Results 1  10
of
69
Low MLDecoding Complexity, Large Coding Gain, FullRate, FullDiversity STBCs for 2 x 2 and 4 × 2 MIMO systems
, 2009
"... This paper deals with low maximumlikelihood (ML)decoding complexity, fullrate and fulldiversity spacetime block codes (STBCs), which also offer large coding gain, for the 2 transmit antenna, 2 receive antenna (2 2) and the 4 transmit antenna, 2 receive antenna (4 2) MIMO systems. Presently, th ..."
Abstract

Cited by 47 (23 self)
 Add to MetaCart
This paper deals with low maximumlikelihood (ML)decoding complexity, fullrate and fulldiversity spacetime block codes (STBCs), which also offer large coding gain, for the 2 transmit antenna, 2 receive antenna (2 2) and the 4 transmit antenna, 2 receive antenna (4 2) MIMO systems. Presently, the best known STBC for the 2 2 system is the Golden code and that for the 4 2 system is the DjABBA code. Following the approach by Biglieri, Hong, and Viterbo, a new STBC is presented in this paper for the 2 2 system. This code matches the Golden code in performance and MLdecoding complexity for square QAM constellations while it has lower MLdecoding complexity with the same performance for nonrectangular QAM constellations. This code is also shown to be informationlossless and diversitymultiplexing gain (DMG) tradeoff optimal. This design procedure is then extended to the 4 2 system and a code,
DMT optimality of LRaided linear decoders for a general class of channels, lattice designs, and system models
 IEEE TRANS. INFOM. THEORY
, 2010
"... The work identifies the first general, explicit, and nonrandom MIMO encoderdecoder structures that guarantee optimality with respect to the diversitymultiplexing tradeoff (DMT), without employing a computationally expensive maximumlikelihood (ML) receiver. Specifically, the work establishes the ..."
Abstract

Cited by 33 (4 self)
 Add to MetaCart
(Show Context)
The work identifies the first general, explicit, and nonrandom MIMO encoderdecoder structures that guarantee optimality with respect to the diversitymultiplexing tradeoff (DMT), without employing a computationally expensive maximumlikelihood (ML) receiver. Specifically, the work establishes the DMT optimality of a class of regularized lattice decoders, and more importantly the DMT optimality of their latticereduction (LR)aided linear counterparts. The results hold for all channel statistics, for all channel dimensions, and most interestingly, irrespective of the particular latticecode applied. As a special case, it is established that the LLLbased LRaided linear implementation of the MMSEGDFE lattice decoder facilitates DMT optimal decoding of any lattice code at a worstcase complexity that grows at most linearly in the data rate. This represents a fundamental reduction in the decoding complexity when compared to ML decoding whose complexity is generally exponential in rate. The results’ generality lends them applicable to a plethora of pertinent communication scenarios such as quasistatic MIMO, MIMOOFDM, ISI, cooperativerelaying, and MIMOARQ channels, in all of which the DMT optimality of the LRaided linear decoder is guaranteed. The adopted approach yields insight, and motivates further study, into joint transceiver designs with an improved SNR gap to ML decoding.
Multigroup ML Decodable Collocated and Distributed Space Time Block Codes
"... In this paper, collocated and distributed spacetime block codes (DSTBCs) which admit multigroup maximum likelihood (ML) decoding are studied. First the collocated case is considered and the problem of constructing spacetime block codes (STBCs) which optimally tradeoff rate and ML decoding complexi ..."
Abstract

