LTE Coordinated Multi-Point Reference Signal Puncturing
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Solution Overview
Problem
In wireless telephony, particularly in LTE and LTE-A networks, existing technologies face challenges in multiplexing and resource management due to conflicts between reference signals from different user equipment, leading to interference and increased overhead during handovers and resource allocation.
Innovation Solution
The solution involves joint processing of downlink coordinated multi-point reference signaling, which includes combining reference signals, determining conflicts, puncturing signals from other cells, and transmitting non-punctured combined signals, allowing for efficient resource management and reduced interference by using coherent and non-coherent combining methods and RE puncturing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reference signals from multiple cells are transmitted simultaneously, then channel estimation and handover performance are improved, but interference between reference signals increases
Solution Approach 1:
The patent segments reference signals by applying cell-specific frequency shifts to CRS from different cells, separating them in the frequency domain. This allows simultaneous transmission from multiple cells while reducing interference, resolving the contradiction between improving handover performance through multi-cell signaling and minimizing reference signal interference.
Solution Approach 2:
The patent moves reference signal separation from the time domain to the frequency domain by introducing frequency shifts based on cell identity. This dimensional change enables multiple cells to transmit reference signals simultaneously without time division while maintaining low interference levels.
2Measurement precision
If reference signals are transmitted for all cells, then channel estimation accuracy is improved, but resource overhead increases
Solution Approach 1:
The patent applies different frequency shift patterns to different cells based on their identity, allowing the network to selectively activate reference signals only for cells that are relevant to each user equipment. This local differentiation reduces overall overhead while maintaining accurate channel estimation for active cells.
3Device complexity
If non-coherent combining is used for reference signals, then implementation complexity is reduced, but channel estimation performance deteriorates
Solution Approach 1:
The patent performs preliminary frequency shifting and orthogonal resource allocation of reference signals before they reach the user equipment. This preliminary structuring enables simpler non-coherent combining at the UE while maintaining good estimation performance, as the reference signals are already optimized for separation and combination.
Data Source
AI summary
This invention concerns multiplexing in Long Term Evolution (LTE) and Long Term Evolution-Advanced (LTE-A) in Evolved Universal Terrestrial Radio Access Network (E-UTRAN) wireless telephony. Joint processing down link coordinated multi-point reference signaling includes combining resource signal types at a user equipment, determining conflicts between resource signals of plural user equipment, puncturing resource signals of other cell upon determining conflicts between resource signals of plural user equipment and transmitting non-punctured combined resource signals from a user equipment.