Multi-Antenna Transmit Precoder Codebook for Signaling Overhead Reduction
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Solution Overview
Problem
Current cellular technology standards face inefficiencies in obtaining channel knowledge for multi-antenna transmit precoding, particularly in cellular networks, where signaling channel estimates from user equipment to the base station consumes significant resources and is undesirable.
Innovation Solution
A transmit precoder codebook is designed for various antenna configurations, allowing user equipment to compute and signal efficient precoders that enable beamforming and multi-stream transmission, reducing overhead by using a two-component precoder signaled at different frequencies to capture long-term and short-term channel variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If channel estimates are signaled from user equipment to base station for multi-antenna transmit precoding, then transmit precoding performance is improved, but signaling overhead and resource consumption increase significantly
Solution Approach 1:
The patent extracts only the essential precoder information (precoder indices) from the full channel estimate, allowing the base station to reconstruct the precoder without receiving complete channel state information. This reduces signaling overhead while maintaining precoding performance.
Solution Approach 2:
The patent uses codebook-based precoding where pre-defined precoder matrices are stored at both user equipment and base station. Instead of signaling actual channel estimates, the system signals indices that reference these pre-shared codebook entries, dramatically reducing signaling overhead while preserving precoding accuracy.
2Measurement precision
If precise channel knowledge is obtained for optimal precoding, then beamforming accuracy is improved, but resource consumption for channel estimation and signaling increases
Solution Approach 1:
The patent employs lightweight precoder index signaling instead of heavy channel estimate transmission. The precoder indices are minimal information elements that reference pre-defined codebook entries, providing sufficient precision for beamforming while consuming minimal signaling resources and energy.
3Productivity
If multi-stream transmission is implemented with multiple antennas, then data throughput is improved, but interference management complexity increases
Solution Approach 1:
The patent applies transmit precoding before multi-stream transmission to pre-shape the transmitted signals. By computing precoders based on channel conditions and applying them to the data streams beforehand, the system ensures that signals from multiple antennas arrive at the user equipment with appropriate weighting and phase relationships, enabling straightforward signal separation without complex interference management at the receiver.
Data Source
AI summary
Systems using a transmit precoder codebook designed for a four-transmitter (4Tx) antenna configuration are described. The 4Tx antenna configuration is an attractive option for base stations in cellular network environments due to site-acquiring advantages and robust performance. In an embodiment, the transmit precoder codebook can be used for a variety of transmit antenna configurations and has a high resolution to enable beamforming and/or nulling. In another embodiment, the transmit precoder codebook is a two-component codebook, with a first precoder component signaled at a first frequency and a second precoder component signaled at a second higher frequency.