Since the introduction of the Diversity-Multiplexing Tradeoff (DMT) by Zheng and Tse for ML reception in frequency-flat MIMO channels, some results have been obtained also for the DMT of frequency-selective MIMO chann...
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ISBN:
(纸本)9781424423538
Since the introduction of the Diversity-Multiplexing Tradeoff (DMT) by Zheng and Tse for ML reception in frequency-flat MIMO channels, some results have been obtained also for the DMT of frequency-selective MIMO channels and for the DMT of suboptimal receivers such as linear (LEs) and decision-feedback equalizers (DFEs) for frequency-selective SIMO channels or frequency-flat MIMO channels. We have recently extended these results to the case of linear receivers for frequency-selective MIMO channels. However, the diversity properties of linear receivers turn out to be fairly catastrophic. In this paper we show that full diversity can be restored by the introduction of a convolutive linear MIMO precoding scheme that we showed earlier to allow to attain the optimal DMT for ML or DFE detection (in the frequency-flat case). The precoder needs to be used with a moderate amount of redundancy in the form of zero-padding, and with a MMSE design for the linear equalizer. A MMSE-ZF design also benefits substantially from the precoding. The proposed scheme is a significant extension of an earlier SISO result by Tepelenlioglu to the MIMO case.
An optimal multi-user MIMO linear precoding scheme based on particle swarm optimization is proposed in this paper. The proposed scheme aims to maximize the system capacity of multi-user MIMO system. This paper explore...
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ISBN:
(纸本)9781424420742
An optimal multi-user MIMO linear precoding scheme based on particle swarm optimization is proposed in this paper. The proposed scheme aims to maximize the system capacity of multi-user MIMO system. This paper explores a simplified function to measure the optimal problem. With the adoption of particle swarm optimization algorithm, the optimal linear precoding vector could he easily searched according to the simplified function. The proposed scheme outperforms the multi-user MIMO linear precoding schemes based on channel inversion and channel block digonolization methods.
Transmitter precoding strategies in broadcast systems generally assume perfect knowledge of channel state information (CSI) at the transmitter. In this paper, we study linear precoding with arbitrary error in the CSI ...
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ISBN:
(纸本)9781424443123
Transmitter precoding strategies in broadcast systems generally assume perfect knowledge of channel state information (CSI) at the transmitter. In this paper, we study linear precoding with arbitrary error in the CSI from an estimation theoretic point of view. We derive a Bayesian Cramer-Rao type bound on the sum mean squared error (SMSE) achievable at the receiver for any linear precoding scheme for arbitrary feedback noise and channel fading. We next specialize this result to power constrained precoders. It is shown that the regularity conditions of the bound may be significantly weakened for power constrained precoders. Interestingly, we obtain a bound whose validity depends on rather weak conditions of continuity and differentiability on the joint distribution of the channel and feedback. We demonstrate the bound by applying it to Gaussian, Nakagami-m and Weibull fading models, with the assumption of feedback corrupted by additive Gaussian noise.
The problem that often occur in multi-antenna wireless communication is how to maximize the throughput. precoding is a generalization of beamforming to support multi-layer transmission in multi-antenna wireless commun...
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ISBN:
(纸本)9781467360562
The problem that often occur in multi-antenna wireless communication is how to maximize the throughput. precoding is a generalization of beamforming to support multi-layer transmission in multi-antenna wireless communications. Beamforming is a signal processing technique used in sensor arrays for directional signal transmission or reception. In conventional single-layer beamforming, the same signal is emitted from each of the transmit antennas with appropriate weighting such that the signal power is maximized at the receiver output. When the receiver has multiple antennas, single-layer beamforming cannot simultaneously maximize the signal level at all of the receive antennas. Thus, in order to maximize throughput in a receiving antenna system, integrated precoding in multi-layer beamforming is required. LTE linear precoding system for the transmitter side is built in this research. The precoding system will be built in VHDL code and will be implemented on FPGA. In this research, the precoding sistem consists of 64-QAM Mapper as input system, and will be connected to OFDM (IFFT) block. The precoding is built based on Transmission Mode (TM) 6 of LTE release 9 and will be using 3GPP codebook standard as the precoding matrix for TM 6 for 2x2 MIMO. [GRAPHICS] The research shows that by the used of linear precoding system in transmission, it decreases the complexion of detection system in precoding block on the receiver side. The implementation process shows that the research is implementable on hardware and will use 62% occupied slices, 11% slice register, and 27% of bounded IOBs resources of FPGA. with 2021 clock in total process, 121 clock in delay process and 1900 clocks to produce one OFDM symbol. The bitrate of the system is 161.68 Mbps.
Combining wprecoding and orthogonal space-time block codes (OSTBCs) can obtain full-diversity order and provide additional array gain. This paper proposes optimal linear precoding and quantization for OSTBCs with erro...
