Channel Estimation in OFDM Systems: BER Performance Analysis

In OFDM systems, bit error rate (BER) performance can be compared across four scenarios: LS channel estimation, DFT-based channel estimation, improved DFT-based channel estimation, and the case without any channel estimation. The Least Squares (LS) channel estimation method, commonly implemented using matrix operations to minimize the squared error between received and transmitted signals, serves as a fundamental approach for initial channel state estimation. DFT-based channel estimation utilizes Discrete Fourier Transform operations to convert time-domain channel estimates to frequency-domain representations, typically implemented through FFT algorithms to improve estimation accuracy by reducing noise components outside the channel delay spread. The improved DFT-based estimation incorporates algorithmic enhancements such as adaptive thresholding or path selection techniques, often involving additional processing steps to identify and preserve significant channel taps while suppressing noise-dominated components. The baseline scenario without channel estimation represents the worst-case performance where no compensation is applied for channel distortions. Through comprehensive BER comparison of these four approaches, system designers can evaluate the trade-offs between computational complexity and performance gains, enabling informed selection of appropriate channel estimation methods for practical OFDM implementations based on specific system requirements and constraints.