Training Symbol Design for Channel Estimation and IQ Imbalance Compensation in OFDM Systems

Abstract

In this paper, training symbol designs for estimation of frequency selective channels and compensation of in-phase (I) and quadrature (Q) imbalances on OFDM transmitters and receivers are studied. We utilize cross entropy (CE) optimization techniques together with convex optimization to design training sequence that minimizes the channel estimate mean squared error (MSE) as well as estimating the effect of I/Q mismatch while lowering the peak power of the training signals. The proposed design provide better channel estimate MSE and bit error rate (BER) performances. The efficacies of the proposed designs are corroborated by analysis and simulation results.

Preamble design for estimation and compensation of channel distortion parameters in OFDM systems

“…In [20,21], cross-entropy (CE) method is employed to search for the near-optimal position of the training symbol that minimizes the channel estimate MSE. The scheme in [20,21] works well and provides similar results as the proposed AMCMC algorithm; however, the convergence of the CE algorithm is inferior to that of the AMCMC algorithm. AMCMC converges faster than the CE scheme due to some restrictions imposed on the generated samples of subcarrier sets.…”

“…Thus we resort to the estimator in [4] for estimation of I / Q imbalance parameters only. In [21], it is demonstrated that, although I / Q imbalance is effectively estimated and compensated for, channel estimation using special pilot pattern is very poor, which in turn cause severe deterioration in bit error rate (BER) performance. Interested readers are referred to [4] for more details about I / Q imbalance parameter estimation and compensation algorithm.…”

“…Instead of exhaustively searching the whole solution space, both AMCMC and the CE algorithm can explore the promising subspaces only, this is due to the fact that the subspace of interest can be represented by a probability distribution [20][21][22][23].…”

Channel Estimation and Carrier Frequency Offset Compensation in Orthogonal Frequency Division Multiplexing System Using Adaptive Filters in Wavelet Transform Domain

“…For example, replacing the direct conversion architecture (DCA) with a superheterodyne configuration scheme with low cost and lower power utilization in silicon compared to the super heterodyne can lead to an imbalance of Inphase and Quadrature (IQ). IQ imbalance can be described as the difference between the gain, phase, and even frequency response of each orthogonal branch of communication systems [4,5].…”