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51
Uniform channel decomposition for MIMO communications
 IEEE Transactions on Signal Processing
, 2005
"... Abstract—Assuming the availability of the channel state information at the transmitter (CSIT) and receiver (CSIR), we consider the joint optimal transceiver design for multiinput multioutput (MIMO) communication systems. Using the geometric mean decomposition (GMD), we propose a transceiver design ..."
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Cited by 51 (8 self)
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Abstract—Assuming the availability of the channel state information at the transmitter (CSIT) and receiver (CSIR), we consider the joint optimal transceiver design for multiinput multioutput (MIMO) communication systems. Using the geometric mean decomposition (GMD), we propose a transceiver design that can decompose, in a strictly capacity lossless manner, a MIMO channel into multiple subchannels with identical capacities. This uniform channel decomposition (UCD) scheme has two implementation forms. One is the combination of a linear precoder and a minimum meansquarederror VBLAST (MMSEVBLAST) detector, which is referred to as UCDVBLAST, and the other includes a dirty paper (DP) precoder and a linear equalizer followed by a DP decoder, which we refer to as UCDDP. The UCD scheme can provide much convenience for the modulation/demodulation and coding/decoding procedures due to obviating the need for bit allocation. We also show that UCD can achieve the maximal diversity gain. The simulation results show that the UCD scheme exhibits excellent performance, even without the use of any error correcting codes. Index Terms—Channel capacity, DBLAST, dirty paper precoder, diversity gain, geometric mean decomposition, joint transceiver
Multiuser MIMOOFDM for NextGeneration Wireless Systems
, 2007
"... This overview portrays the 40year evolution of orthogonal frequency division multiplexing (OFDM) research. The amelioration of powerful multicarrier OFDM arrangements with multipleinput multipleoutput (MIMO) systems has numerous benefits, which are detailed in this treatise. We continue by highl ..."
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Cited by 44 (5 self)
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This overview portrays the 40year evolution of orthogonal frequency division multiplexing (OFDM) research. The amelioration of powerful multicarrier OFDM arrangements with multipleinput multipleoutput (MIMO) systems has numerous benefits, which are detailed in this treatise. We continue by highlighting the limitations of conventional detection and channel estimation techniques designed for multiuser MIMO OFDM systems in the socalled rankdeficient scenarios, where the number of users supported or the number of transmit antennas employed exceeds the number of receiver antennas. This is often encountered in practice, unless we limit the number of users granted access in the base station’s or radio port’s coverage area. Following a historical perspective on the associated design problems and their stateoftheart solutions, the second half of this treatise details a range of classic multiuser detectors (MUDs) designed for MIMOOFDM systems and characterizes their achievable performance. A further section aims for identifying novel cuttingedge genetic algorithm (GA)aided detector solutions, which have found numerous applications in wireless communications in recent years. In an effort to stimulate the cross pollination of ideas across the machine learning, optimization, signal processing, and wireless communications research communities, we will review the broadly applicable principles of various GAassisted optimization techniques, which were recently proposed also
The generalized triangular decomposition
 Mathematics of Computation
, 2006
"... Abstract. Given a complex matrix H, we consider the decomposition H = QRP ∗ , where R is upper triangular and Q and P have orthonormal columns. Special instances of this decomposition include (a) the singular value decomposition (SVD) where R is a diagonal matrix containing the singular values on th ..."
