Title page for ETD etd-12282008-062231 ( Browse

Type of Document

Dissertation

Author

Sasanus, Saowaphak

URN

etd-12282008-062231

Title

SIGNALING OVERLOAD CONTROL FOR WIRELESS CELLULAR NETWORKS

Degree

Doctor of Philosophy

Program

Information Science

School

School of Information Sciences

Advisory Committee

Advisor Name	Title
Dr. David Tipper	Committee Chair
Dr. James B. D. Joshi	Committee Member
Dr. Maria Kihl	Committee Member
Dr. Prashant Krishnamurthy	Committee Member
Dr. Richard Thompson	Committee Member

Keywords

wireless cellular networks
Signaling overload control
adaptive
QoS

Date of Defense

2008-11-20

Availability

unrestricted

Abstract

As the worldwide market of cellular phone increases, many subscribers have come to rely on cellular phone services. In catastrophes or mass call in situations, the load can be greater than what the cellular network can support, and the entire network may become completely non-functional. This raises serious concerns on the survivability of wireless cellular networks in order to provide necessary services such as 911 calls in those circumstances. In high load cases, overload control must be deployed to reserve network resource for emergency traffic and maintenance services. Over the past several years, many catastrophes have revealed the deficiencies of the existing overload control mechanisms in cellular networks. Improvement to the existing overload controls are needed in order to cope with unexpected situations. A key to the survivability of wireless cellular networks lies in the signaling services from database servers that support a call connection throughout its duration (e.g., for monitoring users' locations and supplying authentication codes for secure communications), this dissertation focuses on the overload control at the database servers.

As loss of different signaling services impacts a user's perception differently, the overload control
is proposed to provide differentiation and guaranteed classes of signaling services. Specifically, multi-class token rate controls are proposed due to theirs flexibility in various network configurations and advantages over other controls such as, percentage blocking and call gapping. The concept of adaptive control decision is used so that the proposed controls react quickly to changes in the load. A simulation based performance evaluation of the proposed control is conducted and compared with existing controls. It is shown that the proposed controls outperform the existing multi-class token based controls due to various reasons. First, the proposed controls use adaptive resource
sharing that guarantees a lower bound, where the percentage of resource sharing among classes
is adaptively set. The existing token rate controls either distribute resource among classes using
static ratios or completely share resources among classes. Although using static ratios guarantees the quality of service within each class, it lowers the total utilization of the server. Whereas,
allowing a complete resource sharing among classes may cause large load fluctuations in each class. Second, the proposed controls use the novel concept of integrating information on the availability of the radio resources into the control decision, allowing servers to save theirs resources from serving signaling that later on might be dropped due to unavailable radio resources.

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