PMI Reporting for Flexible Beamforming in Wireless Devices
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Solution Overview
Problem
Current communication networks face inefficiencies in precoding matrix indicator (PMI) reporting, particularly when using analogue beamforming, which limits the ability to simultaneously use multiple beam directions and restricts hardware flexibility, leading to suboptimal precoder selection and increased overhead in reporting processes.
Innovation Solution
A method and system for PMI reporting that allows wireless devices to efficiently pair port identifications with reference signal identifications, enabling flexible beamforming and simultaneous beam scanning, while adhering to hardware architecture restrictions, by transmitting PMI information in a report that combines port and reference signal identifications, thus enabling precoder selection to capture multipath propagations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If analogue beamforming is used to simplify hardware, then device complexity is reduced, but the ability to simultaneously use multiple beam directions is limited
Solution Approach 1:
The patent segments the beamforming functionality by introducing a codebook that contains multiple precoders corresponding to different beam directions. The wireless device can select and report multiple precoder indices (PMIs) from the codebook, enabling multiple beam directions to be represented even with simplified analogue beamforming hardware. This segmentation of the beamforming space into discrete precoder options resolves the contradiction between hardware simplicity and beam direction versatility.
2Loss of information
If a limited set of precoders is reported to reduce overhead, then reporting overhead is reduced, but precoder selection accuracy deteriorates
Solution Approach 1:
The patent introduces a new dimension to the reporting mechanism by implementing a two-dimensional reporting structure: rank indicator (RI) and precoder matrix indicator (PMI). The RI dimension indicates the number of precoders to be used, while the PMI dimension provides the specific precoder selections from the codebook. This dimensional expansion allows the system to convey more precise precoder selection information without proportionally increasing overhead, as the RI dimension enables efficient grouping and selection of multiple precoders.
3Productivity
If multiple precoders are selected to improve performance, then network performance is improved, but reporting overhead increases
Solution Approach 1:
The patent applies preliminary action by pre-defining a codebook of available precoders at both the network side and the wireless device side. This codebook is established beforehand, containing multiple precoders that cover different beam directions and spatial configurations. When reporting is needed, the wireless device simply selects and reports indices (PMIs) to the pre-defined codebook entries rather than reporting full precoder matrices. This preliminary establishment of the codebook structure enables efficient reporting of multiple precoders with minimal overhead, as only compact indices need to be transmitted.
Data Source
AI summary
There is provided mechanisms for precoding matrix indicator (PMI) reporting for a set of ports. A method is performed by a wireless device. The method comprises receiving reference signals, the reference signals having been transmitted from a set of ports of a network node. The method comprises determining PMI information for the received reference signals. The method comprises transmitting the PMI information in a report to the network node, wherein the report comprises a combination of identifications of ports from the set of ports and identifications of the reference signals such that an identification of each port is paired with a respective identification of at most one of the reference signals.