03-01-2013, 12:29 PM
QoS Based Network Selection Scheme for 4G Systems
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Abstract
Exponential growth of user demands on a
single convergence platform has brought researchers to
explore various aspects/features of Fourth Generation (4G)
Mobile Communication System. Selection of application as
per the user preference based on QoS (Quality of Service) is
one salient feature of 4G. This user-centric system works on
the basis to provide best services of the network to the users.
In this paper, a selection algorithm has been proposed which
provides a better way to implement user preferences as per
the features of 4G. Rank based on distance function has been
computed for various available services/access technologies,
called networks. Weighted distance function is obtained based
on multiple QoS parameters as per user needs. The proposed
algorithm shows better results compared to single parameter
based system, under a heterogeneous network system.
INTRODUCTION
In mobile communication systems, after 2G and 3G, the
Fourth Generation (4G) was originally expected as ultra-high
speed broadband wireless system [1]. Further, it was assumed
that the network will have a cellular structure which implies
that it will be built on existing architecture of the preceding
generations. A final agreement on what features characterize
4G mobile system, is yet to be reached. Sharing the 4G
objectives within research community is still open and lot of
features and applications have been suggested by the
researchers. Delivery of services to users in different location,
under different conditions with quality of service (QoS)
available in fixed environment, were some of the major issues
[2]. The Wireless World Research Forum (WWRF), aiming at
defining features of “beyond 3G” wireless communications
[3], the Japanese MIRAI project [4], the MobileVCE (Mobile
Virtual Centre of Excellence in personal and mobile
communications), and several European IST projects (such as
Daidalos, Magnet, Simplicity, Ambient Networks, etc.) are
only a few examples of international groups devoted to 4G
deployment. The European Commission (EC) foresees that
from the service point of view, 4G will be mainly a
personalized services network [5].
USER CUSTOMIZATION PARAMETERS
The new concept, introduced by 4G, is based on
the assumption that each user has his/her own requirements
that are unique [13]. User also demands that the network
selection should be as per his/her needs, even during the
handoff process. The user need not specify his/her specific
requirements at the time of handoff. The device must also
be able to select the network that satisfies the current
session’s QoS requirements. Thus, a novel network
discovery and selection mechanism must be provided. The
proposed network selection algorithm works on the choice
of the user specified QoS parameters. Since handoff must
take place in order to provide continued service, the
network selection is done intelligently out of the available
options for the user. A discovery and selection mechanism
to find a new Base Station (BS) must be done within the
specified time. Hence, we also explore user specific
performance parameters that are used in the network
selection algorithm.
PROPOSED NETWORK SELECTION
ALGORITHM
Distance function: It is a common observation that, while
accessing any network or service, a user demands low
billing rate, high bandwidth and data rate, adequate security,
low call drop etc. With the increase in number of quality
parameters required by the user, the complexity of the
network selection is likely to increase. Multi-parameter
selection technique is required to meet user needs in terms
of automatic network selection during handover. Attempts
have been made in recent studies using static network
interface priority [14], received signal strength [15], cost
function [16]. Various algorithms have also been proposed
using different criterion for optimum network selection,
such as, best network selection [17], score function [18],
vertical handoff decision in [19] and terminal controlled
mobility management [20]. In this paper, optimal network
selection is suggested using distance functions. Several
distance functions have also been proposed earlier. We
focus on the Spearman footrule.
TESTING OF PROPOSED ALGORITHM
Integration of multiple networks (defined in Section I) is one
of the key targets to be achieved by 4G systems. The future
devices based on 4G will be multi-mode and reconfigurable
devices which can exploit inter-working between different coexisting
technologies. One such environment (figure 2) has
been used to test the performance of proposed algorithm for
4G. In this test environment, 4 different networks (net1, net2,
net3 and net4) have been assumed to coexist and three
different users carrying 4G devices and performing different
services. Table 1 gives the features of the test networks and
table 2 contains preferences of the users along with the level
of interest in multiple parameters as per their requirements and
needs. The entire test area has been divided into three regions:
R1, R2, and R3. Net1 is accessible for the users in R1 and R2
(R3 excluded). Net2 is available in R2 and R3 (R1 excluded).
Net3 is available in R1 and R3 (R2 excluded). Net4 is
available in R1 and R2 (R3 excluded). User1 and user2 are in
R1 initially and user1 is moving towards R2 and user2
towards R3. User3 is in R3 initially and moving to R2.
CONCLUSION
The paper proposes a novel algorithm for optimal network
selection based on multiple user preferences under
heterogeneous network. As 4G system supports multi-mode
and reconfigurable devices to support inter-working of
heterogeneous networks. The algorithm selects appropriate
network during handoff based on user preferences and
interests. The user can opt for multiple QoS parameters like
bandwidth, cost of service, security level, call drop probability
etc. to select appropriate networks.
The proposed algorithm uses a distance.