| 1. |
- Bergman, Svante, 1979-, et al.
(författare)
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Joint Bit Allocation and Precoding for MIMO Systems With Decision Feedback Detection
- 2009
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Ingår i: IEEE Transactions on Signal Processing. - : IEEE. - 1053-587X .- 1941-0476. ; 57:11, s. 4509-4521
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Tidskriftsartikel (refereegranskat)abstract
- This paper considers the joint design of bit loading, precoding and receive filters for a multiple-input multiple-output (MIMO) digital communication system employing decision feedback (DF) detection at the receiver. Both the transmitter as well as the receiver are assumed to know the channel matrix perfectly. It is well known that, for linear MIMO transceivers, a diagonal transmission (i.e., orthogonalization of the channel matrix) is optimal for some criteria. Surprisingly, it was shown five years ago that for the family of Schur-convex functions an additional rotation of the symbols is necessary. However, if the bit loading is optimized jointly with the linear transceiver, then this rotation is unnecessary. Similarly, for DF MIMO optimized transceivers a rotation of the symbols is sometimes needed. The main result of this paper shows that for a DF MIMO transceiver where the bit loading is jointly optimized with the transceiver filters, the rotation of the symbols becomes unnecessary, and because of this, also the DF part of the receiver is not required. The proof is based on a relaxation of the available bit rates on the individual substreams to the set of positive real numbers. In practice, the signal constellations are discrete and the optimal relaxed bit loading has to be rounded. It is shown that the loss due to rounding is small, and an upper bound on the maximum loss is derived. Numerical results are presented that confirm the theoretical results and demonstrate that orthogonal transmission and the truly optimal DF design perform almost equally well.
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| 2. |
- Bergman, Svante, 1979-, et al.
(författare)
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Optimal Bit Loading for MIMO Systems with Decision Feedback Detection
- 2009
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Ingår i: 2009 IEEE Vehicular Technology Conference. - : IEEE. - 9781424425167 ; , s. 831-835
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Konferensbidrag (refereegranskat)abstract
- This paper considers the joint design of bit loading, precoding and receive filters for a multiple-input multiple-output (MIMO) digital communication system employing decision feedback (DF) detection at the receiver. Both the transmitter as well as the receiver are assumed to know the channel matrix perfectly. It is well known that, for linear MIMO transceivers, a diagonal transmission (i.e., orthogonalization of the matrix channel) is optimal for some criteria. Surprisingly, it was shown five years ago that for the family of Schur-convex functions an additional rotation of the symbols is necessary. However, if the bit loading is optimized jointly with the linear transceiver, then the rotation is unnecessary. Similarly, for DF MIMO transceivers, a rotation of the symbols is sometimes needed. The main result of this paper shows that for a DF MIMO transceiver where the bit loading is jointly optimized with the transceiver filters, the rotation of the symbols becomes unnecessary and, consequently, also the DF part of the receiver is not required.
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| 3. |
- Wang, Jiaheng, et al.
(författare)
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Robust maximin MIMO precoding for arbitrary convex uncertainty sets
- 2012
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Ingår i: Acoustics, Speech and Signal Processing (ICASSP), 2012 IEEE International Conference on. - : IEEE. - 9781467300469 ; , s. 3045-3048
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Konferensbidrag (refereegranskat)abstract
- We consider a worst-case robust precoding design for multi-input multi-output (MIMO) communication systems with imperfect channel state information at the transmitter (CSIT). Instead of a particular choice, we consider a general imperfect CSIT model that only assumes the channel errors to be within a convex set, which includes most common imperfect CSIT models as special cases. The robust precoding design is formulated as a maximin problem, aiming at maximizing the worst-case received signal-to-noise ratio or minimizing the worst-case error probability. It is shown that the robust precoder can be easily obtained by solving a convex problem. We further provide an equivalent but more practical form of the convex problem that can be efficiently handled with common optimization methods and software packages.
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| 4. |
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| 5. |
- Wang, Jiaheng, et al.
