Granted Patent B2

US 7,474,719 · App. 11/145,622 · Granted Jan 6, 2009

Abstract

Claims (94)

1. A method for de-sensing a composite signal having a plurality of frequency-based channels, the method comprising:

(a) channelizing the composite signal to generate a plurality of channel signals, each channel signal corresponding to a different carrier frequency in the composite signal;

(b) independently adding a specified level of noise to each channel signal to generate a de-sensed channel signal, wherein the specified levels of noise for at least two channel signals are different; and

(c) processing each de-sensed channel signal to enable characterization of effect of the added noise, wherein;

step (a) further comprises performing automatic gain control (AGC) processing;

step (b) comprises, for each channel signal:

(1) processing the channel signal to undo the AGC processing to generate a scaled channel signal;

(2) adding the specified level of noise to the scaled channel signal to generate a noise-scaled channel signal; and

(3) processing the noise-scaled channel signal to redo the AGC processing to generate the de-sensed channel signal.

2. The invention of claim 1 , wherein:

each channel signal has corresponding signal strength data;

step (b)(1) comprises multiplying the channel signal based on the corresponding signal strength data to generate the scaled channel signal;

step (b)(3) comprises inverse scaling the noise-scaled channel signal based on both the corresponding signal strength data and the specified level of added noise to generate the de-sensed channel signal.

3. The invention of claim 2 , wherein:

the signal strength data is expressed in dB as part of the channel signal;

the specified level of noise is expressed in dB;

step (b)(1) comprises:

(i) converting the signal strength data from dB to linear units; and

(ii) multiplying the channel signal by the signal strength data in linear units to generate the scaled channel signal;

step (b)(2) comprises:

(i) converting the specified level of noise from dB to linear units;

(ii) multiplying the specified level of noise in linear units by random data to generate randomized noise in linear units; and

(iii) adding the randomized noise in linear units to the channel signal to generate the noise-scaled channel signal; and

step (b)(3) comprises:

(i) subtracting the specified level of noise in dB from the signal strength data in dB to generate signal-minus-noise data in dB;

(ii) converting the signal-minus-noise data in dB to signal-to-noise (SNR) adjustment data in dB;

(iii)adding the SNR adjustment data in dB to the signal strength data in dB to generate new signal strength data in dB;

(iv) converting the new signal strength data in dB to corresponding inverted scaling data in linear units; and

(v) multiplying the noise-scaled channel signal by the inverted scaling data and applying arithmetic bit-shifting to generate the de-sensed channel signal.

4. The invention of claim 3 , wherein each converting step is implemented using a look-up table (LUT).

5. The invention of claim 1 , wherein:

step (a) is implemented in a digital down converter (DDC);

step (b) is implemented in a digital domain on a processor; and

step (c) is implemented in a baseband processor.

6. The invention of claim 5 , wherein step (b) is implemented in a field-programmable gate array (FPGA).

7. The invention of claim 1 , wherein at least part of step (b) is implemented for all of the channel signals using a single set of time-multiplexed circuitry.

8. The invention of claim 1 , wherein step (c) comprises processing each de-sensed channel signal to recover data from the de-sensed channel signal.

9. A processor for de-sensing a composite signal having a plurality of frequency-based channels in a receiver adapted to channelize the composite signal, upstream of the processor, to generate a plurality of channel signals, each channel signal corresponding to a different carrier frequency in the composite signal, wherein:

the processor is adapted to independently add a specified level of noise to each channel signal to generate a de-sensed channel signal, wherein the specified levels of noise for at least two channel signals are different; and

the receiver is further adapted to process each de-sensed channel signal to enable characterization of effect of the added noise, wherein:

the receiver is adapted to perform AGC processing upstream of the processor;

for each channel signal, the processor comprises:

(1) means for processing the channel signal to undo the AGC processing to generate a scaled channel signal;

(2) means for adding the specified level of noise to the scaled channel signal to generate a noise-scaled channel signal; and

(3) means for processing the noise-scaled channel signal to redo the AGC processing to generate the de-sensed channel signal.

