CDM Group Hopping for Multi-TRP Wireless Interference Mitigation
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Solution Overview
Problem
In wireless communication systems, multi-transmission/reception points (TRPs) often use static DMRS configurations, leading to collisions and errors when neighboring TRPs use the same code division multiplexing (CDM) group, causing interference in downlink transmissions to user equipment (UE).
Innovation Solution
Implementing CDM group hopping, where TRPs coordinate to dynamically associate different CDM groups with each TRP, allowing each TRP to transmit reference signals according to its assigned group, which then changes for subsequent instances, reducing interference by avoiding collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If static DMRS configurations are used in multi-TRP systems, then device complexity is reduced and ease of operation is improved, but interference occurs when neighboring TRPs use the same CDM group
Solution Approach 1:
The patent implements dynamic CDM group association where TRPs switch between different CDM groups based on a hopping pattern. Instead of statically assigning CDM groups to TRPs, the system dynamically changes the CDM group association over time, allowing TRPs to use different CDM groups in different time instances, thereby avoiding persistent interference while maintaining operational simplicity through automated hopping patterns.
Solution Approach 2:
The patent employs periodic CDM group hopping where TRPs systematically cycle through different CDM groups according to a predefined period. This periodic switching ensures that neighboring TRPs use different CDM groups at different time instances, reducing interference through regular, predictable pattern changes while keeping the system complexity manageable through structured periodic behavior.
2Reliability
If CDM group hopping is implemented to mitigate interference, then reliability is improved, but device complexity increases due to coordination requirements
Solution Approach 1:
The patent applies preliminary action by pre-configuring CDM group hopping patterns and parameters before actual data transmission begins. The network entities establish the hopping sequence, CDM group associations, and timing patterns in advance, so that during operation, TRPs simply follow the predetermined pattern without requiring complex real-time coordination decisions, thus maintaining high reliability while limiting complexity increases.
Solution Approach 2:
The patent utilizes parameter changes by systematically varying CDM group indices according to a hopping pattern. Instead of changing the fundamental structure or operation mode, the system achieves interference mitigation by changing specific parameters (CDM group assignments) in a controlled manner, which improves reliability through diversity while keeping complexity changes manageable through parameter-level adjustments rather than structural modifications.
3Object-affected harmful factors
If dynamic CDM group association is used, then interference is reduced, but loss of time occurs due to coordination signaling
Solution Approach 1:
The patent minimizes time loss by performing all necessary CDM group hopping coordination and configuration in advance, before the hopping sequence begins. Network entities exchange and agree upon the hopping patterns, CDM group mappings, and timing information during an initial setup phase, eliminating the need for continuous real-time signaling during data transmission, thus reducing interference through dynamic association while minimizing time loss from coordination overhead.
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AI summary
Methods, systems, and devices for wireless communications are described. A first transmission/reception point (TRP) may coordinate with a second transmission/reception point to configure code division multiplexing group hopping for a user equipment (UE). The first TRP may transmit a signal to the UE indicating that code division multiplexing group hopping is enabled for the first transmission/reception point and the second transmission/reception point. The first TRP may transmit, during a first instance of the code division multiplexing group hopping, a first reference signal to the UE according to a first code division multiplexing group. The first TRP may transmit, during a second instance of the code division multiplexing group hopping, the first reference signal to the UE according to a second code division multiplexing group.