Granted Patent B2

US 9,276,653 · App. 13/859,764 · Granted Mar 1, 2016

Abstract

Claims (49)

1. A method for pilot compression at a base station in a multi-antenna system, comprising:

in response to an activating event, transmitting a plurality of pilot signals through a plurality of transmit antennas at the base station, wherein each of the plurality of transmit antennas transmits a corresponding one of the plurality of pilot signals;

receiving a set of feedback signals from each of a set of mobile stations, wherein for a given mobile station, each of the feedback signals indicates qualities of each channel over which the plurality of pilot signals are received by the given mobile station from the plurality of transmit antennas;

selecting for each mobile station a subset of transmit antennas based on the qualities of the each channel indicated in the set of feedback signals;

identifying a superset of transmit antennas, the superset of transmit antennas including all transmit antennas of the subsets of transmit antennas; and

during normal system operation, periodically performing a selected pilot transmission including transmitting pilot signals through the superset of transmit antennas.

2. The method of claim 1 , wherein the activating event comprises one or more of the following:

a first mobile station for a first preferred user joins a cell associated with the base station;

a throughput of a second mobile station for a second preferred user drops below a predefined threshold;

a quality of Service (QoS) for a third preferred user drops below a predefined level; and

an occurrence of an infrequent periodic event.

3. The method of claim 1 , wherein the selecting the subset of transmit antennas comprises receiving a list of selected antennas from the each of the set of mobile stations; and

wherein the identifying the superset of transmit antennas comprises combining all of the received lists.

4. The method of claim 3 , wherein, the quality metric

maximizes at least multiple-input-multiple-output (MIMO) channel capacity or a received signal-to-noise-ratio (SNR).

5. The method of claim 1 , wherein the selecting the subset of transmit antennas comprises receiving the quality metrics from the set of mobile stations; and

wherein the identifying the superset of transmit antennas comprises combining all subsets of transmit antennas.

6. The method of claim 1 , wherein

the set of feedback signals comprises estimated channels;

wherein the selecting the subset of the transmit antennas comprises

calculating the quality metrics; and

wherein the identifying the superset of transmit antennas comprises combining all subsets of transmit antennas.

7. The method of claim 1 , wherein the multi-antenna system encodes data using orthogonal-frequency-division-multiplexing (OFDM).

8. A system that facilitates pilot compression in a multi-antenna system, comprising:

a base station including multiple transmit antennas; and

a channel-sounding mechanism within the base station;

wherein in response to an activating event, the channel-sounding mechanism is configured to:

transmit a plurality of pilot signals through a plurality of transmit antennas at the base station, wherein each of the plurality of transmit antennas transmits a corresponding one of the plurality of pilot signals;

receive a set of feedback signals from each of a set of mobile stations, wherein for a given mobile station, each of the feedback signals indicates qualities of each channel over which the plurality of pilot signals are received by the given mobile station from the plurality of transmit antennas;

select for each mobile station a subset of transmit antennas based on the qualities of the each channel indicated in the set of feedback signals; identify a superset of transmit antennas, the superset of transmit antennas including all transmit antennas of the subsets of transmit antennas; and

during normal system operation, periodically perform a selected pilot transmission by transmitting pilot signals through the superset of transmit antennas.

9. The system of claim 8 , wherein the activating event comprises one or more of the following:

a first mobile station for a first preferred user joins a cell associated with the base station;

a throughput of a second mobile station for a second preferred user drops below a predefined threshold;

a quality of Service (QoS) for a third preferred user drops below a predefined level; and

an occurrence of an infrequent periodic event.

10. The system of claim 8 , wherein the channel-sounding mechanism is configured to select the subset of transmit antennas comprises receiving a list of selected antennas from the each of the set of mobile stations; and

identify the superset of transmit antennas comprises combining all of the received lists.

11. The system of claim 10 , wherein, the quality metric

maximizes at least multiple-input-multiple-output (MIMO) channel capacity or a received signal-to-noise-ratio (SNR).

12. The system of claim 10 , wherein the channel-sounding mechanism is configured to:

select the subset of transmit antennas comprises receiving the quality metrics from the set of mobile stations; and

identify the superset of transmit antennas comprises combining all subsets of transmit antennas.

13. The system of claim 10 , wherein the set of feedback signals comprises estimated channels and wherein the channel-sounding mechanism is configured to:

calculate the quality metrics;

select a list of antennas for each preferred mobile station based on the calculated performance metrics; and

identify the superset of transmit antennas comprises combining all subsets of transmit.

14. The system of claim 8 , wherein the system is a multiple-input-multiple-output (MIMO) communication system.

15. The system of claim 8 , wherein the system encodes data using orthogonal-frequency-division-multiplexing (OFDM).

Assignments (8)