Reference Signal Placement in OFDM Subbands
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Solution Overview
Problem
In 5G or NR wireless communications, existing reference signal (RS) placement methods within OFDM symbols do not effectively differentiate between resource sets in different subbands, leading to interference and inefficient channel estimation, particularly in multi-cell environments.
Innovation Solution
The proposed method involves designing different RS placements for different resource sets within the same OFDM symbol based on an identifier, such as a cell ID, to minimize interference and enhance channel estimation, with the RS placement being either cell ID dependent or independent, depending on the carrier frequency and intended use of the resource set.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same reference signal placement is used across all resource sets in different subbands, then the system complexity is reduced and implementation is simplified, but interference from neighboring cells increases and channel estimation efficiency deteriorates
Solution Approach 1:
The patent applies local quality by configuring different reference signal placements for different resource sets based on their specific subband locations and service types. Common RS placement is configured for common resource sets while UE-specific RS placement is configured for UE-specific resource sets, optimizing each local region's performance characteristics rather than applying a uniform configuration system-wide.
Solution Approach 2:
The patent changes the placement parameters of reference signals based on the identifier of the resource set. By dynamically adjusting RS placement parameters according to resource set characteristics (common vs. UE-specific), the system achieves optimal performance for each resource type while managing interference through parameter differentiation.
2Measurement precision
If different reference signal placements are designed for different resource sets in the same OFDM symbol, then channel estimation accuracy is improved and interference is reduced, but the system complexity and configuration overhead increase
Solution Approach 1:
Different RS placements are designed for different resource sets based on their specific requirements. Common resource sets use common RS placement optimized for cell-wide channel estimation, while UE-specific resource sets use UE-specific RS placement optimized for individual user channel estimation, thereby improving measurement precision for each local context.
Solution Approach 2:
The patent segments the reference signal placement configuration into distinct types (common RS placement and UE-specific RS placement) corresponding to different resource set categories. This segmentation allows each segment to be optimized independently for its specific function, improving overall channel estimation accuracy without requiring complete redesign of the entire system.
3Object-affected harmful factors
If reference signal placement is made cell ID dependent, then interference coordination between neighboring cells is improved, but the flexibility and adaptability of RS placement configurations decrease
Solution Approach 1:
The patent applies local quality by making RS placement cell ID dependent for common resource sets, where each cell uses its own cell ID to determine RS placement positions. This creates local optimization for interference coordination in each cell while maintaining overall system flexibility through the configurable nature of the placement rules.
Solution Approach 2:
The patent introduces dynamics by allowing RS placement to adapt based on cell ID while maintaining configurability through higher-layer parameters. The system can dynamically adjust RS placement patterns according to cell identification, enabling automatic interference coordination while preserving adaptability through configurable parameters that can be modified based on network conditions.
Data Source
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AI summary
Aspects provide a way for RS in different sub-bands within the same OFDM symbol to have different RS placement designs, e.g., different dependence/independence on cell ID. A base station apparatus transmits a first RS in a first resource set using a first RS placement, wherein the first resource set comprises a first subband of an OFDM symbol. The apparatus also transmits a second RS in a second resource set using a second RS placement, wherein the second resource set comprises a second subband of the OFDM symbol. A UE apparatus identifies a first resource set comprising a first subband in a plurality of subbands of an OFDM symbol transmitted by base station, determines whether a RS tone location utilized with the first subband is dependent upon an identifier of the base station, and receives the RS based on a result of the determining.