Pilot aided joint estimation of doubly selective channel and carrier frequency offset in high mobility OFDMA uplink

In this paper, we propose a novel pilot-aided joint carrier frequency offset (CFO) and channel estimation method for orthogonal frequency division multiple access (OFDMA) uplink systems operating in doubly-selective fading environments. The method makes use of Bernstein basis polynomials (BBP) for capturing the time variations of the channel. By representing the channel in terms of basis functions, we need to track only the slowly varying basis expansion coefficients instead of the actual channel impulse response. The exact solution to this problem requires a multidimensional search which is highly computationally complex. Our proposed method makes use of space alternating generalized expectation maximization (SAGE) algorithm which replaces the multidimensional search with many one dimensional searches. Hence it is suitable practical implementation like mobile wireless communication. Simulation studies demonstrate that the proposed method gives excellent performance even at high mobile velocities.