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International Journal of Computer Applications (0975 8887)
Volume 53 - No. 3, September 2012
Realization of Seamless Mobility in Heterogeneous
Wireless Networks based on IEEE 802.21 Framework
Vimal Kumar
Galgotias University
Plot#2, Sector 17-A Taj Expressway
Greater Noida Gautam Budh Nagar(UP)-201308 India
Neeraj Tyagi
Motilal Nehru National Institute of Technology
Allahabad (UP) India
Ranjan Baghel
Moradabad Institute of Technology
Moradabad (UP) India
ABSTRACT
Wireless and mobile networks are evolving very rapidly. The
mobile nodes in the wireless networks are having multiple inter-
faces with different radio access technologies (RATs) which are
having different capabilities, cost and performance ratio. The use
of non-PC based portable devices is increasing due to their flexible
usage. The wireless and mobile network which is formed by these
non-PC and PC based devices is heterogeneous in nature and these
networks are co-located. Multiple interfaces can be included in the
mobile device by using separate hardware and software modules.
A mobile user wants to be Always Best Connected (ABC) as per its
various requirements and availability in a particular environment.
When a mobile node leaves the current network and joins the
other network, a handover operation is needed and performed. The
Handover operation is used to achieve seamless mobility and is of
two types, first is in between same RATs and second is in between
different RATs. For seamless and smooth handover operations
across heterogeneous networks, IEEE has published a standard,
named as IEEE 802.21. This paper presents a comprehensive
description on the issues and challenges for achieving the seamless
mobility in a heterogeneous environment. Apart from this, we
also present the description of services provided by IEEE 802.21
standard and related vertical handover schemes to realize seamless
mobility in heterogeneous network.
General Terms:
Seamless Mobility, Vertical Handover
Keywords:
Multiple Interfaces, RATs, Heterogeneous Network, ABC, IEEE
802.21
1. INTRODUCTION
Now a days mobile node (MN) is evolving with multiple network
interfaces and MN can have more than interface at the same time.
Along with this, different wireless technologies (such as cellular:
2G, 3G and 4G, project 802: WLAN, WMAN etc.) are also evolv-
ing. These contemporary evolutionary development is forming the
heterogeneous environment and can create the need of the avail-
ability of IP services anywhere at anytime on any network. The
different networks in this heterogeneous environment have differ-
ent RATs that may differ in terms of bandwidth, monetary cost,
latency etc.
To decide the candidate point of attachment (PoA) for the MN, han-
dover management is done for controlled switching of networks
during ongoing active communication session[2]. The main issues
involved with handover management are mobility scenarios, the pa-
rameters for handover and decision making algorithms. On the ba-
sis of movement of the MN among different types of networks, the
mobility scenarios are of two types: horizontal and vertical. In hor-
izontal mobility scenario, the MN roams around the different cells
of the same network. In horizontal mobility scenario, horizontal
handover is needed when the coverage of serving access point (AP)
becomes unavailable because of switching among different cells
of the same network. In vertical mobility scenario, the MN roams
around different types of networks. In heterogeneous mobility sce-
nario, vertical handover is required in between heterogeneous net-
works because of different radio access technology (RATs) used
and different formats of link layer interfaces.
While handling the handover, the major challenges are: to decide
the appropriate time to initiate the handover, to maintain the service
continuity, to decide the candidate PoA, to implement automatic
switching of the network interfaces and finally to achieve seamless
mechanisms [2]. In case of the same RAT,the handover is called
homogeneous handover. Homogeneous (horizontal) handover is al-
ready realized and less challenging due to the same RATs (serving
RAT and candidate RAT).The heterogeneous (vertical) handover
is more challenging and demanding. The vertical handover is not
only initiated because of the connectivity reasons but also to pro-
vide convenience for the user. The vertical handover gives the op-
tions to the user for being always best connected (ABC) specially
when the MN is equipped with multiple interfaces.The objective
of vertical handover is to reduce the signaling overhead, eliminat-
ing the redundant handovers, and satisfying the network and user
requirements.
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International Journal of Computer Applications (0975 8887)
Volume 53 - No. 3, September 2012
Fig. 1. Seamless Mobility in Wi-fi, 3G, WiMax
Ideally, a mobile user always does have a preference to be remain
connected even if the user is on the move and the device is leaving
one network and joining other network. The desperate and obsessed
Internet users are always looking for mobility freedom. This re-
quirement of mobile users is motivating the researchers and Indus-
try to define, formulate and realize the Seamless mobility. Mobil-
ity management in such environment is a real challenge to achieve
seamless mobility.
