RI PMI Selection via Interference Mutual Information Table
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Solution Overview
Problem
Conventional wireless communication systems in LTE downlink MIMO modes do not consider beam coordination between cells, leading to increased interference and complexity, as each UE optimizes its own throughput without accounting for interference to other UEs, especially in MIMO vertical tilting scenarios.
Innovation Solution
A method and apparatus for a UE to determine and transmit RI and PMI values based on a common reference signal, considering both individual and system optimization by using an interference mutual information table, which estimates interference effects, allowing for statistical beam coordination without real-time message exchanges among BSs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If each UE optimizes its own throughput by feedbacking the best RI/PMI, then individual UE throughput is maximized, but interference to other UEs increases and overall system throughput is not maximized
Solution Approach 1:
The patent changes the parameter used for RI/PMI selection from individual throughput maximization to a combined metric that includes both individual throughput and interference to other UEs. The UE selects RI/PMI based on a criterion that balances personal performance with system-wide impact, thereby reducing harmful interference while maintaining acceptable individual throughput.
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of a predefined interference table that mediates between individual UE throughput optimization and system-wide interference consideration. This table provides interference estimates for different RI/PMI combinations, allowing the UE to make informed selections that balance personal and system interests without requiring direct coordination with other UEs or base stations.
2Productivity
If dynamic beam coordination among nearby UEs is implemented, then overall system throughput is maximized, but system complexity and overhead increase due to complicated algorithms and real-time message exchanges among BSs
Solution Approach 1:
The patent applies preliminary action by pre-computing and storing interference estimates in a predefined interference table before actual communication occurs. This table is generated in advance based on channel conditions and beam configurations, eliminating the need for real-time complex calculations and message exchanges during active communication. The UE simply queries this pre-prepared table to determine optimal RI/PMI selections.
Solution Approach 2:
The patent enables self-service by allowing each UE to independently determine optimal RI/PMI values using locally stored interference tables and channel condition information. Each UE autonomously performs the selection without requiring coordination messages from base stations or other UEs, thereby achieving system-wide optimization while maintaining low complexity and avoiding overhead associated with inter-base station communication.
3Device complexity
If conventional RI/PMI feedback is used without beam coordination, then system complexity is reduced, but interference to other UEs increases particularly in MIMO vertical tilting scenarios
Solution Approach 1:
The patent modifies the selection criterion for RI/PMI from purely individual throughput-based to a combined criterion that incorporates interference estimates. By changing the optimization parameter to include both individual performance and interference impact, the system achieves better interference management in MIMO vertical tilting scenarios without requiring complex real-time coordination mechanisms.
Data Source
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AI summary
An apparatus in a user equipment node (UE) is configured to perform a method for channel feedback. The method includes determining, based on a common reference signal received from a base station and one or more channel conditions, a plurality of values for a receiver table. The method also includes determining a plurality of values for a decision table based on corresponding values in the receiver table and a predetermined interference table. The method further includes selecting a value from the decision table. In addition, the method includes transmitting, to the base station, at least one of a rank indicator (RI) value and a precoding matrix indicator (PMI) value associated with the selected value in the decision table.