CHANNEL ESTIMATION DESIGN OF MIMOOFDM SYSTEMS USING MMSE FOR IEEE 802.11N WLAN STANDARD

IEEE 802.11n is the latest development of IEEE 802.11 WLAN communication standard that provides higher significant throughput than IEEE 802.11a/g. With various of transmission channels in wireless communication, has decreased performance of the receiver antennas caused by noise interference and fading channel. Hence, there is a need to analyze channel estimation method to estimate and discover the real condition of channel information between transmitter and receiver for IEEE 802.11n WLAN communication standard. This research simulated the channel estimator using minimum mean squared error (MMSE) algorithm in MIMOOFDM systems with 2x2 and 2x4 schemes. Rectangular shaping filter assumption in time domain is used for the channel approximation due to the multipath Rayleigh fading channel distribution. System performance value is shown in channel impulse response of Tx transmitter to Rx receiver. The simulation results indicate that channel estimator has been working on purpose in MIMO-OFDM system with antenna scheme of 2x2 and 2x4 as well

COMPLEXITY REDUCED CHANNEL ESTIMATION IN WIMAX ENVIRONMENT FOR MIMO–OFDM SYSTEM

Multiple Input Multiple Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) are considered to be major methods for the ensuing high performance in next generation mobile communications. The undesirable effects on the transmitted signals need to be addressed and eliminated to improve the capacity of the systems. These effects depend on the physical properties of the channel. Hence, there is a need to provide perfect estimate of the channel to counteract these effects and thereby delivering precise base-band processes at the receiving end of the system such as signal demodulation and decoding. In this paper, the channel between multiple antenna elements are investigated and analysed for optimum technique with less complexity and less power requirement to estimate the characteristics of the channel. The bit error rate (BER) and normalised mean square error (NMSE) of the channels in MIMO-OFDM systems are examined for different channel tracking techniques. The simulation results are measured to investigate the working of the system model with different algorithms over Worldwide Interoperability for Microwave Access channel. An efficient QRD method is suggested in this paper based on the available system resources and specifications

Joint Carrier Frequency Offset and Fast Time-varying Channel Estimation for MIMO-OFDM Systems

International audienceIn this paper, a novel pilot-aided iterative algorithm is developed for MIMO-OFDM systems operating in fast time-varying environment. An L-path channel model with known path delays is considered to jointly estimate the multi-path Rayleigh channel complex gains and Carrier Frequency Offset (CFO). Each complex gain time-variation within one OFDM symbol is approximated by a Basis ExpansionModel (BEM) representation. An auto-regressive (AR) model is built for the parameters to be estimated. The algorithm performs recursive estimation using Extended Kalman Filtering. Hence, the channel matrix is easily computed and the data symbol is estimated with free intersub-carrier-interference (ICI) when the channel matrix is QR-decomposed. It is shown that only one iteration is sufficient to approach the performance of the ideal case for which the knowledge of the channel response and CFO is available

Joint carrier frequency offset and fast time-varying channel estimation for MIMO-OFDM systems

International audienceIn this paper, a novel pilot-aided algorithm is developed for multiple-input-multiple-output (MIMO) orthogonal frequency-division-multiplexing (OFDM) systems operating in a fast time-varying environment. The algorithm has been designed to work with both the parametric L -path channel model (with known path delays) and the equivalent discrete-time channel model to jointly estimate the multipath Rayleigh channel complex amplitude (CA) and the carrier frequency offset (CFO). Each CA time variation within one OFDM symbol is approximated by a basis expansion model representation. An autoregressive model is built for the parameters to be estimated. The algorithm performs estimation using extended Kalman filtering. The channel matrix is thus easily computed, and the data symbol is estimated without intercarrier interference (ICI) when the channel matrix is QR-decomposed. It is shown that our algorithm is far more robust to high speed than the conventional algorithm, and the performance approaches that of the ideal case for which the channel response and CFO are known

Joint Carrier Frequency Offset and Fast Time-varying Channel Estimation for MIMO-OFDM Systems

International audienceIn this paper, a novel pilot-aided algorithm is developed for MIMO-OFDM systems operating in fast time-varying environment. The algorithm has been designed to work both with parametric L-path channel model (with known path delays) and equivalent discrete-time channel model to jointly estimate the multi-path Rayleigh channel complex amplitudes (CA) and Carrier Frequency Offset (CFO). Each CA time-variation within one OFDM symbol is approximated by a Basis Expansion Model (BEM) representation. An Auto-Regressive (AR) model is built for the parameters to be estimated. The algorithm performs estimation using Extended Kalman Filtering. The channel matrix is thus easily computed and the data symbol is estimated without Inter-sub-Carrier-Interference (ICI) when the channel matrix is QR-decomposed. It is shown that our algorithm is far more robust to high speed than the conventional algorithm, and the performance approaches that of the ideal case for which the channel response and CFO are known