Dynamic Soft FFR for Uplink Interference Mitigation
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Solution Overview
Problem
In 4G and 5G cellular wireless communication networks, inter-cell interference (ICI) at the cell-edge limits system performance, and existing interference mitigation techniques are inefficient in dense LTE deployments, where neighboring cells cause interference due to overlapping resource allocations for user equipment (UEs) at the cell edge.
Innovation Solution
Implementing a Dynamic Soft Fractional Frequency Reuse (FFR) method that classifies UEs as cell-edge or cell-center based on their Transport Block Size Index (ITBS) and allocates different starting Resource Block (RB) indices to minimize interference, using the Physical Cell Identifier (PCI) to determine non-overlapping priority segments for cell-edge UEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional frequency allocation is used in dense LTE deployments, then network coverage is maintained, but inter-cell interference increases due to overlapping resource allocations for cell-edge UEs
Solution Approach 1:
The patent divides the system into two distinct UE categories (cell-center UEs and cell-edge UEs) and allocates different frequency resources to each segment. Cell-center UEs use the entire system bandwidth while cell-edge UEs are restricted to a specific subset of resource blocks, preventing interference between neighboring cells at the cell edge while maintaining full bandwidth access for cell-center users.
Solution Approach 2:
The patent applies different frequency allocation strategies to different spatial locations. Cell-edge UEs in interference-prone regions receive dedicated non-overlapping resource blocks from neighboring cells, while cell-center UEs in low-interference regions maintain access to the full bandwidth. This local differentiation resolves the contradiction by providing interference protection only where needed.
2Object-affected harmful factors
If Frequency Division Duplexing (FDD) is used to mitigate interference, then uplink interference is reduced, but downlink capacity is limited by available frequency resources
Solution Approach 1:
The patent implements dynamic resource allocation where the network can adaptively adjust which resource blocks are assigned to cell-edge UEs based on channel conditions, traffic demand, and interference measurements. This dynamic approach allows the system to optimize both uplink interference mitigation and downlink capacity utilization in real-time, rather than using static FDD resource separation.
Data Source
AI summary
This invention relates to an efficient and simple best effort UL FFR, describing how to effectively partition the bandwidth (BW) into regions and how to allocate different UEs into those partitions. In one embodiment, a method of Uplink (UL) Fractional Frequency Reuse (FFR) includes classifying a User Equipment (UE) as either a cell-edge UE or a cell-center UE; examining each UE before each UL scheduling and updating a status of the UE that was examiner; and choosing a cell-edge segment for each cell, a cell-edge segment including a starting SB index and an end SB index, wherein an SB is a group of Resource Blocks (RBs), wherein the cell edge segment is defined using the physical cell indicator (PCI) as an input.