CoMP JT Feedback and Scheduling for OFDMA Cell-Edge Throughput
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Solution Overview
Problem
Existing coordinated multi-point (CoMP) joint transmission (JT) in OFDMA systems face high feedback and backhaul overhead, and existing scheduling algorithms are complex with suboptimal performance guarantees, particularly affecting cell-edge throughput.
Innovation Solution
The proposed solution includes efficient feedback schemes such as non-coherent JT and pre-scheduling CoMP UE fallback (PSCUF), which reduce signaling overhead and implement an optimal scheduling algorithm to achieve CoMP gains with lower complexity, allowing UEs to dynamically skip CoMP feedback and fallback to single cell transmission when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CoMP JT is implemented with existing feedback schemes, then cell-edge throughput is improved, but feedback overhead increases significantly
Solution Approach 1:
The patent extracts and removes unnecessary feedback elements from the CoMP JT system. Specifically, it eliminates the need for UE to measure and report channel state information (CSI) for all transmission points (TPs) in the CoMP set. Instead, only RSRP measurements for identifying the best serving TP are required, dramatically reducing feedback overhead while maintaining throughput performance
Solution Approach 2:
The patent segments the CoMP JT operation into two distinct modes: coherent JT mode where phase adjustment is applied, and non-coherent JT mode where it is not. This segmentation allows the system to operate in non-coherent mode with minimal feedback (only RSRP) when coherent processing is not necessary, thereby reducing feedback overhead while preserving throughput benefits when needed
2Productivity
If iterative scheduling algorithms are used for CoMP JT, then scheduling performance is improved, but algorithm complexity increases
Solution Approach 1:
The patent employs a low-complexity greedy scheduling algorithm that makes immediate, non-iterative decisions based on current channel conditions. This disposable approach computes scheduling decisions in a single pass without iterative refinement, achieving acceptable scheduling performance with significantly reduced computational complexity compared to iterative algorithms
Solution Approach 2:
The patent applies partial action by implementing a simplified greedy scheduling algorithm that does not fully optimize all parameters iteratively. Instead, it makes sufficient scheduling decisions based on key metrics like RSRP and channel quality, achieving adequate performance without the excessive computational burden of complete iterative optimization
3Measurement precision
If coherent phase difference feedback is implemented, then transmission accuracy is improved, but signaling overhead increases
Solution Approach 1:
The patent implements dynamic mode switching between coherent and non-coherent JT operations. The system adapts its feedback requirements based on channel conditions and traffic requirements, operating in non-coherent mode (with minimal feedback) when phase adjustment is not critical, and switching to coherent mode only when throughput benefits justify the additional feedback overhead
Solution Approach 2:
The patent applies local quality by providing phase adjustment feedback only when and where it is most beneficial. Instead of requiring all UEs in CoMP sets to provide coherent phase feedback, the system selectively enables coherent processing for specific UE-TP pairs where it provides the greatest throughput improvement, thereby minimizing overall signaling overhead
Data Source
AI summary
A method implemented in a user equipment (UE) used in an orthogonal frequency division multiple access (OFDMA) wireless communications system supporting coordinated multi-point (CoMP) joint transmission (JT) is disclosed. The method includes measuring reference signal received power (RSRP), transmitting, to a network, first feedback on the RSRP, receiving, from the network, a CoMP measurement set, conducting pre-scheduling CoMP UE fallback according to the CoMP measurement set, computing channel quality and direction information according to a UE category, and transmitting, to the network, second feedback on the channel quality and direction information. Other methods, apparatuses, and systems also are disclosed.