Packetized Fractional Guard Channel Call Admission Control

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Solution Overview

Problem

Traditional call admission control techniques in wireless communication networks fail to effectively address the unique requirements of packet-switched networks, particularly in minimizing call blocking and dropping probabilities while maximizing bandwidth utilization.

Innovation Solution

The Packetized Fractional Guard Channel (PFG) Call Admission Control (CAC) technique dynamically adjusts to system parameters and traffic conditions, prioritizing handoff calls to prevent drops while maximizing bandwidth utilization by using a distributed, stochastic, and periodic approach that considers information from neighboring cells to set an acceptance ratio for new calls based on target packet loss probabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional call admission control techniques are used in packet-switched networks, then the network architecture supports better sharing of wireless resources, but the techniques fail to effectively minimize call blocking and dropping probabilities

Engineering Contradiction:

Improvepacket-switched network resource sharingVSAvoidcall blocking and dropping probabilities

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent changes the control parameters from circuit-switched metrics to packet-switched metrics by introducing acceptance ratio based on packet loss probability thresholds. The CAC mechanism dynamically adjusts admission decisions using packet-level QoS parameters (average packet loss probability and target packet loss probability) rather than traditional call-level metrics, enabling effective control in packet-switched environments while maintaining reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements dynamic call admission control that continuously monitors system state and traffic conditions. The acceptance ratio is dynamically calculated based on current packet loss probabilities and adjusted in real-time to respond to changing network conditions, allowing the system to adaptively minimize blocking and dropping while maximizing resource utilization

Inventive Principle:

Principle #15Dynamics

2Reliability

If call admission control is implemented to minimize call dropping, then call reliability improves, but bandwidth utilization may be reduced due to conservative admission decisions

Engineering Contradiction:

Improvecall dropping probabilityVSAvoidbandwidth utilization

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies partial guard channel principles by using acceptance ratios that allow more aggressive admission than traditional guard channels while still protecting against excessive packet loss. Instead of reserving fixed channels, the system admits calls partially based on probabilistic thresholds, achieving zero call dropping while utilizing available bandwidth more efficiently through stochastic admission decisions

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent implements feedback mechanisms where the system continuously monitors packet loss probabilities and adjusts acceptance ratios accordingly. When packet loss approaches thresholds, admission becomes more conservative; when conditions improve, admission becomes more liberal. This closed-loop control maintains reliability while optimizing bandwidth utilization through dynamic response to actual network conditions

Inventive Principle:

Principle #23Feedback

3Reliability

If distributed call admission control is implemented considering neighboring cell information, then QoS management improves, but system complexity increases due to inter-cell communication requirements

Engineering Contradiction:

ImproveQoS guaranteeVSAvoidinter-cell communication system

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the CAC function into independent distributed decision-making units at each base station. Each cell autonomously calculates its acceptance ratio using local measurements and simple neighbor count information, rather than requiring complex centralized coordination. This segmentation maintains QoS guarantees through distributed intelligence while minimizing inter-cell communication overhead

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent enables self-service CAC where each base station independently determines its own admission policy based on local packet loss measurements and simple external inputs (number of neighboring cells). The system serves itself by using locally available information and simple calculations rather than requiring complex external control, reducing system complexity while maintaining effective QoS management

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS7512068B1Call admission control for a wireless network

Publication Date: 2009.03.31 APPLE INC

AI summary

A call admission method and apparatus are disclosed which maximizes the wireless channel utilization subject to a predetermined bound on the call dropping and packet loss probabilities for variable-bit-rate traffic in a packet switched network. The call admission scheme is stochastic and dynamic, hence it is able to adapt to a wide range of traffic fluctuations and mobility patterns. The call admission scheme disclosed satisfies a set of constraints on call dropping and packet loss probabilities while maintaining high bandwidth utilization.