Journal of Information Technology Performance of UMTS

Journal of Information Technology Performance of UMTS
Volume 1 No. 1, May 2011
International Journal of Information and Communication Technology Research
©2010-11 IJICT Journal. All rights reserved
http://www.esjournals.org
Performance of UMTS Interworking with WLAN to Provide Consistent
Services
1
S. NandaKumar, 2Praveen Kumar S, 3Nagendran N.S
School of Electronics, Vit University
Vellore-632014
1
2
3
snandakumar@vit.ac.in, praveenkumars2007@vit.ac.in, praveens_erd@yahoo.co.in
ABSTRACT
Intersystem handover with ongoing mobility management between the networks is a serious issue for operators to focus on.
Therefore the proposed model represents an intersystem handover algorithm between UMTS and WLAN. The presented
Network model will achieve unified mobile and for cellular and broadband wireless access coverage. Here coupling
methods like loose coupling scheme and tight coupling scheme in the interworking also discussed and the results were
compared. By having a method with MIPV4 implementation, the intersystem handover issue can be resolved. The
approach of this model is to reduce the packet loss during handover. As a result the end user can get services continuously
with minimum packet loss.
Keywords: WLAN, UMTS, Vertical Handover, MIPv4,OPNET, Loose Coupling, Tight Coupling
I. INTRODUCTION
The motivation of 4G networks is the ubiquitous
wireless access abilities which provide the seamless
handover for the end users in the heterogeneous networks
of different access technologies. All the available
technologies have some advantages and disadvantages.
These technologies differ in terms of spectrums,
bandwidths, media access technologies, security
mechanisms and so on. The well established 3G network
like UMTS can provide high mobility with wide area
coverage but can support low to medium data rate which is
not sufficient to satisfy data-intensive applications and the
service charge is also very high. UMTS is not suitable for
small, indoor and densely populated areas. The recently
invented WLAN(IEEE 802.11g) was standardized to
support mobility to the end user with wider coverage and
faster speed. The salient features of the Mobile WLAN
(IEEE 802.16e) are high data rates up to 63 Mbps for DL
and 28 Mbps for UL, QoS, scalability, security and
mobility supporting handover schemes with latencies less
than 50 ms . Also the deployment cost of the Mobile
WLAN (IEEE 802.11g) is very low. The average 3G
spectrum cost/Hz is 1000 times higher than the average
WLAN spectrum cost/Hz in Europe. But the vital
drawback of the WLAN is that the standard does not fully
define the complete network infrastructure. So it is still a
far future to deploy the WLAN network of its own. But it
can be interworked with the existing networks.
The vertical handoff process between different
existing networks in the wireless communication has
become one of biggest challenge for the operators. The
interworking between WLAN and UMTS can be useful to
get the benefits from both the systems and the handover
between these two networks will make the end user
connected whenever, wherever and for any services.
The rest of the paper is organized as follows:
Firstly our proposed method of Loose coupling, tight
coupling and handover algorithm is described briefly. The
simulation environment built by the OPNET Modeler 14.5
and the results are described in the third section and finally
we abrogate with a short concluding remarks followed by
the acknowledgement of the work.
A. Interworking Architecture
The most critical elements to be resolved for
intersystem handover area)avoid the change of IP.
Henceforth, Mobile IP is used as a solution of the network
layer issue.
The next issues are maximum packet loss during
handover. To minimize packet loss the preferred type of
handover would be soft handover. But to achieve soft
handover in different network environment, the mobile
device must have multiple interfaces to communicate with
the different networks at the same time as needed for soft
handover. Hence, the mobile device assumed to have two
transceivers; one for WLAN interface and one for UMTS
interface. The mobile device is designed such that it has
the intelligence to monitor the signal strength and can
make the decisions of handover. Hence, the handover is
mobile initiated.
The next issue is the version of IP to be used.
3GPP IMS is mainly designed for IPv6 but according to
the early releases IMS can also be implemented using the
IPv4. The WLAN can support both IPv4 and IPv6 but the
UMTS SGSN does not support the IPv6. Hence, if IPv6 is
used there will be an additional latency regarding to the
NAT every time passing through the SGSN. But if IPv4 is
used for IMS.
The proposed overall network, as shown in Fig.
