Dynamic Point Selection for CoMP Using SRS Channel Estimation
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Solution Overview
Problem
Release 8/9 UEs do not support TM10, which limits their ability to perform dynamic point selection (DPS) due to lack of multiple CSI feedback, leading to challenges in cell-edge performance and load balancing in CoMP schemes.
Innovation Solution
The method involves estimating channel quality using SRS/Demodulation Reference Signal transmissions, determining the best serving TP based on these measurements, and forwarding data from the primary TP to the serving TP, while separately transmitting PDCCH and PDSCH, to overcome the limitations of RE overhead and channel fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TM10 and multiple CSI feedback framework are used for DPS, then cell-edge performance and load balancing are improved, but Release 8/9 UEs cannot benefit due to lack of support
Solution Approach 1:
The patent changes the feedback parameter from multiple CSI reports (TM10 requirement) to a single CQI report, making the system compatible with Release 8/9 UEs while maintaining DPS functionality through alternative channel quality assessment methods
Solution Approach 2:
The patent uses SRS transmissions from the UE to copy/estimate the downlink channel quality, replacing the need for direct downlink CSI feedback and enabling DPS for UEs that cannot provide multiple CSI reports
2Productivity
If serving TP is switched dynamically among CoMP set, then throughput and load balancing are improved, but interference management and coordination complexity increase
Solution Approach 1:
The patent implements a feedback mechanism where each TP in the CoMP set reports estimated channel quality to a selecting entity, enabling dynamic serving TP selection based on real-time channel conditions while maintaining coordinated management
Solution Approach 2:
The patent introduces a selecting entity (which can be one of the TPs or a separate controller) that acts as an intermediary to receive channel quality reports from all TPs and make the serving TP selection decision, simplifying the coordination architecture
3Adaptability or versatility
If PDCCH and PDSCH are transmitted by different TPs, then DPS flexibility is improved, but control channel reliability and UE synchronization become challenging
Solution Approach 1:
The patent segments the transmission functions by separating PDCCH transmission (control channel) from PDSCH transmission (data channel), allowing them to be performed by different TPs while maintaining reliable control through the primary TP's PDCCH transmissions
Data Source
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Figure 3
Figure 4A~4B
AI summary
Methods and apparatus for realizing dynamic point selection improve the cell-edge throughput and geometric mean of release 8/9 UEs. The method comprises a step of receiving estimated channel quality reported by all the TPs in the CoMP set, a step of switching the serving TP for the UEs based on the estimated channel quality and/or cell load, a step of forwarding the scheduled data from the primary TP to the serving TP, a step of separately transmitting PDCCH to the UEs by the primary TP and transmitting PDSCH to the UEs by the serving TP. the implementation of the method and apparatus improves the cell-edge throughput and geometric mean of UE throughput by serving UEs instantaneously from the cell that provides better throughput accounting for fast time-scale channel fluctuations and/or load. It helps in reducing interference due to data getting drained faster when users are served from cells with better channel conditions.