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ISBN:
(纸本)9781424448203
Combining wprecoding and orthogonal space-time block codes (OSTBCs) can obtain full-diversity order and provide additional array gain. This paper proposes optimal linear precoding and quantization for OSTBCs with erroneous feedback. Lloyd algorithm is used for designing codebooks with noisy quantized feedback in general case. In two extreme cases, the transmitter can obtain perfect CSI and no CSI available, the optimal unquantized precoder for each case are presents and quantization scheme is analysed. The result shows that the quantized codebook proposed in this paper can obtain better performance compared to open loop systems when feedback link is erroneous
In this paper, we study the iterative weighted sum rate (WSR) maximizing linear precoder algorithm proposed by Christensen et al. in large correlated MISO broadcast channels. We propose a novel approximation of the si...
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ISBN:
(纸本)9781424493326
In this paper, we study the iterative weighted sum rate (WSR) maximizing linear precoder algorithm proposed by Christensen et al. in large correlated MISO broadcast channels. We propose a novel approximation of the signal-to-interference plus noise ratio (SINR) at every iteration. Moreover, for identical distributed channels the proposed approximation of the WSR maximizing precoder is of closed form and has the well known regularized zero-forcing (RZF) structure. Simulation results show that under correlated channels, the novel SINR approximation is more accurate than previously proposed estimates based on the RZF precoder.
Cyclic delay diversity (CDD) is considered a simple approach to exploit the frequency diversity, to improve the system performance in orthogonal frequency division multiplexing (OFDM) systems. Also, the linear precodi...
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ISBN:
(纸本)9788955191387
Cyclic delay diversity (CDD) is considered a simple approach to exploit the frequency diversity, to improve the system performance in orthogonal frequency division multiplexing (OFDM) systems. Also, the linear precoding technique can significantly improve the performance of communication systems by exploiting the channel state information (CSI). In order to achieve enhanced performance, we propose applying linear precoding to the conventional CDD-OFDM transmit diversity schemes over Rayleigh fading channels. The proposed scheme works effectively with the accurate CSI in time-division-duplex (TDD) OFDM systems with CDD, where the reciprocity is assumed instead of channel state feedback. For a bit error rate (BER) of 10(-4) and the mobility of 3 km/h, simulation results show that a gain of 6 dB is achieved by the proposed scheme over both flat fading and Pedestrian A (Ped A) channels, compared to the conventional CDD-OFDM system. On the other hand, for a mobility of 120 km/h, a gain of 2.7 dB and 3.8 dB is achieved in flat fading and Vehicular A (Veh A) channels, respectively.
In this paper, we investigate linear precoding and scheduling algorithms for downlink multi-user multiple input multiple output (MU-MIMO) systems. In order to eliminate the multi-user interference and improve the bit ...
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ISBN:
(纸本)9781467300407
In this paper, we investigate linear precoding and scheduling algorithms for downlink multi-user multiple input multiple output (MU-MIMO) systems. In order to eliminate the multi-user interference and improve the bit error rate (BER) system performance, block diagonalization precoding could be combined with geometric mean decomposition (BD-GMD) scheme. We propose GMD linear precoding approaches utilizing oblique projection (OP-GMD). This paper also derives system capacity in closed-form through applying water-filling power allocation algorithm into the system model. Our simulation results show that the proposed scheduling algorithms perform better with the increase of the number of transmit antennas. In terms of system capacity, the proposed OP-GMD algorithms significantly outperform the precoding scheme based on BD-GMD at low SNRs.
In this paper, we propose a low-complexity transmit antenna selection algorithm for MIMO multiuser channels. This algorithm greedily finds the optimal transmit antenna subset in base station. When the transmit power f...
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ISBN:
(纸本)9781424456383
In this paper, we propose a low-complexity transmit antenna selection algorithm for MIMO multiuser channels. This algorithm greedily finds the optimal transmit antenna subset in base station. When the transmit power for individual data streams is equal, the proposed algorithm can be applied to the zero-forcing and the MMSE precoding schemes to further simplify the computational complexity. Simulation results show that the proposed low-complexity suboptimal antenna selections can achieve very close performance with the optimal antenna selection scheme in [6]. As a result, a good trade-off between complexity and performance is attained by the proposed antenna selection schemes.
Both channel coding over a finite field and linear precoding over a complex field can improve the system performance in wireless fading channels. In this paper, we investigate the potential benefit of linear precoding...
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ISBN:
(纸本)9781467308298;9781467308304
Both channel coding over a finite field and linear precoding over a complex field can improve the system performance in wireless fading channels. In this paper, we investigate the potential benefit of linear precoding in a nonbinary LDPC coded underwater acoustic OFDM system. Real precoders of small sizes are selected in different setups, in order to avoid any complexity increase at the receiver. Simulations and emulated experimental results demonstrate the benefits of linear precoding, particularly when the receiver has a small number of hydrophones.
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