Interference Reporting in N-MIMO Systems
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Solution Overview
Problem
In Network MIMO communication systems, traditional Channel Quality Indicator (CQI) metrics are insufficient for coordination strategy selection due to unpredictable serving cell composition and changing coordination strategies, leading to difficulties in computing achievable rates for user equipment (UE).
Innovation Solution
A method is introduced where user equipment (UE) measures and reports total interference from non-serving cells, and serving cells process this interference report to select a coordination strategy, potentially silencing or reducing power during null pilot intervals, and adjust transmission accordingly to minimize interference and maximize system throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional CQI metrics are used for coordination strategy selection, then the system can maintain simple measurement procedures, but the system cannot accurately compute achievable rates for user equipment due to unpredictable serving cell composition and changing coordination strategies
Solution Approach 1:
The patent segments the interference measurement process by introducing dedicated null pilot resources specifically for interference measurement, separate from regular data transmission resources. This segmentation allows the UE to measure interference from non-serving cells independently, improving the accuracy of achievable rate computation without requiring complex integrated measurements
Solution Approach 2:
The patent introduces an intermediary interference report mechanism that bridges the gap between traditional CQI metrics and coordination strategy selection. The interference report serves as an intermediate parameter that, when combined with CQI, enables accurate achievable rate computation while maintaining relatively simple measurement and reporting procedures at the UE side
2Productivity
If serving cells conduct full transmission continuously, then the system can maximize data throughput, but non-serving cells create unpredictable interference that degrades coordination strategy selection
Solution Approach 1:
The patent implements periodic action by scheduling null pilot intervals at regular intervals rather than continuously silencing non-serving cells. This periodic approach allows the system to maintain high throughput during data transmission while periodically measuring interference during null pilot intervals, thus balancing productivity with interference management
Solution Approach 2:
The patent converts the harmful interference from non-serving cells into a beneficial measurement opportunity. By scheduling null pilot intervals during which non-serving cells remain active, the system transforms interference into useful information that improves coordination strategy selection and achievable rate computation, while maintaining overall system throughput
3Measurement precision
If null pilot intervals are scheduled for interference measurement, then the system can improve interference reporting accuracy, but transmission is reduced during these intervals
Solution Approach 1:
The patent applies partial action by scheduling null pilot intervals only during specific subframes rather than continuously, and by measuring interference only on specific resource elements. This partial measurement approach achieves sufficient interference measurement accuracy while minimizing the loss of transmission time, as the null pilot intervals occupy only a fraction of the total transmission resources
Data Source
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AI summary
A method and apparatus is described. The method comprising defining an interference reporting schedule for a user equipment (110) in relation to a serving set (102) of serving cells (120), scheduling null pilot intervals based on the interference reporting schedule, conducting limited transmission upon occurrence of a scheduled null pilot interval, the limited transmission comprising one of silencing transmission upon occurrence of the scheduled null pilot interval or reducing transmit power by a power backoff value upon occurrence of the scheduled null pilot interval, receiving an interference report from the user equipment (110) subsequent to occurrence of a null pilot interval, the interference report comprising an indication of interference associated with one or more non-serving cells (130) not within the serving set (102) and scheduling a communication by one or more serving cells (120) of the serving set (102) to the user equipment (110) based at least in part on the received interference report. Also a method and apparatus for sending an interference report.