Efficient frame tracking in mobile receivers

Abstract

A method for determining the validity of a most significant path in a wireless communication system wherein data is transmitted in frame units in a multipath environment begins by accumulating a correlated data sequence N times, each time at a frame offset apart from the previous time. A preliminary noise estimate (PNE) is calculated as an average of the accumulated data values. A preliminary noise threshold (PNT) is calculated according to the equation C 1 ×PNE. A final noise estimate (FNE) is calculated as the average of accumulated data values below the PNT. A final noise threshold (FNT) is calculated according to the equation C 2 ×FNE. The validity of the most significant path is determined if the most significant path value is greater than the FNT.

What is claimed is: 
     
         1 . An apparatus for use in a wireless communication system, comprising:
 an extract and split unit for receiving an input signal and splitting the input signal into even samples and odd samples;   two even midamble correlators for even sample processing, each even midamble correlator connected to said extract and split unit;   an even sample delay unit connected to one of said even midamble correlators;   an even correlator adder connected to the other of said even midamble correlators and said even sample delay unit;   an even sample accumulator connected to said even correlator adder;   two odd midamble correlators for odd sample processing, each odd midamble correlator connected to said extract and split unit;   an odd sample delay unit connected to one of said odd midamble correlators;   an odd correlator adder connected to the other of said odd midamble correlators and said odd sample delay unit;   an odd sample accumulator connected to said odd correlator adder; and   a frame tracker processor connected to said even sample accumulator and said odd sample accumulator.   
     
     
         2 . The apparatus according to  claim 1 , wherein said even sample delay unit and said odd sample delay unit each provide a 57 chip delay. 
     
     
         3 . The apparatus according to  claim 1 , wherein said frame tracker processor outputs:
 a first significant path location; and   a most significant path valid indicator.   
     
     
         4 . The apparatus according to  claim 3 , wherein said first significant path location and said most significant path valid indicator are used to generate a frame synchronization correction signal. 
     
     
         5 . The apparatus according to  claim 1  further comprising a timing manager configured to receive the frame synchronization correction signal and perform a timing adjustment.