Link Adaptation Back-Off Value Adjustment for Rank Utilization
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Solution Overview
Problem
In MIMO systems with adaptive rank-specific back-off values, time-variant parameters can lead to underutilization of ranks due to unnecessarily large back-off values, and subsequent performance degradation when underutilized ranks are selected, resulting in periods of high block errors.
Innovation Solution
The method involves determining underutilized ranks and decreasing their back-off values over time to favor their selection, and applying an offset value to the back-off value of recently underutilized ranks to prevent immediate performance degradation upon selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If back-off values are increased to ensure reliable transmission, then error protection level is improved, but rank utilization deteriorates due to underutilization
Solution Approach 1:
The back-off value is transformed from a static parameter to a dynamic one that changes over time based on rank usage patterns. The system continuously monitors whether a rank has been used during a historical period and adjusts the back-off value accordingly, allowing the parameter to adapt to changing channel conditions and rank availability.
Solution Approach 2:
The system changes the back-off value parameter based on observed rank usage. When a rank is detected as underutilized (not used during a historical period), the back-off value for that rank is decreased, making it more attractive for selection. This parameter change directly addresses the contradiction by lowering the protection level for underutilized ranks to improve their utilization while maintaining high protection for actively used ranks.
2Productivity
If back-off values are decreased to improve rank selection, then rank utilization is improved, but transmission reliability deteriorates due to insufficient error protection
Solution Approach 1:
The system performs preliminary action by pre-adjusting the back-off value for underutilized ranks before they are selected for transmission. By detecting ranks that have not been used during a historical period and proactively decreasing their back-off values, the system prepares these ranks for future selection while ensuring that the adjustment takes effect before the rank is actually used, thus preventing performance degradation.
Solution Approach 2:
The system implements a feedback mechanism where the usage pattern of each rank is monitored over a historical period, and this feedback information is used to adjust the back-off values. The system continuously observes which ranks are underutilized and responds by modifying their back-off parameters, creating a closed-loop control system that adapts to actual transmission performance and rank availability.
3Adaptability or versatility
If adaptive back-off adjustment is implemented, then link adaptation performance is improved, but system complexity increases due to historical period monitoring
Solution Approach 1:
The system segments the back-off adjustment process by rank, maintaining separate back-off values and usage history for each rank. This segmentation allows independent optimization of each rank's back-off parameter based on its specific usage patterns, improving adaptability while keeping the complexity manageable through modular processing of individual ranks rather than treating all ranks as a single group.
Data Source
AI summary
The present application discloses systems and methods for adjusting a back-off value for a rank. In some embodiment, the method includes the steps of: (a) determining whether the rank is underutilized and (b) in response to determining that the rank is underutilized, decreasing the back-off value as a function of time while the rank remains underutilized.