Seamless Mobility can be defined as the movement of a mobile
node (MN) without interruption of the ongoing connection regard-
less of wherever the MN is. This is shown in the figure 1. The real-
ization of seamless mobility will also benefit for the mobile users in
terms of cost and quality trade-off. To provide seamless mobility,
a media independence service layer has to be developed and de-
ployed in between the link layer and higher layers. To do this, we
have to consider the compatibility issues among signaling schemes
of different types of radio access technologies (RATs). There are
basically the following issues with respect to seamless mobility[1-
3,5]:
(1) Keeping the connection of the mobile node (MN) intact while
it is moving
(2) Detecting the different network types
(3) Selecting the most appropriate network type based on the need,
environment and services offered.
(4) Network Discovery
(5) Network selection and routing and connection update proce-
dures
(6) Initiating handover operation
(7) Executing handover operation
The considered network technologies may include both wired,
wireless and cellular technologies which are given in table 1.
These all network technologies are converged and a common
billing procedure is developed. Seamless mobility can be achieved
by either implementing the component somewhere in the network
or it is implemented in the mobile node(MN). Network-controlled
seamless mobility method is prominent then MN-controlled, be-
cause in network-controlled seamless mobility method, load infor-
mation of the cell and network status can be considered to achieve
Table 1.
RATs
S.No Network Technology Category RATs
1. Wired Ethernet,Gigabit Ethernet
2. Wireless Wi-fi,Wi-MAX,Blue-tooth,
3. Cellular 2.5 G to 4 G
4. Wired-cum- Wireless DVB
load balancing and effective utilization of the available resources.
The key challenge before the standardization bodies for the devel-
opment of next generation networks (NGN) to provide seamless
mobility is to focus on three mobility aspects:To provide seamless
horizontal handover between same RATs,To provide seamless ver-
tical handover between different RATs, Integration of different net-
works and RATs under same IP backbone, Maintaining the required
QoS and security while switching among different RATs. The rest
of this paper is organized as follows. First we described the mo-
bility management at IP layer and application layer. Next we de-
scribed media independent handover framework published by IEEE
802.21 working group.Next, we described network selection based
on service zone for macro-mobility. Next we discussed the vertical
handover management in which we described the issues and chal-
lenges to realize seamless mobility. Next We presented the simula-
tion of vertical handover between WLAN and UMTS and various
observations in tabular format. Finally the paper is concluded.
2. MOBILITY MANAGEMENT AT IP LAYER
Mobile IP provides the fundamental methods for mobility manage-
ment at IP layer. As it is already described that mobility related
functionality is either implemented in MN or somewhere in the
network entity. This method is based on the concept of allocating
two addresses for the MN. These two addresses helps in keeping
the TCP connection intact while MN is visiting the foreign net-
works. In the two addresses assigned to the MN, one is the global
address(permanent address) and other is the care of address (COA).
The global address is the address of the MN in its home network
and the COA is the address of MN in its current network which
is called its foreign network. When the COA is obtained by the
FA advertisements , it is called the FA-COA and when MN ob-
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International Journal of Computer Applications (0975 8887)
Volume 53 - No. 3, September 2012
tains it by using some external mechanism (DHCP), it is called the
collocated-COA. When MN moves from its home network to the
other network, first it has to inform its home network about its cur-
rent location via an entity called the home agent (HA). Then HA
registers the current address (COA), and whenever in the future the
packet comes to the MN from the correspondent node (CN) the HA
forwards the packet to the COA of the MN. This whole procedure
is implemented with the concept of tunneling and IP-in-IP encap-
sulation. Whenever there is a change in the COA of the MN it is
updated at HA by using location update signaling.
On the other hand when MN has to send the packets to CN, it
can do send it first to FA (if FA-COA is being used by MN) or
it can send directly to CN (if it is using collocated-COA). In this,
a very inefficient scenario is developed when CN and MN are in
close topological proximity and HA is very far away from MN.