1, shows the components of MIP. The main components
1
Volume 1 No. 1, May 2011
International Journal of Information and Communication Technology Research
©2010-11 IJICT Journal. All rights reserved
http://www.esjournals.org
of MIP are the foreign agent (FA) and the home agent
(HA).
supporting Mobile IP for heterogeneous roaming. The
main objectives of this paper are to integrate WLAN with
cellular network using different architecture and to
analyze the performance of the proposed architecture.
C. Interworked
Networks
Fig 1 Components of MIP
In UMTS network GGSN acts as a home agent
since MN initially in the UMTS network and in WLAN
network router acts as a foreign agent. The server
bandwidth is distributed among the network according to
the speed to be supported and server channel frequency is
kept less than the channel frequency of the base station so
that there remains no in-transit packet in queue during the
handover to eliminate the packet loss in the radio path.
B. Mobile IPV4
Mobile IP is the standard protocol defined for
terminal mobility in the Internet; therefore, Mobile IP is
proposed as the basic mechanism to provide service
continuity. Mobile IP is the key protocol to enable mobile
computing and networking, which brings together two of
the world's most powerful technologies, the Internet and
mobile communication. In Mobile IP, two IP addresses are
provided for each computer: home IP address which is
fixed and care- of IP address which is changing as the
computer moves. When the mobile moves to a new
location, it must send its new address to an agent at home
so that the agent can tunnel all communications to its new
address timely. The article limits its scope to Mobile IPv4,
Mobile IP for IP version 4.
The Internet Protocol version 4 (IPv4) is a
fundamental network layer protocol that contains
addressing information and some control information that
enables data packets to berouted. Mobile IPv4 can provide
transparency to the upper layers while providing seamless
mobility using the care-of addresses. It is noted that
Mobile IP provides service continuity, and seamless
service continuity can be provided using standardized
extensions of the base protocol such as Fast handover.
Mobile IP requires the deployment of home agents and a
protocol between the mobile nodes, home agent, and
corresponding nodes. The home agent placement and
home address assignment issues are addressed for
WLAN
/
3G
Cellular
When a MN moves from the UMTS coverage
area into the WLAN network as depicted in Figure 8, the
VHO procedure occurs. Specifically, the MN of the
UMTS network first scans to ensure that a WLAN
network access within the vicinity is available. The
cellular UMTS/BS periodically transmits a CoA
advertisement for the outgoing MNs to WLAN networks
to track the availability of the UMTS network. When the
MN detects the advertisement, it begins examining the
received signal strength (RSS) to make the VHO decision.
The MN first estimates the RSS from the WLAN access
router and compares it with the UMTS network. If the
RSS of the WLAN is found to be greater than the UMTS,
then the VHO procedure is initiated. Otherwise, the MN
maintains its connectivity with the UMTS network. The
RSS of the UMTS will continue to get weaker as the MN
moves away from the UMTS/BS towards the WLAN/AP.
As the MN approaches the overlapping area of two
networks, it informs the CN to start the bicasting of data
packets via both UMTS-IP1 and WLAN-IP2.As the
movement towards the WLAN network intensifies, the
MN senses the high RSS of the new link and transmits a
registration request to the access router of the cellular
UMTS. It then assigns a new CoA from the old access
router to the new WLAN-IP2 network. The WLAN HA
then begins to track the location of the MN during the
course of the in MIP. Similarly, when the MN moves into
the coverage area of the cellular UMTS, it begins a reverse
VHO procedure. VHO procedure is clearly explained in
Fig 2
Fig 2 Vertical Handover Algorithm
2
Volume 1 No. 1, May 2011
International Journal of Information and Communication Technology Research
©2010-11 IJICT Journal. All rights reserved
http://www.esjournals.org
D. Loose Coupling
In the loose coupling architecture both networks
interconnect independently and utilizing one common
subscription. They provide independent services. In loose
coupling the interworking point is after the interface point
of GGSN (Gateway GPRS Node) with the IP network and
the network interconnection uses MIP mechanism for
mobility between WLAN and UMTS. it has no direct link
to 3 G network equipment. As a result the data traffic from
WLAN goes through the internet and does not pass
through UMTS core network. In case of third party
network mobility and roaming is enabled via dedicated
connections between the operator and wireless LAN. The
WLAN gateway must support MIP functionalities for
handling mobility access the different networks.The one
advantage of using loose coupling is it allows independent
deployment & traffic engineering of heterogeneous
network. It also enables 3G operators without major
investment to take advantage of WLAN.
