Method and apparatus for canceling pilot interference in a CDMA communication system
First Claim
1. In a wireless communication system, a method for canceling pilot interference at a receiver unit that receives first and second pilot signals and first and second data signals, comprising:
- generating a first PN sequence corresponding to the first pilot signal;
despreading the first PN sequence with a second PN sequence corresponding to the second pilot signal;
multiplying the despread first PN sequence with an estimated gain and phase of the first pilot signal to generate a first multiplied signal; and
subtracting the first multiplied signal from the second data signal.
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Abstract
Techniques for canceling pilot interference in a wireless (e.g., CDMA) communication system. A received signal typically includes a number of signal instances (i.e., multipaths). For each multipath desired to be processed, the other multipaths act as interference on the desired multipath. If the pilot is generated based on a known data pattern (e.g., all zeros) and covered with a known channelization code (e.g., a Walsh code of zero), then the pilot in an interfering multipath may be estimated as the spreading sequence at a time offset corresponding to the arrival time of that multipath. The pilot interference from each interference multipath may be estimated based on the spreading sequence for the interfering multipath and the despreading sequence for the desired multipath. The total pilot interference from a number of interfering multipaths may be subtracted from the data component in the desired multipath to provide pilot-canceled data having improved performance.
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Citations
29 Claims
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1. In a wireless communication system, a method for canceling pilot interference at a receiver unit that receives first and second pilot signals and first and second data signals, comprising:
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generating a first PN sequence corresponding to the first pilot signal;
despreading the first PN sequence with a second PN sequence corresponding to the second pilot signal;
multiplying the despread first PN sequence with an estimated gain and phase of the first pilot signal to generate a first multiplied signal; and
subtracting the first multiplied signal from the second data signal. - View Dependent Claims (2, 3, 4)
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5. A system for canceling pilot interference in a receiver unit that receives first and second pilot signals and first and second data signals, comprising:
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a first PN generator configured to generate a first PN sequence corresponding to the first pilot signal;
a first despreader configured to despread the first PN sequence with a second PN sequence corresponding to the second pilot signal;
a first multiplier configured to multiply the despread first PN sequence with an estimated gain and phase of the first pilot signal to generate a first multiplied signal; and
a first adder configured to subtract the first multiplied signal from the second data signal. - View Dependent Claims (6, 7, 8)
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9. In a wireless communication system, a digital signal processor for canceling pilot interference in a receiver unit that receives first and second pilot signals and first and second data signals, comprising:
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a set of one or more multipliers configured to multiply a despread first PN sequence with an estimated gain and phase of the first pilot signal to generate a first multiplied signal; and
a set of one or more adders configured to subtract the first multiplied signal from the second data signal. - View Dependent Claims (10)
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11. In a wireless communication system, a pre-processor for canceling pilot interference in a receiver unit that receives first and second pilot signals and first and second data signals, comprising:
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a first PN generator configured to generate a first PN sequence corresponding to the first pilot signal;
a second PN generator configured to generate a second PN sequence corresponding to the second pilot signal; and
a first despreader configured to despread the first PN sequence with the second PN sequence corresponding to the second pilot signal. - View Dependent Claims (12, 13, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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14. In a wireless communication system, a method for canceling pilot interference at a receiver unit, comprising:
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receiving a signal comprised of a plurality of signal instances, wherein each signal instance includes a pilot component and a data component; and
processing each of one or more signal instances in the received signal to provide demodulated data for the signal instance, wherein the processing for each desired signal instance includes estimating pilot interference from each of at least one interfering signal instance on the desired signal instance, deriving a total pilot interference from the at least one interfering signal instance on the desired signal instance, and subtracting the total pilot interference from the desired signal instance.
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Specification