MU-MIMO PHICH Collision Handling via ACK Ratio
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Solution Overview
Problem
In MU-MIMO systems, the limited PHICH resources lead to collisions among users, which existing solutions either attempt to avoid through resource enlargement or smart allocation, but these methods either fail to completely resolve collisions or increase computing complexity, limiting scheduling abilities and system throughput.
Innovation Solution
The proposed method allows PHICH collisions to occur among users sharing the same resource, dynamically controlling retransmissions by determining a majority ACK or NACK feedback, triggering adaptive or non-adaptive retransmissions based on an ACK ratio, thereby balancing collision and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PHICH resources are enlarged to avoid collisions, then collision avoidance is improved, but device complexity and resource consumption increase
Solution Approach 1:
The patent converts the harmful PHICH collision problem into a beneficial shared feedback mechanism. Instead of treating collisions as errors to be avoided, the system allows multiple users to share the same PHICH resource and uses majority voting (ACK/NACK ratio) to determine retransmission behavior. This transforms the collision from a harmful interference into a functional feature that enables robustness in MU-MIMO systems.
Solution Approach 2:
The patent introduces dynamic retransmission control based on real-time feedback analysis. The eNodeB dynamically adjusts retransmission decisions by monitoring the ACK/NACK ratio from shared PHICH resources and switching between adaptive and non-adaptive retransmission modes. This dynamic approach allows the system to adapt to varying channel conditions and user requirements without requiring additional dedicated PHICH resources.
2Reliability
If smart PHICH allocation methods are used, then collision resolution is improved, but computing complexity increases and scheduling ability is limited
Solution Approach 1:
The patent merges the PHICH resources of multiple users into a single shared feedback channel. Instead of allocating separate PHICH resources for each user in MU-MIMO, the system combines feedback from multiple users sharing the same resource and uses majority voting to determine the overall feedback status. This merging approach simplifies the scheduling complexity while maintaining reliable feedback identification.
Solution Approach 2:
The patent implements a feedback mechanism where the eNodeB monitors the ACK/NACK ratio from shared PHICH resources and uses this feedback to dynamically control retransmission behavior. The feedback loop allows the system to adjust scheduling decisions based on actual channel conditions, reducing the need for complex pre-calculated allocation schemes.
3Productivity
If multiple users share the same PHICH resource, then system throughput is improved, but feedback ambiguity increases
Solution Approach 1:
The patent converts feedback ambiguity caused by shared PHICH resources into a beneficial majority voting mechanism. Instead of treating ambiguous feedback as errors, the system uses the ACK/NACK ratio from multiple users to determine the dominant feedback status. This transforms the ambiguity problem into a robust decision-making mechanism that accurately reflects the overall channel condition.
Solution Approach 2:
The patent changes the feedback representation from individual user-specific feedback to a aggregated feedback status based on ACK/NACK ratio. By transforming the feedback parameter from binary user-level signals to a ratio-based group-level indicator, the system eliminates ambiguity while maintaining throughput benefits of resource sharing.
Data Source
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AI summary
Embodiments of the present disclosure provide methods, apparatus and computer readable storage medium for controlling data retransmission in a multi-user system. A method comprises determining whether data transferred by any of multiple users are received unsuccessfully. The multiple users share a same resource in a feedback channel, for carrying feedback information of whether or not data transferred by respective users are received successfully. When data transferred by any of the multiple users are received unsuccessfully, the method also comprises causing data retransmission in a first retransmission mode or a second retransmission mode. In the first retransmission mode, positive feedback is sent via the same resource to the multiple users, and adaptive retransmission is triggered for the users whose data are received unsuccessfully. In the second retransmission mode, negative feedback is sent via the same resource to the multiple users, so that non-adaptive retransmission is triggered for the multiple users.