Patent ID: 7006557

Claim:
A time tracking apparatus, operable with a base station configured for transmit diversity, transmitting a first pilot sequence on a first antenna and a second pilot sequence on a second antenna, the second pilot sequence generated by multiplying each symbol of the first pilot sequence by a value from an orthogonalizing sequence, the symbols consisting of a first pre-determined number of chips, comprising: a first timing offset for receiving input samples and for generating an early sequence of samples corresponding to a first pre-determined offset before a timing reference; a second timing offset for receiving input samples and for generating a late sequence of samples corresponding to a second pre-determined offset after a timing reference; a first despreader for despreading the early sequence of samples with the first pilot sequence; a second despreader for despreading the late sequence of samples with the first pilot sequence; a first accumulator for accumulating despread samples from the first despreader for a second pre-determined number of chips to produce a first accumulation; a second accumulator for accumulating despread samples from the second despreader for the second pre-determined number of chips to produce a second accumulation; a first magnitude squarer for generating a first squared magnitude from the first accumulation; a second magnitude squarer for generating a second squared magnitude from the second accumulation; a subtractor for generating the difference between the first and second squared magnitudes; a tracking loop for receiving the difference from the subtractor and for generating the timing reference in response to the difference; and a pilot decover for estimating the first and second pilots from the input samples in accordance with the timing reference.