An Overview of MIMO Communications—A Key to Gigabit Wireless

Paulraj, A.; Gore, D.; Nabar, R.U.; Bölcskei, Helmut

doi:10.1109/jproc.2003.821915

Cited by 1,735 publications

(986 citation statements)

References 56 publications

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“…The VB-Soft-KF algorithm expressed by (41)-(44) can also be obtained by applying the standard KF [30] to the state-space model expressed by (45) and (2). When the channel is fast fading, the soft symbols with low reliabilities render the state-space model to be an inaccurate error-in-variable model [6] and generate outliers, which may make the KF diverge from the real channel trajectory.…”

Section: Tracking Of Channel Impulse Responsementioning

confidence: 99%

“…One of the important advantages of OFDM is its robustness to frequency-selective channels [1]. Multiple antennas can be used in conjunction with OFDM to improve the channel capacity and quality of communication systems [2]. MIMO-OFDM has been adopted in many wireless communication standards, such as the Worldwide Interoperability for Microwave Access (WiMAX) IEEE 802.16 e/m standard and the Third Generation Partnership Project long term evolution (3GPP LTE).…”

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confidence: 99%

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Variational-Bayes-Assisted Joint Signal Detection, Noise Covariance Estimation, and Channel Tracking in MIMO-OFDM Systems

Zhang

Xiao

et al. 2014

IEEE Trans. Veh. Technol.

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This paper introduces an improved variational bayes (Improved-VB) receiver algorithm for joint signal detection, noise covariance matrix estimation and channel impulse response (CIR) tracking in MIMO-OFDM systems over time varying channels. The variational bayes (VB) framework and turbo principle are combined to accomplish the parameter estimation and data detection. In the proposed Improved-VB receiver, a modified linear minimum mean-square-error interference cancellation (LMMSE-IC) soft detector is developed based on the VB theory, which adaptively sets the log-likelihood ratio (LLR) clipping value according to the reliability of detection on each subcarrier to mitigate the error propagation. Following the signal detection, an adaptive noise covariance matrix estimator is derived for the effective noise covariance estimation. Furthermore, in order to track time varying channels, a VB softinput Kalman filter (VB-Soft-KF) is first derived. However, unreliable soft symbols introduce outliers, which degrade the performance of VB-Soft-KF. To tackle this problem, we propose a robust VB softinput Kalman filter (VB-Robust-KF) based on the Huber M estimation theory. Finally, the performance The material has been presented in parts at IEEE PIMRC 2010, Istanbul, Turkey, Sep. 26-30.

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Section: Tracking Of Channel Impulse Responsementioning

confidence: 99%

mentioning

confidence: 99%

Variational-Bayes-Assisted Joint Signal Detection, Noise Covariance Estimation, and Channel Tracking in MIMO-OFDM Systems

Zhang

Xiao

et al. 2014

IEEE Trans. Veh. Technol.

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“…In [1], The outline is variety of cost, technology and regulatory constraints make such a brute force solution unattractive if not impossible. The use of multiple antennas at transmitter and receiver, popularly known as multiple input multiple-output (MIMO) wireless is an emerging cost-effective technology that offers substantial leverages in making 1Gbps wireless links a reality.…”

Section: Literature Surveymentioning

confidence: 99%

Transmission Characteristics of 2x2 MIMO System Using OSTBC Multiplexing for Different Detector Systems

