Method and apparatus for mitigating inter-channel interference in adaptive array systems
First Claim
1. In an antenna array system, a method for reducing inter-channel interference, the method comprising:
- providing a first channel on which to transmit a downlink signal to a first remote user terminal;
obtaining the spatial characteristic of a signal transmitted on a second channel for communication used by a second remote user terminal, wherein the signal is susceptible to interference caused by the downlink signal; and
based on the spatial characteristic, transmitting the downlink signal on the first channel with a region of reduced gain at the location of the second remote user terminal.
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Accused Products
Abstract
A method and apparatus for mitigating co-channel and inter-channel interference in an antenna array system. According to one aspect, the channel-select filter of a base station or other communication device is modified to detect inter-channel interference on at least one non-primary channel when the transmitter is communicating with a remote user terminal on a primary channel. The spatial characteristic of the interference is determined and used to obtain a weight that mitigates the inter-channel interference. According to another aspect, the spatial characteristic of co-channel and/or inter-channel ghost signal interference caused by a transmitter is determined and used to mitigate the effects of such interference.
44 Citations
16 Claims
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1. In an antenna array system, a method for reducing inter-channel interference, the method comprising:
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providing a first channel on which to transmit a downlink signal to a first remote user terminal;
obtaining the spatial characteristic of a signal transmitted on a second channel for communication used by a second remote user terminal, wherein the signal is susceptible to interference caused by the downlink signal; and
based on the spatial characteristic, transmitting the downlink signal on the first channel with a region of reduced gain at the location of the second remote user terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
receiving a first uplink signal transmitted by the first remote user terminal on the first channel;
receiving energy on the second channel; and
filtering the first uplink signal such that the energy on the second channel is detected while receiving the first uplink signal on the first channel.
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3. The method of claim 2, further comprising widening a filter of the antenna array system, the filter tuned to the first channel, to detect the energy present on the second channel.
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4. The method of claim 1 wherein the first and second channels are frequency channels.
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5. The method of claim 1 wherein the first and second channels are code channels.
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6. The method of claim 1 wherein the first and second channels are time channels.
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7. The method of claim 1 wherein the first and second channels are adjacent channels.
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8. The method of claim 1, further comprising:
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determining a first uplink covariance matrix corresponding to an uplink transmission of the first remote user terminal;
adding a second uplink covariance matrix to the first uplink covariance matrix to form a third covariance matrix, wherein the second covariance matrix corresponds to a scaled version of energy detected on the second channel; and
generating a set of downlink weights as function of the third covariance matrix, the set of downlink weights to provide the region of reduced gain when transmitting the downlink signal.
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9. The method of claim 1, further comprising:
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receiving a first uplink signal transmitted at least in part by the first remote user terminal;
receiving a second uplink signal, the second uplink signal transmitted at least in part by the second remote user terminal;
adding the first and second uplink signals to form a combined received signal;
determining a covariance matrix for the combined received signal; and
generating a set of downlink weights as function of the covariance matrix, the set of downlink weights to provide the region of reduced gain when transmitting the downlink signal.
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10. The method of claim 1, further comprising:
providing a first filter to output a combined signal comprising at least a portion of an uplink signal transmitted by the first remote user terminal on the first channel and at least a portion of energy transmitted by the second remote user terminal on the second channel.
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11. The method of claim 10, further comprising:
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determining an uplink weight as a function of the combined signal;
providing a second filter to output a post-filtered signal, the post-filtered signal representing the combined signal having removed therefrom at least a portion of the energy; and
demodulating the post-filtered signal.
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12. The method of claim 1, further comprising:
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outputting a combined signal comprising an uplink signal transmitted by the first remote user terminal at least in part on the first channel and at a least a portion of energy present on the second channel; and
dynamically varying the amount of the energy present on the second channel.
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13. The method of claim 12, wherein dynamically varying the amount of energy present further comprises:
attenuating the amount of the energy present in inverse proportion to the amplitude of the energy present on the second channel.
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14. The method of claim 1, further comprising:
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receiving an uplink signal from the first remote user terminal;
generating an uplink weight as a function of the uplink signal;
applying the uplink weight to the uplink signal to obtain a weighted uplink signal;
performing temporal filtering on the weighted uplink signal to generate a filtered uplink signal;
demodulating the filtered uplink signal; and
determining a beamforming strategy that provides the region of reduced gain while transmitting the downlink signal.
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15. The method of claim 1, further comprising:
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causing at least a portion of the energy detected on the second channel to alias into the first channel; and
determining the spatial characteristic as a function of the energy.
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16. The method of claim 1, further comprising providing a channel-select filter to allow an aliased component of the energy to be present in proximity to a band edge of the first channel.
Specification