NR UE CRS Interference Cancellation in LTE Coexistence
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Solution Overview
Problem
NR throughput degrades by 10-20% when coexisting with LTE in the same spectrum due to lack of CRS interference suppression/cancellation support in NR, leading to interference from LTE CRS to NR PDSCH.
Innovation Solution
A method for NR UEs to receive dedicated RRC signals providing LTE CRS configuration information, enabling interference suppression or cancellation by determining LTE CRS configuration and frequency location, using FDD or TDD duplexing, and performing interference suppression/cancellation in NR DL transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If NR coexists with LTE in the same spectrum without CRS interference suppression, then device complexity is reduced, but NR throughput degrades by 10-20%
Solution Approach 1:
The network acts as an intermediary by providing assistance information about LTE CRS configurations to the NR UE. This mediator approach allows the UE to perform interference suppression without having to independently detect and analyze all LTE signals, thereby improving throughput while limiting complexity growth.
Solution Approach 2:
The network performs preliminary action by pre-configuring the UE with LTE CRS parameters (frequency locations, bandwidth, antenna ports) before NR data reception. This advance preparation enables the UE to efficiently suppress interference during NR PDSCH reception without performing complex real-time analysis of LTE signals.
2Ease of operation
If NR uses high-density CRS like LTE, then synchronization is easier to maintain, but inter-cell interference increases
Solution Approach 1:
The patent extracts the harmful CRS transmissions from the NR system while retaining the beneficial synchronization function through alternative means. NR removes high-density CRS and instead uses periodic synchronization signals and the extracted LTE CRS information from the network for interference suppression, thereby reducing inter-cell interference while maintaining synchronization capability.
3Productivity
If LTE CRS suppression is implemented in NR, then NR throughput improves, but device complexity increases
Solution Approach 1:
The network serves as a mediator by providing pre-configured LTE CRS assistance information to the UE. This approach enables interference suppression functionality while limiting UE complexity growth, as the UE relies on network-provided parameters rather than performing independent LTE signal analysis.
Solution Approach 2:
The system implements a form of self-service where the network automatically provides the necessary LTE CRS configuration information to UEs that need interference suppression. This eliminates the need for complex inter-base station coordination or manual configuration, allowing the system to self-configure for optimal performance.
Data Source
AI summary
A method, applied to a UE, to mitigate interference for coexistence of OFDM-based radio access technologies, wherein the method includes receiving a dedicated RRC signal providing LTE CRS configuration information of neighboring LTE cells in one or more LTE carriers and providing the corresponding frequency location and bandwidth of the LTE carriers for an NR serving cell, wherein NR and LTE coexist in the same spectrum; determining the LTE CRS configuration and the corresponding frequency location of LTE CRS based on the received dedicated RRC signal; and performing LTE CRS interference suppression or cancellation in NR downlink (DL) transmission.