Bhagya¹,

ANANTH²

2014

IJAREEIE

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ABSTRACT:A detail analysis of the performance of 2X2 MIMO (Multiple Input Multiple Output) antenna systems has been carried out for three different types of detectors at the receiver end by determining the transmit diversity using OSTBC multiplexing techniques. The transmission characteristics of the MIMO system have been determined for BPSK, QPSK and 16-QAM modulation schemes presuming Additive White Gaussian Noise (AWGN) and for the flat fading Rayleigh channel. On the receiver side, equalization detection technique are determined by combining Successive Interference Cancellation with Zero Forcing (ZF-SIC), Minimum Mean Square Equalization (MMSE-SIC) and Maximum Likelihood (ML-SIC) has been employed for determining the BER Vs SNR performance of the communication channel. The simulation results show that for BER of ~10 -3 , the SNR increases with higher modulation schemes from BPSK to 16-QAM. Further the results of the analysis for different detector systems indicate that for BPSK modulation at BER ~10 -3 , the SNR values are found to be ~24.46 dB for ZF-SIC, SNR ~20.6 dB for MMSE-SIC and SNR ~14.46 dB for ML-SIC detectors. Thus the BER performance of 2X2 MIMO-OSTBC transmission channel shows the reduction of SNR ~10 dB for ML detectors. A comparison of the MIMO performance with OSTBC multiplexing techniques indicate that the 2x2 MIMO-OSTBC transmission channel for BPSK modulation depicts better performance for OSTBC multiplexing with ML detector system at the receiving end. The simulations results are presented and discussed in the paper. KEYWORDS: I.INTRODUCTIONA mobile radio channel is characterized by a multipath fading environment. The signal is offered to the receiver contains not only line of sight of radio wave , but also a large number of reflected radio waves that arrive at the receiver at different times. Delayed signals are the result of reflections from terrain features such as trees, hills, mountains, vehicles or buildings. These reflected delayed waves interfere with direct waves and cause Inter Symbol Interference (ISI) which causes significant degradation of network performance. MIMO technology has attracted attention in wireless communications, because it offers significant increases in data throughput and link range without additional bandwidth or transmit power. It achieves this by higher spectral efficiency and link reliability or diversity (reduced fading). Because of these properties, MIMO is an important part of modern wireless communication standards such as IEEE 802.11n (Wi-Fi), 4G, 3GPP Long Term Evolution and WiMAX [1,2 ,3]. OSTBCs are attractive techniques for MIMO wireless communications. They exploit full spatial diversity order and employ symbol-wise decoding such as ZF, MMSE and ML. MIMO-OSTBC with detectors is used to reduce complexity and noise in flat fading Rayleigh channels. MIMO techniques offer the promise of high spectral efficiency and robustness to fading. Key to their success is the MIMO detector at the receiver, whose job is to recover the symbols that are transmitt...

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“…where the functionP b is given by the average Rayleigh error probability (11). Equation (19) has been checked by means of numerical integration.…”

Section: Antenna Diversitymentioning

confidence: 99%

“…In a second step, these expressions have been extended by taking into consideration the presence of interferences in AWGN and Rayleigh channels. Finally, the concept of antenna diversity [11,12] is introduced to increase the probability of detection in presence of interferences. Antenna diversity allows for reducing considerably the reader-to-reader distance in a Rayleigh channel down to a distance close to the AWGN channel case.…”

Section: Introductionmentioning

confidence: 99%

Effects of Interferences in Uhf Rfid Systems

Lázaro¹,

Girbau²,

Villarino³

2009

PIER

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Abstract-The Radio Frequency Identification (RFID) applications are growing rapidly, especially in the UHF frequency band that is being used in inventory management. Passive UHF tags are preferred for these applications. In this paper, RFID reader-to-reader interference is analyzed. A model to estimate the minimum distance between readers to achieve a desired probability of detection in real multipath environments is derived and compared to the ideal case (AWGN channel). Diversity techniques to combat multipath and interference effects are proposed and studied.

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An Overview of MIMO Communications—A Key to Gigabit Wireless

Cited by 1,735 publications

References 56 publications

Variational-Bayes-Assisted Joint Signal Detection, Noise Covariance Estimation, and Channel Tracking in MIMO-OFDM Systems

Variational-Bayes-Assisted Joint Signal Detection, Noise Covariance Estimation, and Channel Tracking in MIMO-OFDM Systems

Transmission Characteristics of 2x2 MIMO System Using OSTBC Multiplexing for Different Detector Systems

Effects of Interferences in Uhf Rfid Systems

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