A robust frequency estimation technique for synchronization over frequency-selective channels

Conventional estimation algorithms utilize either a tone or squarewave in the preamble for frequency estimation. However, such patterns for the preamble sequence are nonoptimal when the channel is frequency selective. Furthermore, the problem is exacerbated for packet-switched systems, such as wireless LANs, which require frequency synchronization on a per packet basis. This paper presents a low complexity frequency estimation algorithm that is robust in frequency selective fading channels. The algorithm is non-decision aided and does not require a priori frame synchronization. Compared against conventional techniques, a factor of 5-10 reduction in BER and a factor of 3 reduction in convergence time are achieved.