Uplink MIMO Precoding via DCI PMI Fields
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Solution Overview
Problem
Existing wireless communication systems, particularly in 4G networks, face challenges in efficiently reporting channel state information (CSI) for large antenna arrays, which limits the effectiveness of uplink multiple-input multiple-output (MIMO) operations, especially in scenarios with high mobility or inter-cell interference.
Innovation Solution
The implementation of dynamic and semi-dynamic beamforming techniques, along with advanced CSI reporting mechanisms, allows for efficient precoding in uplink transmissions by using precoding information fields in downlink control information (DCI) to guide user equipment (UE) in transmitting data using multiple precoders or precoder groups, enabling frequency-selective and reciprocity-based MIMO operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing channel quality reporting processes are used, then the system maintains simplicity in CSI reporting, but the system cannot sufficiently accommodate reporting of channel state information for large antenna arrays
Solution Approach 1:
The patent segments the precoding information field into multiple components including PMI (Precoding Matrix Indicator) and RI (Rank Indicator). This segmentation allows the system to handle large antenna arrays by breaking down the complex precoding information into manageable parts that can be reported efficiently, resolving the contradiction between adaptability and complexity.
Solution Approach 2:
The patent introduces a new dimension for CSI reporting by implementing multi-dimensional antenna array support through extended precoding matrices. This allows the system to accommodate large 2D antenna arrays without proportionally increasing reporting overhead, as the precoding information efficiently captures the spatial characteristics across multiple dimensions.
2Measurement precision
If dynamic beamforming techniques are implemented, then precoding accuracy is improved, but the system requires more CSI information which increases reporting overhead
Solution Approach 1:
The patent implements partial feedback mechanisms where the UE reports only the most critical CSI components (PMI and RI) rather than complete channel state information. This partial action approach maintains sufficient precoding accuracy for dynamic beamforming while significantly reducing reporting overhead, resolving the contradiction between precision and information loss.
Solution Approach 2:
The patent changes the parameter representation by using compact PMI and RI fields instead of reporting full channel matrices. This parameter transformation maintains the essential information needed for accurate precoding while reducing the amount of data that needs to be transmitted, thereby balancing precision requirements with overhead constraints.
3Productivity
If uplink MIMO operations are enabled with multiple transmit antennas, then data transmission capacity is increased, but the system faces challenges in channel estimation and precoding under limited CSI availability
Solution Approach 1:
The patent implements preliminary channel estimation using downlink reference signals before uplink transmission. The base station performs channel estimation based on uplink sounding references, and this preliminary information is used to configure appropriate precoding matrices before actual data transmission, ensuring reliable MIMO operations even with limited real-time CSI availability.
Solution Approach 2:
The patent implements feedback mechanisms where the UE reports PMI and RI to the base station, creating a closed-loop system. This feedback allows the base station to adapt precoding configurations based on actual channel conditions, maintaining high data transmission rates while ensuring reliable channel estimation through iterative refinement of precoding parameters.
Data Source
AI summary
Methods and apparatuses enabling uplink multiple-input multiple-output (MIMO) are provided. A user equipment (UE) includes a transceiver and a processor operably connected to the transceiver. The transceiver is configured to receive an uplink (UL) grant for an UL transmission. The processor is configured to decode a precoding information field in downlink control information (DCI) associated with the UL grant. The precoding information field includes at least one precoding matrix indicator (PMI) corresponding to a plurality of precoders. The transceiver is further configured to precode a data stream according to the precoders indicated by the precoding information field and transmit the precoded data stream on an UL channel.