596 research outputs found
Asymptotically-Optimal, Fast-Decodable, Full-Diversity STBCs
For a family/sequence of STBCs , with
increasing number of transmit antennas , with rates complex symbols
per channel use (cspcu), the asymptotic normalized rate is defined as . A family of STBCs is said to be
asymptotically-good if the asymptotic normalized rate is non-zero, i.e., when
the rate scales as a non-zero fraction of the number of transmit antennas, and
the family of STBCs is said to be asymptotically-optimal if the asymptotic
normalized rate is 1, which is the maximum possible value. In this paper, we
construct a new class of full-diversity STBCs that have the least ML decoding
complexity among all known codes for any number of transmit antennas and
rates cspcu. For a large set of pairs, the new codes
have lower ML decoding complexity than the codes already available in the
literature. Among the new codes, the class of full-rate codes () are
asymptotically-optimal and fast-decodable, and for have lower ML decoding
complexity than all other families of asymptotically-optimal, fast-decodable,
full-diversity STBCs available in the literature. The construction of the new
STBCs is facilitated by the following further contributions of this paper:(i)
For , we construct -group ML-decodable codes with rates greater than
one cspcu. These codes are asymptotically-good too. For , these are the
first instances of -group ML-decodable codes with rates greater than
cspcu presented in the literature. (ii) We construct a new class of
fast-group-decodable codes for all even number of transmit antennas and rates
.(iii) Given a design with full-rank linear dispersion
matrices, we show that a full-diversity STBC can be constructed from this
design by encoding the real symbols independently using only regular PAM
constellations.Comment: 16 pages, 3 tables. The title has been changed.The class of
asymptotically-good multigroup ML decodable codes has been extended to a
broader class of number of antennas. New fast-group-decodable codes and
asymptotically-optimal, fast-decodable codes have been include
Fast-Decodable Asymmetric Space-Time Codes from Division Algebras
Multiple-input double-output (MIDO) codes are important in the near-future
wireless communications, where the portable end-user device is physically small
and will typically contain at most two receive antennas. Especially tempting is
the 4 x 2 channel due to its immediate applicability in the digital video
broadcasting (DVB). Such channels optimally employ rate-two space-time (ST)
codes consisting of (4 x 4) matrices. Unfortunately, such codes are in general
very complex to decode, hence setting forth a call for constructions with
reduced complexity.
Recently, some reduced complexity constructions have been proposed, but they
have mainly been based on different ad hoc methods and have resulted in
isolated examples rather than in a more general class of codes. In this paper,
it will be shown that a family of division algebra based MIDO codes will always
result in at least 37.5% worst-case complexity reduction, while maintaining
full diversity and, for the first time, the non-vanishing determinant (NVD)
property. The reduction follows from the fact that, similarly to the Alamouti
code, the codes will be subsets of matrix rings of the Hamiltonian quaternions,
hence allowing simplified decoding. At the moment, such reductions are among
the best known for rate-two MIDO codes. Several explicit constructions are
presented and shown to have excellent performance through computer simulations.Comment: 26 pages, 1 figure, submitted to IEEE Trans. Inf. Theory, October
201
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
A New Low-Complexity Decodable Rate-1 Full-Diversity 4 x 4 STBC with Nonvanishing Determinants
Space-time coding techniques have become common-place in wireless
communication standards as they provide an effective way to mitigate the fading
phenomena inherent in wireless channels. However, the use of Space-Time Block
Codes (STBCs) increases significantly the optimal detection complexity at the
receiver unless the low complexity decodability property is taken into
consideration in the STBC design. In this letter we propose a new
low-complexity decodable rate-1 full-diversity 4 x 4 STBC. We provide an
analytical proof that the proposed code has the Non-Vanishing-Determinant (NVD)
property, a property that can be exploited through the use of adaptive
modulation which changes the transmission rate according to the wireless
channel quality. We compare the proposed code to existing low-complexity
decodable rate-1 full-diversity 4 x 4 STBCs in terms of performance over
quasi-static Rayleigh fading channels, detection complexity and Peak-to-Average
Power Ratio (PAPR). Our code is found to provide the best performance and the
smallest PAPR which is that of the used QAM constellation at the expense of a
slight increase in detection complexity w.r.t. certain previous codes but this
will only penalize the proposed code for high-order QAM constellations.Comment: 5 pages, 3 figures, and 1 table; IEEE Transactions on Wireless
Communications, Vol. 10, No. 8, AUGUST 201
Training-Embedded, Single-Symbol ML-Decodable, Distributed STBCs for Relay Networks
Recently, a special class of complex designs called Training-Embedded Complex
Orthogonal Designs (TE-CODs) has been introduced to construct single-symbol
Maximum Likelihood (ML) decodable (SSD) distributed space-time block codes
(DSTBCs) for two-hop wireless relay networks using the amplify and forward
protocol. However, to implement DSTBCs from square TE-CODs, the overhead due to
the transmission of training symbols becomes prohibitively large as the number
of relays increase. In this paper, we propose TE-Coordinate Interleaved
Orthogonal Designs (TE-CIODs) to construct SSD DSTBCs. Exploiting the block
diagonal structure of TE-CIODs, we show that, the overhead due to the
transmission of training symbols to implement DSTBCs from TE-CIODs is smaller
than that for TE-CODs. We also show that DSTBCs from TE-CIODs offer higher rate
than those from TE-CODs for identical number of relays while maintaining the
SSD and full-diversity properties.Comment: 7 pages, 2 figure
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
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
Four-Group Decodable Space-Time Block Codes
Two new rate-one full-diversity space-time block codes (STBC) are proposed.
They are characterized by the \emph{lowest decoding complexity} among the known
rate-one STBC, arising due to the complete separability of the transmitted
symbols into four groups for maximum likelihood detection. The first and the
second codes are delay-optimal if the number of transmit antennas is a power of
2 and even, respectively. The exact pair-wise error probability is derived to
allow for the performance optimization of the two codes. Compared with existing
low-decoding complexity STBC, the two new codes offer several advantages such
as higher code rate, lower encoding/decoding delay and complexity, lower
peak-to-average power ratio, and better performance.Comment: 1 figure. Accepted for publication in IEEE Trans. on Signal
Processin
- …