Adjacent Precoded Symbol Mapping for LTE-A Resource Blocks
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Solution Overview
Problem
The introduction of Demodulation Reference Signals (DM-RS) and Channel State Information Reference Signals (CSI-RS) in LTE-Advanced systems changes resource locations, causing performance degradation when using precoding and resource mapping methods designed for LTE systems, as these methods are not applicable without modification.
Innovation Solution
A resource mapping/demapping method and apparatus that precodes and arranges pairs of symbols adjacently in resource blocks, allowing for improved decoding performance by selecting and precoding symbol pairs, and notifying receivers of the mapping method through control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precoding and resource mapping methods designed for LTE system are applied to LTE-A system, then transmission diversity is maintained, but decoding performance degrades due to symbols being mapped to resource elements positioned far apart
Solution Approach 1:
The resource block is segmented into multiple resource element groups, and symbols are mapped to adjacent resource elements within the same group. This segmentation ensures that precoded symbol pairs remain spatially close, maintaining decoding performance in LTE-A systems while preserving transmission diversity benefits.
Solution Approach 2:
Different mapping patterns are applied to different resource element groups within the resource block. By optimizing the local mapping quality within each group to keep precoded symbols adjacent, the overall system achieves improved decoding performance while maintaining the global transmission diversity structure.
2Adaptability or versatility
If DM-RS and CSI-RS are introduced in LTE-A system, then channel state information and demodulation capabilities are improved, but resource locations change causing incompatibility with LTE precoding methods
Solution Approach 1:
The resource mapping method is made dynamic and configurable, allowing the system to adapt the mapping pattern based on the presence of DM-RS and CSI-RS. This enables the LTE-A system to maintain precoding compatibility while accommodating the new reference signals through flexible, configurable mapping strategies.
Solution Approach 2:
The mapping parameters such as resource element allocation patterns and precoding application points are changed to accommodate DM-RS and CSI-RS locations. By adjusting these parameters, the system maintains compatibility with LTE precoding methods while supporting the enhanced channel state information capabilities of LTE-A.
Data Source
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AI summary
It is provided a method performed by a user equipment, UE, in a wireless communication system, the method comprising: receiving, from a base station, a signal comprising precoded data symbol pairs; identifying resource elements, REs, to be used for receiving the precoded data symbol pairs in available REs in an orthogonal frequency division multiplexing, OFDM, symbol of a resource block; demapping the precoded data symbol pairs from the identified REs; and decoding the precoded data symbol pairs, wherein at least one available RE in the OFDM symbol is not used for receiving the precoded data symbol pairs, in case that a difference between subcarrier indices of two available REs in the OFDM symbol is three or more, and wherein the demapping of the precoded data symbol pairs is skipped for the at least one available RE.