Uplink DM-RS Generation Using Virtual Cell ID
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Solution Overview
Problem
In multi-node wireless communication systems, the interference between uplink reference signals increases with the number of user equipment (UEs) due to shared physical cell IDs, which affects system performance and data reception accuracy.
Innovation Solution
A method where user equipment (UE) generates and transmits uplink demodulation reference signals (DM-RS) using a virtual cell ID instead of a physical cell ID, with parameters for the virtual ID being UE-specific and used to cyclically shift base sequences, thereby reducing interference between UEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple UEs share the same physical cell ID in a multi-node system, then the number of handover attempts is decreased and cooperative communication becomes easier, but interference between uplink reference signals increases
Solution Approach 1:
The patent segments the single physical cell ID into two distinct components: a common physical cell ID shared by all nodes for basic identification and handover, and UE-specific virtual cell IDs assigned to individual user equipments for uplink reference signal generation. This segmentation allows the system to maintain the benefits of cell ID sharing while eliminating the interference problem by ensuring each UE uses a unique identifier for reference signals.
Solution Approach 2:
The patent applies local quality by differentiating the use of cell IDs based on their specific function. The physical cell ID is used globally for node identification and handover procedures, while virtual cell IDs are used locally and specifically for uplink reference signal generation. This functional differentiation ensures that the common physical cell ID provides cooperative communication benefits without causing reference signal interference.
2Device complexity
If multiple UEs use the same physical cell ID for generating uplink signals, then device complexity is reduced, but measurement precision of channel estimation deteriorates
Solution Approach 1:
The patent segments the identifier system into physical cell ID for basic identification and virtual cell ID for reference signal generation. This segmentation maintains simple device operation since UEs still use a single physical cell ID for most functions, while introducing virtual cell IDs specifically for reference signals to ensure unique identification and prevent interference, thereby maintaining measurement precision.
Solution Approach 2:
The virtual cell ID acts as an intermediary between the shared physical cell ID and the uplink reference signal generation process. It mediates the conflict by providing a unique identifier for each UE's reference signals without requiring UEs to manage complex identification schemes, thus maintaining both device simplicity and estimation accuracy.
3Ease of operation
If UEs generate uplink reference signals using physical cell ID, then ease of operation is maintained, but system performance deteriorates due to increased interference
Solution Approach 1:
The patent segments the cell ID usage into two distinct purposes: physical cell ID for general identification and handover operations, and virtual cell ID for uplink reference signal generation. This segmentation maintains ease of operation by keeping the physical cell ID system simple while introducing virtual cell IDs specifically for reference signals to eliminate interference and improve system performance.
Solution Approach 2:
The patent applies local quality by assigning different qualities to different cell ID usage scenarios. The physical cell ID provides global consistency for handover, while virtual cell IDs provide local uniqueness for reference signal generation. This differentiated approach maintains operational simplicity while improving system performance through interference reduction.
Data Source
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AI summary
The present invention relates to a method for transmitting an uplink reference signal in a multi-node system and a terminal using same. The method comprises the steps of: receiving a synchronization signal from a node; receiving parameters for a virtual cell identifier(ID) from the node; generating an uplink demodulation reference signal(DM-RS) using the parameters for the virtual cell ID; and transmitting the generated uplink DM-RS to the node, wherein a physical cell ID is a cell ID obtained from the synchronization signal, and the parameters for the virtual cell ID are parameters used for generating the uplink DM-RS in the replacement of the physical cell ID.