(författare)
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Robust MIMO Precoding for the Schatten Norm Based Channel Uncertainty Sets
- 2013
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Ingår i: 2013 IEEE Global Communications Conference (GLOBECOM). - : IEEE Communications Society. - 9781479913534 ; , s. 3394-3399
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Konferensbidrag (refereegranskat)abstract
- In this paper, we consider robust MIMO precoding designs against deterministic imperfect channel state information at the transmitter (CSIT). In contrast to the existing works based on one or two particular channel uncertainty models, we consider a general uncertainty set defined by a generic matrix norm, called the Schatten norm, which includes most deterministic imperfect CSIT as special cases. Adopting worst-case robustness, the robust MIMO precoding design is formulated as a maximin problem to maximize the worst-case received signal-to-noise ratio or minimize the worst-case error probability. We show that the robust precoder admits a channel-diagonalizing structure for all Schatten norm based uncertainty sets, and then simplify the complex-valued matrix problem to a real-valued vector power allocation problem. We further show that the simplified power allocation problem can be analytically solved in a waterfilling manner, thus leading to a fully closed-form solution to the robust precoding design. Finally, we also investigate the robustness of beamforming and uniform-power transmission.
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| 6. |
- Zhang, Xi, et al.
(författare)
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Robust design of linear MIMO transceiver for low SNR
- 2005
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Ingår i: 2005 39th Asilomar Conference on Signals, Systems and Computers, Vols 1 and 2. - NEW YORK : IEEE. ; , s. 398-402
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Konferensbidrag (refereegranskat)abstract
- In practical systems, the design of linear MIMO transceivers should be robust to partial or imperfect channel state information (CSI). This paper considers the case in which only the second-order statistics of the channel is known at the transmitter while the receiver has a perfect CSI. In such a case, it is possible to optimally design robust MIMO transceivers based on a general cost function covering several well known performance criteria. In particular, two families are considered in detail: Schur-convex and Schur-concave functions. Approximations are used in the low SNR regime to obtain simple optimization problems that can be readily solved. Numerical examples show substantial gains compared to other methods.
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| 7. |
- Zhang, Xi, et al.
(författare)
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Robust design of linear MIMO transceivers under channel uncertainty
- 2006
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Ingår i: 2006 IEEE International Conference on Acoustics, Speech, and Signal Processing. ; , s. 77-80
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Konferensbidrag (refereegranskat)abstract
- This paper considers the robust design of a linear transceiver with imperfect channel state information (CSI) at the transmitter of a MIMO link. The framework embraces the design problem when CSI at the transmitter consists of the channel mean and covariance matrix or, equivalently, the channel estimate and the estimation error covariance matrix. The design of the linear MIMO transceiver is based on a general cost function covering several well known performance criteria. In particular, two families are considered in detail: Schur-convex and Schur-concave functions. Approximations are used in the low SNR and high SNR regimes separately to obtain simple optimization problems that can be readily solved. Numerical examples show gains compared to other suboptimal methods.
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| 8. |
- Zhang, Xi, et al.
(författare)
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Robust MAC MIMO transceiver design with partial CSIT and CSIR
- 2007
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Ingår i: CONFERENCE RECORD OF THE FORTY-FIRST ASILOMAR CONFERENCE ON SIGNALS, SYSTEMS & COMPUTERS, VOLS 1-5. - NEW YORK : IEEE. - 9781424421091 ; , s. 324-328
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Konferensbidrag (refereegranskat)abstract
- In practical wireless systems, the design of linear MIMO transceivers should be robust to imperfect channel state information (CSI), especially in multiuser systems where accurate CSI is difficult to obtain. This paper considers the case in which the CSI is perturbed at both sides of the link. In such a case, it is possible to optimally design robust MIMO transceivers to minimize the average sum MSE of all the data streams and the users. For systems with a sum power constraint, our robust design can be shown to be a convex SDP problem; for systems with individual power constraints, our robust design is based on an underlying SDP problem.
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| 9. |
- Zhang, Xi, et al.
(författare)
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Statistically robust design of linear MIMO transceivers
- 2008
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Ingår i: IEEE Transactions on Signal Processing. - : IEEE. - 1053-587X .- 1941-0476. ; 56:8, s. 3678-3689
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Tidskriftsartikel (refereegranskat)abstract
- The treatment of channel state information (CSI) is critical in the design of MIMO systems. Accurate CSI at the transmitter is often not possible or may require high feedback rates. Herein, we consider the robust design of linear MIMO transceivers with perfect CSI either at the transmitter or at both sides of the link. The framework considers the design problem where the imperfect CSI consists of the channel mean and covariance matrix or, equivalently, the channel estimate and the estimation error covariance matrix. The robust transceiver design is based on a general cost function of the average MSEs as well as a design with individual MSE based constraints. In particular, a lower bound of the average MSE matrix is explored for the design when only the CSI at the transmitter is imperfect. Under different CSI conditions, the proposed robust transceivers exhibit a similar structure to the transceiver designs for perfect CSI, but with a different equivalent channel and/or noise covariance matrix.
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