Femtocell Resource Allocation via Fractional Frequency Reuse

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Solution Overview

Problem

Current methods for mitigating interference between femtocells and macrocells are impractical due to complexity and inefficiency, leading to suboptimal resource utilization and communication quality.

Innovation Solution

A resource allocation apparatus and method that uses fractional frequency reuse (FFR) information to determine unoccupied partitions in the wireless network, allocating these resources to subscriber stations to reduce interference and improve communication quality by generating and conveying allocation messages between macro base stations and subscriber stations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If TDM or FDM based approach is used to interlace the used resource of different cell, then interference between femtocell and macrocell is reduced, but the complexity of scheduling and control increases and resource efficiency decreases

Engineering Contradiction:

Improveinterference between femtocell and macrocellVSAvoidcomplexity of scheduling and control

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent changes the resource allocation parameters by introducing fractional frequency reuse (FFR) information that divides frequency resources into different reuse factors (e.g., 1/2, 1/4, 1/8). This allows dynamic adjustment of frequency allocation patterns without requiring complex time-domain scheduling, thereby reducing interference while maintaining scheduling simplicity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent transitions from time-domain multiplexing (TDM) to frequency-domain multiplexing with fractional reuse, adding a frequency dimension to resource allocation. This dimensional shift allows multiple cells to simultaneously utilize different frequency partitions, reducing interference without increasing scheduling complexity in the time domain.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If TDM or FDM based approach is used to interlace the used resource of different cell, then interference between femtocell and macrocell is reduced, but resource efficiency and system utilization become suboptimal

Engineering Contradiction:

Improveinterference between femtocell and macrocellVSAvoidresource efficiency and system utilization

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent dynamically adjusts the fractional frequency reuse parameter (1/K where K=2,4,8) based on traffic conditions and interference levels. This allows the system to optimize resource efficiency by allocating more frequency resources to femtocells when macrocell interference is low, while maintaining interference protection when needed, thereby improving overall system utilization.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements dynamic resource allocation where the fractional frequency reuse configuration can change based on network conditions. The macro base station can adjust the FFR information conveyed to subscriber stations, allowing the system to adapt to varying traffic demands and interference patterns, thus optimizing resource efficiency in real-time.

Inventive Principle:

Principle #15Dynamics

3Productivity

If fractional frequency reuse information is conveyed from macro base station to subscriber station, then resource allocation optimization is achieved, but the control signaling overhead increases

Engineering Contradiction:

Improveresource allocation optimizationVSAvoidcontrol signaling overhead

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

The patent integrates fractional frequency reuse information into existing control message structures used in LTE systems. The FFR information is conveyed within the same downlink control information (DCI) format that carries resource allocation grants, allowing the control signaling to serve multiple functions (resource allocation + FFR configuration) simultaneously, thereby minimizing additional overhead.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the FFR indication with the resource allocation grant message that is already transmitted from macro base station to subscriber station. By merging the FFR information with the existing control signaling structure rather than sending separate messages, the patent reduces the total control overhead while still conveying the necessary resource allocation optimization information.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS9191949B2Macrocell network, resource allocation method, and non-transitory computer readable medium

Publication Date: 2015.11.17 INSTITUTE FOR INFORMATION INDUSTRY

AI summary

The present invention relates to a subscriber station, resource allocation method, and non-transitory computer readable medium thereof. The subscriber station using in a femtocell network comprises a receiving interface and a processor. The receiving interface receives a frame of the femtocell network. The processor, electrically connected to the receiving interface, blindly decodes a first logical frequency resource unit (LRU) of a frequency partition of the frame to obtain an allocation message, determines the allocation message is relative to the subscriber station, and proceeds a data transmission in the femtocell network according to the allocation message.