Base Station Scheduling Using Partial CSI for MIMO
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Solution Overview
Problem
The introduction of four branch MIMO in wireless communications systems requires a new feedback channel structure to efficiently report CQI and PCI information, leading to increased signaling overhead and scheduling delays, especially for high-speed user equipment.
Innovation Solution
A method where the base station schedules user equipment using partial CSI reports, determining the type of data stream and selecting an appropriate transmission type based on the received CSI, allowing for immediate scheduling without waiting for complete channel information, and reusing existing feedback channel structures to minimize standard changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a new feedback channel structure is introduced for four branch MIMO, then CQI and PCI reporting capability is improved, but signaling overhead increases
Solution Approach 1:
The feedback channel structure is segmented into two parts: Part 1 contains RI and first CQI/PCI information, while Part 2 contains remaining CQI/PCI information. This segmentation allows the system to support four branch MIMO with enhanced reporting capability while managing signaling overhead by distributing information across multiple channels and time instances.
2Measurement precision
If complete CSI is waited for before scheduling, then scheduling accuracy is improved, but scheduling delay increases
Solution Approach 1:
The base station performs preliminary scheduling based on Part 1 of the CSI feedback before receiving the complete CSI information. By making scheduling decisions with partial information available, the system reduces scheduling delay while maintaining acceptable accuracy, as the preliminary schedule can be refined later when complete CSI is received.
Solution Approach 2:
Instead of waiting for complete CSI feedback before scheduling, the system performs scheduling action with partial CSI information. This partial action approach trades some scheduling accuracy for significant reduction in scheduling delay, which is particularly beneficial for high-speed user equipment where channel conditions change rapidly.
3Loss of information
If CSI is reported in two parts over multiple TTIs, then information completeness is improved, but scheduling delay increases
Solution Approach 1:
The base station performs scheduling operations using only Part 1 of the CSI feedback before Part 2 is received. This preliminary scheduling action ensures that scheduling decisions are made without unnecessary delays, while the system maintains information completeness by eventually receiving both parts of the CSI feedback for future refinements.
Data Source
AI summary
The embodiments herein relate to a method in a base station (301) for scheduling a user equipment (305) in a communication system (300). The user equipment (205) receives a part of a CSI from the user equipment (305) in a TTI. The CSI comprises at least one of a CQI, a RI, a PCI, and an HARQ ACK/NACK. The user equipment (205) determines a type of data stream in which the part of the CSI was received and determines whether the type of data stream is equal to a predetermined type. The user equipment (205) schedules the user equipment (305) with a first transmission type when the type of data stream is equal to the predetermined type with a second transmission type when the type of data stream is different from the predetermined type.