Power control in MIMO transceiver

• US 20070109955A1
• Filed: 10/04/2006
• Published: 05/17/2007
• Est. Priority Date: 11/11/2005
• Status: Abandoned Application

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Moorti, Rajendra, Trachewsky, Jason
• Application Number:
  US11/542,913
• Publication Number:
  US 20070109955A1
• Time in Patent Office: Days
• US Class Current: 370/206
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

A method of controlling power levels on a plurality of transmit streams in a single radio transceiver includes, for each of the plurality of transmit streams, detecting an output power level and sampling the output power level, digitizing the sample output power level, producing the digitized sample to a baseband processor. The baseband processor is operable to perform rate based compensation on the digital sample, to integrate and dump a plurality of digitized samples over a period that exceeds a transmission frame period to produce an average value over a specified number of samples. Thereafter, the processor is operable to convert the integrated plurality of digitized samples to a normalized value and to comparing the normalized value to a target value to generate a power index value to determine an output power level with rate based compensation.

Claims

1. A method of controlling power levels on a plurality of transmit streams in a single radio transceiver, comprising, for each of the plurality of transmit streams:

detecting an output power level and sampling the output power level;

digitizing the sample output power level;

producing the digitized sample to a baseband processor;

within, the baseband processor;

performing rate based compensation on the digital sample;

integrating and dumping a plurality of digitized samples over a period that exceeds a transmission frame period to produce an average value over a specified number of samples;

converting the integrated plurality of digitized samples to a normalized value;

comparing the normalized value to a target value to generate a power index value that will result in the normalized value being substantially equal to the target value;

determining an output power level based upon the power index value; and

performing rate based compensation for the determined output power level.

2. The method of claim 1 wherein performing the rate based compensation includes compensating for constellation type.

3. The method of claim 1 wherein performing the rate based compensation includes compensating for coding rate.

4. The method of claim 1 wherein performing the rate based compensation includes compensating for a number of concurrently transmitting spatial streams.

5. The method of claim 1 further including compensating for I/Q imbalance based upon the power index value.

6. The method of claim 1 further including compensating for LO feedthrough based upon the power index value.

7. A transmitter with transmit power control circuit, comprising:

processing logic operable to produce outgoing communication signals;

radio front end circuitry operable to upconvert outgoing signals to radio frequency;

a power amplifier operable to amplify the outgoing radio frequency signals for transmission to produce an amplified transmission signal;

a power detect block operable to produce a transmit signal strength indication based upon the amplified transmission signal;

power control logic operable to produce a gain control signal and a core select signal to select a core of a plurality of cores for the gain control signal;

wherein the power control logic is further operable to produce a digital-to-analog (DAC) control signal to set operational parameters for the DAC; and

wherein the power control logic is further operable to produce a digital scaling signal to scale a magnitude of the outgoing communication signals produced by the processing logic.

8. The transmitter of claim 7 wherein the power control logic further includes:

an eight bit counter for selecting samples from a stream of transmit signal strength indications (TSSI);

a power look-up table for mapping TSSI values to output power estimates; and

circuitry for adjusting the output power estimates based upon at least one of frame type, code rate, modulation scheme and space/time frequency mode of operation.

9. The transmitter of claim 8 wherein the circuitry for adjusting the output power estimates further includes an index generation logic block that is operably disposed to receive at least one of frame type, code rate, modulation scheme and space/time frequency mode of operation and is operable to produce a transmit power index.

10. The transmitter of claim 9 further including a rate adjustment table that produces the power adjust signal based upon the power adjustment index produced by the index generation logic block.

11. The transmitter of claim 10 further including a first core transmit gain setting table for determining a gain value based upon the transmit power index.

12. The transmitter of claim 10 further including a first core transmit gain setting table for determining a DAC control value based upon the transmit power index.

13. The transmitter of claim 10 further including a first core transmit gain setting table for determining a digital scaling value based upon the transmit power index.

14. The transmitter of claim 10 further including a first core transmit gain setting table for determining an I/Q imbalance compensation value based upon the transmit power index.

15. The transmitter of claim 10 further including a first core transmit gain setting table for determining an LO feedthrough compensation value based upon the transmit power index.

16. A transmitter, comprising:

a transmit power adjustment block operable to produce a power adjust signal;

an index calculation block for producing a transmit power index signal based upon the power adjust signal; and

transmit gain and compensation logic for generating, for a specified core of a plurality of cores having a radio front end for transmitting outgoing RF signals, at least one of a gain control signal, a DAC control signal, a digital scaling signal, an I/Q imbalance compensation signal and an LO feedthrough compensation signal based upon the transmit power index signal

17. The transmitter of claim 16 wherein the transmit power adjustment block further includes:

an eight bit counter for producing selected samples from a stream of transmit signal strength indications (TSSI);

a power look-up table for producing output power estimates based upon the selected TSSI values;

an index generation logic block that is operably disposed to receive at least one of frame type, code rate, modulation scheme and space/time frequency mode of operation and is operable to produce a transmit power adjustment index based upon a combination of at least one of frame type, code rate, modulation scheme and space/time frequency mode of operation;

a rate adjustment table that produces a power adjust signal based upon the power adjustment index produced by the index generation logic block; and

a combining element that produces the estimated power adjustment based upon the output power estimate and the power adjust signal.

18. The transmitter of claim 17 further including a first core transmit gain setting table for determining a gain value based upon the transmit power index for a selected core of a plurality of cores.

19. The transmitter of claim 17 further including a second core transmit gain setting table for determining a gain value based upon the transmit power index for a selected core of a plurality of cores.

20. The transmitter of claim 17 further including a first core transmit gain setting table for determining a gain setting, a DAC control signal and a digital compensation value based upon the transmit power index for a selected core of a plurality of cores.

21. The transmitter of claim 17 further including a first core transmit compensation table for determining an I/Q imbalance compensation value based upon the transmit power index for a selected core of a plurality of cores.

22. The transmitter of claim 18 further including a first core transmit compensation table for determining an LO feedthrough compensation value based upon the transmit power index for a selected core of a plurality of cores.