Abstract
The present invention relates to digital receivers in a frequency-selective (wideband) channel and in particular to frame/symbol timing and carrier frequency synchronization in the reception of orthogonal frequency-division multiplexing (OFDM) signals. The present invention provides a method of synchronizing a receiver to a received signal, wherein the signal includes a training symbol having two identical parts, the method including determining a degree of autocorrelation between parts of the signal at the spacing of the two identical parts, and a degree of cross-correlation between parts of the received signal and a reference copy of the training symbol, and multiplying together the autocorrelation and crosscorrelation to determine at least one of the timing and the frequency of the received signal. This may be achieved by multiplying the cross-correlation and autocorrelation directly, or by multiplying a function, which may be referred to as a timing metric, of one of them with the other, or my multiplying functions of both of them together.
A method and apparatus is provided for rapid frame/symbol timing and carrier frequency synchronization of a digital receiver to an orthogonal frequency division multiplexing (OFDM) signal and other transmissions (either continuous or burst) over a frequency-selective (wideband) channel. The method makes use of the autocorrelation and cross- correlation properties of one training symbol, having two or more identical parts. Its timing estimation performance approaches the ideal with a very low mean square error while its frequency accuracy is competitive when compared with conventional methods. It also has a wide frequency estimation range of half the signal bandwidth, yet it has a low, scalable and adaptive complexity that can be optimized to any specific application.