5G NR PDCCH Rate Matching for LTE Reference Signal Collision Avoidance
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Solution Overview
Problem
In dynamic spectrum sharing scenarios where multiple radio access technologies like LTE and 5G NR share the same frequency band, collisions between signals can occur, leading to performance degradation for both technologies, particularly affecting 5G NR PDCCH signaling and LTE downlink reference signals.
Innovation Solution
Implementing rate matching techniques and a PDCCH demodulation reference signal (DMRS) design in user equipment (UE) to avoid collisions, including restrictions on when rate matching is performed and configuring DMRS to minimize overlap with LTE cell-specific reference signals, ensuring backwards compatibility and efficient spectrum use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple RATs share the same frequency band for dynamic spectrum sharing, then spectrum utilization efficiency is improved, but signal collision between different RATs occurs causing performance degradation
Solution Approach 1:
The patent segments the frequency band into different time-frequency resources for different RATs. Specifically, it divides the spectrum into resource blocks and further into resource element groups (REGs), where certain REGs are allocated for LTE downlink reference signals and others for 5G NR PDCCH, preventing signal collision while maintaining spectrum sharing
Solution Approach 2:
The patent applies local quality by assigning different properties to different parts of the frequency band. Certain resource element groups are designated with specific properties (e.g., LTE reference signal resources) while others are allocated for 5G control channels, allowing each region to serve its intended function without interference
2Adaptability or versatility
If 5G NR PDCCH and LTE downlink reference signals are transmitted simultaneously in the same frequency band, then dynamic spectrum sharing capability is improved, but collision between PDCCH and reference signals degrades performance
Solution Approach 1:
The patent implements preliminary action by pre-configuring rate matching patterns and resource allocations before actual transmission. The UE is provided with information about LTE reference signal resources in advance, allowing it to pre-determine which resource element groups to skip during PDCCH reception, thereby avoiding collision before it occurs
Solution Approach 2:
The patent introduces dynamics through configurable rate matching patterns that can be adapted based on traffic conditions and network requirements. The network can dynamically adjust the allocation of resource element groups between LTE reference signals and 5G PDCCH, allowing flexible spectrum sharing while maintaining signal integrity
Data Source
AI summary
A user equipment (UE) is configured to perform rate matching for reference signals under certain conditions. The UE receives information associated with a downlink reference signal for a first radio access technology (RAT), wherein the first RAT is different than a currently camped second RAT, identifies reference signal occasions for the downlink reference signal and receives downlink control information from the second RAT via a physical downlink control channel (PDCCH).