Browse Prior Art Database

Call Admission Control for priority attempts in an overloaded system

IP.com Disclosure Number: IPCOM000202208D
Original Publication Date: 2010-Dec-08
Included in the Prior Art Database: 2010-Dec-08
Document File: 3 page(s) / 207K

Publishing Venue

Motorola

Related People

Narayan, Kartick N: INVENTOR [+4]

Abstract

The invention provides a call admission control (CAC) method to admit priority call attempts into the system at any point of time. This method ensures that full system capacity is utilized during normal conditions. This method also ensures that Quality of Service (QoS) of already admitted calls is not degraded during periods of severe overload in times of emergency.

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Call Admission Control for priority attempts in an overloaded system

By Kartick N, Rajavarma Bhyrraju, Douglas White, Kashif Khan

Motorola, Inc.

Networks

 

ABSTRACT

The invention provides a call admission control (CAC) method to admit priority call attempts into the system at any point of time.  This method ensures that full system capacity is utilized during normal conditions. This method also ensures that Quality of Service (QoS) of already admitted calls is not degraded during periods of severe overload in times of emergency.

PROBLEM

In various and unexpected circumstances, telecommunication systems can be subjected to severe overload and congestion conditions.  This could occur, for example, during natural and man-made disasters. Special emergency and other priority services are often provided by the telecommunication system, where during overload events, the priority attempts compete for limited resources with non-priority attempts.  An example of such a service is the Wireless Priority Service (WPS), where National Security/Emergency Preparedness (NS/EP) users are granted special treatment during overload conditions by wireless telecommunication systems.

In times of emergency, the telecommunication system receives bursts of call attempts from the subscribers, both priority and normal subscribers, leading to overload in various nodes of a telecommunication system. In such severe overload conditions, the telecommunication system has to ensure that call attempts made by priority personnel are admitted into the system for further processing without discarding already admitted attempts, even if the system is in an overloaded state. Once the priority attempt is admitted into the system, various strategies can be employed to provide a high probability of successful call setup for priority calls during periods of network congestion. Some of the methods utilized to guarantee admission of call attempts by priority users into the system reserve system resources statically [1], thus leading to under-utilization of the system during normal circumstances. Still, other methods bypass overload control for priority calls [2], thus leaving the system vulnerable to Denial of Service (DoS) attacks. Admission of a large number of “fake” priority attempts during a DoS attack degrades the QoS of already admitted call attempts when the system is in an overloaded state.

SOLUTION

This invention provides a CAC method that admits access attempts from priority users into the system at any point of time, without having to preempt existing calls, nor statically reserve some resources for priority use. In normal conditions, this method uses full capacity of the system. In overloaded condition where system capacity reaches the defined maximum level, the system lowers the capacity for normal subscribers for a very short period of time to allow some amount of system capacity to be used for priority attempts. This ensures that the percentage of normal subscribers blo...