Active Acknowledgment Source Selection for Wireless Handoff

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Solution Overview

Problem

In wireless communication systems, especially during soft handoffs, excessive transmission power is required for acknowledgment signals, leading to reduced system connection capacity and inefficiencies due to concurrent data communication with multiple base stations, which worsens with leg imbalances and results in unnecessary noise and power consumption.

Innovation Solution

A method and apparatus that selectively suppress acknowledgment signals from certain data receiving transceivers, evaluating the effectiveness of each potential acknowledger to determine which ones are necessary, and providing disablement indications to reduce unnecessary acknowledgment transmissions, thereby conserving power and minimizing noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If acknowledgment signals are transmitted from all base stations in the active set during soft handoff, then reliability of acknowledgment delivery is improved, but transmission power consumption increases and system capacity decreases

Engineering Contradiction:

Improveacknowledgment signal delivery reliabilityVSAvoidtransmission power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies local quality by differentiating the acknowledgment transmission behavior of different base stations based on their individual channel conditions. Instead of uniform acknowledgment transmission from all base stations, each base station's acknowledgment signal is selectively enabled or disabled based on its specific leg quality metrics (Ec/Io, signal strength), thereby optimizing power usage while maintaining reliability where needed.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements partial action by having only a subset of base stations transmit acknowledgment signals during soft handoff. The network determines that full acknowledgment transmission from all base stations is excessive, and instead enables acknowledgment transmission only from base stations with sufficient channel quality, reducing overall power consumption while maintaining adequate reliability.

Inventive Principle:

Principle #16Partial or excessive action

2Reliability

If acknowledgment signals are transmitted from multiple base stations during soft handoff, then acknowledgment coverage is improved, but noise interference increases and detection accuracy decreases

Engineering Contradiction:

Improveacknowledgment signal coverageVSAvoidnoise interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by evaluating the channel conditions of each individual base station and selectively enabling acknowledgment transmission only from base stations with adequate signal quality. This prevents poor-quality acknowledgment signals from degrading the overall signal environment, thereby reducing noise interference while maintaining sufficient coverage through selective participation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent converts the potential harm of excessive acknowledgment transmissions into benefit by using the channel quality information itself as the selection criterion. Base stations with poor channel conditions (which would generate harmful noise) are excluded from transmission, while those with good conditions contribute usefully, thereby transforming the channel assessment mechanism into a filtering tool that eliminates harmful signals.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If all base stations in the active set transmit acknowledgment signals, then system robustness is improved, but device complexity and coordination overhead increase

Engineering Contradiction:

Improvesystem robustnessVSAvoidacknowledgment coordination complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements partial action by having the network perform selective enablement of acknowledgment transmission from base stations. Instead of requiring complex coordination among all base stations to manage their acknowledgment transmissions, the network centrally determines which base stations should participate, simplifying the coordination mechanism while maintaining system robustness through selective participation.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent applies preliminary action by having the network pre-determine and configure which base stations should transmit acknowledgment signals based on their channel conditions. This configuration is established before the actual data transmission occurs, allowing base stations to simply follow predetermined instructions rather than engaging in complex real-time coordination, thereby reducing operational complexity.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS7567536B2Active acknowledgment source selection

Publication Date: 2009.07.28 APPLE INC

AI summary

A wireless communication mobile station (MS or UE) evaluates and categorizes an expected effectiveness of base stations (BSs or Node-Bs) in its Active Set for receiving uplink data, and instructs at least the less effective BSs to suppress some or all acknowledgment signals with respect to particular uplink data packets from the UE. A Target Select message is described for notifying the BSs of their Acknowledgment Target Select category, and a Target Select channel is described for conveying the Target Select message to all Active Set BSs so that they can suppress acknowledgment signaling with respect to corresponding data packets as appropriate for their Acknowledgment Target Select category.