Synchronization of OFDM signals

Abstract

A method is described for temporally aligning a received symbol that is transmitted via orthogonal channels, e.g., OFDM channels, with a reference symbol and/or an earlier received symbol. The method includes computing phases of the first symbol for the orthogonal transmission channels and comparing the computed phases of the first symbol with phases of the reference. The phases of the first symbol are successively displaced by a predetermined phase shift which depends on the channel frequency to obtain a correlation result. The temporal alignment is determined by detecting a correlation maximum based on the correlation result and used to synchronize the first symbol with the reference. The reference can also be an earlier received symbol to provide autocorrelation. The received symbols can be processed by applying a window function, e.g. a Hanning, Hamming or Blackman window. Phase correlation provides reliable time synchronization in the presence of jammers emitting narrowband signals in excess of 32 dB above the signal level.

Dependencies are inferred from the claim text.