Uplink Subband Precoding via FD Bases
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Solution Overview
Problem
Current wireless communication technologies, such as NR and LTE, face challenges in improving uplink transmission efficiency, particularly in supporting multiple users and diverse communication services with varying latency and reliability requirements.
Innovation Solution
The implementation of subband level precoding for uplink transmission, where user equipment (UE) receives information on frequency domain (FD) bases and linear combination coefficients from a network entity, and applies these to perform subband precoding for transmitting the physical uplink shared channel (PUSCH).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If wideband precoding is used for uplink transmission, then device complexity is reduced, but spectral efficiency and transmission quality deteriorate due to inability to capture frequency-selective channel characteristics
Solution Approach 1:
The uplink transmission bandwidth is divided into multiple subbands, and separate precoding matrices are applied to each subband. This segmentation allows the system to capture frequency-selective channel characteristics while maintaining manageable complexity through codebook-based selection.
Solution Approach 2:
The patent changes the precoding parameter from a single wideband matrix to multiple subband-specific matrices selected from codebooks. This parameter change enables adaptation to frequency-selective fading while controlling complexity through codebook indexing rather than full matrix computation.
2Productivity
If subband precoding is implemented, then spectral efficiency and transmission quality improve, but device complexity and signaling overhead increase
Solution Approach 1:
The patent employs universal codebooks that can be applied across different subbands and user equipment. These codebooks provide a standardized framework that enables subband precoding functionality while reusing the same mathematical structures and selection procedures across multiple subbands, reducing overall system complexity.
Solution Approach 2:
Instead of computing unique precoding matrices for each subband, the system copies and applies selected precoding matrices from standardized codebooks. This copying approach dramatically reduces computational complexity while maintaining the ability to adapt to frequency-selective conditions through codebook selection.
3Reliability
If frequency domain bases are used for precoding, then channel adaptation improves, but processing complexity and computational requirements increase
Solution Approach 1:
The patent applies different precoding characteristics to different frequency subbands based on local channel conditions. Each subband can independently select precoding matrices that best match its specific fading characteristics, achieving local optimization without requiring complex global optimization across the entire bandwidth.
Data Source
AI summary
Certain aspects of the present disclosure provide techniques for using subband precoding for uplink transmissions. In some cases, a UE may transmit sounding reference signals (SRS) to a network entity, receive information indicating at least one of a set of one or more frequency domain (FD) bases and linear combination coefficients, determined based on the SRS transmission, determine subband precoding based at least in part on linear combinations of the FD bases based on the linear combination coefficients, and transmit a physical uplink shared channel (PUSCH) with the subband precoding.