12-09-2012, 03:54 PM
Field Architecture for Traffic and Mobility Modeling in Mobility Management
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Abstract:
With the emergence of new technologies in mobile communication, users’
demand on service quality is growing aggressively, which makes mobility management in
the stage of great challenge and opportunity. Aggregate mobility modeling, researching on
macroscopic rule of human movement, will make a huge contribution to the performance of
mobility management. This paper is primarily focused on establish an architecture based
on field theory, using scalar and vector field to describe service and mobility respectively.
Based on their temporal-spatial evolvement, we try to discover the relationship between
traffic field and mobility field. Moreover, Principal Components Analysis is adopted to
decompose mobility field in order to find its typical patterns in the perspective of both
time and space. Meanwhile, we make use of complex analysis to describe the details of the
inner movement for mobility field. This field architecture fits for mobility management in
large temporal-spatial scale, since it not only benefits for qualitative analysis of service
and mobility in the perspective of field, but also provides a theoretical foundation and
solution inspiration for issues in mobile communication.
Introduction
Mobility is believed to be one of the key characters
of current and future networks, which provides
the technologies of mobility management with more
challenge and opportunity. Mobility management aims
to support seamless roam for person single or in
group in the network, and one basic issue it is to
explore the underlying rule of movement. However,
this consideration is not thought much of in most
of previous researches. People are basically considered
as moving randomly or in a simply way. But in
fact, they are surely constrained by both behavior
habits and geographic factors. This kind of determinate
rule underlying uncertain movement behavior needs
exploring. Mobility modeling provides model parameters
for system design and performance analysis.
Traffic Field
Data Source and Pretreatment
In this section, the database is from the practical records
of mobile communication system in a certain district of
a northern city of China. It contains several quantities
describing traffic of several thousands of base stations
within a week, with temporal scale as 1 hour. The
distribution of base stations is shown in figure 2(a). Here
the Traffic CHannel (TCH) load is adopted as the field
quantity in modeling, whose unit is Erl.
Moreover, symmetrical gridding method is
introduced to carve up the background area into
hundreds of grids, with the spatial scale as 1 km, and
traffic is distributed into every grid according to its area
proportion of the cell. As an example, the traffic field at
certain time is shown in figure 2(b).
Decomposition of mobility field
Ambulatory population field, as the flux of mobility field,
reflect the macro principle of population distribution
and movement, but their underlying rules are still
in need of further discussing. Facing the complex
structure of mobility field, its regular changing part
is the foundation of modeling. So the decomposition
of mobility field is first proposed in this section, and
a familiar mathematical tool is adopted, Principal
Component Analysis (PCA) (Hotelling, 1933).
PCA is a linear dimension reduction technology,
exploring the underlying structure of data. Essentially, it
uses orthogonal transformation to seek for low dimension
expression of redundant space.
Due to the symmetrical griding of background area,
ambulatory population field at a certain time can be
denoted as a matrix.When fixing a time, this matrix can
be further rearranged into a column vector. If arranging
these vectors of different times into a new matrix, marked
as X, it contains the information both spatial and
temporal.
Conclusion
This paper proposed a field architecture for mobility
management in large temporal and spatial scale, which
united traffic and mobility into a uniform theoretical
system. The main contributions are intuitionistic
expression benefitting for qualitative analysis of
characteristic quantities, and theoretical deduction
combining with matrix theory and complex analysis to
provide support for further discussion.
Based on the different attributes of traffic and
mobility, they are modeled as scalar field and vector
field respectively. By qualitative analysis of traffic field
in temporal and spatial evolvement, some conclusions
according with common sense of daily life have been
drawn. Moreover, traffic hotspots reflect the asymmetry
of traffic distribution in network, and the consideration
of treating it as a kind of regular outburst lies a
foundation for load balance and resource optimization.
On the other hand, mobility field describes the rule
of aggregate mobility. Some changing patterns were
discovered by analyzing the flux of mobility field,
adopting the mathematical tool of PCA. This associated
temporal and spatial analysis method helped for further
concretely description of its underlying structure using
complex analysis.