Home Base Station Channel Fingerprinting for Interference Control

Solution Overview

Problem

In cellular networks, closed subscriber group (CSG) femto base stations interfere with non-CSG user equipment (UEs) due to lack of direct knowledge about radio bearers and interference levels, making it difficult to adjust transmit power effectively without degrading communication quality.

Innovation Solution

A home base station performs radio channel measurements and uses a database of historical channel data to predict channel conditions and interference, allowing it to adaptively reduce transmit power and minimize interference while maintaining communication quality for other UEs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If CSG HeNB reduces transmit power to reduce interference to non-CSG MUEs, then interference is reduced, but received signal power for CSG HUEs is also reduced

Engineering Contradiction:

Improveinterference to non-CSG MUEsVSAvoidcommunication quality for CSG HUEs

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The system performs preliminary channel measurements and builds a database of historical channel data (channel fingerprinting) before interference occurs. This allows the HeNB to predict channel conditions and expected interference signal power in advance, enabling proactive power adjustment that reduces interference while maintaining service quality for authorized users

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements a feedback mechanism where the HeNB continuously monitors uplink signals from UEs, identifies non-CSG MUEs experiencing interference, and adjusts downlink transmit power based on this feedback. The channel fingerprinting database is continuously updated with new measurements, creating a closed-loop system that adapts to changing conditions

Inventive Principle:

Principle #23Feedback

2Object-affected harmful factors

If CSG HeNB uses autonomous power control based on received signal power from non-CSG MUEs, then interference reduction is attempted, but accuracy of interference estimation is insufficient

Engineering Contradiction:

Improveinterference to non-CSG MUEsVSAvoidinterference estimation accuracy

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The system performs preliminary channel measurements and builds a database of historical channel data (channel fingerprinting) before interference occurs. This allows the HeNB to predict channel conditions and expected interference signal power in advance, enabling proactive power adjustment that reduces interference while maintaining service quality for authorized users

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system introduces channel fingerprinting database as an intermediary that stores historical channel data. This database acts as a mediator between the HeNB and non-CSG MUEs, providing accurate predictions of channel conditions and interference levels without requiring direct communication with the interfered UEs

Inventive Principle:

Principle #24Intermediary (Mediator)

3Object-affected harmful factors

If HeNB avoids scheduling UEs on same radio bearers as non-CSG MUEs, then interference is mitigated, but capacity of HeNB is reduced

Engineering Contradiction:

Improveinterference to non-CSG MUEsVSAvoidcapacity of HeNB

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The system performs preliminary channel measurements and builds a database of historical channel data (channel fingerprinting) before interference occurs. This allows the HeNB to predict channel conditions and expected interference signal power in advance, enabling proactive power adjustment that reduces interference while maintaining service quality for authorized users

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of changing scheduling parameters (avoiding same radio bearers), the system changes the power parameter dynamically. By adjusting downlink transmit power based on predicted interference levels, the HeNB can maintain full scheduling flexibility and capacity while still mitigating interference through precise power control

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP2695451B1Autonomous maximum power setting based on channel fingerprint

Publication Date: 2015.10.21 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

A home base station (HBS) (104, 801) performs radio channel measurements to detect one or more user equipments (UEs)(107) not served by the HBS which may be in a potentially interfering environment caused at least in part by the HBS. A database (812) of historical channel data (channel fingerprinting) of the HBS coverage area is used to predict the channel conditions and expected interference signal power seen by the detected UE(s). Based on a combination of the radio measurements(813) and historical channel data, the HBS can accurately and adaptively reduce its transmit power to a level that reduces or eliminates interference with the detected UE(s), while also not significantly degrading communication quality between other UEs served by the HBS.