This scenario is termed as triangular routing. This inefficient trian-
gular routing problem is solved in mobile IPv6 (MIPv6). MIPv6
possesses some inherent field in header which removes triangu-
lar routing and provides support for route optimization. There is
no need of FA in MIPv6. However when the MN sends packets
directly (route optimization) , there is disadvantage which is as-
sociated with the MIPv6, that the CN must be capable to support
mobility-aware operations. Hence although the MIPv6 is solving
the triangular routing problem and providing route optimization, it
is still showing weakness, when both CN and MN are on-the-go.
The situation becomes worst when MN and CN are moving simul-
taneously.
Thus we see that the fundamental Mobile IP methods are having
the problems in performing real time applications handover. This
is because of the longer delays involved in movement detection of
MN and CN, configuration of the new COA, and location update
signaling on each network change instance. Some more optimiza-
tions are being done in this regard like Fast MIPv6 (FMIPv6) and
hierarchical MIPv6 (HMIPv6).
2.1 Optimizations of MIP
2.1.1 FMIPv6. FMIPv6 is providing a better freedom for seam-
less mobility and closer seamless experience. The working of
FMIPv6 is very proactive by allowing the MN to fetch the required
information about the future subnet in advance before the handover
and begins to use next link before getting the location update of
the CN id decided. As shown in figure 2 handover operation prepa-
ration is started pro-actively between MN and previous first hop
router (FHR) and in between previous FHR and next FHR. Only
the context ( access control, QoS profile and header compression)
is being transferred between FHRs and new are setup between MN
and CN. The complexity is increased at MN and FHRs in FMIPv6.
2.1.2 HMIPv6. HMIPv6 uses the local mobility anchor point
(LMAP) to achieve local mobility management as shown in fig-
ure 2. In this LMAP works as HA in the local mobility domain.
Whenever the MN moves to other subnet in the local mobility do-
main, the COA belonging to FHR is bind with LMAP which also
contain its regional-COA. No change is implemented in the tun-
nel from LMAP to outside network only the local binding is done.
In this way HMIPv6 also reduces the delay to some extant. All
these protocols discussed so far, are based on the fundamental Mo-
bile IP methods in which mobility related functionalities are im-
plemented in the MN. When the mobility related functionalities
are implemented somewhere in the network entities then a better
resource utilization and load balancing can be achieved (because
in this case every cell load information is available). IETF devel-
oped a new network controlled mobility protocol named as Proxy
MIPv6 (PMIPv6). PMIPv6 implements the mobility related func-
tionalities in FHRs and in LMAPs. In this FHR keeps a closer look
on the movement of the MN, and whenever there is change in the
network it informs LMAP for signaling COA update. All these dis-
cussions so far, focuses on the implementation of the interaction be-
tween different network entities, i.e. Inter-entity interaction (opti-
mizations at network layer). But handover delays are not only based
on inter-entity interaction but also on intra-entity interaction. The
delays due to intra-entity interactions are generated because of the
latencies induced by the functions. The latencies could be both at
link layer and network layer. Like for example the factors for link
layer latencies are late detection of link state changes, and lengthy
scanning of authentication and association procedures. Similarly at
network layer, late detection of the loss of IP connectivity or late
movement detection of MN.
2.2 Mobility Management at Application Layer[12]
End-to-end mobility management is handled by session initiation
protocol (SIP), which is an application layer protocol to perform
signaling. SIP has been selected by the Third Generation Partner-
ship Project (3GPP) as the signaling protocol to set up and control
real-time multimedia sessions.
3. IEEE 802.21:MEDIA INDEPENDENT
HANDOVER FRAMEWORK [8]
3.1 Objectives of IEEE 802.21
The main objective of this IEEE standard is to facilitate the han-
dover between heterogeneous networks.This standard provides the
support for the following:
(1) Vertical handover for both stationary and mobile users
(2) Changing the link according to the speed and bandwidth re-
quirements of an application
(3) Maintaining the service continuity during handover up to a
possible extent.
(4) Cooperation of information between MN and network infras-
tructure
(5) Available Networks detection
Information stored within network infrastructure is as follows:
Neighborhood cell lists, Location of mobile nodes, Higher Layer
Service Availability The initiation of handover process is done us-
ing measurement reports and triggers provided by the L2 on the
mobile node.
3.2 Need for Media Independent Handover
Framework Standard
Since there are multiple RATs which are available around the MN.