Cited by 26 (18 self)
 Add to MetaCart
(Show Context)
In this paper, collocated and distributed spacetime block codes (DSTBCs) which admit multigroup maximum likelihood (ML) decoding are studied. First the collocated case is considered and the problem of constructing spacetime block codes (STBCs) which optimally tradeoff rate and ML decoding complexity is posed. Recently, sufficient conditions for multigroup ML decodability have been provided in the literature and codes meeting these sufficient conditions were called Clifford Unitary Weight (CUW) STBCs. An algebraic framework based on extended Clifford algebras is proposed to study CUW STBCs and using this framework, the optimal tradeoff between rate and ML decoding complexity of CUW STBCs is obtained for few specific cases. Code constructions meeting this tradeoff optimally are also provided. The paper then focuses on multigroup ML decodable DSTBCs for application in synchronous wireless relay networks and three constructions of fourgroup ML decodable DSTBCs are provided. Finally, the OFDM based Alamouti spacetime coded scheme proposed by LiXia for a 2 relay asynchronous relay network is extended to a more general transmission scheme that can achieve full asynchronous cooperative diversity for arbitrary number of relays. It is then shown how differential encoding at the source can be combined with the proposed transmission scheme to arrive at a new transmission scheme that can achieve full cooperative diversity in asynchronous wireless relay networks with no channel information and also no timing error knowledge at the destination node. Fourgroup decodable DSTBCs applicable in the proposed OFDM based transmission scheme are also given.
Fast MaximumLikelihood Decoding of the Golden Code
 IEEE Trans. on Wireless Comm., accepted
, 2009
"... Abstract—Because each golden code codeword conveys four information symbols from an Mary QAM alphabet, the complexity of an exhaustivesearch decoder is proportional to M 4. In this paper we prove that the golden code is fastdecodable, meaning that maximumlikelihood decoding is possible with a wo ..."
Abstract

Cited by 24 (1 self)
 Add to MetaCart
Abstract—Because each golden code codeword conveys four information symbols from an Mary QAM alphabet, the complexity of an exhaustivesearch decoder is proportional to M 4. In this paper we prove that the golden code is fastdecodable, meaning that maximumlikelihood decoding is possible with a worstcase complexity proportional to only M 2.5. The golden code retains its fastdecodable property regardless of whether the channel varies with time. We also present an efficient implementation of a fast maximumlikelihood decoder that exhibits a low average complexity. Index Terms—Golden code, maximumlikelihood decoding. I.
FastGroupDecodable SpaceTime Block Code
"... Abstract—To make the implementation of highrate STBC realistic in practical systems, groupdecodable and fastdecodable code structures have been separately introduced into STBC to reduce the sphere decoding complexity. However, no STBC has both the two code structures until now. In this paper, hig ..."
Abstract

Cited by 17 (1 self)
 Add to MetaCart
(Show Context)
Abstract—To make the implementation of highrate STBC realistic in practical systems, groupdecodable and fastdecodable code structures have been separately introduced into STBC to reduce the sphere decoding complexity. However, no STBC has both the two code structures until now. In this paper, highrate fastgroupdecodable STBC (FGDSTBC, which has both fastdecodable and groupdecodable code structures) is proposed for the first time. We first derive the condition for fastdecodable code structure with the lowest sphere decoding complexity, then we prove that such fastdecodable code structure can be integrated with the groupdecodable STBC for FGDSTBC construction. Analysis and simulation show that the proposed FGDSTBC has much lower decoding complexity and comparable performance with the existing fastdecodable STBC (FDSTBC). I.
A systematic design of spacetime block codes achieving fulldiversity with partial interference cancelation group decoding
 Proc. Globecom 2009
"... A partial interference cancellation (PIC) group decoding based spacetime block code (STBC) design criterion was recently proposed by Guo and Xia, where the decoding complexity and the code rate tradeoff is dealt when the full diversity is achieved. In this paper, a systematic design of STBC is pro ..."
Abstract

