Wireless Handoff via Activity Correlation

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Solution Overview

Problem

In wireless communication networks, femtocells often share non-unique pseudorandom number or pseudorandom noise codes, leading to unsuccessful handoffs between access nodes, resulting in dropped calls and poor user experience due to inability to uniquely identify target femtocells for handoff.

Innovation Solution

A handoff controller selects a target femtocell for handoff based on correlation with prior communications, such as time, geography, and destination address, ensuring that the encoding identifiers or PN codes are consistent, allowing seamless handoff coordination between macrocells and femtocells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If non-unique pseudorandom codes are used in femtocells to allow shared identifiers, then device complexity and configuration ease are improved, but handoff reliability deteriorates due to inability to uniquely identify target femtocells

Engineering Contradiction:

Improvefemtocell configuration complexityVSAvoidhandoff success rate

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The system performs preliminary correlation analysis of communication activities between the wireless device and potential target femtocells before handoff execution. The handoff controller proactively identifies candidate femtocells by analyzing temporal, geographic, and destination address correlations in advance, preparing handoff candidates before the actual handoff event occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The handoff controller acts as an intermediary that mediates between the macrocell and femtocells during handoff. It receives communication activity information from multiple femtocells, performs correlation analysis to identify the most suitable target, and coordinates the handoff process, resolving the ambiguity caused by non-unique identifiers.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If pseudorandom codes are shared across multiple femtocells, then identifier uniqueness is improved for resource efficiency, but communication reliability deteriorates due to dropped calls during handoff

Engineering Contradiction:

Improveidentifier reusabilityVSAvoidcommunication session continuity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system implements feedback mechanisms where femtocells report their communication activity information (temporal patterns, geographic locations, destination addresses) to the handoff controller. The controller analyzes this feedback to identify correlation patterns and uses this information to make informed handoff decisions, ensuring seamless transitions despite code sharing.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system moves from relying solely on identifier uniqueness (one-dimensional identification) to multi-dimensional correlation analysis. By examining temporal, geographic, and destination address dimensions simultaneously, the system can uniquely identify target femtocells even when their pseudorandom codes are identical, effectively adding multiple identification dimensions.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Speed

If traditional handoff methods are used without activity correlation, then handoff processing speed is improved, but handoff accuracy deteriorates leading to unsuccessful handoffs

Engineering Contradiction:

Improvehandoff processing speedVSAvoidtarget femtocell identification accuracy

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8358628B2Wireless handoffs based upon activity correlation

Publication Date: 2013.01.22 T MOBILE INNOVATIONS LLC

AI summary

A femtocell node exchanges user data with a wireless communication device. Subsequently, a macrocell node exchanges other user data with the wireless communication device. A handoff controller selects the femtocell node for a handoff from the macrocell node based on a correlation with the prior communications between the wireless communication device and the femtocell node. For example, the prior communications between the wireless communication device and the femtocell node may correlate in time, geography, and/or destination address with prior interrupted communications between the wireless communication device and the macrocell node.