DFT-Compressed CSI Feedback Amplitude Restriction
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Solution Overview
Problem
In cellular wireless networks, existing techniques for reducing intercell interference, such as mechanically down-tilted antennas and Codebook Subset Restriction (CBSR), are limited in effectively managing power transmission and interference, especially with the advent of two-dimensional antenna arrays and DFT-compressed CSI feedback, where it is challenging to constrain transmitted power in specific directions.
Innovation Solution
The method involves codebook subset restriction for DFT-compressed CSI feedback, where a set of FD coefficients is defined and transmitted, with amplitude restriction ratios calculated to limit the power in configured directions, by scaling or setting to zero coefficients that exceed specified thresholds, thereby constraining the transmitted power in restricted beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If mechanically down-tilted gNB antennas are used to reduce intercell interference, then intercell interference is reduced, but signal power received by UE devices is reduced
Solution Approach 1:
The patent applies local quality by configuring different amplitude restriction ratios for different beams in the codebook. Specifically, beams pointing toward adjacent cells are assigned lower amplitude restriction ratios to reduce interference, while other beams maintain higher ratios to preserve signal power. This directional differentiation resolves the contradiction by locally optimizing power distribution based on spatial location.
Solution Approach 2:
The patent changes the amplitude restriction ratio parameter dynamically based on beam direction and neighboring cell configurations. By adjusting this parameter for specific beams rather than applying a uniform restriction, the system can reduce interference in critical directions while maintaining signal strength in other directions, thus resolving the power-interference tradeoff.
2Object-affected harmful factors
If Codebook Subset Restriction is used to constrain transmitted power in specific directions, then intercell interference is reduced, but adaptability of the system is reduced
Solution Approach 1:
The patent introduces dynamics by making the codebook subset restriction configurable and adaptable through higher-layer parameters. The amplitude restriction ratios and restricted beam configurations can be adjusted based on network conditions, UE location, and interference scenarios. This dynamic configuration maintains system adaptability while achieving interference reduction goals.
Solution Approach 2:
The patent uses parameter changes to maintain adaptability by allowing the network to configure amplitude restriction ratios and beam restrictions based on varying conditions. Rather than fixed restrictions, the system can modify these parameters in response to changing channel conditions, UE mobility, and interference patterns, thus preserving versatility while reducing interference.
3Productivity
If DFT-compressed CSI feedback is used to reduce feedback overhead, then signaling efficiency is improved, but ability to constrain transmitted power in specific directions is reduced
Solution Approach 1:
The patent applies segmentation by dividing the interference control function into two parts: (1) DFT-compressed CSI feedback for efficient channel state reporting, and (2) separate amplitude restriction ratio configuration for precise power control. This segmentation allows the system to maintain signaling efficiency through compression while achieving interference control through the dedicated amplitude restriction mechanism.
Solution Approach 2:
The patent introduces an intermediary mechanism (amplitude restriction ratios configured via higher-layer signaling) that bridges the gap between DFT-compressed feedback and interference control. This intermediary allows the system to use compact feedback while still enabling precise power constraint in specific directions through the additional configuration layer.
Data Source
AI summary
A codebook subset restriction configuration can be received (410) from a network entity. A set of reference signals can be received (420) from the network entity. A set of frequency domain coefficients can be defined (430). The set of frequency domain coefficients can be an element of a discrete Fourier transform-compression codebook. The set of frequency domain coefficients can be generated (440) based on at least the restriction of the function of the amplitude restriction ratio of each beam in the set of restricted beams. At least one channel state information report containing the set of frequency domain coefficients can be transmitted (450).