Cited by 12 (1 self)
 Add to MetaCart
(Show Context)
A partial interference cancellation (PIC) group decoding based spacetime block code (STBC) design criterion was recently proposed by Guo and Xia, where the decoding complexity and the code rate tradeoff is dealt when the full diversity is achieved. In this paper, a systematic design of STBC is proposed for any number of transmit antennas that can obtain full diversity when a PIC group decoding (with a particular grouping scheme) is applied at receiver. The proposed STBC are designed from multiple diagonal layers and each layer is composed of a fixed number of coded symbols which are encoded from a cyclotomic lattice design. With the PIC group decoding and an appropriate grouping scheme for the decoding, the proposed STBC are shown to obtain the same diversity gain as the ML decoding, but have a much less decoding complexity compared to the ML decoding. Moreover, the code rate of the proposed STBC can be up to full, i.e., M symbols per channel use for an MIMO system with M transmit antennas when the codeword length is sufficiently large. Some code design examples are given from the systematic code design approach. Simulation results show that the newly proposed STBC can obtain full diversity over Rayleigh fading channels and outperform some existing codes given the same bandwidth efficiency.
Decoding by Sampling: A Randomized Lattice Algorithm for Bounded Distance Decoding
, 2011
"... Despite its reduced complexity, lattice reductionaided decoding exhibits a widening gap to maximumlikelihood (ML) performance as the dimension increases. To improve its performance, this paper presents randomized lattice decoding based on Klein’s sampling technique, which is a randomized version of ..."
Abstract

Cited by 9 (4 self)
 Add to MetaCart
(Show Context)
Despite its reduced complexity, lattice reductionaided decoding exhibits a widening gap to maximumlikelihood (ML) performance as the dimension increases. To improve its performance, this paper presents randomized lattice decoding based on Klein’s sampling technique, which is a randomized version of Babai’s nearest plane algorithm (i.e., successive interference cancelation (SIC)). To find the closest lattice point, Klein’s algorithm is used to sample some lattice points and the closest among those samples is chosen. Lattice reduction increases the probability of finding the closest lattice point, and only needs to be run once during preprocessing. Further, the sampling can operate very efficiently in parallel. The technical contribution of this paper is twofold: we analyze and optimize the decoding radius of sampling decoding resulting in better error performance than Klein’s original algorithm, and propose a very efficient implementation of random rounding. Of particular interest is that a fixed gain in the decoding radius compared to Babai’s decoding can be achieved at polynomial complexity. The proposed decoder is useful for moderate dimensions where sphere decoding becomes computationally intensive, while lattice reductionaided decoding starts to suffer considerable loss. Simulation results demonstrate nearML performance is achieved by a moderate number of samples, even if the dimension is as high as 32.
FastGroupDecodable STBCs via Codes over GF(4)
"... Abstract—In this paper we construct low ML decoding complexity STBCs by using the Pauli matrices as linear dispersion matrices. In this case the HurwitzRadon orthogonality condition is shown to be easily checked by transferring the problem to F4 domain. The problem of constructing low ML decoding c ..."
Abstract

Cited by 7 (2 self)
 Add to MetaCart
(Show Context)
Abstract—In this paper we construct low ML decoding complexity STBCs by using the Pauli matrices as linear dispersion matrices. In this case the HurwitzRadon orthogonality condition is shown to be easily checked by transferring the problem to F4 domain. The problem of constructing low ML decoding complexity STBCs is shown to be equivalent to finding certain codes over F4. It is shown that almost all known low ML decoding complexity STBCs can be obtained by this approach. New classes of codes are given that have the least known ML decoding complexity in some ranges of rate. I.
Hybrid ARQ in MultipleAntenna Slow Fading Channels: Performance Limits and Optimal Linear Dispersion Code Design
, 2009
"... This paper focuses on studying the fundamental performance limits and linear dispersion code design for the MIMOARQ slow fading channel. Optimal average rate of wellknown HARQ protocols is analyzed. The optimal design of spacetime coding for the MIMOARQ channel is discussed. Informationtheoreti ..."
Abstract

Cited by 6 (0 self)
 Add to MetaCart
(Show Context)
This paper focuses on studying the fundamental performance limits and linear dispersion code design for the MIMOARQ slow fading channel. Optimal average rate of wellknown HARQ protocols is analyzed. The optimal design of spacetime coding for the MIMOARQ channel is discussed. Informationtheoretic measures are used to optimize the rate assignment and derive the optimum design criterion, which is then used to evaluate the optimality of existing spacetime codes. A different design criterion, which is obtained from the error probability analysis of spacetime coded MIMOHARQ, is presented. Examples are studied to reveal the gain of ARQ feedback in spacetime coded MIMO systems.