TRS Pattern Shift for LTE-NR Coexistence
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Solution Overview
Problem
In wireless communication networks, particularly in 5G networks, there is a challenge in coexisting radio access technologies like LTE and NR, where interference between different radio access technologies occurs due to overlapping frequency ranges, leading to inefficiencies in resource utilization and increased signaling overhead.
Innovation Solution
The method involves transmitting and receiving tracking reference signaling (TRS) in a pattern shifted relative to the LTE carrier's central frequency subcarrier, allowing TRS to be scheduled without crossing the LTE CRS pattern, thereby avoiding interference and reducing signaling overhead. This is achieved by configuring the TRS pattern to fit within the frequency range of the LTE carrier, using a comb structure that does not overlap with LTE reference signals, and utilizing control information for scheduling and configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If TRS is transmitted in the same frequency range as LTE carrier, then resource utilization is improved, but interference with LTE reference signals increases
Solution Approach 1:
The frequency range is segmented into distinct regions: TRS is transmitted in non-central subcarriers while LTE CRS occupies central subcarriers. This segmentation allows both systems to coexist in the same frequency range without interference, as each system operates in its designated subcarrier region.
Solution Approach 2:
Different quality characteristics are assigned to different frequency regions. The central frequency region is reserved for LTE reference signals with high protection, while non-central regions allow TRS transmission. This local differentiation enables coexistence by giving each system appropriate resource quality in its designated area.
2Object-affected harmful factors
If TRS pattern is shifted to avoid LTE CRS, then interference is reduced, but signaling overhead increases
Solution Approach 1:
Instead of shifting TRS to avoid LTE CRS as traditionally done, the patent inverts the approach by having TRS deliberately occupy non-central subcarriers while LTE CRS occupies central subcarriers. This inversion naturally avoids overlap without requiring additional shift signaling, as the different subcarrier allocation strategies inherently provide separation.
Solution Approach 2:
The TRS and LTE CRS systems serve themselves by autonomously selecting different subcarrier regions based on their respective requirements. TRS uses non-central subcarriers for flexibility, while LTE CRS uses central subcarriers for stability, eliminating the need for coordination signaling about pattern shifts.
3Ease of operation
If TRS uses central frequency subcarrier, then alignment with reference is improved, but overlap with LTE CRS occurs
Solution Approach 1:
Asymmetric subcarrier allocation is implemented where TRS and LTE CRS occupy different regions relative to the central frequency. LTE CRS is anchored to central subcarriers for its reference function, while TRS deliberately avoids the center and uses non-central subcarriers. This asymmetric arrangement provides both alignment benefits for各自 systems while preventing overlap.
Data Source
AI summary
There is disclosed a method of operating a user equipment in a radio access network, wherein the method comprises receiving tracking reference signaling, TRS, in a TRS pattern. The TRS pattern represents a distribution of subcarriers for carrying TRS over a range of subcarriers shifted relative to a reference subcarrier corresponding to a central frequency subcarrier of an LTE carrier.