CRS Rate Matching in Multi-RAT Networks
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Solution Overview
Problem
The coexistence of NR and LTE base stations in multi-radio access technology (RAT) communication networks poses a challenge due to differences in reference signal configurations, leading to increased interference and degraded performance for UEs.
Innovation Solution
The proposed solution involves rate matching a downlink channel around reserved resource elements associated with always-on signals from neighboring LTE cells, while transmitting additional signals in these reserved elements using the same antenna ports as the downlink communication, allowing UEs to accurately determine interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LTE base stations transmit always-on reference signals in shared spectrum, then LTE UEs can maintain continuous connectivity and perform channel estimation, but NR UEs experience increased interference and degraded performance
Solution Approach 1:
The resource elements are segmented into two categories: reserved REs for LTE CRS transmission and non-reserved REs for NR data transmission. This segmentation allows LTE reference signals to be transmitted in specific resource elements while NR data occupies other resource elements, reducing mutual interference between the two RATs
Solution Approach 2:
Different quality characteristics are applied to different resource elements. Reserved REs are designed with LTE CRS transmission characteristics (always-on, specific power levels), while non-reserved REs are optimized for NR data transmission. This local differentiation allows each RAT to operate with appropriate signal characteristics in its designated resources
2Reliability
If NR base stations rate match around reserved resource elements to avoid LTE CRS interference, then NR UE performance improves, but LTE UEs cannot accurately determine interference for channel estimation
Solution Approach 1:
A rate matching pattern configuration acts as an intermediary between NR data transmission and LTE CRS transmission. This configuration informs NR UEs about the locations of reserved REs, enabling them to correctly rate match around these elements. Simultaneously, it allows LTE UEs to identify reserved REs for accurate interference measurement, resolving the contradiction between NR performance improvement and LTE measurement accuracy
3Productivity
If spectrum sharing is implemented between NR and LTE base stations, then spectral efficiency and resource utilization improve, but reference signal configuration differences cause increased interference
Solution Approach 1:
The rate matching pattern configuration enables dynamic adaptation of NR data transmission around LTE CRS resources. The gNB can flexibly adjust the rate matching pattern based on traffic conditions and interference levels, allowing spectrum sharing to remain productive while managing reference signal interference through configurable resource element reservations
Data Source
AI summary
Mechanisms for rate matching a downlink communication channel in a multi-radio access technology (RAT) communication scenario are described. In one aspect, a method for wireless communication performed by a base station (BS) includes rate matching, based on a rate matching pattern indicating a plurality of reserved resource elements, a downlink (DL) communication channel. The method further includes transmitting, to a user equipment (UE) on one or more antenna ports, a DL communication in the rate matched DL communication channel. The method further includes transmitting, on the one or more antenna ports, one or more signals in the plurality of reserved resource elements. The one or more signals transmitted in the plurality of reserved resource elements may allow UEs associated with other RATs to estimate the rate matched DL communication channel.