Dynamic Uplink Beamforming Switching for Multiflow Reliability
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Solution Overview
Problem
In 3GPP Rel-11, multiflow (MF) technology faces challenges in maintaining reliable uplink channel performance, especially for the assisting base station, due to link imbalance between cells, which can lead to incorrect reception of CQI and HARQ messages, compromising downlink performance.
Innovation Solution
The solution involves an apparatus and method that determine which cell provides feedback for uplink transmit diversity, allowing both the serving and assisting cells to participate in closed-loop transmit diversity (CLTD) feedback, optimizing the uplink channel by selecting the cell with better quality or less reconfigurations, and dynamically choosing the cell to provide feedback based on quality and data transmission criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the link imbalance between cells is increased to expand the multiflow operation area, then more UEs can be involved in MF operation and higher MF gains are achieved, but the reception reliability of HS-DPCCH in the weaker cell deteriorates
Solution Approach 1:
The patent implements dynamic switching of the feedback-providing cell between serving and assisting cells based on real-time uplink channel quality measurements. The network dynamically determines which cell should provide CLTD feedback to the UE, allowing the system to adapt to changing channel conditions and maintain reliable feedback reception even when link imbalance varies, thus resolving the contradiction between expanding MF operation area and maintaining feedback reliability.
2Reliability
If only the serving cell provides CLTD feedback to the UE, then the uplink performance from the serving cell viewpoint is improved, but the assisting cell cannot reliably receive CQI and HARQ messages
Solution Approach 1:
The patent introduces a network-side intermediary (RNC or eNB) that receives CQI and HARQ feedback from both serving and assisting cells, processes the information, and determines which cell should provide CLTD feedback to the UE. This intermediary coordinates the feedback mechanism to ensure both cells receive necessary information while maintaining system-wide optimization, resolving the contradiction between serving cell performance and assisting cell information reception.
3Reliability
If the assisting cell provides CLTD feedback, then the uplink channel is optimized for the assisting cell, but the feedback may not be optimal for the serving cell data transmission
Solution Approach 1:
The patent implements dynamic parameter switching where the network can change which cell provides CLTD feedback based on traffic conditions, channel quality, and cell roles. The system can switch between having the serving cell or assisting cell provide feedback, and can also adjust the weighting or prioritization of different feedback sources, allowing optimization for different operational scenarios and resolving the contradiction between assisting cell reception quality and overall downlink efficiency.
Data Source
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AI summary
It is provided a method, comprising deciding if any of a first cell device and a second cell device provides a feedback for an uplink transmit diversity of at least two antennas of a terminal, determining, if it is decided that the feedback is to be provided, whether the first cell device or the second cell device or both provide the feedback; providing the determination whether the first cell or the second cell provides the feedback to at least one of the first cell device and the second cell device.