CSI-RS Port Mapping Using Even Odd Resource Block Segmentation
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Solution Overview
Problem
The existing LTE NZP CSI-RS designs face challenges in efficiently transmitting and receiving more than 16 CSI-RS ports in a subframe due to increased resource element overhead and reduced available configurations, which can lead to interference and decreased channel state information estimation quality, especially at high load conditions.
Innovation Solution
The proposed solution involves transmitting more than 16 CSI-RS ports by aggregating legacy LTE CSI-RS resources, where a fraction of the ports are sent over even resource blocks and the remaining ports over odd resource blocks, using orthogonal cover codes to efficiently pack more ports within each aggregated resource, thereby reducing overhead and maintaining configuration availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If more than 16 CSI-RS ports are transmitted using existing LTE designs, then the number of transmitted ports increases, but resource element overhead increases and configuration availability decreases
Solution Approach 1:
The patent divides the transmission of CSI-RS ports across multiple resource blocks by separating even and odd ports into different resource blocks. This segmentation allows efficient packing of more than 16 ports while controlling overhead by distributing ports across available resource elements in a structured manner.
Solution Approach 2:
The patent extends the CSI-RS port mapping into additional dimensions by utilizing both even and odd resource blocks separately for different port groups. This dimensional expansion in the resource block domain enables supporting more ports without proportionally increasing overhead in the time-frequency grid.
2Quantity of substance
If more than 16 CSI-RS ports are transmitted using existing LTE designs, then the number of transmitted ports increases, but the number of available configurations decreases
Solution Approach 1:
By segmenting ports into even and odd groups mapped to different resource blocks, the patent creates multiple independent configuration options. Each resource block can be independently configured, thereby increasing the total number of available configurations even as the number of ports increases.
Solution Approach 2:
The patent creates a universal mapping framework that can accommodate varying numbers of ports (more than 16) while maintaining multiple configuration possibilities. The same resource structure serves multiple functions by supporting different port counts and configuration scenarios through the even/odd resource block separation.
3Quantity of substance
If CSI-RS resources are densely packed to transmit more ports, then port capacity increases, but interference from neighboring cells increases
Solution Approach 1:
The patent segments CSI-RS transmissions into even and odd resource blocks, which can be strategically allocated to reduce overlap with neighboring cell transmissions. This segmentation provides flexibility in frequency-domain placement to minimize interference while maintaining high port capacity.
Solution Approach 2:
The patent applies different mapping patterns and resource block allocations for different port groups (even vs. odd ports), optimizing local resource usage in different frequency regions. This local optimization reduces interference in specific frequency bands while maintaining overall system capacity.
Data Source
AI summary
According to some embodiments, a method for use in a network node of transmitting channel state information reference signals (CSI-RS) comprises transmitting a number M of CSI-RS ports to one or more wireless devices. A fraction of the M ports are transmitted over a first physical resource block (PRB) and a remaining fraction of the M ports are transmitted over a second PRB. Some embodiments further comprise mapping the number M of CSI-RS ports to resource elements of a radio subframe. A fraction of the M ports are mapped to a first PRB of the subframe and a remaining fraction of the M ports are mapped to a second PRB of the subframe.