A Full Performance Analysis Of Channel Estimation Methods For Time Varying OFDM Systems

Abstract

In this paper, we have evaluated various methods of time-frequency-selective fading channels estimation in OFDM system and some of them improved under time varying conditions. So, these different techniques will be studied through different algorithms and for different schemes of modulations (16 QAM, BPSK, QPSK,…).Channel estimation gathers different schemes and algorithms, some of them are dedicated for slowly time varying (such as block type arrangement insertion, Bayesian Cramer-Rao Bound, Kalman estimator, Subspace estimator,…) whereas the others concern highly time varying channels (comb type insertion,…) . There are others methods that are just suitable for stationary channels like blind or semi blind estimators. For this aim, diverse algorithms were used for these schemes such as Least Squares estimator LS, Least Minimum Squares LMS, Minimum Mean-Square-ErrorMMSE, Linear Minimum Mean-Square-Error LMMSE, Maximum Likelihood ML,…to refine estimators shown previously.

FER Performance Evaluation and Enhancement of IEEE 802.11 a/g/p WLAN over Multipath Fading Channels in GNU Radio and USRP N200 Environment

“…OFDM is widely used in almost all wireless communication standards such as cellular standards like LTE advance and WiMAX, digital broadcasting standards known as DVB-T, IEEE 802.11 WLAN standards etc [4], [10]. In OFDM, parallel high rate data symbols are loaded on comparatively low rate several numbers of closely spaced orthogonal sub-carriers [4]- [6] having safety guard interval between two adjacent symbols and each sub-carriers are performed with conventional digital modulation schemes such as BPSK, M-PSK, M-QAM [10] etc. For the precise symbol duration, the sub-carriers are independent to each other.…”

“…There are several 802.11 WLAN standards are exists among them few are given at Table 1. In wireless communication, multipath fading effect causes time and frequency dispersion of wireless radio signals as the mobile devices are not stationary [6]. These effects have the impact on the FER of any modulation schemes as mobile radio channels cause the significant fade or distort of the transmitted signal with compared to AWGN channel [9], [11].…”

Design and Simulation of Hartley based Multi Orthogonal Band OFDM

“…By this way the symbol rate on each sub channel is greatly reduced, and then the inter symbol interference (ISI) due to channel dispersion in time caused by multipath delay spread is reduced. For more ISI reduction, Guard interval can also be inserted between OFDM symbols [2,3].…”

OFDM-System Design Using Adaptive Modulation and Channel Estimation for Underwater Acoustic Communication

“…Both Process noise and measurement noise is assumed to be Gaussian noise. All the OFDM parameters are tabulated in table (1). The channel under consideration is Rayleigh fading channel.…”

“…The switching of modulation scheme is dependent on the UWA channel parameters as well as the SNR of the channel. The increasing demand for high bit rate digital communications makes efficient channel estimation and equalization techniques very attractive [1]. In this work the Kalman filter is used for effective channel estimation.…”