Universal Resource Element Mapping for LTE Interference
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Solution Overview
Problem
In LTE communication systems, the existing resource element to resource element group mapping is cell and UE specific, leading to interference issues and reduced spectral efficiency due to the blocking of resource elements by reference signals, particularly affecting Space-Frequency Block Coding (SFBC) transmissions.
Innovation Solution
A universal mapping approach is proposed where resource elements are assigned to enhanced resource element groups in a predetermined order, cyclically extended, and spaced apart by 3 or 6 subcarriers to minimize the impact of reference signals, ensuring that all resource elements are utilized regardless of their blocking by reference signals, and allowing for efficient SFBC transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If resource elements are mapped in a cell and UE specific manner, then the mapping can be optimized for specific configurations, but interference issues arise and spectral efficiency is reduced due to blocking by reference signals
Solution Approach 1:
The patent applies a universal mapping rule that is independent of cell ID and UE specific parameters. The mapping function f(k,l) = (k mod 4)*3 + (l mod 4) provides a consistent pattern across all cells and UEs, eliminating the cell-specific and UE-specific variations that cause interference. This universal approach ensures that reference signals from different cells do not consistently block the same resource elements, thereby improving spectral efficiency while maintaining adaptability through the standardized pattern.
2Productivity
If resource elements are spaced closely in the frequency domain, then more resource elements can be utilized, but reference signals block more resource elements affecting SFBC transmissions
Solution Approach 1:
The patent introduces an asymmetric spacing pattern where resource elements are spaced by 3 subcarriers in the frequency domain (k mod 4 pattern). This asymmetric distribution ensures that not all resource elements fall on the same subcarrier positions as reference signals, reducing the blocking effect. The pattern creates a deliberate offset between data resource elements and reference signal positions, allowing better resource utilization while maintaining SFBC transmission quality.
3Reliability
If a universal mapping is applied, then consistency across cells and UEs is achieved, but flexibility for specific configurations is reduced
Solution Approach 1:
The patent uses parameter-based configuration where the universal mapping function includes configurable parameters such as the subcarrier spacing (set to 3) and the modulo operations (mod 4). These parameters can be adjusted to optimize performance for different deployment scenarios while maintaining the universal structure. The standardized function f(k,l) = (k mod 4)*3 + (l mod 4) provides consistency, while the parameter values can be modified to adapt to specific configuration requirements.
Data Source
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AI summary
The invention relates to a universal mapping of resource elements (REs) to enhanced resource element groups (e REG) that applies to both the PDCCH and PDSCH regions; the mapping is universal since it is not user or cell-specific but applies to the resource block pairs irrespective of the actual reference signals used. The mapping is such that all REs of the resource block pair are assigned to one out of a plurality of e REGs. According to the mapping, the REs are sequentially assigned to the e REGs, in predetermined orders. Within an OFDM symbol a pair of REs is assigned to the same e REG, wherein the two REs are spaced apart from each other by 3 or 6 subcarriers.