Configuration of Tracking Area Code (TAC) for Paging
Optimization in Mobile Communication Systems
Hyung-Woo Kang1,*, Woo-Ju Kim1, Seok-Joo Koh1,
Hyon-Goo Kang2, and Jung-Bae Moon2
1
Kyungpook National University, Daegu, Korea
{hwkang0621,kachukun}@gmail.com, sjkoh@knu.ac.kr
2
SK Telecom Acess Network Lab, Seoul, Korea
{hyongoo.kang,jbmoon}@sk.com
Abstract. Recently, the mobile telecommunication traffics have been rapidly
increasing due to the growth of smart phone services. In this paper, we propose
a new scheme for configuration of TAC (Tracking Area Code) to maximize the
paging success rates in the LTE-based mobile communication networks. The
proposed scheme includes the initial configuration of TAC, the local
optimization algorithm, and the re-clustering algorithm for further improvement
of the TAC configuration. From the performance analysis with real traffic data
of service provider, we see that the proposed TAC configuration scheme can
improve the paging success rates in the LTE networks, compared to the existing
TAC configuration scheme.
Keywords: LTE, Tracking Area Code, Paging, Optimization.
1 Introduction
With the popularity of smart phones, mobile communication has been rapidly changes
from 3GPP to Long Term Evolution (LTE). Recently, LTE is emerging as the new
mobile communication technology [1-3].
A mobile user typically moves around in a zone that is composed of many cells in
a mobile communication system. When a call request to a specific user arrives, the
cellular system should page the user in the cells to locate the user in the network. It is
noted that the cellular systems require efficient methods to find a specific mobile user
in the paging process [4-6]. In particular, the paging success rate is a very important
factor in the design of the paging areas. A paging area is defined by a Tracking Area
Code (TAC).
In this paper, we propose a new scheme for configuration of TACs to improve the
paging success rates in the paging process. A TAC consists of a group of cells to
which a paging signal is broadcast in the paging process. The proposed TAC
configuration scheme can be used to increase the paging success rate and to reduce
the overhead of paging traffic in the LTE networks.
*
Corresponding author.
Y.-S. Jeong et al. (eds.), Ubiquitous Information Technologies and Applications, 59
Lecture Notes in Electrical Engineering 280,
DOI: 10.1007/978-3-642-41671-2_9, © Springer-Verlag Berlin Heidelberg 2014
60 H.-W. Kang et al.
This paper is organized as follows. In Section 2, we discuss the TAC optimization
issue and how to configure the TAC in the mobile communication system.
In Section 3, we describe the proposed TAC configuration algorithm. Section 4
describes the experimental analysis and comparison with the existing scheme. Finally,
Section 5 concludes this paper.
2 TAC Optimization in Mobile Communication System
2.1 TAC Configuration
At present, most of the mobile operators configure the TAC in an arbitrary way, in
which only the topological location information of all cells are considered and the
network manager manually configures a group of cells as a TAC. TAC is defined as a
group of cells. The TAC is coded into a 2-bytes hexadecimal digit, in which the first
byte represents the area code, called the Tracking Area List. When a call request is
required for a specific user, if the user was registered with a TAC, then a paging
signal will be broadcast to all of the cells contained in the TAC.
Usually, when a mobile user is connected to a cell in network attachment phase,
the user is assigned to the TAC that the cell is associated with. If the user moves to a
new cell in the dormant mode, the TAC of the user may be changed, if the TAC of the
new cell is different from that of the old cell. Accordingly, the TAC should be
configured by considering the mobility and traffic of users in the mobile network.
The Self-Organizing Network (SON) system is used in the LTE-based mobile
communication in order to configure and manage a mobile network. For TAC
configuration, the TAC optimization S/W provides the information of optimized TAC
configuration to the SON system. Figure 1 describes the overview of SON system [7].
Fig. 1. SON system and TAC Configuration
With such TAC configuration, when a paging request to a specific user arrives, the
paging operations are performed as follows. In the first paging, the paging request
message (or signal) will be broadcast to the cells contained in the TAC. If the paging
request fails (i. e., no response to the paging request from the mobile user), then the
second paging is performed, in which the paging request will be broadcast to all of the
cells in the area. Therefore, it is important to optimize the TAC configuration so as to