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Cited by 32 (4 self)
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Abstract. Given a complex matrix H, we consider the decomposition H = QRP ∗ , where R is upper triangular and Q and P have orthonormal columns. Special instances of this decomposition include (a) the singular value decomposition (SVD) where R is a diagonal matrix containing the singular values on the diagonal, (b) the Schur decomposition where R is an upper triangular matrix with the eigenvalues of H on the diagonal, (c) the geometric mean decomposition (GMD) [The Geometric Mean Decomposition, Y. Jiang, W. W. Hager, and J. Li, December 7, 2003] where the diagonal of R is the geometric mean of the positive singular values. We show that any diagonal for R can be achieved that satisfies Weyl’s multiplicative majorization conditions: k� k� ri  ≤ σi, 1 ≤ k < K, i=1 i=1 K� K� ri  = σi, where K is the rank of H, σi is the ith largest singular value of H, and ri is the ith largest (in magnitude) diagonal element of R. We call the decomposition H = QRP ∗ , where the diagonal of R satisfies Weyl’s conditions, the generalized triangular decomposition (GTD). The existence of the GTD is established using a result of Horn [On the eigenvalues of a matrix with prescribed singular values, Proc. Amer. Math. Soc., 5 (1954), pp. 4–7]. In addition, we present a direct (nonrecursive) algorithm that starts with the SVD and applies a series of permutations and Givens rotations to obtain the GTD. The GMD has application to signal processing and the design of multipleinput multipleoutput (MIMO) systems; the lossless filters Q and P minimize the maximum error rate of the network. The GTD is more flexible than the GMD since the diagonal elements of R need not be identical. With this additional freedom, the performance of a communication channel can be optimized, while taking into account differences in priority or differences in quality of service requirements for subchannels. Another application of the GTD is to inverse eigenvalue problems where the goal is to construct matrices with prescribed eigenvalues and singular values. Key words. Generalized triangular decomposition, geometric mean decomposition, matrix factorization, unitary factorization, singular value decomposition, Schur decomposition, MIMO systems, inverse eigenvalue problems
A framework for designing MIMO systems with decision feedback equalization or TomlinsonHarashima precoding
 Proc. of the ICASSP
, 2007
"... We consider joint transceiver design for general MultipleInput MultipleOutput communication systems that implement interference (pre)subtraction, such as those based on Decision Feedback Equalization (DFE) or TomlinsonHarashima precoding (THP). We develop a unified framework for joint transceive ..."
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Cited by 27 (1 self)
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We consider joint transceiver design for general MultipleInput MultipleOutput communication systems that implement interference (pre)subtraction, such as those based on Decision Feedback Equalization (DFE) or TomlinsonHarashima precoding (THP). We develop a unified framework for joint transceiver design by considering design criteria that are expressed as functions of the Mean Square Error (MSE) of the individual data streams. By deriving two inequalities that involve the logarithms of the individual MSEs, we obtain optimal designs for two classes of communication objectives, namely those that are Schurconvex and Schurconcave functions of these logarithms. For Schurconvex objectives, the optimal design results in data streams with equal MSEs. This design simultaneously minimizes the total MSE and maximizes the mutual information for the DFEbased model. For Schurconcave objectives, the optimal DFE design results in linear equalization and the optimal THP design results in linear precoding. The proposed framework embraces a wide range of design objectives and can be regarded as a counterpart of the existing framework of linear transceiver design.
MIMO Transceivers With Decision Feedback and Bit Loading: Theory and Optimization
, 2010
"... This paper considers MIMO transceivers with linear precoders and decision feedback equalizers (DFEs), with bit allocation at the transmitter. Zeroforcing (ZF) is assumed. Considered first is the minimization of transmitted power, for a given total bit rate and a specified set of error probabilities ..."
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Cited by 16 (6 self)
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This paper considers MIMO transceivers with linear precoders and decision feedback equalizers (DFEs), with bit allocation at the transmitter. Zeroforcing (ZF) is assumed. Considered first is the minimization of transmitted power, for a given total bit rate and a specified set of error probabilities for the symbol streams. The precoder and DFE matrices are optimized jointly with bit allocation. It is shown that the generalized triangular decomposition (GTD) introduced by Jiang, Li, and Hager offers an optimal family of solutions. The optimal linear transceiver (which has a linear equalizer rather than a DFE) with optimal bit allocation is a member of this family. This shows formally that, under optimal bit allocation, linear and DFE transceivers achieve the same minimum power. The DFE transceiver using the geometric mean decomposition (GMD) is another member of this optimal family, and is such that optimal bit allocation yields identical bits for all symbol streams—no bit allocation is necessary—when the specified error probabilities are identical for all streams. The QRbased system used in VBLAST is yet another member of the optimal family and is particularly wellsuited when limited feedback is allowed from receiver to transmitter. Two other optimization problems are then considered: a) minimization of power for specified set of bit rates and error probabilities (the QoS problem), and b) maximization of bit rate for fixed set of error probabilities and power. It is shown in both cases that the GTD yields an optimal family of solutions.
