5G Reference Signal Precoding for Scalable CSI Reporting
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Solution Overview
Problem
The 5G communication system faces challenges in uplink resource allocation, precoding for multiple channels, and channel state information reporting, particularly with increased bandwidth and the need for efficient CSI-RS transmission in FD-MIMO systems, where existing methods are inadequate for supporting multiple layers and terminals, and adapting to changing channel conditions.
Innovation Solution
A method that involves cyclic precoding for each resource element, combining multiple RBs for DMRS transmission, and using aperiodic CSI-RS transmission to efficiently allocate uplink resources, improve channel state information reporting, and support multi-user MIMO in the 5G system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a larger number of precoding matrices are cycled to enhance performance, then system capacity and MIMO transmission efficiency are improved, but the current DMRS structure limits support to only 8 precoded channels per RB, creating a bottleneck for utilizing more precoders
Solution Approach 1:
The patent divides the RB into multiple groups, with each group containing multiple REs that can be associated with different precoding matrices. This segmentation allows the system to support more than 8 precoded channels by distributing precoder associations across different RE groups within the same RB, effectively removing the 8-channel limitation while maintaining the existing DMRS structure.
Solution Approach 2:
The patent introduces a new dimension for precoder association by mapping precoding matrices to specific RE locations within an RB rather than limiting to one precoder per RB. This dimensional expansion allows multiple precoders to be utilized within the same RB by associating different precoders with different REs, thereby increasing system capacity without requiring additional DMRS resources.
2Speed
If beamforming and massive MIMO techniques are deployed to increase transmission distance and data rates, then propagation loss is decreased and throughput is improved, but the complexity of channel state information measurement and reporting increases significantly
Solution Approach 1:
The patent applies different precoding matrices to different REs within an RB based on local channel conditions. The terminal measures channel state information for each RE group and reports CSI corresponding to specific precoders, allowing localized optimization without requiring comprehensive CSI reporting for all possible precoders, thus reducing overall complexity while maintaining high data rates.
Solution Approach 2:
Instead of requiring the terminal to measure and report CSI for all 32 or more precoding matrices, the patent enables selective CSI reporting for a subset of precoders (e.g., 8 representative precoders) that are most relevant for the current transmission. This partial action approach reduces the burden on terminal devices while still providing sufficient information for effective beamforming and MIMO operations.
3Adaptability or versatility
If 32 or more precoding matrices are used for PDSCH transmission to enhance system capacity, then more layers and terminals can be supported, but the existing DMRS structure in LTE only supports up to 8 DMRSs per RB, creating a signaling bottleneck
Solution Approach 1:
The patent makes the existing DMRS structure universal by enabling it to support both the traditional 8-precoder case and the extended 32+ precoder case through the same DMRS resources. By associating multiple precoders with different REs within an RB and using the same DMRS for channel estimation across all precoders, the system achieves multi-functionality without requiring additional DMRS overhead, thus supporting more layers and terminals with the same resource budget.
Data Source
AI summary
The present disclosure relates to a communication technique for combining a 5G communications system that supports higher data transmission rates after 4G systems with IoT technology, and a system therefor. The present disclosure can be applied to intelligent services based on 5G communications technology and IoT related technology (for example, smart homes, smart buildings, smart cities, smart cars or connected cars, healthcare, digital education, retail businesses, security and safety related services, and the like). The method for a terminal according to the present invention is characterized by comprising the steps of: receiving a reference signal; generating channel state information by means of a circular application of a precoding matrix for each resource element; and transmitting the channel state information to a base station.