Offset MBSFN Subframes for LTE-NR CRS Interference Avoidance
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Solution Overview
Problem
Time-frequency resource conflicts exist between LTE cell reference signals (CRS) and NR synchronization signals (SSB) during spectrum sharing, as not all subframes occupied by NR SSBs can be configured as MBSFN subframes, leading to interference.
Innovation Solution
A communication method and apparatus that configures MBSFN subframes by determining an offset based on the positions of NR signals to align with MBSFN subframe configurations, allowing NR signals to be sent on time-frequency resources free from LTE CRS interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MBSFN subframes are configured to avoid LTE CRS interference, then NR signal transmission quality is improved, but the number of available subframes for NR SSB is limited causing time-frequency resource conflicts
Solution Approach 1:
The patent applies preliminary action by pre-configuring MBSFN subframe positions and notifying the NR base station of these positions before NR SSB transmission. The LTE base station determines MBSFN subframe configurations in advance and sends this information to the NR base station, allowing the NR system to plan its SSB transmissions to avoid conflicts with LTE CRS, thereby ensuring both transmission quality and subframe availability.
2Area of stationary object
If LTE CRS is transmitted in full bandwidth, then LTE reference signal coverage is improved, but time-frequency resource conflicts with NR signal occur during spectrum sharing
Solution Approach 1:
The patent applies segmentation by dividing the time-frequency resources into distinct segments: MBSFN subframes are specifically designated for NR signal transmission and are segmented from regular subframes. Within MBSFN subframes, the LTE CRS is further segmented to be transmitted only in the control region rather than across the full bandwidth, allowing NR signals to occupy the data region without interference while maintaining LTE reference signal functionality.
Solution Approach 2:
The patent applies local quality by creating different transmission characteristics in different time-frequency regions. MBSFN subframes are configured with specific local properties where LTE CRS is restricted to the control region only, while the data region is made suitable for NR signal transmission. This local differentiation allows simultaneous operation of LTE and NR signals in the same bandwidth without full-bandwidth interference.
3Ease of operation
If NR SSB uses subframes #0 and #1, then synchronization signal transmission is simplified, but these subframes cannot all be configured as MBSFN subframes leading to resource conflicts
Solution Approach 1:
The patent introduces an intermediary mechanism through the introduction of MBSFN subframes as a mediator between LTE CRS transmission and NR SSB transmission. The MBSFN subframe configuration acts as an intermediary layer that reconciles the conflicting requirements: it allows LTE CRS to be transmitted in a controlled manner while creating protected time-frequency resources for NR SSB, thereby eliminating direct interference without requiring changes to the fundamental SSB subframe numbering.
Data Source
AI summary
This disclosure provides a communication method and apparatus. In the method, the first network device receives a first position from a second network device, where the first position is a position of one or more subframes occupied by first information; determines a first offset and configures a multicast-broadcast single-frequency network (MBSFN) subframe, where the first offset is for determining a second position, the second position is a position obtained by offsetting the first position by the first offset, the first range is a position that supports configuration of the MBSFN subframe, and a position of the MBSFN subframe includes the second position; and sends the first offset and first MBSFN configuration information to the second network device. According to the method, the second network device may send the first information on the MBSFN subframe, to avoid time-frequency resource conflicts between the first information and a cell reference signal (CRS).