10. The invention of claim 9 , wherein:

each channel signal has corresponding signal strength data;

the processor is adapted to undo the AGC processing by multiplying the channel signal based on the corresponding signal strength data to generate the scaled channel signal;

the processor is adapted to redo the AGC processing by inverse scaling the noise-scaled channel signal based on both the corresponding signal strength data and the specified level of added noise to generate the de-sensed channel signal.

11. The invention of claim 10 , wherein:

the signal strength data is expressed in dB as part of the channel signal;

the specified level of noise is expressed in dB;

the processor is adapted to undo the AGC processing by:

(i) converting the signal strength data from dB to linear units; and

(ii) multiplying the channel signal by the signal strength data in linear units to generate the scaled channel signal;

the processor is adapted to add the specified level of noise by:

(i) converting the specified level of noise from dB to linear units;

(ii) multiplying the specified level of noise in linear units by random data to generate randomized noise in linear units; and

(iii)adding the randomized noise in linear units to the channel signal to generate the noise-scaled channel signal; and

the processor is adapted to redo the AGC processing by:

(i) subtracting the specified level of noise in dB from the signal strength data in dB to generate signal-minus-noise data in dB;

(ii) converting the signal-minus-noise data in dB to SNR adjustment data in dB;

(iii)adding the SNR adjustment data in dB to the signal strength data in dB to generate new signal strength data in dB;

(iv) converting the new signal strength data in dB to corresponding inverted scaling data in linear units; and

(v) multiplying the noise-scaled channel signal by the inverted scaling data and applying arithmetic bit-shifting to generate the de-sensed channel signal.

12. The invention of claim 11 , wherein the processor uses a LUT to implement each conversion.

13. The invention of claim 9 , wherein:

the receiver comprises a DDC adapted to channelize the composite signal;

the processor is adapted to operate in a digital domain; and

the receiver further comprises a baseband processor adapted to process each de-sensed channel signal.

14. The invention of claim 13 , wherein the processor is an FPGA.

15. The invention of claim 9 , wherein the processor comprises time-multiplexed circuitry adapted to operate on all of the channel signals.

16. A radio processor comprising:

front-end circuitry adapted to receive and process a composite signal having a plurality of frequency-based channels;

a DDC adapted to channelize the composite signal to generate a plurality of channel signals, each channel signal corresponding to a different carrier frequency in the composite signal; and

a processor adapted to independently add a specified level of noise to each channel signal to generate a de-sensed channel signal, wherein the specified levels of noise for at least two channel signals are different; and

a baseband processor adapted to process each de-sensed channel signal to enable characterization of effect of the added noise, wherein;

the DDC is adapted to perform AGC processing upstream of the processor;

for each channel signal, the processor is adapted to

(1) process the channel signal to undo the AGC processing to generate a scaled channel signal;

(2) add the specified level of noise to the scaled channel signal to generate a noise-scaled channel signal: and

(3) process the noise-scaled channel signal to redo the AGC processing to generate the de-sensed channel signal.

17. The invention of claim 16 , wherein the front-end circuitry is adapted to process a plurality of versions of the composite signal received at a plurality of receive antennas associated with the radio processor.

18. A receiver comprising:

a radio processor comprising:

front-end circuitry adapted to receive and process a composite signal having a plurality of frequency-based channels;

a DDC adapted to channelize the composite signal to generate a plurality of channel signals, each channel signal corresponding to a different carrier frequency in the composite signal; and

a processor adapted to independently add a specified level of noise to each channel signal to generate a de-sensed channel signal, wherein the specified levels of noise for at least two channel signals are different; and

a baseband processor adapted to process each de-sensed channel signal to enable characterization of effect of the added noise, wherein:

the DDC is adapted to perform AGC processing upstream of the processor;

for each channel signal, the processor is adapted to

(1) process the channel signal to undo the AGC processing to generate a scaled channel signal;

(2) add the specified level of noise to the scaled channel signal to generate a noise-scaled channel signal; and

(3) process the noise scaled channel signal to redo the AGC processing to generate the de-sensed channel signal.

Assignments (8)