Combined RSSI/SNR-driven intermodulation-mitigation scheme for CDMA terminals
First Claim
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1. A method for use in wireless equipment for processing a received signal, the method comprising the steps of:
- (a) selecting one of a number of attenuation states as a function of a measured signal strength associated with the received signal, each attenuation state associated with a respective attenuation level of the received signal;
(b) in the selected attenuation state, measuring a signal to noise ratio (SNR) associated with the received signal;
(c) changing the attenuation state to a new attenuation state selected from one of the number of attenuation states;
(d) in the new attenuation state, measuring another SNR associated with the received signal; and
(e) changing the attenuation state back to the selected attenuation state if the measured SNR in step (d) is not greater than the measured SNR in step (b).
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Abstract
A wireless receiver includes a variable attenuator, a signal-to-noise ratio (SNR estimator), and a received signal strength indicator (RSSI) level detector. The RSSI level of the received signal is used as a primary criterion on setting the attenuator status. Once the attenuator is set based upon the RSSI readings, an SNR check is made to determine the possible presence of IM. Then, further adjustment on the attenuator status is made according to the SNR check.
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Citations
15 Claims
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1. A method for use in wireless equipment for processing a received signal, the method comprising the steps of:
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(a) selecting one of a number of attenuation states as a function of a measured signal strength associated with the received signal, each attenuation state associated with a respective attenuation level of the received signal; (b) in the selected attenuation state, measuring a signal to noise ratio (SNR) associated with the received signal; (c) changing the attenuation state to a new attenuation state selected from one of the number of attenuation states; (d) in the new attenuation state, measuring another SNR associated with the received signal; and (e) changing the attenuation state back to the selected attenuation state if the measured SNR in step (d) is not greater than the measured SNR in step (b). - View Dependent Claims (2, 3, 4, 5)
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6. Apparatus for use in a receiver, the apparatus comprising:
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an attenuator element for use in attenuating a received signal; a signal-to-noise estimator for producing an estimate of a signal-to-noise ratio (SNR) associated with the received signal; a received signal strength indicator (RSSI) for producing an RSSI signal associated with the received signal; and a controller for setting an attenuation level of the attenuator element by using the RSSI signal as a primary indicator and the SNR as a secondary indicator; wherein the controller sets the attenuation level by performing a method, the method comprising the steps of; (a) selecting one of a number of attenuation states as a function of the RSSI signal, each attenuation state associated with a respective attenuation level; (b) in the selected attenuation state, storing a measure of the SNR; (c) changing the attenuation state to a new attenuation state selected from one of the number of attenuation states; (d) in the new attenuation state, storing another measure of the SNR; and (e) changing the attenuation state back to the selected attenuation state if the measured SNR in step (d) is not greater than the measured SNR in step (b). - View Dependent Claims (7, 8, 9, 10)
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11. Apparatus for use in a receiver, the apparatus comprising:
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an attenuator element for use in attenuating a received signal; and processing circuitry that (a) determines an estimate of a signal-to-noise ratio (SNR) associated with the received signal, (b) determines a received signal strength indicator (RSSI) signal associated with the received signal; and
(b) sets an attenuation level of the attenuator element by using the RSSI signal as a primary indicator and the SNR as a secondary indicator;wherein the processing circuitry sets the attenuation level by performing a method, the method comprising the steps of; (a) selecting one of a number of attenuation states as a function of the RSSI signal, each attenuation state associated with a respective attenuation level; (b) in the selected attenuation state, storing a measure of the SNR; (c) changing the attenuation state to a new attenuation state selected from one of the number of attenuation states; (d) in the new attenuation state, storing another measure of the SNR; and (e) changing the attenuation state back to the selected attenuation state if the measured SNR in step (d) is not greater than the measured SNR in step (b). - View Dependent Claims (12, 13, 14, 15)
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Specification