Tunable channel decomposition for MIMO communications using channel state information
 IEEE Transactions on Signal Processing
, 2006
"... Abstract—We consider jointly designing transceivers for multipleinput multipleoutput (MIMO) communications. Assuming the availability of the channel state information (CSI) at the transmitter (CSIT) and receiver (CSIR), we propose a scheme that can decompose a MIMO channel, in a capacity lossless ..."
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Cited by 16 (1 self)
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Abstract—We consider jointly designing transceivers for multipleinput multipleoutput (MIMO) communications. Assuming the availability of the channel state information (CSI) at the transmitter (CSIT) and receiver (CSIR), we propose a scheme that can decompose a MIMO channel, in a capacity lossless manner, into multiple subchannels with prescribed capacities, or equivalently, signaltointerferenceandnoise ratios (SINRs). We refer to this scheme as the tunable channel decomposition (TCD), which is based on the recently developed generalized triangular decomposition (GTD) algorithm and the closedform representation of minimum meansquarederror VBLAST (MMSEVBLAST) equalizer. The TCD scheme is particularly relevant to the applications where independent data streams with different qualitiesofservice (QoS) share the same MIMO channel. The TCD scheme has two implementation forms. One is the combination of a linear precoder and a minimum meansquarederror VBLAST (MMSEVBLAST) equalizer, which is referred to as TCDVBLAST, and the other includes a dirty paper (DP) precoder and a linear equalizer followed by a DP decoder, which we refer to as TCDDP. We also include the optimal codedivision multipleaccess (CDMA) sequence design as a special case in the framework of MIMO transceiver designs. Hence, our scheme can be directly applied to optimal CDMA sequence design, both in the uplink and downlink scenarios. Index Terms—Channel capacity, channel decomposition, dirty paper (DP) precoding, generalized triangular decomposition, joint transceiver design, multipleinput multipleoutput (MIMO), optimal CDMA sequences, qualityofservice, VBLAST. I.
Precoder design for multiuser MIMO ISI channels based on iterative LMMSE detection
 ISIT 2010
, 2009
"... Abstract—Precoding has been widely investigated for multipleinput multipleoutput (MIMO) and intersymbol interference (ISI) channels. Most related work so far has been on uncoded systems and the impact of forwarderrorcorrection (FEC) codes has not been well studied. In this paper, we present an ..."
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Cited by 11 (8 self)
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Abstract—Precoding has been widely investigated for multipleinput multipleoutput (MIMO) and intersymbol interference (ISI) channels. Most related work so far has been on uncoded systems and the impact of forwarderrorcorrection (FEC) codes has not been well studied. In this paper, we present an optimized precoding technique that takes into account iterative joint LMMSE detection and FEC decoding. The proposed scheme has some interesting features. First, the design problem is convex. Second, the proposed scheme achieves waterfilling gain when channel state information at the transmitter (CSIT) is available and diversity gain when CSIT is not available, as well as multiuser gain in multiuser environments. Third, the waterfilling gain is achieved using a single code (instead of multiple codes as in conventional approaches), which greatly simplifies the design and implementation problems. Both simulation and evolution analyses are provided to show that significant performance improvement can be achieved with the proposed scheme. Index Terms—Iterative linear minimummeansquareerror (LMMSE) detection, multipleinput multipleoutput (MIMO) intersymbol interference (ISI) multipleaccess channel, precoder. I.
