Self-interference cancellation for MIMO radios
First Claim
1. A wireless communication system comprising:
- first transmit path adapted to transmit first transmit signal from a first antenna;
a second transmit path adapted to transmit a second transmit signal from a second antenna;
a first receive path adapted to receive a first receive signal;
a second receive path adapted to receive a second receive signal;
a first interference cancellation circuit coupled to the first and the second transmit paths and adapted to remove a first portion of an interference signal from the first receive signal corresponding to the first transmit signal and a second portion of the interference signal from the first receive signal corresponding to the second transmit signal, the first interference cancellation circuit comprising a plurality of filter taps each including a variable element;
a second interference cancellation circuit coupled to the first and the second transmit paths and adapted to remove a first portion of an interference signal corresponding to the first transmit signal from the second receive signal and a second portion of the interference signal corresponding to the second transmit signal from the second receive signal, the second interference cancellation circuit comprising a second plurality of filter taps each including a variable element; and
a controller adapted to dynamically vary a value applied to each of the plurality of variable elements in accordance with frequency response characteristics of the variable element;
wherein the controller is further adapted to dynamically vary a value applied to each of the plurality of variable elements in the second plurality of filter taps in accordance with frequency response characteristics of the variable element.
1 Assignment
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Accused Products
Abstract
A MIMO wireless communication device includes, in part, a first transmit path adapted to transmit a first transmit signal from a first antenna, a second transmit path adapted to transmit a second transmit signal from a second antenna, a first receive path adapted to receive a first receive signal, an interference cancellation circuit and a controller. The cancellation circuit includes a cascaded filter structure each filter including a multitude of filter taps each including a variable element. The controller dynamically varies a value applied to each of the plurality of variable elements in accordance with frequency response characteristics of the variable element to remove a portion of a self-interference and/or cross-talk interference signal present in a signal received by the device. The device measures the frequency response characteristic of a multitude of communication channels, used in determining the values, via one or more preamble symbols that are jointly transmitted from the first transmit antenna and the second transmit antenna. A second portion of the interference signal is removed by a digital cancellation circuit using a multitude of samples of a transmitted signal.
147 Citations
23 Claims
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1. A wireless communication system comprising:
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first transmit path adapted to transmit first transmit signal from a first antenna; a second transmit path adapted to transmit a second transmit signal from a second antenna; a first receive path adapted to receive a first receive signal; a second receive path adapted to receive a second receive signal; a first interference cancellation circuit coupled to the first and the second transmit paths and adapted to remove a first portion of an interference signal from the first receive signal corresponding to the first transmit signal and a second portion of the interference signal from the first receive signal corresponding to the second transmit signal, the first interference cancellation circuit comprising a plurality of filter taps each including a variable element; a second interference cancellation circuit coupled to the first and the second transmit paths and adapted to remove a first portion of an interference signal corresponding to the first transmit signal from the second receive signal and a second portion of the interference signal corresponding to the second transmit signal from the second receive signal, the second interference cancellation circuit comprising a second plurality of filter taps each including a variable element; and a controller adapted to dynamically vary a value applied to each of the plurality of variable elements in accordance with frequency response characteristics of the variable element;
wherein the controller is further adapted to dynamically vary a value applied to each of the plurality of variable elements in the second plurality of filter taps in accordance with frequency response characteristics of the variable element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of operating a wireless communication system, the method comprising:
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transmitting a first transmit signal from a first transmit path using a first antenna; transmitting a second transmit signal from a second transmit path using a second antenna; receiving a first receive signal at a first receive path using the first antenna, the first receive signal comprising a self-interference component corresponding to the first transmit signal, and a cross-talk interference component corresponding to the second transmit signal; dynamically varying a value applied to each of a plurality of variable elements disposed in the wireless communication system in accordance with frequency response characteristics of the variable elements to remove, from the first receive signal, the self-interference component and the cross-talk interference component;
wherein the variable elements are variable attenuators;storing in a memory at least one frequency response characteristic associated with at least one attenuation value of each of the plurality of the variable attenuators; and generating a plurality of attenuation values for the plurality of variable attenuators in accordance with an S parameter associated with the variable attenuators. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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23. A wireless communication system comprising:
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first transmit path adapted to transmit first transmit signal from a first antenna; a second transmit path adapted to transmit a second transmit signal from a second antenna; a first receive path adapted to receive a first receive signal; a first interference cancellation circuit coupled to the first and the second transmit paths and adapted to remove a first portion of an interference signal from the first receive signal corresponding to the first transmit signal and a second portion of the interference signal from the first receive signal corresponding to the second transmit signal, the first interference cancellation circuit comprising a plurality of filter taps each including a variable element;
wherein the first interference cancellation circuit comprises a cascaded filter structure comprising a first filter having N parallel filter taps and a second filter having C parallel filter taps, N and C being integer values greater than one; anda controller adapted to dynamically vary a value applied to each of the plurality of variable elements in accordance with frequency response characteristics of the variable element;
wherein the controller is further adapted to jointly determine a first plurality of N values corresponding to the variable elements in the first filter and a second plurality of C values corresponding to the variable elements in the second filter.
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Specification