MIMO Beam Pair Feedback Signaling for Low-Overhead Beamforming
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Solution Overview
Problem
In 5G wireless networks operating in the millimeter-wave band, the high frequency signals are prone to significant path loss and signal attenuation due to factors like distance and diffraction, necessitating dynamic beamforming adjustments, which result in excessive system overheads and signaling needs.
Innovation Solution
A feedback signaling mechanism that groups transmitter beams for efficient reporting by mobile devices, minimizing the use of dedicated reference signals to enhance beam management and reduce overhead and latency, particularly in MIMO systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dynamic beamforming adjustments are performed to compensate for path loss and signal attenuation in millimeter-wave bands, then link budget and coverage are improved, but system overheads and signaling needs increase excessively
Solution Approach 1:
The patent combines transmit beam identification and receive beam identification into a single unified feedback mechanism. The UE reports both TX beam index and RX beam index together, allowing the gNB to determine the complete beam pair link in one signaling exchange, thereby reducing system overheads while maintaining reliable beamforming adjustments for millimeter-wave coverage
Solution Approach 2:
The patent implements a feedback mechanism where the UE measures reference signals on multiple transmit beams, identifies the best transmit and receive beam pairs, and reports beam identification information back to the gNB. This feedback loop enables dynamic beamforming adjustments to compensate for path loss while optimizing signaling efficiency through consolidated beam pair reporting
2Reliability
If narrow RF beams are used at both BS and UE sides to compensate for propagation loss, then antenna gain and coverage are improved, but the radio link becomes vulnerable to blockage by user's hand or body
Solution Approach 1:
The patent enables dynamic beamforming where the gNB and UE can adjust their beam directions in real-time based on feedback from the UE. The system measures reference signals across multiple transmit beams and can switch between different beam pairs dynamically, allowing the radio link to adapt when blockage occurs by selecting alternative non-blocked beam paths
Solution Approach 2:
The patent changes the beamforming parameters by identifying and reporting multiple best beam pairs with different spatial directions. When blockage is detected through feedback, the system can switch to a different beam pair with altered directional parameters, maintaining coverage reliability while avoiding the fixed vulnerability of static narrow beams
3Reliability
If beamformer training and beam tracking are performed dynamically to adjust directivity, then beamforming performance is improved, but signaling overhead and latency increase
Solution Approach 1:
The patent performs preliminary beam training by measuring reference signals on multiple transmit beams before actual data transmission begins. The UE identifies the best transmit and receive beam pairs in advance and reports beam identification information to the gNB, so that beamforming parameters are established beforehand, reducing the need for continuous tracking signaling and lowering latency during data transmission
Solution Approach 2:
The patent merges beam training and beam tracking functions into a unified feedback mechanism. The same beam identification reporting structure is used for both initial beam training and subsequent beam tracking, consolidating signaling overhead and reducing latency by eliminating redundant separate procedures
Data Source
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AI summary
The specification and drawings present methods and apparatuses for feedback signaling for beamforming purposes in a multiple input-multiple output (MIMO) radio environment. According to an embodiment of the invention, a mobile device is configured to measure an integer number P of different beam groups, each group representing one or more transmit beams and each group corresponding to one or more antenna ports at the mobile device (502). The mobile device is triggered according to the configuration to provide feedback (504). The radio access node (506) transmits reference signals on each of the transmit beams across all of the groups for measurement by the mobile device and receives the triggered feedback comprising, for each of the different beam groups, at least one best match between a transmit beam of the respective group and a corresponding antenna port and an indication of measurement results for the best match (508).