Active cancellation tuning to reduce a wireless coupled transmit signal

• US 6,915,112 B1
• Filed: 11/12/2000
• Issued: 07/05/2005
• Est. Priority Date: 11/12/2000
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Sutton, Todd, Soledade, Carlos
• Primary Examiner(s): CRAVER, CHARLES R
• Application Number:
  US09/711,159
• Time in Patent Office: 1,696 Days
• Field of Search: 455/423, 455/425, 455/501, 455 631- 677, 455/69, 4551151-1154, 4552261-2264, 455302-307, 455/310, 455/24, 455/73, 455/296, 455/295, 455/305, 455/78
• US Class Current: 455/67.13
• CPC Class Codes: H04B 1/126 having multiple inputs, e.g. auxiliary antenna for receiving interfering signal aerials in general H01Q
• CPC Class Codes: H04B 1/408 the transmitter oscillator frequency being identical to the receiver local oscillator frequency
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver

Abstract

An active cancellation controller receives a signal strength indicator that indicates a power level of a coupled signal from a local wireless transmitter at a local wireless receiver. The active cancellation controller tunes an active cancellation circuit to reduce the signal strength indicator. The active cancellation circuit is to generate a cancellation signal to combine with the coupled signal at the local wireless receiver.

Claims

1. A method comprising:

receiving a signal strength indicator that indicates a power level of a coupled signal from a local wireless transmitter at a local wireless receiver; and

tuning an active cancellation circuit to reduce the signal strength indicator, said active cancellation circuit to generate a cancellation signal to combine with the coupled signal at the local wireless receiver, wherein the tuning the active cancellation control signal further comprises;

measuring a first level of the signal strength indicator;

adjusting an active cancellation control signal in a first direction;

measuring a second level of the signal strength indicator;

further adjusting the active cancellation control signal in the first direction if the second level is lower than the first level; and

adjusting the active cancellation control signal in an opposite direction if the second level is higher than the first level; and

iteratively measuring the signal strength indicator and either further adjusting the active cancellation control signal or adjusting the active cancellation control signal in the opposite direction depending on a comparison of a current measurement of the signal strength indicator and a previous measurement of the signal strength indicator;

wherein the active cancellation control signal locks after adjustment of the active cancellation control signal has switched directions at least twice.

2. A method comprising:

receiving a signal strength indicator that indicates a power level of a coupled signal from a local wireless transmitter at a local wireless receiver; and

tuning an active cancellation circuit to reduce the signal strength indicator, said active cancellation circuit to generate a cancellation signal to combine with the coupled signal at the local wireless receiver, wherein the tuning the active cancellation control signal further comprises;

measuring a first level of the signal strength indicator;

adjusting an active cancellation control signal in a first direction;

measuring a second level of the signal strength indicator;

further adjusting the active cancellation control signal in the first direction if the second level is lower than the first level; and

adjusting the active cancellation control signal in an opposite direction if the second level is higher than the first level; and

iteratively measuring the signal strength indicator and either further adjusting the active cancellation control signal or adjusting the active cancellation control signal in the opposite direction depending on a comparison of a current measurement of the signal strength indicator and a previous measurement of the signal strength indicator;

wherein the active cancellation control signal comprises a first dimension control signal, and wherein tuning the active cancellation signal further comprises;

iteratively measuring the signal strength indicator and either adjusting a second dimension control signal in the first direction or adjusting the second dimension control signal in the opposite direction depending on a comparison of a current measurement of the signal strength indicator and a previous measurement of a signal strength indicator.

3. The method of claim 2 wherein the method further comprises:

switching from tuning the first dimension control signal to tuning the second dimension control signal when the first dimension control signal locks; and

switching from tuning the second dimension control signal to tuning the first dimension control signal when the second dimension control signal locks.

4. A method comprising:

receiving a signal strength indicator that indicates a power level of a coupled signal from a local wireless transmitter at a local wireless receiver; and

tuning an active cancellation circuit to reduce the signal strength indicator, said active cancellation circuit to generate a cancellation signal to combine with the coupled signal at the local wireless receiver, wherein the tuning the active cancellation control signal further comprises;

measuring a first level of the signal strength indicator;

adjusting an active cancellation control signal in a first direction;

measuring a second level of the signal strength indicator;

further adjusting the active cancellation control signal in the first direction if the second level is lower than the first level; and

adjusting the active cancellation control signal in an opposite direction if the second level is higher than the first level; and

iteratively measuring the signal strength indicator and either further adjusting the active cancellation control signal or adjusting the active cancellation control signal in the opposite direction depending on a comparison of a current measurement of the signal strength indicator and a previous measurement of the signal strength indicator;

wherein the active cancellation control signal is initially adjusted by a first step size and adjusted by a smaller step size once the active cancellation control signal has locked at least once.

5. A method comprising:

receiving a signal strength indicator that indicates a power level of a coupled signal from a local wireless transmitter at a local wireless receiver; and

tuning an active cancellation circuit to reduce the signal strength indicator, said active cancellation circuit to generate a cancellation signal to combine with the coupled signal at the local wireless receiver, wherein the tuning the active cancellation control signal further comprises;

measuring a first level of the signal strength indicator;

adjusting an active cancellation control signal in a first direction;

measuring a second level of the signal strength indicator;

further adjusting the active cancellation control signal in the first direction if the second level is lower than the first level; and

adjusting the active cancellation control signal in an opposite direction if the second level is higher than the first level; and

iteratively measuring the signal strength indicator and either further adjusting the active cancellation control signal or adjusting the active cancellation control signal in the opposite direction depending on a comparison of a current measurement of the signal strength indicator and a previous measurement of the signal strength indicator;

wherein the signal strength indicator is initially measured over a first integration time and measured over a longer integration time once the active cancellation control signal has locked at least once.

6. A method comprising:

receiving a signal strength indicator that indicates a power level of a coupled signal from a local wireless transmitter at a local wireless receiver;

tuning an active cancellation circuit to reduce the signal strength indicator, said active cancellation circuit to generate a cancellation signal to combine with the coupled signal at the local wireless receiver; and

enabling tuning only when the local wireless transmitter is an only local wireless transmitter that is transmitting and when the local wireless receiver is not being used to receive a signal from a remote transmitter.

7. A method comprising:

receiving a signal strength indicator that indicates a power level of a coupled signal from a local wireless transmitter at a local wireless receiver;

tuning an active cancellation circuit to reduce the signal strength indicator, said active cancellation circuit to generate a cancellation signal to combine with the coupled signal at the local wireless receiver wherein tuning the active cancellation circuit comprises making adjustments to an active cancellation control signal, the method further comprising;

detecting when at least one local wireless transmitter is transmitting and the local wireless receive is being used to receive a signal from a remote transmitter; and

providing the active cancellation control signal at a particular level.

8. The method of claim 7 wherein the particular level of the active cancellation control signal comprises a most recently tuned level.

9. The method of claim 7 wherein providing the active cancellation control signal at the particular level comprises:

identifying a center frequency of the local wireless receiver; and

retrieving the particular level of the active cancellation signal from a memory location corresponding to the center frequency of the local wireless receiver.

10. The method of claim 9 wherein providing the active cancellation control signal at the particular level further comprises:

identifying additional center frequencies of the local wireless receiver as the local wireless receiver frequency hops; and

retrieving additional particular levels of the active cancellation control signal from additional memory locations corresponding respective ones of the additional center frequencies.