Interference cancellation in a CDMA receiving system
First Claim
1. A method of processing received signals, said method comprising:
- receiving a combined signal at a receiving station containing mobile terminal transmissions from a plurality of mobile terminals;
despreading said combined signal to obtain a first received signal from a first mobile terminal and a second received signal from a second mobile terminal, wherein said first and second received signals each comprise a plurality of successive signal samples;
determining channel estimates for propagation channels between each of said first and second mobile terminals and said receiving station;
determining interference correlations between first and second spreading codes used respectively by said first and second mobile terminals;
computing filter coefficients of an interference suppression filter/matrix based on said channel estimates and said interference correlation; and
combining said first and second received signal with said interference suppression filter/matrix to reduce interference in said first received signal attributable to said second received signal.
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Accused Products
Abstract
Transmitted signals from plurality of mobile terminals are received at one or more base stations in a Code Division Multiple Access system. The base stations send the received signals to a central processor in the form of complex signal sample streams. The central processor determines the correlations between the spreading codes used by the mobile terminals and combines the interference correlations with channel estimates to form an interference matrix. The central processor uses the interference matrix to process the received signals reduce the interference between signals from different mobile terminals.
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Citations
41 Claims
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1. A method of processing received signals, said method comprising:
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receiving a combined signal at a receiving station containing mobile terminal transmissions from a plurality of mobile terminals;
despreading said combined signal to obtain a first received signal from a first mobile terminal and a second received signal from a second mobile terminal, wherein said first and second received signals each comprise a plurality of successive signal samples;
determining channel estimates for propagation channels between each of said first and second mobile terminals and said receiving station;
determining interference correlations between first and second spreading codes used respectively by said first and second mobile terminals;
computing filter coefficients of an interference suppression filter/matrix based on said channel estimates and said interference correlation; and
combining said first and second received signal with said interference suppression filter/matrix to reduce interference in said first received signal attributable to said second received signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of processing received signals from a plurality of mobile terminals in a diversity receiving system, said method comprising:
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receiving combined signals at a plurality of receiving stations, each said combined signal containing transmissions from a plurality of mobile terminals;
despreading said combined signals at each receiving station to obtain a plurality of received signal sample streams, each received signal sample stream depending primarily on a sequence of symbols transmitted from a corresponding mobile terminal;
inputting said received signal sample streams to a central processor;
combining said received signal sample streams at said central processor so as to cancel interference in each sample stream due to symbols transmitted from mobile terminals other than that on which the sample stream primarily depends. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A system for processing signals received from a plurality of mobile transmitters, said apparatus comprising:
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a plurality of rake receivers to despread said received signals at at least one base station to obtain a plurality of rake-combined signals, wherein each rake receiver uses a spreading code assigned to a corresponding one of said mobile terminals to obtain a received signal from said corresponding mobile terminal;
one or more channel estimators for generating channel estimates for propagation channels between each one of said mobile terminals and one or more of said base stations; and
a filter array comprising a first set of interference suppression filters for further combining said rake-combined signals to cancel mutual interference between different mobile transmitters to obtain mutual interference-free signals, and a processor to compute filter coefficients for said first set of interference suppression filters based on said channel estimates and interference correlations between interfering pairs of said mobile transmitters. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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Specification