Femtocell Radio Resource Allocation for Macrocell Interference

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Solution Overview

Problem

Femtocells interfere with macrocell signals, particularly in the downlink direction, causing access issues and increasing power expenditure for user equipment due to the large number of near neighbors, and existing solutions either require expensive spectrum reallocation or limit coverage and data rate.

Innovation Solution

Allocating radio resource blocks for femtocells that do not overlap with those used by macrocell base stations for signaling, allowing simultaneous transmission and maximizing data capacity without additional spectrum requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If femtocells use the same frequency band as macrocells, then spectrum utilization is improved, but interference with macrocell signals increases

Engineering Contradiction:

Improvespectrum utilizationVSAvoidinterference with macrocell signals

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The frequency band is segmented into different resource blocks, with specific resource blocks allocated for signaling purposes. Femtocells are allowed to use the same overall frequency band as macrocells, but they are restricted from using the signaling resource blocks, thereby preventing interference while maintaining spectrum utilization efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the frequency spectrum are assigned different functions: certain resource blocks are designated for signaling (where femtocells are restricted) and other resource blocks are available for general data transmission (where femtocells can operate). This local differentiation allows coexistence while preventing harmful interference.

Inventive Principle:

Principle #3Local quality

2Reliability

If femtocells are deployed in large numbers, then coverage improvement is improved, but power expenditure for measurements increases

Engineering Contradiction:

Improvecoverage improvementVSAvoidpower expenditure for measurements

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The signaling resource blocks are extracted from the general frequency band and reserved exclusively for macrocell signaling. User equipment can identify femtocells through their restricted resource block usage patterns, reducing the need for extensive measurements of all nearby base stations and thereby reducing power expenditure.

Inventive Principle:

Principle #2Taking out (Extraction)

3Productivity

If femtocells use same resource blocks as macrocells for signaling, then resource efficiency is improved, but communication reliability deteriorates

Engineering Contradiction:

Improveresource efficiencyVSAvoidcommunication reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The resource blocks are segmented into signaling-specific blocks and data blocks. Femtocells are prohibited from using signaling resource blocks but can use data resource blocks, ensuring that critical signaling communications remain reliable while still allowing femtocells to utilize spectrum resources efficiently for data transmission.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS8885624B2Radio resource allocation for cellular wireless networks

Publication Date: 2014.11.11 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

A cellular wireless network employs a method of allocating radio resources to femtocells so that the transmissions from femtocells do not occupy the same radio resource blocks as those used by a macrocell for signalling.