Open Loop Precoding with Interleaved Matrices for High Mobility
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Solution Overview
Problem
Existing open loop precoding schemes in wireless multiple antenna radio communications systems, particularly in high mobility scenarios, face challenges in maintaining effective Channel Quality Information (CQI) due to rapid channel variations when using UE-specific reference signals, leading to reduced performance.
Innovation Solution
The method involves using multiple precoding matrices within a resource unit, with data and demodulation reference signals being precoded using different matrices in an interleaved fashion, allowing for denser precoder cycling and improved CQI reliability, while avoiding the need for explicit precoding matrix signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If single precoding matrix is used per resource unit, then signaling overhead is reduced, but CQI reliability deteriorates in high mobility scenarios
Solution Approach 1:
The resource unit is segmented into multiple resource blocks, and different precoding matrices are applied to different resource blocks. This segmentation allows the system to track rapid channel variations in high mobility scenarios by updating precoding matrices at a finer granularity, thereby improving CQI reliability without requiring a single complex matrix to cover the entire resource unit.
Solution Approach 2:
The system dynamically selects and switches between multiple precoding matrices based on channel conditions and mobility characteristics. By making the precoding configuration dynamic rather than static, the system adapts to rapid channel changes, improving the reliability of CQI estimates in high mobility environments.
2Measurement precision
If multiple precoding matrices are used within a resource unit, then CQI estimate reliability is improved, but signaling overhead increases
Solution Approach 1:
The system uses self-service mechanisms where the UE autonomously determines which precoding matrix to use based on pre-configured mapping relationships between resource blocks and precoding matrices. The network only needs to signal the starting precoding matrix index and the number of matrices, rather than explicitly signaling each matrix selection, thereby reducing signaling overhead while maintaining measurement precision.
Solution Approach 2:
The precoding matrix configurations and their mappings to resource blocks are pre-configured and stored at both the network side and UE side. This preliminary action eliminates the need for real-time signaling of each precoding matrix selection, reducing signaling overhead while ensuring that the UE can accurately determine the appropriate precoding matrix for CQI measurement.
3Reliability
If dense precoder cycling is implemented, then transmission quality is improved, but scheduling flexibility is reduced
Solution Approach 1:
The system allows dynamic adjustment of parameters such as the number of precoding matrices, the resource block allocation pattern, and the starting matrix index. By changing these parameters based on traffic conditions and channel characteristics, the system can achieve dense precoder cycling for high reliability when needed, while maintaining scheduling flexibility by adjusting parameters for different service requirements.
Data Source
AI summary
The invention concerns a method for precoding in an open loop transmission communications system. The method includes precoding data at each of M REs with a precoding matrix, precoding each of DM-RSs with one column of a precoding matrix which is same as that used for precoding M data REs. The method is distinguished by using at least L≥2 different precoding matrices from a set of precoding matrices W to precode the M REs and the E allocated REs such that REs precoded with a first precoding matrix are interleaved with REs precoded with at least one additional, different precoding matrix and the number of used precoding matrices L is adapted to the transmission rank r and number N of available DM-RS.