Beam Group Selection Using Double Codebook Feedback
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Solution Overview
Problem
Current communication systems face challenges in efficiently managing increased communication channel dimensionality and degrees of freedom associated with downlink antenna beam formation, particularly in supporting high data rates and accommodating a large number of wireless communication devices with limited transmit power, while maintaining effective channel state information reporting.
Innovation Solution
An apparatus and method that measure channel state information to select a beam group and a subset of beams based on wideband properties, using a double codebook format with a processor and memory configured to identify beam groups and subsets according to transmission rank, enabling efficient communication by forming precoders for transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If downlink antenna beam formation with increased dimensionality is implemented to support high data rates, then spectral efficiency is improved, but channel state information reporting burden on uplink increases
Solution Approach 1:
The patent segments the channel state information feedback into two distinct parts: wideband channel quality indicators (reporting overall channel conditions across the entire bandwidth) and subband precoder indicators (reporting beam-specific precoding information for specific frequency subbands). This segmentation reduces the overall feedback overhead by avoiding redundant wideband information transmission for each subband, thereby resolving the contradiction between maintaining high spectral efficiency through detailed beam formation and reducing uplink reporting burden.
2Productivity
If multiple transmit antennas are used to increase data transmission capacity, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent divides the complex beam formation process into two manageable stages: wideband channel quality assessment (determining overall channel conditions) and subband precoder selection (selecting specific beams for specific frequency subbands). This segmentation transforms the complex task of managing multiple antennas into a structured two-step process, reducing computational complexity while maintaining the ability to support high data transmission capacity through multiple spatial layers.
Solution Approach 2:
The patent introduces a frequency-domain dimension to the beam formation process by implementing subband-specific precoding. Instead of applying a single wideband precoder across all frequencies, the system selects different precoders for different frequency subbands based on frequency-selective channel conditions. This dimensional approach enables more precise beam formation that adapts to frequency variations, improving data transmission capacity while keeping complexity manageable through structured selection procedures.
3Productivity
If beam selection is optimized for specific subbands to improve SU-MIMO performance, then productivity is improved, but feedback overhead increases
Solution Approach 1:
The patent segments feedback into hierarchical levels: wideband channel quality indicators provide coarse-grained information about overall channel conditions, while subband precoder indicators provide fine-grained beam selection information only where needed. This hierarchical segmentation enables optimized SU-MIMO performance through subband-specific beam selection while controlling feedback overhead by avoiding transmission of detailed subband information for all subbands, instead using compact precoder indicator representations.
Data Source
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AI summary
An apparatus and method for selecting a beam group and a subset of beams in a communication system are disclosed. The method includes: measuring channel state information (CSI) on a downlink from a base station (920); identifying a selected beam group out of a set of beam groups according to a wideband property of the CSI (930); identifying a selected subset of beams in the selected beam group according to at least one subband (940). Wherein the characteristic of the set of beam groups depends on a transmission rank and the number of beams in the selected subset of beams is equal to the transmission rank. The method further includes: generating encoded feedback information identifying the selected beam group and the selected subset of beams for each subband in a double codebook format (950), transmitting the encoded feedback information to the base station. A computer program product comprising the computer program code which is configured to cause the apparatus to implement above operations is also disclosed.