Distributed MU-MIMO Beamforming via Over-the-Air Feedback
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently coordinating beamforming between multiple access points (APs) to serve multiple user terminals in distributed multi-user multiple input multiple output (MU-MIMO) systems, leading to interference and reduced accuracy in channel feedback, especially due to channel aging, phase offsets, and gain mismatches.
Innovation Solution
The method involves transmitting an announcement frame for beamforming procedures, including identifiers of user terminals in different basic service sets, and coordinating feedback information to perform distributed transmissions using beamforming procedures based on channel measurements, allowing multiple APs to form groups and coordinate beamforming over the air rather than relying on backhaul communication, thereby reducing interference and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple APs coordinate beamforming through backhaul communication, then beamforming accuracy can be improved, but data congestion on backhaul networks increases and bandwidth usage is excessive
Solution Approach 1:
The patent extracts the channel feedback coordination function from the backhaul communication path and relocates it to over-the-air communication. APs exchange channel feedback information directly with user terminals wirelessly, eliminating the need to transport this data through congested backhaul networks, thus reducing bandwidth consumption while maintaining beamforming accuracy
Solution Approach 2:
The patent introduces user terminals as intermediaries in the beamforming coordination process. Terminals receive channel feedback from multiple APs over the air, process this information, and enable coordinated beamforming without requiring direct backhaul communication between APs, thereby reducing backhaul bandwidth usage while preserving measurement precision
2Productivity
If multiple APs serve multiple user terminals simultaneously in distributed MU-MIMO, then data transmission efficiency is improved, but interference between transmissions increases
Solution Approach 1:
The patent implements a feedback mechanism where user terminals measure channels from multiple APs and report this channel state information back to the APs over the air. This feedback enables APs to adjust their beamforming weights and power levels to minimize mutual interference, allowing simultaneous service to multiple terminals while maintaining high transmission efficiency
Solution Approach 2:
The patent dynamically changes transmission parameters including beamforming weights, power levels, and resource allocation based on real-time channel feedback from user terminals. By adjusting these parameters, the system optimizes the balance between maintaining high data transmission efficiency through simultaneous transmissions and minimizing interference between concurrent streams
Data Source
AI summary
This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for group formation and sounding for distributed multi-user multiple input multiple output (MU-MIMO). Some implementations include a method of wireless communication. The method includes transmitting, from a first access point of a plurality of access points, an announcement frame for performing a beamforming procedure for a distributed transmission. The distributed transmission includes a transmission from the plurality of access points. The announcement frame includes at least one identifier of a user terminal in a different basic service set than a basic service set of the first access point. The method further includes transmitting a packet for measuring a channel. The method further includes receiving feedback information from the user terminal based on the packet for measuring the channel. The method further includes transmitting the distributed transmission using the beamforming procedure.