Method and apparatus for channel quality feedback within a communication system

• US 20050289256A1
• Filed: 04/25/2003
• Published: 12/29/2005
• Est. Priority Date: 04/25/2003
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Classon, Brian K., Cudak, Mark C., Talukdar, Anup
• Granted Patent: US 7,640,373 B2
• Time in Patent Office: Days
• US Class Current: 710/62
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0023 characterised by the signalling
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/1803 Stop-and-wait protocols
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/03802 Signalling on the reverse channel
• CPC Class Codes: H04L 25/0212 of impulse response
• CPC Class Codes: H04L 25/0222 Estimation of channel variability, e.g. coherence bandwidth, coherence time, fading frequency

Abstract

A base station (101) will request the transmission of quality information from a particular remote stations (102, 103) only when data is queued to be transmitted to the remote stations. Once a remote station begins the transmission of channel quality information, the transmission of such information continues until the data transmission is successfully delivered to the remote station. The base station receives the channel quality information and adjusts the modulation and coding of the remote stations accordingly. Where data is transmitted simultaneously to a plurality of remote stations, a set of queues (303) for the multiple remote stations is maintained, and based on queue status, a channel quality request messages is sent to a sub-set of remote stations with data queued.

Claims

1. A method comprising the steps of:

determining if data is queued to be sent to a remote station; and

based on whether or not data is queued, transmitting a channel quality request message to the remote station, causing the remote station to transmit a channel quality report indicating a perceived channel quality.

2. The method of claim 1 further comprising the step of:

receiving the channel quality report; and

determining a modulation and coding scheme based on the channel quality report.

3. The method of claim 1 further comprising the step of:

transmitting a queue status to the remote station causing the remote station to continue transmitting channel quality reports.

4. The method of claim 3 wherein the remote station continues transmitting channel quality reports until the queue status indicates no further data is to be transmitted to the remote station.

5. The method of claim 3 wherein the step of transmitting the queue status comprises the step of transmitting a last packet indicator to the remote station.

6. A method comprising the steps of:

receiving a channel quality request message from a base station;

in response to the channel quality request message, transmitting a channel quality report message to the base station indicating a perceived channel quality; and

continuing to transmit channel quality report messages to the base station until a data packet is successfully received from the base station.

7. The method of claim 6 wherein the step of continuing to transmit comprises the step of continuing to transmit channel quality report messages to the base station until a next data packet is successfully received from the base station.

8. The method of claim 6 wherein the step of continuing to transmit comprises the step of continuing to transmit channel quality report messages to the base station until a data packet is successfully received from the base station, wherein the data packet comprises an indicator that a channel quality report message is no longer required.

9. The method of claim 6 wherein the step of continuing to transmit comprises the step of continuing to transmit channel quality report messages to the base station until a data packet is received indicating the data packet to be a last packet requiring a channel quality report.

10. The method of claim 6 wherein the step of transmitting the channel quality report message comprises the step of transmitting the channel quality report message further indicating a modulation level for each of a plurality of sub-bands.

11. The method of claim 6 wherein the step of continuing to transmit the channel quality report message comprises the step of continuing to transmit the channel quality report message until a timer expires.

12. The method of claim 11 further comprising the step of resetting the timer upon a successful reception of the data packet.

13. The method of claim 6 further comprising the step of receiving the data packet having a modulation level that was identified in a previously-transmitted channel quality report message.

14. A method comprising the steps of:

determining that data is queued for a plurality of remote stations;

transmitting a plurality of channel quality request reports to a first subset of the plurality of remote stations causing the first subset of the plurality of remote stations to transmit a plurality of channel quality reports indicating a perceived channel quality; and

based on the plurality of channel quality reports, transmitting queued data to a second subset of the plurality of remote stations.

15. The method of claim 14 wherein the step of transmitting the queued data comprises the steps of:

determining a modulation and coding scheme for each of the remote stations, wherein the modulation and coding scheme is based on the plurality of channel quality reports; and

transmitting the queued data to the second subset of the plurality of remote stations utilizing the modulation and coding scheme.

16. The method of claim 15 wherein the step of determining the modulation and coding scheme comprises the step of determining the modulation and coding scheme based on the channel quality report message indicating a modulation level.

17. The method of claim 15 wherein the step of transmitting the queued data comprises the step of transmitting the queued data to the subset of the plurality of remote stations utilizing the modulation and coding scheme, wherein the remote station knows the modulation and coding scheme of the transmitted data based on a previously transmitted channel quality report message.

18. The method of claim 14 wherein the step of transmitting the queued data comprises the step of transmitting queued data to the subset of the plurality of remote stations, wherein the subset of the plurality of remote stations is chosen based on perceived channel conditions.

19. The method of claim 14 wherein the step of transmitting the queued data comprises the step of transmitting queued data to the subset of the plurality of remote stations comprises the step of transmitting queued data to those remote stations having good perceived channel conditions while failing to transmit data to remote stations perceiving poor channel conditions.

20. An apparatus comprising:

a plurality of data queues;

logic circuitry determining remote units that have data queued within the plurality of data queues; and

a transmitter, transmitting a channel quality request message to the remote station in response to the logic circuitry determining that data is queued for the remote unit, the channel quality request message causing the remote station to transmit a channel quality report indicating a perceived channel quality.

21. The apparatus of claim 20 further comprising:

a receiver receiving the channel quality report; and

adaptive modulation circuitry utilizing a modulation and coding scheme based on the channel quality report.