If we implement the mapping of each RAT with the upper layer
protocol format, the complexity becomes very high. Let us con-
sider that there are n number of RATs, available around the MN in
an overlapped manner. Each RAT is having its own extension. The
number of mappings needed for n RATs will be n(n-1)/2. These
mappings and their emerging complexity is shown in figure 2. To
overcome this problem, we need one standard which is automati-
cally providing the mappings between various RATs. IEEE 802.21
is doing this for us. It is not only doing this but also helping in
choosing appropriate RAT which is most suitable for the MN in the
particular mobility scenario.
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International Journal of Computer Applications (0975 8887)
Volume 53 - No. 3, September 2012
Fig. 2. Mobility Scenario and Mobility Entities in IP Networks
Fig. 3. Mapping Complexity of Multiple RATs
3.3 Realization of Seamless Mobility Based on IEEE
802.21 Framework
Figure 5 shows the placement of logical entity based on IEEE
802.21 to realize the seamless mobility in future multi-access Het-
erogeneous network. As shown in the figure 5 the logical entity
MIHF is placed in between layer 2 and layer 3 or upper layers.
The figure also shows various service access points (SAPs) towards
layer 2 and towards upper layers. On upper layer side, various MIH
users (MIP, SIP etc) are residing. There are two types of interfaces
which are used by MIHF to provide mobility freedom: one is Media
Independent Interfaces and second is Media dependent interfaces.
All these interfaces are implemented by using SAPs. There are ba-
sic three types of SAPs:
(1) MIH SAP
(2) MIH Link SAP
(3) MIH NET SAP
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International Journal of Computer Applications (0975 8887)
Volume 53 - No. 3, September 2012
Fig. 4. MIHF and Its Interfaces, Deployment Location and MIH users[7, 14]
MIH SAP is media independent interface, while MIH Link SAP
and MIH NET SAP are media dependent interfaces. Some of the
media dependent interfaces are as follows:
(1) MLME SAP: This is the interface between MIHF and the man-
agement plane of an IEEE 802.11 (WLAN) network. It is used
to send MIH messages between MIHF and local link layer en-
tities and between peer MIHF entities.
(2) C SAP: This is the interface between MIHF and functions of
control plane of IEEE 802.16 (Wi-MAX).
(3) M SAP: This is the interface between MIHF and functions of
management plane of IEEE 802.16 (Wi-MAX).
(4) MSGCF SAP: This is the interface between MIHF and IEEE
802.11 MAC state machine.
(5) MIH 3GLINK SAP: This is the interface between MIHF and
different protocols of cellular systems.
(6) LSAP: This is the interface between MIHF and logical link
control (LLC) of IEEE 802.3 (Ethernet), and IEEE 802.11
(WLAN)
(7) CS SAP: This is the interface between MIHF and service spe-
cific convergence sublayer of IEEE 802.16 (Wi-MAX).
The basic purpose of the IEEE 802.21(MIH) standard is to facil-
itate handover between heterogeneous networks to provide seam-
less mobility. The standard supports handover for both mobile as
well as stationary users. For mobile users , handover can occur
when wireless link conditions change due to MN movement. For
stationary users handover can occur environmental changes. The
handover process can be initiated by using measurement reports
and link layer triggers the handover. The measurement reports can
include the metrics such as- signal quality, synchronization time
differences and transmission error rates. There are two paradigm
for handover initiation, one make-before-break and other is break-
before-make. MIHF provides three types of service specifications:
MIES, MICS and MIIS
3.3.1 Media Independent Event Service (MIES).It detects
change in logical link characteristics dynamically such as link sta-
tus and link quality. It also initiates changes in physical, data link
layers. It has two types of events: one is link events which originate
from lower layers and proceeds towards upper layers, other is MIH
events which are initiated by MIHF.
3.3.2 Media Independent Command Service (MICS).It facili-
tates controlling of a link state. MICS uses commands for local
events and remote events separately. Local events happen within the
same protocol stack by local MIHF and remote events happen be-
tween local MIHF and remote MIHF subscribed by a remote node.
3.3.3 Media Independent Information Service (MIIS).The
MIIS provides the information which is required to perform han-
dover and is linked to the appropriate module for each MIH enabled
entity. It gathers the following information which either locally or
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International Journal of Computer Applications (0975 8887)
Volume 53 - No. 3, September 2012
remotely available:
Access Network Related:-
(1) List of Available Networks.
