Transmit diversity pilot processing

A wireless communication device, comprising:

• a sum estimator for producing an estimate of the sum of a primary channel and a diversity channel in response to a received symbol;
• a difference estimator for producing an estimate of the difference of the primary channel and the diversity channel in response to a received symbol;
• a controller for updating the sum estimator when the received symbol comprises a sum of the primary and diversity channels and for updating the difference estimator when the received symbol comprises a difference of the primary and diversity channels;
• and
• a parameter estimator for producing a primary channel estimate and a diversity channel estimate from the estimate of the sum and the estimate of the difference of the primary and diversity channels.

A communication system, comprising:

• a sum estimator for producing an estimate of the sum of a primary channel and a diversity channel in response to a received symbol;
• a difference estimator for producing an estimate of the difference of the primary channel and the diversity channel in response to a received symbol;
• a controller for updating the sum estimator when the received symbol comprises a sum of the primary and diversity channels and for updating the difference estimator when the received symbol comprises a difference of the primary and diversity channels;
• and
• a parameter estimator for producing a primary channel estimate and a diversity channel estimate from the estimate of the sum and the estimate of the difference of the primary and diversity channels.

An apparatus, operable with a base station configured for transmit diversity, the base station transmitting a first pilot sequence on a first antenna and a second pilot sequence on a second antenna, the second sequence generated by multiplying each symbol of the first pilot sequence by a value from an orthogonalizing sequence, the symbols consisting of a pre-determined number of chips, comprising:

• a despreader for despreading received samples with the first pilot sequence;
• an accumulator for accumulating the pre-determined number of despread samples to produce a received symbol;
• a first filter for filtering received symbols when the current value of the orthogonalizing sequence is positive;
• a second filter for filtering received symbols when the current value of the orthogonalizing sequence is negative;
• and
• a parameter estimator for generating a primary channel estimate and a diversity channel estimate from the output of the first and second filters.

A method of channel estimation for use in a transmit diversity communication system, comprising:

• producing a difference estimate with a most recently received symbol when the symbol comprises a difference between the primary and diversity channels;
• producing a sum estimate with a most recently received symbol when the symbol comprises a sum of the primary and diversity channels;
• producing a primary channel estimate from the difference estimate and the sum estimate;
• and
• producing a diversity channel estimate from the difference estimate and the sum estimate.

A method of channel estimation, suitable for use in a transmit diversity communication system, including a base station transmitting a first pilot sequence on a first antenna and a second pilot sequence on a second antenna, the second sequence generated by multiplying each symbol of the first pilot sequence by a value from an orthogonalizing sequence, the symbols consisting of a pre-determined number of chips, the method comprising:

• filtering a current received symbol when the current value of the orthogonalizing sequence is positive to produce a sum estimate;
• filtering a current received symbol when the current value of the orthogonalizing sequence is negative to produce a difference estimate;
• and
• generating a primary channel estimate and a diversity channel estimate from the sum estimate and the difference estimate.

An apparatus, comprising:

• means for producing a difference estimate with a most recently received symbol when the symbol comprises a difference between the primary and diversity channels;
• means for producing a sum estimate with a most recently received symbol when the symbol comprises a sum of the primary and diversity channels;
• means for producing a primary channel estimate from the difference estimate and the sum estimate;
• and
• means for producing a diversity channel estimate from the difference estimate and the sum estimate.

A wireless communication device, comprising:

• means for producing a difference estimate with a most recently received symbol when the symbol comprises a difference between the primary and diversity channels;
• means for producing a sum estimate with a most recently received symbol when the symbol comprises a sum of the primary and diversity channels;
• means for producing a primary channel estimate from the difference estimate and the sum estimate;
• and
• means for producing a diversity channel estimate from the difference estimate and the sum estimate.

A communication system, comprising:

• means for producing a difference estimate with a most recently received symbol when the symbol comprises a difference between the primary and diversity channels;
• means for producing a sum estimate with a most recently received symbol when the symbol comprises a sum of the primary and diversity channels;
• means for producing a primary channel estimate from the difference estimate and the sum estimate;
• and
• means for producing a diversity channel estimate from the difference estimate and the sum estimate.

An apparatus, operable with a base station configured for transmit diversity, the base station transmitting a first pilot sequence on a first antenna and a second pilot sequence on a second antenna, the second sequence generated by multiplying each symbol of the first pilot sequence by a value from an orthogonalizing sequence, the symbols consisting of a pre-determined number of chips, comprising:

• a means for filtering a current received symbol when the current value of the orthogonalizing sequence is positive to produce a sum estimate;
• a means for filtering a current received symbol when the current value of the orthogonalizing sequence is negative to produce a difference estimate;
• and
• a means for generating a primary channel estimate and a diversity channel estimate from the sum estimate and the difference estimate.

Processor readable media operable to perform the following steps:

• producing a difference estimate with a most recently received symbol when the symbol comprises a difference between the primary and diversity channels;
• producing a sum estimate with a most recently received symbol when the symbol comprises a sum of the primary and diversity channels;
• producing a primary channel estimate from the difference estimate and the sum estimate;
• and
• producing a diversity channel estimate from the difference estimate and the sum estimate.

Processor readable media, operable with a base station transmitting a first pilot sequence on a first antenna and a second pilot sequence on a second antenna, the second sequence generated by multiplying each symbol of the first pilot sequence by a value from an orthogonalizing sequence, the symbols consisting of a pre-determined number of chips, the media operable to perform the following steps:

• filtering a current received symbol when the current value of the orthogonalizing sequence is positive to produce a sum estimate;
• filtering a current received symbol when the current value of the orthogonalizing sequence is negative to produce a difference estimate;
• and
• generating a primary channel estimate and a diversity channel estimate from the sum estimate and the difference estimate.