Integrity and Quality Monitoring and Signaling for Sounding and Reduced Feedback

Abstract

A method of sounding and feedback with channel quality information and reduced overhead is provided. A receiving station receives a sounding signal transmitted from an access point over multiple sub-channels of a wide channel in a wireless network. The receiving station detects channel quality based on the received sounding signal for each sub-channel. The receiving station then performs channel estimation based on the received sounding signal and thereby determining feedback information. Finally, the receiving station transmits a feedback message to the access point, the feedback message contains NULL feedback information, reduced feedback information, or channel integrity/quality indicators based on the channel quality information for each sub-channel. Based on the feedback message, the access point may repeat the sounding process, narrow the transmission bandwidth, or select only stations who have indicated uncorrupted channel sounding for MU-MMO transmission.

1 . A method comprising:
 (a) receiving a sounding signal transmitted from an access point over a wide channel in a wireless network, wherein the sounding signal is transmitted over one or multiple sub-channels of the wide channel;   (b) detecting channel quality based on the received sounding signal for each sub-channel;   (c) performing channel estimation based on the received sounding signal and thereby determining feedback information; and   (d) transmitting a feedback message to the access point, wherein the feedback message contains NULL feedback information, or reduced feedback information, and/or indicators based on the channel quality information detected in (b) for each sub-channel.   
     
     
         2 . The method of  claim 1 , wherein the detecting in (b) involves performing clear channel assessment (CCA) prior to the arrival of the sounding signal. 
     
     
         3 . The method of  claim 1 , wherein the sounding signal contains a cyclic redundancy check (CRC), and wherein the detecting in (b) involves checking the CRC for each sub-channel. 
     
     
         4 . The method of  claim 1 , wherein the sounding signal contains a fixed bit pattern, and wherein the detecting in (b) involves checking the fixed bit pattern for each sub-channel. 
     
     
         5 . The method of  claims 1  and  6 , wherein the null feedback information does not include beamforming report if the channel suffers significant degradation. 
     
     
         6 . The method of  claim 1 , wherein the reduced feedback information only includes beamforming report for the sub-channels that do not suffer significant degradation. 
     
     
         7 . The method of  claim 1 , wherein the feedback message contains an integrity or quality indicator comprising a plurality of bits, each bit indicates whether each corresponding sub-channel suffers significant degradation. 
     
     
         8 . The method of  claim 1 , wherein the sounding signal and feedback message are transmitted for MU-MIMO sounding and feedback, or for transmit beamforming sounding and feedback. 
     
     
         9 . A device, comprising:
 a receiver that receives a sounding signal transmitted from an access point over a wide channel in a wireless network, wherein the sounding signal is transmitted over one or multiple sub-channels of the wide channel;   a channel quality detecting module that detects channel quality based on the received sounding signal for each sub-channel;   a channel estimation module that performs channel estimation based on the received sounding signal and thereby determining feedback information; and   a transmitter that transmits a feedback message to the access point, wherein the feedback message contains NULL feedback information, or reduced feedback information, and/or indicators based on the detected channel quality information for each sub-channel.   
     
     
         10 . The device of  claim 9 , wherein the feedback message contains an integrity or quality indicator comprising a plurality of bits, each bit indicates whether each corresponding sub-channel suffers degradation. 
     
     
         11 . The device of  claim 9 , wherein the null feedback information does not include beamforming report if the channel suffers significant degradation. 
     
     
         12 . The device of  claim 9 , wherein the reduced feedback information only includes beamforming report information for the sub-channels that do not suffer significant degradation. 
     
     
         13 . A method, comprising:
 (a) transmitting a sounding signal by an access point to a plurality of stations over a wide channel in a wireless network, wherein the sounding signal is transmitted over one or multiple sub-channels of the wide channel; and   (b) receiving feedback messages from the corresponding stations, wherein one or more feedback messages contain NULL feedback information, or reduced feedback information, and/or indicators that indicate channel quality information for each sub-channel of a corresponding station.   
     
     
         14 . The method of  claim 13 , further comprising:
 retransmitting the sounding signal to a first station if the feedback message from the first station indicates significant degradation.   
     
     
         15 . The method of  claim 13 , further comprising:
 transmitting multi-user multiple-input multiple-output (MU-MIMO) signals to a selected subset of the plurality of stations based on the channel quality information indicated in each feedback message.   
     
     
         16 . The method of  claim 13 , further comprising:
 transmitting multi-user multiple-input multiple-output (MU-MIMO) signals over a selected subset of the sub-channels based on the channel quality information indicated in each feedback message.   
     
     
         17 . The method of  claim 13 , wherein the access point makes dynamic transmission bandwidth adjustments based on the channel quality information indicated in each feedback message. 
     
     
         18 . A device, comprising:
 a transmitter that transmits a sounding signal to a plurality of stations over a wide channel in a wireless system, wherein the sounding signal is transmitted over one or multiple sub-channels of the wide channel; and   a receiver that receives feedback messages from the corresponding stations, wherein one or more feedback messages contain NULL feedback information, or reduced feedback information, and/or indicators that indicate channel quality information for each sub-channel of a corresponding station.   
     
     
         19 . The device of  claim 18 , wherein the device retransmits the sounding signal to a first station if the feedback message from the first station indicates significant degradation. 
     
     
         20 . The device of  claim 18 , wherein the device transmits multi-user multiple-input multiple-output (MU-MIMO) signals to a selected subset of the plurality of stations based on the channel quality information indicated in each feedback message. 
     
     
         21 . The device of  claim 18 , wherein the device transmits multi-user multiple-input multiple-output (MU-MIMO) signals over a selected subset of the sub-channels based on the channel quality information indicated in each feedback message. 
     
     
         22 . The device of  claim 18 , wherein the device makes dynamic transmission bandwidth adjustments based on the channel quality information indicated in each feedback message.