results, which compare the
codeword error rate (CER) performance, are presented.Comment: Submitted to IEEE Globecom - 2008. 6 pages, 3 figures, 1 tabl
Generalized Silver Codes
For an transmit, receive antenna system (
system), a {\it{full-rate}} space time block code (STBC) transmits complex symbols per channel use. The well known Golden code is an
example of a full-rate, full-diversity STBC for 2 transmit antennas. Its
ML-decoding complexity is of the order of for square -QAM. The
Silver code for 2 transmit antennas has all the desirable properties of the
Golden code except its coding gain, but offers lower ML-decoding complexity of
the order of . Importantly, the slight loss in coding gain is negligible
compared to the advantage it offers in terms of lowering the ML-decoding
complexity. For higher number of transmit antennas, the best known codes are
the Perfect codes, which are full-rate, full-diversity, information lossless
codes (for ) but have a high ML-decoding complexity of the order
of (for , the punctured Perfect codes are
considered). In this paper, a scheme to obtain full-rate STBCs for
transmit antennas and any with reduced ML-decoding complexity of the
order of , is presented. The codes constructed are
also information lossless for , like the Perfect codes and allow
higher mutual information than the comparable punctured Perfect codes for . These codes are referred to as the {\it generalized Silver codes},
since they enjoy the same desirable properties as the comparable Perfect codes
(except possibly the coding gain) with lower ML-decoding complexity, analogous
to the Silver-Golden codes for 2 transmit antennas. Simulation results of the
symbol error rates for 4 and 8 transmit antennas show that the generalized
Silver codes match the punctured Perfect codes in error performance while
offering lower ML-decoding complexity.Comment: Accepted for publication in the IEEE Transactions on Information
Theory. This revised version has 30 pages, 7 figures and Section III has been
completely revise
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