Joint Timing, Carrier Frequency and Sampling Clock Offset Estimation for MIMO OFDM WLAN Systems

This paper proposes time, frequency and clock synchronization technique for a Q transmit and L receive (Q x L), Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) for Wireless Local Area Network (WLAN) systems. OFDM is a multi-carrier modulation scheme that transmits a large number of closely spaced sub-carriers to be modulated with a conventional modulation technique. MIMO OFDM is a promising candidate for achieving high data rate transmission in mobile environment. However OFDM technique is sensitive to time offset, frequency offset and clock offset. OFDM is resistant to multi-path fading; it requires a high degree of synchronization to maintain sub-carrier orthogonality. Estimating the start of the frame minimizes the Inter Symbol Interference (ISI) and estimating the correct Carrier Frequency Offset (CFO) and Sampling Clock Offset (SCO) minimizes the Inter Carrier Interference (ICI).