Wireless Precoder Signaling With Rank Override Feedback
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Solution Overview
Problem
The existing communication systems face significant signaling overhead due to large feedback payloads in multi-antenna wireless communication systems, particularly in scenarios with frequency-selective precoding, and the inefficiencies in precoder reporting and rank override mechanisms lead to performance degradation.
Innovation Solution
Implementing a method and device that support efficient rank override by confirming the use of recommended precoders and transmission ranks through a confirmation message, allowing partial use of precoders and flexible codeword-to-layer mappings, thereby reducing signaling overhead and improving system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency-selective precoding is used to improve system performance and adapt to channel variations, then the data rate and reliability are improved, but the signaling overhead increases due to large feedback payloads requiring multiple precoders to be signaled
Solution Approach 1:
The patent segments the precoding feedback into two parts: (1) a first feedback message containing a recommended precoder from a codebook, and (2) a second feedback message containing a precoder override indicator that specifies whether to use the recommended precoder or a different precoder. This segmentation reduces the immediate signaling overhead while preserving the ability to adapt to channel variations through the override mechanism.
Solution Approach 2:
The patent introduces a dynamic precoder selection mechanism where the transmitter can switch between using the recommended precoder and an alternative precoder based on the precoder override indicator. This dynamic adaptation allows the system to respond to changing channel conditions without continuously signaling complete precoder information, thus reducing overhead while maintaining reliability.
2Adaptability or versatility
If multiple precoders are signaled to cover frequency variations, then the adaptability to channel conditions is improved, but the feedback payload size increases leading to large signaling overhead
Solution Approach 1:
Instead of signaling complete precoder information for multiple frequency subbands, the patent signals only a recommended precoder and a compact precoder override indicator. This partial action approach provides sufficient adaptability by allowing the receiver to indicate whether the recommended precoder is suitable or if an alternative should be used, without transmitting full precoder details for each subband.
Solution Approach 2:
The patent introduces a codebook as an intermediary structure that contains predefined precoders. The feedback messages reference this codebook rather than transmitting complete precoder matrices, significantly reducing the feedback payload size while maintaining the ability to adapt to different channel conditions through codebook indexing and override indicators.
3Productivity
If the transmitter uses a different transmission rank than recommended by the receiver, then the system can optimize for current channel conditions and load, but the receiver needs additional information to correctly decode the transmission
Solution Approach 1:
The patent implements a feedback mechanism where the receiver sends a precoder override indicator that implicitly or explicitly conveys information about the transmission rank. This feedback loop allows the transmitter to adjust the transmission rank based on receiver conditions while the receiver can correctly interpret the transmission by understanding the relationship between the override indicator and the rank information.
Solution Approach 2:
The patent changes the parameter representation by using a precoder override indicator that can convey both precoder selection and transmission rank information in a unified manner. This parameter transformation allows the system to optimize throughput by varying the transmission rank while keeping the control information structure relatively simple through the use of indexed references to codebook entries.
Data Source
AI summary
The invention relates to devices and methods for signalling control information associated with transmission of data over a wireless channel. A second communication device receives (S2) data from a first communication device, wherein the data comprises an indication of recommended precoders and a recommendation of a first transmission rank to possibly use during transmission. The second communication device determines (S4) a second transmission rank to use for transmitting data, and transmits (S6) a confirmation message to the first communication device. The confirmation message comprises a confirmation that transmission of data from the second communication device is using at least parts of each recommended precoder associated with a frequency resource that falls within the transmission of data and an indicator of the second transmission rank to use.