PUCCH Resource Allocation for eIMTA Collision Avoidance
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Solution Overview
Problem
The existing HARQ resource allocation methods for Enhanced Interference Management and Traffic Adaptation (eIMTA) on the Physical Uplink Control Channel (PUCCH) face conflicts and inefficiencies due to overlapping resource spaces between legacy and eIMTA UEs, leading to potential collisions and increased overhead.
Innovation Solution
The proposed solution involves dividing downlink subframes into two groups (Group A and Group B) for resource allocation, with distinct starting points and interleaving strategies for each, allowing eIMTA UEs to use separate PUCCH resources that do not overlap with legacy UE resources, thereby avoiding collisions and optimizing resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single shared PUCCH resource space is used for both legacy UEs and eIMTA UEs, then resource allocation simplicity is maintained, but resource collisions occur between the two UE types
Solution Approach 1:
The PUCCH resource space is segmented into two distinct sets: a first set of PUCCH resources for legacy UEs and a second set of PUCCH resources for eIMTA UEs. This segmentation is achieved by defining different starting points (first starting point and second starting point) for resource allocation, ensuring that legacy UEs and eIMTA UEs operate in separate resource domains and cannot collide. The base station configures these separate resource sets through RRC signaling, maintaining reliability while managing complexity through structured resource division.
2Reliability
If separate PUCCH resource sets are allocated for legacy UEs and eIMTA UEs, then resource collisions are avoided, but PUCCH resource overhead increases
Solution Approach 1:
The resource allocation system dynamically adapts to UE capability through capability indication mechanisms. When eIMTA is not configured, the system uses a single PUCCH resource set, minimizing overhead. When eIMTA is configured, the system transitions to using two separate resource sets, optimizing for collision avoidance. This dynamic behavior allows the system to adjust its resource allocation strategy based on actual network conditions and UE capabilities, balancing overhead and reliability requirements.
3Adaptability or versatility
If PUCCH resources are allocated without considering eIMTA configuration, then backward compatibility is maintained, but eIMTA functionality cannot be supported
Solution Approach 1:
The system performs preliminary configuration of separate PUCCH resource sets before eIMTA operation begins. The base station configures the second set of PUCCH resources and their starting point in advance through RRC signaling, so that when eIMTA UEs need to transmit acknowledgments, they have pre-allocated dedicated resources available. This preliminary action ensures that eIMTA functionality can be immediately supported without disrupting existing legacy operations, maintaining backward compatibility while enabling new functionality.
Data Source
Figure 1
Figure 2~3
Figure 4A~4C
AI summary
A base station determines a first set of PUCCH resources to use for a first set of UEs to send acknowledgment information to the base station for a first group of DL subframes. The first set of PUCCH resources starts at a first index. The base station determines a second set of PUCCH resources to use for a second set of UEs to send acknowledgment information to the base station for a second group of DL subframes. The second set of PUCCH resources starts at a second index. The UEs in the first set only use the first set of PUCCH resources. The UEs in the second set use the first and second sets of PUCCH resources. For an UL reception, acknowledgement information is received from the first UEs using the first set of PUCCH resources and from the second UEs using the first and second sets of PUCCH resources.