Cyclic Prefix (CP) is a technique used to mitigate the effects of multipath propagation and improve the performance of the communication system. The cyclic prefix involves the addition of a guard interval at the beginning of each OFDM symbol. This guard interval is a copy of the latter part of the symbol and is appended before the symbol itself. The purpose of the cyclic prefix is to combat intersymbol interference (ISI) caused by multipath propagation, where delayed versions of the transmitted signal interfere with the current symbol.

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Blind Cyclic Prefix-based CFO Estimation in MIMO-OFDM Systems

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Low-complexity estimation and correction of carrier frequency offset (CFO) are essential in orthogonal frequency division multiplexing (OFDM). In this paper, we propose a low overhead blind CFO estimation technique based on cyclic prefix (CP), in multi-input multi-output (MIMO)-OFDM systems. We propose to use antenna diversity for CFO estimation. Given that the RF chains for all antenna elements at a communication node share the same clock, the carrier frequency offset (CFO) between two points may be estimated by using the combination of the received signal at all antennas. We improve our method by combining the antenna diversity with time diversity by considering the CP for multiple OFDM symbols. We provide a closed-form expression for CFO estimation and present algorithms that can considerably improve the CFO estimation performance at the expense of a linear increase in computational complexity. We validate the effectiveness of our estimation scheme via extensive numerical analysis.

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