Access Point Handover Parameter Determination for Mobility Management
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Solution Overview
Problem
Wireless communication networks face challenges in indoor environments due to channel characteristics like path loss, fading, and multipath, leading to coverage issues and poor user experiences, particularly with unplanned deployments of femto cells, which can cause ping-ponging effects and outages during access terminal mobility between macro and femto cells.
Innovation Solution
Dynamically determining and transmitting cell reselection and handover parameters by access points based on signal quality and proximity to improve mobility management, mitigating ping-ponging and outages by setting appropriate parameters for idle mode cell reselection and active mode handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If access terminal frequently reselects between femto cell and macro cell, then coverage is improved, but ping-ponging effect occurs causing network performance degradation
Solution Approach 1:
The patent dynamically adjusts cell reselection parameters (Qhyst, Qqualmin, Treselection) based on signal quality measurements and terminal velocity. When terminal velocity exceeds a threshold or signal quality is poor, parameters are modified to prevent frequent reselections, thereby eliminating ping-ponging effects while maintaining adequate coverage.
2Loss of time
If access terminal remains on femto cell longer, then reselection overhead is reduced, but call drops occur due to outdated parameters
Solution Approach 1:
The patent implements dynamic parameter adjustment where Qhyst, Qqualmin, and Treselection are not fixed but adapt based on current signal quality conditions and terminal mobility state. This allows the system to balance between maintaining stable connection (reducing reselection overhead) and responding to deteriorating conditions (preventing call drops).
Solution Approach 2:
The system continuously monitors signal quality metrics (RSCP, Ec/Io) and terminal velocity, using this feedback to adjust reselection parameters in real-time. This closed-loop control ensures parameters remain appropriate for current conditions, preventing both unnecessary reselections and missed handovers.
3Reliability
If access terminal performs continuous cell searches, then mobility management is improved, but battery life is reduced
Solution Approach 1:
The patent implements selective cell search behavior where the access terminal performs full cell searches only when necessary (based on signal quality thresholds and velocity conditions). During stable conditions, reduced-search modes are used, decreasing energy consumption while maintaining adequate mobility management.
Data Source
AI summary
A parameter for transmission by an access point is determined in a manner that facilitates access terminal mobility. For example, a cell reselection parameter and/or a handover parameter may be determined based on the quality of a signal from one access point (e.g., a macro cell) at another access point (e.g., a femto cell). In addition, a cell reselection parameter and/or a handover parameter may be determined based on the proximity of one access point (e.g., a femto cell) to another access point (e.g., a macro cell). Through the use of these techniques, a parameter may be determined in a manner that mitigates access terminal ping-ponging between access points and that mitigates outages that may otherwise occur as a result of an access terminal remaining on an access point too long.