(2) List of Authorized users
(3) Target QoS Parameters for ongoing sessions
(4) Number of Connections per PoA
(5) Load Factor(Uplink or Downlink)
(6) Available Bandwidth
MN Related:-
(1) Detected Networks
(2) Parameters for context Transfer
(3) PHY Parameters
(4) QoS Parameters for the Network
(5) Measured QoS Parameters Experienced For the Network
MIHF uses the triggers from link layer to support handover initi-
ation and handover preparation. Handover initiation consists three
phases:
(i) Network Discovery
(ii) Network Selection
(iii) Handover Negotiation. While the handover preparation has two
steps: (i) Lower and upper layer connectivity (ii) Resource Reser-
vation
MN can work with WLAN, WPAN, DVB, 3GPP and some other
unlicensed mobility interfaces and uses the facilities provided by
the MIHF to achieve seamless mobility. The MIH users of MIHF at
the MN side are MIP, mobile stream control transmission protocol
(mSCTP), service initiation protocol (SIP) respectively at network,
transport and application layers.
4. NETWORK SELECTION BASED ON SERVICE
ZONE[13]
The authors have described the vertical handover for macro mobil-
ity by proposing VHO technique for selection of networks based
on network service zone using GPS among multiple available net-
works for seamless network connectivity. They have assumed that
the MN is assisted by a GPS server to track the real time loca-
tion. This is depicted in figure 3. In [13], the network selection
and switching technique is proposed by considering the user pref-
erences and network performance without using network hardware
dependent metrics (eg., RF strength, RF link quality, and so on) and
is independent of network metrics such as RTT (Round Trip Time)
and PLR (Packet Loss Rate).
5. VERTICAL HANDOVER MANAGEMENT
Handover management handles the movement of MN by keeping
the connection active while changing the PoA (access point, base
station).
5.1 Vertical Handover
The process of changing the PoA by MN across the networks is
known as vertical handover. It is defined as the switch between two
different RAT or the switch between two different radio access net-
works operating with the same technology if the IP address of the
MN changes as a result of the handover. Vertical handover pro-
vides media independence using IEEE 802.21, therefore it is also
known as media independent handover. We have simulated the me-
dia independent handover between WLAN and UMTS (3G cellular
technology) in [14].
5.2 Need of Vertical Handover
Now the MN is being equipped with multiple network interfaces.
These multiple network interfaces can help extend the range of
the wireless networks. Vertical handover is needed in this extended
wireless network of overlapped coverage of various types of RATs.
Also, VHO provides flexibility and cost effective usage of over-
lapped RATs coverage. VHO is also being used to achieve load
balancing.
5.3 Vertical Handover Performance Issues
VHO is the main barrier to be crossed in the way of achieving seam-
less mobility. There are many issues which derives the performance
of VHO such as discovering the available RATs around the multi-
interface enabled MN, detection of received signal strength (RSS)
of each RAT, selecting the optimal RAT according to the user pref-
erences, RAT is preferred by user, determining the gain of handing
over to the preferred RAT, determining the exact time of VHO and
execution of VHO.
VHO involves the following decision factors: Decision Criteria,
Decision Policies, Decision Algorithms, Decision Control Schemes
5.4 VHO Decision Criteria
In [2], following VHO decision criteria is described:
(1) User Preferences
(2) Network Conditions (Received Signal Strength (RSS), QoS
Parameters, Mobility Pattern)
(3) Application Requirements (Velocity of MN)
(4) MN Capabilities (Processing Power, Battery Status, Interface
Support)
5.5 VHO Decision Algorithms[2]
(1) Function-based algorithms
(2) User-centric algorithms
(3) Multiple attributes based algorithms
(4) Fuzzy Logic and Neural Network based algorithms
(5) Context aware algorithms
5.5.1 Service History based VHO Algorithms [11]. In [11], ser-
vice history based VHO algorithm is used to reduce un-necessary
and frequent handovers. Seamless handover is an important
issue either it is achieved using horizontal or vertical handover
algorithms. Each candidate network is evaluated for multiple
attribute such as available bandwidth, delay, data rate and cost.
