In this paper, we analyze the performance of an adaptive Multiple Input Multiple Output (MIMO) system employing transmit antenna selection and rate adaptation based on channel state information (CSI). Imperfections in CSI due to estimation error and feedback delay are considered. Since CSI is imperfect, the rate of transmission is chosen in order to meet a target outage probability. The average throughput is evaluated for various cases of imperfect CSI using Monte Carlo simulations. Simulation results show that rate adaptation provides significant gains even with imperfect CSI. Furthermore, prediction can be used to effectively combat the effect of feedback delay. © 2010 IEEE.

Srikrishna Bhashyam

Department of Electrical Engineering

AVERAGE THROUGHPUT

Estimation errors

FEEDBACK DELAY

IMPERFECT CSI

IMPERFECT CSIT

MIMO ANTENNA

Monte Carlo simulation

MULTIPLE-INPUT-MULTIPLE-OUTPUT SYSTEMS

Outage Probability

Rate adaptation

Simulation result

TRANSMIT ANTENNA SELECTION

Antennas

Communication systems

Computer simulation

MIMO systems

Monte Carlo methods

Channel state information

Fulltext

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IIT Madras

Rate adaptation in MIMO antenna selection system with imperfect CSIT

2010 2nd International Conference on COMmunication Systems and NETworks, COMSNETS 2010

We analyze the asymptotic performance of rate adaptation for Transmit Antenna Selection (TAS) and Maximum Eigenmode Beamforming (MEB) schemes in Multiple-Input Multiple-Output (MIMO) systems under imperfect channel state information (CSI) and feedback delay. The rate is adapted according to a target outage probability. We derive lower and upper bounds to this rate. We also asymptotically characterize the multi-step prediction error when MMSE prediction is used to combat feedback delay. Using the bounds and the prediction error asymptotics, we show that the rate gap from the ideal CSI scenario asymptotically grows logarithmically with SNR. The slope is at most the target outage probability. We find that when the target outage probability is decreased faster than an identified growth rate and prediction error goes to zero, then the rate gap remains bounded. ©2010 IEEE.

GLOBECOM - IEEE Global Telecommunications Conference

Rate gap analysis for rate-adaptive antenna selection and beamforming schemes

Adaptive transmit beamforming based on channel state information (CSI) is a key feature in next generation wireless cellular systems. However, CSI available for adaptation is imperfect due to feedback delay and estimation errors. In this work, we analyze the outage performance of maximum eigen-mode beamforming with imperfect CSI. First we analyze the outage probability in terms of the correlation coefficient ρ between the CSI available at the transmitter (CSIT) and the CSI available at the receiver (CSIR). The analysis shows that feedback delay leads to significant degradation at medium and high signal-to-noise ratios (SNR). Furthermore, the effect of delay can be overcome only if ρ tends to one with increasing SNR. Then, we study whether linear minimum mean squared error (MMSE) prediction can achieve the required behavior in ρ. The length of the prediction filter required is numerically evaluated and shown to increase with SNR. Finally, the asymptotic diversity order is analyzed as a function of the rate at which 1 - ρ approaches 0 as the SNR → ∞. Results show that for 1 - ρ proportional to SNR -1, the asymptotic diversity order remains unaltered. © 2009 IEEE.

IEEE International Symposium on Information Theory - Proceedings

Eigen-beamforming with delayed feedback and channel prediction

Antenna selection in Multiple-Input-Multipleoutput (MIMO) systems preserves diversity gain while significantly reducing hardware complexity. However, imperfect Channel State Information (CSI) affects performance. In this paper, we first analyze the performance of a MIMO system employing antenna selection at the transmitter and Maximal Ratio Combining (MRC) at the receiver in the presence of feedback delay and channel estimation errors. Then, wedetermine whether channel prediction can compensate for the effect of feedback delay. Outage probability is analyzed as a function of ρ, the correlation coefficient between the CSI used at the receiver for decoding (CSIR) and the CSI used at the transmitter for selection (CSIT). Analytical results show that the effect of feedback delay is more significant than the effect of estimation error. In order to overcome the effect of delay, ρ should increase with SNR. For a given SNR, the length of the Linear Minimum Mean Square Error (LMMSE) prediction filter required is calculated and shown to increase with SNR. Finally, we determine the asymptotic diversity order as a function of the feedback quality. Results show that if 1 - ρ α SNR-1, the diversity order with imperfect CSI is same as that with perfect CSI. © 2009 IEEE.

IEEE Transactions on Wireless Communications

Using delayed feedback for antenna selection in MIMO systems

Antenna subset diversity with non-ideal channel estimation

2007 IEEE Wireless Communications and Networking Conference

Performance Analysis of MRT and Transmit Antenna Selection with Feedback Delay and Channel Estimation Error

IEEE Transactions on Vehicular Technology

Analysis of Transmit Antenna Selection/Maximal-Ratio Combining in Rayleigh Fading Channels

Journal	2010 2nd International Conference on COMmunication Systems and NETworks, COMSNETS 2010
Open Access	Yes