PTRS Subcarrier Index Offset for 5G Inter-Cell Interference
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Solution Overview
Problem
In 5G communication systems, inter-cell interference between Phase Tracking Reference Signals (PTRS) occurs when neighboring cells allocate PTRS to the same subcarrier index, degrading phase tracking performance.
Innovation Solution
Implementing a Resource Element (RE)-level offset for PTRS mapping based on unique cell IDs or UE-specific parameters to allocate PTRS on different subcarrier indices, reducing inter-cell interference without additional signaling overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If PTRS are allocated to the same subcarrier index in neighboring cells, then resource allocation is simple and consistent, but inter-cell interference occurs degrading phase tracking performance
Solution Approach 1:
The patent applies local quality by making the PTRS subcarrier index cell-specific through the formula k_ptrs = k_dmrs + (cell_id mod N), where each cell assigns PTRS to different local subcarrier positions within the RB. This ensures that while the allocation method remains systematic and simple, neighboring cells do not experience inter-cell interference because their PTRS are mapped to different subcarrier indices locally.
2Reliability
If PTRS are allocated to different subcarrier indices in neighboring cells, then inter-cell interference is reduced, but resource allocation complexity increases
Solution Approach 1:
The patent changes the parameter of subcarrier index allocation by introducing a cell_id-dependent offset: k_ptrs = k_dmrs + (cell_id mod N). This parameter change ensures that different cells automatically assign PTRS to different subcarrier indices, reducing inter-cell interference. The complexity is managed by using a simple modular arithmetic operation rather than complex coordination mechanisms.
3Loss of information
If implicit derivation methods are used for PTRS allocation, then signaling overhead is reduced, but interference coordination between cells becomes difficult
Solution Approach 1:
The patent implements self-service by enabling each cell to autonomously determine its PTRS subcarrier index using the formula k_ptrs = k_dmrs + (cell_id mod N), where cell_id is a locally known parameter. This implicit derivation method eliminates the need for inter-cell signaling or coordination while naturally avoiding inter-cell interference, as each cell independently selects different subcarrier positions based on its unique cell identifier.
Data Source
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AI summary
The present disclosure relates to a communication method and system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The present disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. Disclosed is a method of subcarrier index mapping for application to Phase Tracking Reference Signal, PTRS, within a Resource Block, RB, in a telecommunication system, wherein a particular subcarrier index to which PTRS is mapped is determined on the basis of one or more of: Cell ID, DMRS Port Index, DMRS SCID UE-specific ID (RNTI).