Uplink Codebook Subset Selection for Antenna Port Flexibility
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Solution Overview
Problem
Current mobile communication systems face challenges in supporting high-speed data services, large data traffic, increased user connections, low latency, and energy efficiency, necessitating advanced techniques such as small cell enhancement, dual connectivity, and non-orthogonal multiple access.
Innovation Solution
A method for transmitting an uplink signal based on a codebook in a wireless communication system, where a user equipment (UE) receives downlink control information including a transmit precoding matrix indicator (TPMI), determines a codebook subset, and transmits the uplink signal using discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) with specific codewords and power scaling, optimizing antenna port selection and combining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a codebook for rank 1 using four antenna ports is configured with specific codewords for single antenna port selection, then antenna port selection flexibility is improved, but codebook complexity increases
Solution Approach 1:
The codebook is segmented into multiple codebook subsets, each corresponding to different antenna port selection scenarios. Each subset contains codewords optimized for specific port configurations, allowing the system to select appropriate subsets based on channel conditions and requirements, thereby managing complexity while maintaining flexibility.
Solution Approach 2:
The codebook configuration is made dynamic through TPMI indication, where the terminal can be directed to use different codebook subsets based on real-time channel state information and transmission requirements. This dynamic selection allows the system to adapt to varying conditions without permanently increasing complexity across all operating modes.
2Reliability
If DFT-s-OFDM with specific codewords is used for uplink signal transmission, then transmission performance is improved, but signaling overhead increases
Solution Approach 1:
Instead of providing complete and independent codebook information for all possible scenarios, the patent provides partial codebook information through TPMI indication. The terminal already possesses the full codebook structure, so only the necessary subset identification is signaled, reducing overhead while maintaining the ability to achieve optimal transmission performance.
Solution Approach 2:
The terminal maintains a local copy of the codebook structure, eliminating the need to transmit the entire codebook definition over the air interface. Only references (TPMI values) to specific codewords or subsets are signaled, leveraging the terminal's local copy to minimize signaling overhead while ensuring accurate reproduction of the intended precoding configuration.
3Use of energy by moving object
If power scaling factor is applied to codewords based on UE capability, then energy efficiency is improved, but control signaling complexity increases
Solution Approach 1:
The power scaling factor is introduced as a configurable parameter that can be adjusted based on UE capability reports. By changing this parameter dynamically according to terminal capabilities, the system optimizes power consumption while managing the complexity of control signaling through standardized parameter management procedures.
Data Source
AI summary
This specification provides a method of transmitting an uplink signal based on a codebook in a wireless communication system. More specifically, the method performed by a UE includes receiving, from a base station, downlink control information (DCI) including a first transmit precoding matrix indicator (TPMI), determining a codebook subset related to the transmission of the uplink signal based on the first TPMI, and transmitting, to the base station, the uplink signal based on the determined codebook subset. Accordingly, there is an advantage in that flexibility in the transmission antenna design of a UE can be increased because the degree of freedom of antenna port selection is increased.