Reverse-Link Power Control for Dropped Call Prevention

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Solution Overview

Problem

In wireless networks, especially CDMA and EV-DO systems, mobile stations often face issues with reverse-link transmission power control, leading to dropped calls due to varying interference levels and load conditions, which existing power control mechanisms struggle to manage effectively, resulting in inefficient power usage and increased dropped call rates.

Innovation Solution

A base station identifies active mobile stations most likely to experience dropped calls by determining their individual contributions to reverse noise rise (RNR) and adjusts reverse-link power-control settings, such as lowering RFER targets or raising Eb/Nt setpoints, to prevent call drops, while monitoring and adjusting these settings to maintain an optimal power balance across the network.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If reverse-link power control is implemented to manage transmission power, then power efficiency is improved, but call drop rate increases due to inability to handle varying interference levels and load conditions

Engineering Contradiction:

Improvepower efficiencyVSAvoidcall drop rate

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies local quality by differentiating power control strategies based on individual mobile station characteristics and interference contributions. Instead of uniform power control, the system identifies mobile stations with high reverse noise rise contributions and applies targeted power management, allowing each station to have customized power settings that balance efficiency and reliability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system dynamically adjusts power control parameters in real-time based on changing network conditions, interference levels, and mobile station contributions. The base station continuously monitors reverse noise rise and adapts power control settings accordingly, transitioning between different power management modes to prevent call drops while maintaining efficiency.

Inventive Principle:

Principle #15Dynamics

2Reliability

If power control settings are adjusted to prevent call drops, then call reliability is improved, but overall network power efficiency deteriorates

Engineering Contradiction:

Improvecall reliabilityVSAvoidnetwork power efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements local quality by selectively applying power control adjustments only to mobile stations that contribute significantly to reverse noise rise. Rather than increasing power for all stations, the system identifies and targets specific stations with high interference contributions, thereby improving call reliability for critical users while preserving overall network power efficiency.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The system applies partial action by providing enhanced power control protection only to the extent necessary for stations with high drop risk. The base station calculates individual mobile station contributions to reverse noise rise and applies power adjustments proportionally, avoiding excessive power increases for stations that do not require special protection.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If individual mobile station interference contributions are monitored and controlled, then call drop rate is reduced, but system complexity increases

Engineering Contradiction:

Improvecall drop rateVSAvoidpower control complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs feedback mechanisms where the base station continuously monitors reverse noise rise and mobile station contributions, using this information to dynamically adjust power control settings. The system feeds back individual station interference levels to the power control algorithm, enabling automated adaptation that reduces call drops while managing complexity through closed-loop control.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8290532B1Selectively conducting reverse-link power control and call admission control

Publication Date: 2012.10.16 SPRINT SPECTRUM LLC

AI summary

Methods and systems are provided for selectively conducting reverse-link power control and call admission control. In an embodiment, a base station identifies a set of mobile stations more likely than others to experience a dropped call. For each mobile station in the set, the base station relaxes at least one reverse-link power-control setting, to foster an increased actual and/or allowed reverse-link transmission-power level. The base station thereafter detects the dropped-call rate exceeding a first threshold, and responsively decreases the degree to which at least one setting was relaxed. The base station thereafter detects the dropped-call rate exceeding a higher threshold, and responsively drops at least one active call and/or blocks at least one new call.