CSI-RS Port Mapping for Base Station Beamforming Complexity
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Solution Overview
Problem
Current CSI-RS port to resource element and OFDM symbol mapping in NR causes high implementation complexity due to the need to transmit multiple beams in the same OFDM symbol, leading to increased complexity and cost in hardware implementation.
Innovation Solution
Alternative resource element mapping of CSI-RS ports such that ports corresponding to the same beam are mapped to the same OFDM symbol, reducing the number of different beamforming vectors required per symbol, achieved by modifying the structure of the Type II port selection codebook and CSI-RS port mapping, including reordering of port numbering and introducing new CSI-RS resource configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current CSI-RS port to resource element and OFDM symbol mapping is used, then channel state information measurement capability is maintained, but implementation complexity increases due to transmitting multiple beams in the same OFDM symbol
Solution Approach 1:
The patent segments the transmission by mapping each beam to a separate OFDM symbol instead of transmitting multiple beams simultaneously in the same symbol. This divides the complex multi-beam transmission into simpler sequential single-beam transmissions, reducing hardware complexity while maintaining the ability to measure channel state information for multiple beams.
Solution Approach 2:
The patent employs periodic action by transmitting different beams in different OFDM symbols in a sequential manner. Each beam is transmitted periodically across different symbols, allowing the UE to measure channel state information for each beam over time while the base station avoids the complexity of simultaneous multi-beam transmission.
2Adaptability or versatility
If multiple beams are transmitted in the same OFDM symbol, then beamforming diversity is achieved, but hardware complexity and cost increase
Solution Approach 1:
The patent transitions from transmitting multiple beams simultaneously in the frequency-time plane to transmitting beams sequentially in the time dimension (different OFDM symbols). This dimensional change allows beamforming diversity to be achieved through time-division rather than frequency-division, reducing hardware complexity while maintaining adaptability.
3Adaptability or versatility
If current port mapping structure is used, then existing NR compatibility is maintained, but processing resources are consumed by complex beamforming operations
Solution Approach 1:
The patent introduces dynamic behavior by allowing the system to switch between different port mapping configurations. The new mapping structure can be activated when resources need to be freed for other operations, while maintaining compatibility with existing NR operations when needed, thus dynamically optimizing resource allocation.
Data Source
AI summary
A method for reducing the number of beams required per symbol. The method is performed by a base station (gNB). The method includes transmitting reference signals (RSs) and receiving a report from a UE (302), the report identifying a matrix. The method also includes using the identified matrix to transmit data to the UE or schedule the UE. The matrix identified by the UE is equal to (I) and Wps is a port selection matrix and (II) denotes the Kronecker product.