Frequent handover occurs because of variations in these parame-
ters. Disconnection probability also tends towards high because of
change in these parameters. Following decision criteria is used in
service history based VHO algorithm:
DecisionCriteria =F(av ailablebandwidth, delay, datarate, cost)
(1)
In [11], an objective function is proposed which is specifying two
parameters from service history information: first parameter is cu-
mulative service time since the last handover at a particular serving
network, second parameter is time duration since the last handover
blocking from a particular network. Both these parameters were
optimized so that frequent handover (ping ponging) and handover
blocking is avoided.
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International Journal of Computer Applications (0975 8887)
Volume 53 - No. 3, September 2012
Fig. 5. Typical Stages of Vertical Handover for seamless macromobility
5.6 Vertical Mobility Management Architectures
A comprehensive survey of vertical mobility management archi-
tectures is provided in [15]. In this it is described that protocols for
mobility, fair comparision of different solutions at each layer and
their various associated problems, design and performance evalu-
ation of different handoff procedures are the current architectural
issues which are point of concern among researchers.
6. SIMULATION & RESULTS
6.1 Simulation of MIH for IEEE 802.11 and UMTS
We simulated a heterogeneous network which contains two types
of networks: UMTS and IEEE 802.11 (WLAN). Universal Mo-
bile Telecommunications System is a 3G cellular technology, while
Wireless Local Area Network is member of IEEE 802 project. We
have simulated the vertical handover between these two by using
NS-2.29 version of NS and mobility extensions package provided
by National Institute of Standards and Technology(NIST).
6.1.1 Simulation Scenario. The considered simulation scenario
to draw simulation results, has an assumption that the coverage
area of UMTS cell is the entire simulation map. The WLAN cell
is located inside the UMTS cell. The UMTS cell has a base sta-
tion(BS) and the WLAN cell has access point(AP). Initially, the
multi-interface equipped MN is connected to the UMTS BS. The
preference is always given to the WLAN interface as soon as it is
available. The simulation scenario is shown in the figure 3. It is
clear from figure 4 that MN performs two handovers, one handover
when it leaves UMTS cell and joins WLAN cell. and other han-
dover is when it leaves WLAN cell and the traffic is redirected to
UMTS BS.
Fig. 6. MIH Simulation Scenario
6.1.2 Simulation Parameters. Tables 2, 3, 4 & 5 show the pa-
rameters for simulation of MIH to and from WLAN and UMTS.
We have considered straight line mobility model. The application
traffic type for MN is UDP with packet size 500 bytes and packet
interval time is 0.02s.
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International Journal of Computer Applications (0975 8887)
Volume 53 - No. 3, September 2012
Table 2.
Topology
S.No Parameter Value
1. UMTS Cell Coverage Entire Simulation Map
2. WLAN Cell Coverage 20m
3. Propagation Delay CN-MN 0.09s for RTT + Mac access delay
4. Nodes in WLAN Hotspots 0 To 20
Table 3.
Parameters of the Router
S.No Parameter Value
1. MIN RA DELAY 200s
2. MAX RA DELAY 3XMIN RA DELAY
3. Router Lifetime 3XMIN RA DELAY
4. MIN DELAY Between RA 0
Table 4.
MAC Parameters
S.No Parameter Value
1. WLAN beacon interval 0.1s
2. Default Scanning Mode Passive
3. MinChannelTime 0.02s
4. MaxChannelTime 0.06s
5. ProbeDelay 0.002s
7. CONCLUSIONS & FUTURE WORK
Mobility solutions are are required at almost all layers of layered
architecture. We have described the mobility solutions at applica-
tion layer and network layer. The main obstacle in achieving seam-
less mobility is vertical handover and its related issues and chal-
lenges. In this paper we have presented a comprehensive descrip-
tion of issues and challenges to achieve seamless mobility in a het-
erogeneous wireless networks. The main issues to achieve seam-
less mobility are discovery of available RATs, optimal selection of
user preferred RAT, deciding exact time of initiating and complet-
ing VHO, VHO algorithms. As a case study, we simulated verti-
cal handover between IEEE 802.11 (WLAN) and UMTS(Cellular
Technology) and presented our observations using NS2. We are still
working on other issues to achieve the seamless mobility like to
estimate exact time to perform vertical handover, RAT detection,
developing multi-parameter cost function.
Acknowledgments
We wish to thank the anonymous reviewers for their valuable sug-
gestions. Our sincere thanks to Dr. Avdhesh Kumar (Head, CSE
and CIS) Galgotias University and our friends for their support dur-
ing this work.
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S.No Parameter Value
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