Phase Feedback for Millimeter Wave Multi-User Beamforming
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Solution Overview
Problem
Current millimeter wave (mmWave) multi-user beamforming technologies face challenges in accurately estimating channel conditions due to limited feedback information, particularly the lack of phase information and UE-specific codebook details, which hampers downlink performance and resource utilization in wireless communication systems.
Innovation Solution
User equipment (UE) determines phase estimates for received beams during beam training or channel estimation, providing feedback to the base station, including phase indices, measurements, and cross-correlation information, allowing the base station to reconstruct a more accurate estimated channel matrix, thereby improving channel estimation and resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If limited feedback information is used in mmWave multi-user beamforming, then device complexity and feedback overhead are reduced, but channel estimation accuracy and downlink performance deteriorate
Solution Approach 1:
The patent implements a feedback mechanism where the user equipment (UE) sends phase information and beam index feedback to the base station. This feedback enables the base station to reconstruct the channel matrix more accurately by incorporating phase details that were previously lost in conventional feedback schemes. The feedback loop transforms incomplete channel state information into actionable data for improved downlink beamforming.
Solution Approach 2:
The patent introduces phase information as an intermediary element that bridges the gap between limited feedback and accurate channel estimation. By extracting and transmitting phase details from the channel state information, the system creates an intermediate representation that preserves critical channel characteristics without requiring full channel matrix feedback, thus resolving the contradiction between feedback overhead and estimation accuracy.
2Measurement precision
If phase information is included in feedback, then channel state estimation accuracy improves, but feedback overhead and processing complexity increase
Solution Approach 1:
The patent extracts only the essential phase information from the complete channel state information and transmits it as feedback. Instead of sending the entire channel matrix or all channel state parameters, the system selectively extracts phase details that are most critical for downlink beamforming reconstruction. This extraction approach maintains estimation accuracy while significantly reducing feedback processing complexity compared to transmitting complete channel state information.
3Productivity
If comprehensive channel estimation is performed, then downlink performance improves, but resource utilization efficiency decreases due to limited feedback
Solution Approach 1:
The patent changes the parameter representation by transforming channel state information into phase-specific feedback. Instead of using conventional feedback parameters that lose phase information, the system converts channel state data into phase angles and beam indices that can be efficiently transmitted. This parameter transformation enables comprehensive channel estimation to be performed at the base station using compact feedback, thereby improving downlink performance without sacrificing resource utilization efficiency.
Data Source
AI summary
Certain aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine at least one phase estimate for at least one beam received by the user equipment during a beam training or channel estimation procedure; and/or provide the at least one phase estimate to a base station from which the at least one beam is received for the base station to reconstruct an estimated channel matrix of the user equipment. In some aspects, a base station may receive feedback information from a UE identifying phase estimates for a plurality of beams transmitted to the UE, wherein the feedback information relates to a selected beam for the UE and one or more other beams of the plurality of beams; and/or determine an estimated channel matrix for the UE based at least in part on the feedback information. Numerous other aspects are provided.