MU-MIMO Feedback Protocol Using Triggered Channel Sounding
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Solution Overview
Problem
The existing sounding protocol for acquiring feedback information in multi-user multiple-input multiple-output (MU-MIMO) systems, particularly in High Efficiency Wi-Fi (HEW), is inefficient as it involves individual polling of receiving devices, leading to increased messaging overhead and wireless medium congestion.
Innovation Solution
A protocol that appends non-precoded long training fields (LTFs) to MU-MIMO packets, allowing all devices to perform channel estimation and provide feedback information without individual polling, with feedback reports piggybacked onto acknowledgement packets or data packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual polling protocol is used to acquire feedback information from receiving devices, then feedback information can be acquired reliably, but messaging overhead increases and wireless medium congestion occurs
Solution Approach 1:
The patent combines feedback information from multiple receiving devices into a single aggregated feedback report. Instead of transmitting separate feedback packets from each device, the access point consolidates channel state information from multiple stations into one report, reducing the total number of messages transmitted across the wireless medium while maintaining reliable feedback acquisition.
Solution Approach 2:
The feedback report structure is designed to universally accommodate feedback information from multiple receiving devices simultaneously. A single feedback report can contain channel state information from multiple stations, making the messaging mechanism multi-functional and eliminating the need for separate polling and feedback exchanges with each individual device.
2Measurement precision
If individual polling protocol is used to acquire feedback information, then each device can provide accurate feedback, but wireless medium congestion increases
Solution Approach 1:
Multiple feedback reports from different receiving devices are merged into a single aggregated feedback message. This consolidation maintains the precision of individual channel measurements while reducing wireless medium congestion by transmitting one combined report instead of multiple separate reports.
3Measurement precision
If frequent polling cycles are implemented to maintain up-to-date feedback information, then channel state accuracy is improved, but system overhead increases
Solution Approach 1:
The patent merges feedback acquisition for multiple devices into a single polling cycle, where the access point can solicit and receive aggregated feedback from multiple stations simultaneously. This approach maintains current channel state accuracy for all devices while reducing the time loss associated with repeated individual polling sequences.
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AI summary
In a wireless network having a plurality of devices configured to communicate using a beamforming technique, a method includes sending a trigger packet from a first device of the wireless network to a plurality of second devices of the wireless network. The trigger packet includes trigger data configured to cause the plurality of second devices to perform channel measurement based on the trigger data. The method also includes receiving feedback information from each of the plurality of second devices in response to the trigger packet.