Dynamic Fractional Frequency Reuse Allocation in LTE Networks
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Solution Overview
Problem
Current small cell RAN technologies face inefficiencies in frequency reuse, particularly in 3D deployments like multi-floor buildings, where static frequency allocation for cell-edge users is wasteful and distributed algorithms are slow to adapt to changing network conditions, limiting spectral efficiency and resource allocation.
Innovation Solution
Implementing a hierarchical architecture with a central controller that dynamically computes fractional frequency reuse (FFR) allocations and configures individual MAC schedulers within each radio node, using interference graphs and heuristic algorithms to optimize frequency usage based on UE loads and interference patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If static frequency allocation is used for cell-edge users, then implementation simplicity is maintained, but spectral efficiency is reduced due to wasteful resource allocation
Solution Approach 1:
The patent implements dynamic frequency allocation where the FFR parameter is adjusted in real-time based on network conditions, UE buffer occupancy, and interference measurements. The central controller continuously updates the FFR configuration for different cell types (macro, pico, femto) and user categories (cell-edge, interior) to optimize spectral efficiency while maintaining manageable complexity through centralized control.
2Adaptability or versatility
If distributed algorithms are used for frequency coordination, then system autonomy is maintained, but adaptation speed to changing network conditions is slow
Solution Approach 1:
The patent introduces a central controller as an intermediary between radio nodes and the core network. This controller collects interference measurements, UE buffer occupancy information, and traffic load data from multiple radio nodes, computes optimal FFR parameters centrally, and distributes configurations back to the nodes. This intermediary approach enables fast adaptation to changing conditions while managing coordination complexity through centralized processing.
3Productivity
If FFR is dynamically computed with centralized control, then spectral efficiency is improved through accurate real-time decisions, but system complexity increases due to centralized processing requirements
Solution Approach 1:
The patent segments the network into hierarchical levels: a central controller for global optimization and radio nodes for local execution. The central controller handles high-level FFR parameter computation based on aggregate network state, while individual radio nodes execute local MAC scheduling and resource allocation. This segmentation allows dynamic FFR computation to improve spectral efficiency without requiring every node to perform complex centralized processing.
Solution Approach 2:
The system performs preliminary computation of FFR parameters at the central controller based on predicted traffic patterns and historical interference data. These pre-computed configurations are then distributed to radio nodes before actual data transmission begins, allowing the system to adapt to changing conditions proactively rather than reactively, thereby improving spectral efficiency while reducing real-time processing complexity at individual nodes.
Data Source
AI summary
A services node or central controller or coordinator is provided that dynamically computes fractional frequency reuse allocation among user equipment in a radio access network. The central controller or coordinator communicates the fractional frequency reuse allocation and configures the individual MAC schedulers within each radio node in the radio access network. Inputs to the central coordinator may include its serving radio node, a detected set of radio nodes, and information about user equipment buffer status both in the downlink and uplink. In one implementation, interference graphs are constructed for downlinks and uplink separately and the same are used with a heuristic independent set algorithm to compute the frequency allocation.