Joint CFO and channel acquisition and tracking based on parametric channel modeling for OFDM systems in the presence of high mobility

Abstract

The work presented herein proposes an algorithm for joint Carrier Frequency Offset (CFO) and channel estimation, acquisition and tracking, for OFDM systems in the presence of very high mobility. The algorithm is based on a parametric channel model. Assuming the path delays are known, the multi-path Rayleigh channel Complex Gains (CG) variation, within one OFDM symbol, is approximated by a Basis Expansion Model (BEM) representation. For acquisition, the proposed algorithm uses a preamble sequence that allows for joint CFO and CG estimation. The proposed method is based on MAP techniques. We demonstrate that the estimation of the CFO from the preamble is sufficiently accurate such that there is no need to subsequently refine this estimate value from the payload. Then, the obtained CFO estimate is used to compensate for the CFO prior to performing the CG tracking. The proposed method for the CG tracking is based on Kalman filtering which enables to take advantage of the channel time-correlation. Computer simulations show that our algorithm is able to operate for speeds up to around 300 km/h.