II. RESULTS
ANALYSIS
AND
PERFORMANCE
We have implemented our proposed method
described in the previous section by the OPNET Modeler
14.5 and carried out the simulations to characterize the
performance of the proposed method of intersystem
handover.
A. Simulation Model
We have designed two different networks for
scenarios which are loose coupling scheme and tight
coupling scheme for interworking between WLAN and
UMTS. Network design for the two scenarios is shown in
the figures below.
E. Tight coupling
In a tight coupling scenario the WLAN are
directly connected with 3G(UMTS)core network as in any
other radio access network (RAN).In this context WLAN
can execute functions that are available in the
3G(RAN).The WLAN gateway will introduce to achieve
integration and hides the detail of its own network to
3G/UMTS
network.
All
3G
protocol
is
implemented(mobility management ,authentication etc).As
a result the data from WLAN user will goes through
3G/UMTS core network then to internet or packet data
network PND. In this context each network will modify
their protocol interfaces and services for supporting
interworking requirement. In a tight coupling the
interconnection with WLAN can be made at a core level
(GGSN, SGSN) or Access level (RNC).
Fig 3 Loose Coupling and Tight Coupling
Fig 4 Loose Coupling
Fig 5 Tight Coupling
3
Volume 1 No. 1, May 2011
International Journal of Information and Communication Technology Research
©2010-11 IJICT Journal. All rights reserved
http://www.esjournals.org
B. Simulation Results
The simulation was performed for FTP session
and HTTP session.FTP Upload and download response
time, HTTP page response time results were analyzed.
Fig 8 Downlink Traffic Received
Fig 6 FTP Download Response Time
Fig 6 shows that loose coupling scheme takes
response time more than tight coupling scheme. As the
time increases the response time gradually decreases. It is
clear from that users move from UMTS to WLAN.WLAN
has higher bandwidth than UMTS. So users take less
download response time for FTP.
Fig 8 shows the graphs of traffic sent and traffic
received In UMTS network while the users start moving
from UMTS network to WLAN network, as users move to
WLAN network very few people left in UMTS network
and results in lower data sent and received and if we
compare loose coupling to the tight coupling data sent and
received for UMTS network is higher in loose coupling
architecture.
Response time (seconds) for user applications
in UMTS and WLAN networks.
Applications
Minimum
Maximum
Average
Network
HTTP
0.909
1.755
1.268
UMTS
FTP
7.094
14.347
7.071
UMTS
HTTP
0.013
0.049
0.032
WLAN
FTP
0.775
3.657
0.510
WLAN
III. CONCLUSIONS
Fig 7 HTTP Page Response Time
Fig 7 shows that initially users take more
response time, as the time gradually increases HTTP page
response time decreases it is clear from that users move
from UMTS to WLAN. Here loose coupling is better than
tight coupling for HTTP.
In this article we described the integration model
for UMTS AND Wireless LAN .And we have explained
two types of integration models between the UMTS and
WLAN(loose coupling architecture ,tight coupling
architecture ).We have discussed here in this chapter the
benefits an drawbacks of integration models. we have
performed the simulation by using OPNET 14.5 as a
simulation tool. We have compared the two integration
schemes (loose coupling architecture, tight coupling
architecture) our results shows that loose coupling
architecture is better than the tight coupling architecture
scheme. Our results shows that response time for FTP,
HTTP is smaller in loose coupling architecture scheme as
compare to the tight coupling scheme. We have also
computed user movement between two different
technology networks,
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Volume 1 No. 1, May 2011
International Journal of Information and Communication Technology Research
©2010-11 IJICT Journal. All rights reserved
http://www.esjournals.org
There will be some packet loss and session
interruption when the user move between two different
networks .this can be resolved by implementing 3 GPP
SIP-IMS model. By implementing SIP-IMS model end
user can get the services continuously without any
interruption. Implementation of SIP-IMS model and
maintenance of the session management is the future
work.
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