Block Diagonal Geometric Mean Decomposition (BDGMD) for MIMO Broadcast Channels
, 2008
"... In recent years, the research on multipleinput multipleoutput (MIMO) broadcast channels has attracted much interest, especially since the discovery of the broadcast channel capacity achievable through the use of dirty paper coding (DPC). In this paper, we propose a new matrix decomposition, called ..."
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Cited by 6 (1 self)
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In recent years, the research on multipleinput multipleoutput (MIMO) broadcast channels has attracted much interest, especially since the discovery of the broadcast channel capacity achievable through the use of dirty paper coding (DPC). In this paper, we propose a new matrix decomposition, called the block diagonal geometric mean decomposition (BDGMD), and develop transceiver designs that combine DPC with BDGMD for MIMO broadcast channels. We also extend the BDGMD to the block diagonal uniform channel decomposition (BDUCD) with which the MIMO broadcast channel capacity can be achieved. Our proposed schemes decompose each user’s MIMO channel into parallel subchannels with identical SNRs/SINRs, thus equalrate coding can be applied across the subchannels of each user. Numerical simulations show that the proposed schemes demonstrate superior performance over conventional schemes.
Generalized Triangular Decomposition in Transform Coding
, 2010
"... A general family of optimal transform coders (TCs) is introduced here based on the generalized triangular decomposition (GTD) developed by Jiang et al. This family includes the Karhunen–Loeve transform (KLT) and the generalized version of the predictionbased lower triangular transform (PLT) introd ..."
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Cited by 4 (2 self)
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A general family of optimal transform coders (TCs) is introduced here based on the generalized triangular decomposition (GTD) developed by Jiang et al. This family includes the Karhunen–Loeve transform (KLT) and the generalized version of the predictionbased lower triangular transform (PLT) introduced by Phoong and Lin as special cases. The coding gain of the entire family, with optimal bit allocation, is equal to that of the KLT and the PLT. Even though the original PLT introduced by Phoong et al. is not applicable for vectors that are not blocked versions of scalar wide sense stationary processes, the GTDbased family includes members that are natural extensions of the PLT, and therefore also enjoy the socalled MINLAB structure of the PLT, which has the unit noisegain property. Other special cases of the GTDTC are the geometric mean decomposition (GMD) and the bidiagonal decomposition (BID) transform coders. The GMDTC in particular has the property that the optimum bit allocation is a uniform allocation; this is because all its transform domain coefficients have the same variance, implying thereby that the dynamic ranges of the coefficients to be quantized are identical.
Joint optimization of transceivers with decision feedback and bit loading
 in Proc. 42nd Asilomar Conf. Signals, Systems, and Computers
, 2008
"... Abstract — The transceiver optimization problem for MIMO channels has been considered in the past with linear receivers as well as with decision feedback (DFE) receivers. Joint optimization of bit allocation, precoder, and equalizer has in the past been considered only for the linear transceiver (tr ..."
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Cited by 3 (3 self)
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Abstract — The transceiver optimization problem for MIMO channels has been considered in the past with linear receivers as well as with decision feedback (DFE) receivers. Joint optimization of bit allocation, precoder, and equalizer has in the past been considered only for the linear transceiver (transceiver with linear precoder and linear equalizer). It has also been observed that the use of DFE even without bit allocation in general results in better performance that linear transceivers with bit allocation. This paper provides a general study of this for transceivers with the zeroforcing constraint. It is formally shown that when the bit allocation, precoder, and equalizer are jointly optimized, linear transceivers and transceivers with DFE have identical performance in the sense that transmitted power is identical for a given bit rate and error probability. The developments of this paper are based on the generalized triangular decomposition (GTD) recently introduced by Jiang, Li, and Hager. It will be shown that a broad class of GTDbased systems solve the optimal DFE problem with bit allocation. The special case of a linear transceiver with optimum bit allocation will emerge as one of the many solutions. 1