Preamble Design for Joint estimation of Channel, CFO and Receiver I/Q-Imbalance in OFDM Systems

Abstract

In this paper, preamble design for estimation of frequency selective channels, carrier frequency offset (CFO) and inphase/quadrature-phase (I/Q) imbalance in orthogonal frequency division multiplexing (OFDM) systems is proposed. First we utilize convex optimization to optimize power of all active subcarriers, then we employ adaptive Markov chain Monte Carlo (AMCMC) techniques to select preamble sequence that minimizes the channel estimate mean squared error (MSE) while suppressing the effect of the I/Q mismatch. To estimate CFO, maximum likelihood (ML) based scheme that utilizes two successive OFDM preambles is employed. The CFO is estimated by considering the phase rotation between two consecutive received OFDM preambles. Numerical simulations are provided to verify the efficacy of the proposed design.