US 2004/0165655 A1 · Time tracking in a non-negligible multipath spacing environment

Abstract

In an antenna diversity environment, the timing offset of the receiver's fingers are based on the timing offset of the received peaks of the base station transmit signals. In a system with non-negligible multipath spacing, the timing offset of the received peaks of the base station transmit signals are not necessarily at the same location. In one embodiment, the demodulating elements for the signal from each base station antenna use the same offset for demodulating and determining an error signal based on pilot signal sampling prior to the timing offset and subsequent to the timing offset. The error signals are averaged and used by a time tracking loop to track the incoming signal. In another embodiment, the demodulating elements for the signal from each base station antenna independently time track the signals with different timing offsets for each finger. The preferred embodiment depends on the method used by the base station to multiplex the data onto multiple transmit antennas.

Claims19

Dependent claims

A method for offset time tracking in a non-negligible multipath spacing environment encompassing an antenna diversity system, the antenna diversity system comprising a plurality of antennas each transmitting a modulated signal, the method comprising:

demodulating a first modulated signal of the plurality of modulated signals into a first demodulated signal in response to a first offset, a first data despreading sequence, and a first pilot estimate;
demodulating a second modulated signal of the plurality of modulated signals into a second demodulated signal in response to a second offset, a second data despreading sequence, and a second pilot estimate;
generating a first error signal for the first demodulated signal in response to sampling of a pilot signal, associated with the first modulated signal, a predetermined time prior to the first offset and a predetermined time subsequent to the first offset;
generating a second error signal for the second demodulated signal in response to sampling of a pilot signal, associated with the first modulated signal, a predetermined time prior to the second offset and a predetermined time subsequent to the second offset;
generating a first updated offset in response to the first time error signal;
and
generating a second updated offset in response to the second time error signal.

4 more elements

An offset time tracking apparatus that tracks a time offset in a non-negligible multipath spacing environment encompassing an antenna diversity system, the antenna diversity system comprising a plurality of antennas each transmitting a modulated signal, the apparatus comprising:

a first timing offset that provides an indication of the first modulated signal location;
a second timing offset that provides an indication of the second modulated signal location;
a first demodulator, coupled to the first modulated signal and the first timing offset, that generates a first demodulated signal;
a second demodulator, coupled to the second modulated signal and the second timing offset, that generates a second demodulated signal;
means for generating a first error signal for the first demodulated signal, the means for generating coupled to the first timing offset and the first modulated signal;
means for generating a second error signal for the second demodulated signal, the means for generating coupled to the second timing offset and the second modulated signal;
a first time tracking loop coupled to the means for generating the first error signal, the first time tracking loop generating an updated first timing offset that is used for subsequent demodulation of the first modulated signal;
and
a second time tracking loop coupled to the means for generating the second error signal, the second time tracking loop generating an updated second timing offset that is used for subsequent demodulation of the second modulated signal.

6 more elements

generating a demodulated signal in response to a modulated signal of the plurality of modulated signals, an offset, a data despreading sequence, and a plurality of pilot signal estimates;
generating an early despread signal for the demodulated signal in response to a sampling of an associated pilot signal prior to the offset and a pilot despreading sequence;
accumulating the early despread signal over a predetermined chip interval to generate a first symbol;
generating a first sum for the early despread signal that is made up of the first symbol and a delayed first symbol;
generating a second sum for the early despread signal that is made up of the first symbol and a negative of the delayed first symbol;
generating a first error signal in response to a sampling of the first and second sums for the early despread signal;
generating a late despread signal for the demodulated signal in response to a sampling of the associated pilot signal subsequent to the offset and the pilot despreading sequence;
accumulating the late despread signal over the predetermined chip interval to generate a second symbol;
generating a first sum for the late despread signal that is made up of the first symbol and a delayed first symbol;
generating a second sum for the late despread signal that is made up of the first symbol and a negative of the delayed first symbol;
generating a second error signal in response to a sampling of the first and second sums for the late despread signal;
generating an average error signal in response to a weighted sum between the first and second error signals;
and
generating an updated offset in response to the average error signal.

11 more elements

Dependencies are inferred from the claim text.

Time tracking in a non-negligible multipath spacing environment

Life of this patent

Time tracking in a non-negligible multipath spacing environment

Life of this patent

Abstract

Claims19