Processing diversity signals using a delay
Processing a downlink signal includes receiving a downlink signal at the antennas of a mobile device, where each antenna generates a diversity signal associated with the downlink signal, and where the downlink signal includes information. Diversity signals are generated and a delay of less than one chip duration is applied to at least one of the diversity signals. The diversity signals are then processed to obtain the information. Processing a transmit signal includes receiving a transmit signal at a splitter, where the transmit signal includes information. The transmit signal is split into split signals. At least one delay is applied to at least one of the split signals to yield transmit diversity signals, and the transmit diversity signals are transmitted.
1. A system for processing receive diversity signals, comprising:
a plurality of antennas operable to:
receive a downlink signal, the downlink signal comprising information; and
generate a plurality of diversity signal associated with the downlink signal, each of the plurality of antennas operable to generate a diversity signal of the plurality of diversity signals;
a plurality of filters, each filter of the plurality of filters coupled to an antenna of the plurality of antennas and operable to filter each of the diversity signals received from the plurality of antennas;
a delay module coupled to at least one of the plurality of filters and operable to apply a delay to at least one of the plurality of diversity signals, the delay being less than one chip duration, the delay comprising a delay of 0.4 to 0.8 microseconds;
an antenna combiner operable to:
sum the plurality of diversity signals after applying the delay; and
yield a combined signal comprising the delayed at least one of the plurality of diversity signals;
an analog-to-digital converter operable to convert the combined signal from analog mode to digital mode; and
a processor coupled to the delay module and operable to process the combined signal using the delay to obtain the information, the delay operable to allow at least one multipath signal associated with the downlink signal to be distinguishable, the processor comprising a baseband processor, the baseband processor comprising:
a rake receiver module operable to:
separate the combined signal in the time domain to yield a plurality of fingers, the plurality of fingers corresponding to the plurality of diversity signals, at least one finger of the plurality of fingers comprising the delay; and
coherently combine the plurality of fingers to yield a combined symbol signal, the combined symbol signal corresponding to the downlink signal; and
a decoder coupled to the rake receiver module and operable to decode the combined symbol signal to generate the information.
2. A system for processing a transmit signal, comprising:
a splitter operable to:
receive a transmit signal, the transmit signal comprising information; and
split the transmit signal into a plurality of split signals;
a delay module coupled to the splitter and operable to:
apply at least one delay to at least one of the plurality of split signals to yield a plurality of transmit diversity signals, the delay module comprising a buffer operable to introduce the at least one delay, the at least one delay comprising a first delay and a second delay, the first delay being less than the second delay;
introduce the first delay at a first split signal of the plurality of split signals, the first delay comprising a delay in the range between 0.25 microseconds and five microseconds; and
introduce the second delay at a second split signal of the plurality of split signals, the second delay comprising a delay in the range between 0.5 microseconds and ten microseconds; and
a plurality of antennas operable to transmit the plurality of transmit diversity signals in order to process the plurality of transmit diversity signals, the transmit diversity signals comprising the information.