Hierarchical CoMP Feedback Design for Cell Edge Performance
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Solution Overview
Problem
Current CoMP technologies face challenges in efficiently coordinating multipoint transmission due to increased feedback and scheduling complexity, leading to suboptimal performance for cell edge users, as cooperation sets are often static and do not account for varying channel strengths between User Equipment (UE) and Base Stations (BSs, resulting in interference and reduced system performance.
Innovation Solution
A method and apparatus for hierarchical CoMP feedback design, where User Equipment (UE) reports different sets of parameters based on cell membership within its cooperation set, using Channel Quality Indicator (CQI), Precoding Matrix Indicator (PMI), and inter-cell combiners for intra-set Joint Processing CoMP, and best/worst companion PMIs for inter-set Coordinated Beamforming/Coordinated Scheduling CoMP, optimizing feedback accuracy and reducing redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all cells in the network cooperate in ideal CoMP, then system performance is maximized, but feedback and scheduling complexity becomes unmanageable
Solution Approach 1:
The network is segmented into multiple cooperation sets, where each set contains a subset of cells that cooperate together. This segmentation reduces the feedback and scheduling complexity by limiting the coordination scope to smaller groups while still achieving good system performance through hierarchical coordination between sets.
Solution Approach 2:
The patent introduces a hierarchical dimension to CoMP operation, with intra-set Joint Processing and inter-set Coordinated Beamforming. This two-level hierarchical structure allows the system to manage complexity by operating at different levels of coordination rather than requiring all cells to coordinate simultaneously.
2Device complexity
If static cooperation sets are used for all UEs, then scheduling complexity is reduced, but cell edge users cannot achieve optimal performance
Solution Approach 1:
The patent enables dynamic selection of cooperation sets for each UE based on channel conditions. UEs can be served by different cooperation sets depending on their location and channel strength to various cells, allowing cell edge users to dynamically access their optimal cooperation set rather than being constrained by a static assignment.
Solution Approach 2:
The system changes the parameter of cooperation set membership dynamically based on UE position and channel conditions. By allowing UEs to be associated with different cooperation sets depending on their specific circumstances, the system optimizes performance for cell edge users while maintaining manageable scheduling complexity through the hierarchical structure.
3Reliability
If different cooperation sets are assigned to different UEs based on optimal channel strength, then user performance is improved, but scheduling complexity becomes extremely complicated
Solution Approach 1:
By segmenting the network into overlapping but structured cooperation sets, the patent enables the system to assign different sets to different UEs based on their optimal channel conditions. The segmentation provides a manageable framework that prevents scheduling complexity from becoming unmanageable while still allowing performance optimization for each user.
Solution Approach 2:
The hierarchical CoMP framework provides universal applicability across different UE scenarios. The same two-level structure (intra-set JP and inter-set CB) serves multiple purposes: it enables optimal cooperation for cell center users, provides fallback options for cell edge users, and maintains scheduling manageability through the standardized hierarchical approach.
4Reliability
If JP CoMP is used for all cells, then transmission performance is improved, but feedback overhead increases significantly
Solution Approach 1:
The patent applies different CoMP schemes with different feedback requirements to different spatial locations and user types. JP CoMP with full feedback is applied within cooperation sets where it provides maximum benefit, while inter-set coordination uses reduced feedback mechanisms. This local differentiation of quality and feedback intensity optimizes transmission performance while controlling overall feedback overhead.
Data Source
AI summary
The present invention provides a method, apparatus and a computer program product for feedback design of hierarchical coordinated multipoint transmission. The present invention includes obtaining, at a user equipment, a list including a predetermined number of cells, identifying, at the user equipment, a cooperation set of cells including the cell serving the user equipment, determining, at the user equipment, for each cell included in the list whether the cell belongs to the identified cooperation set of the user equipment, and if the cell belongs to the cooperation set of the user equipment, reporting a first predetermined set of parameters, and if the cell does not belong to the cooperation set of the user equipment, reporting a second predetermined set of parameters.