detection of primary synchronization signal in LTE

Hi All,
        According to  LTE frame structure every frame  have primary
synchronization signals.And for primary synchronization signal zadoff-
chu sequence is used beacuse of its good periodic autocorrelation as
well as periodic cross correlation properties.
I thought of using noncoherent correlation in time domain.I tried this
method in matlab and seems working for me.
My problem is its taking lot of time to detect primary synchronization
signal because in worst case we have to do 1 lag autocorrelation
(5*14-1)*2048 times.And for 1 autocorrelation value 2048
multiplications and additions required.hence total number of
multiplication required for worstcase may go upto (5*14-1)*2048*2048.

for more clarification 5 is number of subframes(we are taking half of
frame data to detect PSS)
                                14 is number of Ofdma sybols in 1
subframe


My question is is there any fast method for autocorrelation for zadoff-
chu type of sequence?or this is the only method .


Thanks
Anurag