System access and synchronization methods for mimo ofdm communications systems and physical layer packet and preamble design

Abstract

A method and apparatus are provided for performing acquisition, synchronization and cell selection within an MIMO-OFDM communication system. A coarse synchronization is performed to determine a searching window. A fine synchronization is then performed by measuring correlations between subsets of signal samples, whose first signal sample lies within the searching window, and known values. The correlations are performed in the frequency domain of the received signal. In a multiple-output OFDM system, each antenna of the OFDM transmitter has a unique known value. The known value is transmitted as pairs of consecutive pilot symbols, each pair of pilot symbols being transmitted at the same subset of sub-carrier frequencies within the OFDM frame.

1 . A method comprising:
 transmitting an OFDM preamble comprising a prefix followed by a plurality of correlated header symbols.   
     
     
         2 . The method of  claim 1  wherein the prefix is a cyclic repetition of a portion of one of the header symbols. 
     
     
         3 . The method of  claim 1  wherein the plurality of correlated header symbols comprises two header symbols. 
     
     
         4 . The method of  claim 1  wherein the plurality of correlated header symbols comprises two identical symbols. 
     
     
         5 . The method of  claim 1  wherein the plurality of correlated header symbols comprises two identical symbols, and wherein the prefix is a cyclic repetition of one of the header symbols.