US 7,890,059 B2Granted

Successive interference cancellation in code division multiple access system using variable interferer weights

AssigneeBroadcom Corporation

InventorsArkady Molev-Shteiman, Arie Heiman

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Abstract

A method for successive interference cancellation in code division multiple access (CDMA) systems is provided that uses variable interferer weights. This method allows interfering signals to be cancelled in order to recover a transmitted data signal. This method involves receiving the data signal subject to interference from at least one interfering signal. A first interfering signal is identified. Then an interferer weight coefficient associated with the first interfering signal is generated. This allows the first interfering signal to be cancelled from the received data signal using the interferer weight coefficient. These processes may then be reiterated for other interfering signals. It is then possible to recover the transmitted data signal from the received data signal.

Claims28

Dependent claims

A method to cancel interfering signals to recover a transmitted data signal, the method comprising:

receiving a data signal subject to interference from a plurality of interfering signals;
identifying a first interfering signal of the plurality of interfering signals;
identifying a second interfering signal of the plurality of interfering signals;
generating a first interferer weight coefficient associated with the first interfering signal based on a first probability that the first interfering signal affecting the data signal and a first signal strength of the first interfering signal;
generating a second interferer weight coefficient associated with the second interfering signal based on a second probability that the second interfering signal affecting the data signal and a second signal strength of the second interfering signal;
during a first interference cancellation iteration:
canceling the first interfering signal from the received data signal using the first interferer weight coefficient and a first spreading factor;
canceling the second interfering signal from the received data signal using the second interferer weight coefficient and a second spreading factor;
during a second interference cancellation iteration:
updating the first interferer weight coefficient and the first spreading factor based on the second interferer weight coefficient and the second spreading factor;
and
canceling the first interfering signal from the received data signal using the updated first interferer weight coefficient and the updated first spreading factor;
and
after completing a plurality of interference cancellation iterations on the received data signal, recovering the transmitted data signal from the received data signal.

11 more elements

A method to cancel interfering signals to recover a transmitted data signal, the method comprising:

receiving a data signal subject to interference from a plurality of interfering signals;
identifying a first interfering signal of the plurality of interfering signals;
identifying a second interfering signal of the plurality of interfering signals;
generating a first interferer weight coefficient associated with the first interfering signal based on a first probability that the first interfering signal affecting the data signal and a first signal strength of the first interfering signal;
generating a second interferer weight coefficient associated with the second interfering signal based on a second probability that the second interfering signal affecting the data signal and a second signal strength of the second interfering signal;
during a first interference cancellation iteration:
canceling the first interfering signal from the received data signal using the first interferer weight coefficient and a first spreading factor;
canceling the second interfering signal from the received data signal using the second interferer weight coefficient and a second spreading factor;
during a second interference cancellation iteration:
updating the first interferer weight coefficient and the first spreading factor based on the second interferer weight coefficient and the second spreading factor;
and
canceling the first interfering signal from the received data signal using the updated first interferer weight coefficient and the updated first spreading factor;
and
monitoring the first probability and the second probability for identifying when the first probability falls below a first predetermined threshold;
monitoring the second probability and the second probability for identifying when the second probability falls below a second predetermined threshold;
when the first probability falls below the first predetermined threshold and the second probability falls below the second predetermined threshold, completing a plurality of interference cancellation iterations on the received data signal and recovering the transmitted data signal from the received data signal;
extracting data from the recovered, transmitted data signal;
re-encoding the data;
and
employing the re-encoded data for performing equalization of the data extracted from the recovered, transmitted data signal.

17 more elements

A communication device, comprising:

an input, communicatively coupled to a communication channel, for receiving a a data signal subject to interference from a plurality of interfering signals;
at least one processing module, communicatively coupled to the input, for:
identifying a first interfering signal of the plurality of interfering signals;
identifying a second interfering signal of the plurality of interfering signals;
generating a first interferer weight coefficient associated with the first interfering signal based on a first probability that the first interfering signal affecting the data signal and a first signal strength of the first interfering signal;
generating a second interferer weight coefficient associated with the second interfering signal based on a second probability that the second interfering signal affecting the data signal and a second signal strength of the second interfering signal;
during a first interference cancellation iteration:
canceling the first interfering signal from the received data signal using the first interferer weight coefficient and a first spreading factor;
canceling the second interfering signal from the received data signal using the second interferer weight coefficient and a second spreading factor;
during a second interference cancellation iteration:
updating the first interferer weight coefficient and the first spreading factor based on the second interferer weight coefficient and the second spreading factor;
and
canceling the first interfering signal from the received data signal using the updated first interferer weight coefficient and the updated first spreading factor;
and
after completing a plurality of interference cancellation iterations on the received data signal, recovering the transmitted data signal from the received data signal.

12 more elements

Dependencies are inferred from the claim text.