Enhanced frequency offset estimation based on pilot signal design over flat-fading channel

The problem of pilot assisted frequency offset estimation over flat-fading channel is investigated in this paper. By studying the pilot signal design and the generalized Crámer-Rao lower bound (CRLB), it is shown that the equivalent-preamble-postamble (EPP) pilot design is not optimal for the time-varying fading channel. Specifically, based on the numerical analysis and simulation results, it is unveiled that, the equally spaced pilot (ESP) design will outperform the EPP design when the spacing between pilot symbols is large enough owing to the ‘spacing gain’ on the effective signal-to-noise ratio (SNR), especially within slow fading region. In practical applications, the spacing gain from the reasonably devised pilot placement scheme could be transformed into the favorable saving in either the number of pilot symbols or the SNR for a targeted mean square error estimation performance.