The availability of diverse wireless access technologies such as (Wi-Fi), (WiMAX), and (UMTS) allows users to stay “always on” in fast roaming too using IEEE802.21. Vertical handovers had made possible for user to transfer itself to other technology service without disturbances in ongoing process. Its is known that security problems in GSM authentication when it comes to high speed moving users, because of there frequent change of cell sites. Handover could be horizontal or vertical and per user requirement. MIH (media independent handover) though provide vertical handover but on other hand 802.11had provided us fast and secure connection oriented handover from one access point to another with in same mobility domain. Thus feature of security and authentication is integrated with handover for user security. What are heterogeneous networks? Evolutions of Generations The Cellular GSM Transitions Overview of 4G Communications Concept of Handover /Handoff Handovers distinguished according to criteria The Vertical handover IEEE 802.21 & its phases. VHO Management procedures Requirements of Handover mechanism in heterogeneous networks Performance evaluation (Technology ) Performance evaluation in Handover mechanisms

1. A PRESENTATION
MASTER OF TECHNOLOGY IN ELECTRONICS ENGG.(P.T.)
Presented by:
Narendra Kumar
Roll No. 1181043007
Under the Guidance of
Department of Electronics Engineering
, UP, India
OVERVIEW OF HANDOVER TECHNIQUES IN
HETEROGENEOUS WIRELESS NETWORKS

2.  The availability of diverse wireless access technologies such
as (Wi-Fi), (WiMAX), and (UMTS) allows users to stay “always
on” in fast roaming too using IEEE802.21.
 Vertical handovers had made possible for user to transfer
itself to other technology service without disturbances in
ongoing process.
 Its is known that security problems in GSM authentication
when it comes to high speed moving users, because of there
frequent change of cell sites.
 Handover could be horizontal or vertical and per user
requirement. MIH (media independent handover) though
provide vertical handover but on other hand 802.11had
provided us fast and secure connection oriented handover
from one access point to another with in same mobility
domain.
 Thus feature of security and authentication is integrated with
handover for user security.

3.  What are heterogeneous networks?
 Evolutions of Generations
 The Cellular GSM Transitions
 Overview of 4G Communications
 Concept of Handover /Handoff
 Handovers distinguished according to criteria
 The Vertical handover IEEE 802.21 & its phases.
 VHO Management procedures
 Requirements of Handover mechanism in heterogeneous
networks
 Performance evaluation (Technology )
 Performance evaluation in Handover mechanisms
 Conclusions
 References

4.  An interconnection of multiple networks irrespective of
topology, network architecture etc. The networks may be
multiple IP networks, Cellular networks, ad hoc networks, and
satellite networks with prescribed bandwidth capacity, link
speeds and other parameters. Each network has respective
performance metrics for describing their characteristics.
 The next generation communication aims at integration of
different networks. The communicating devices needs
frequent mobility and communicate to each other in the
different architectural and topological networks.
 However, if a mobile devices moves among different types of
network during communication, there is a serious problem of
call drop or interrupted communication due to improper
handoff It also affects it’s QoS.

5. WIMAX
WiFi
Short range
LAN/PAN/
WAN
Wireless
Broadband
Cellular GSM
2G
Cellular 4G
WIMAX
USERCellular 3G
( UMTS)

8. 3G: UMTS
2.5G: GSM + GPRS
2G : GSM
Core Network
Gateway
MSC
VLR
HLR
MSC
Mobile
Switching
Center
BSC
Base
Station
Controller
BTS
Base
Transceiver
Stations
Internet
ISDN
PLMN
PSTN
SIM
Mobile
Equipment
Mobile
Station
Core Network
Gateway
MSC
VLR
HLR
MSC
Mobile
Switching
Center
Gateway
GPRS
Support
node
Serving
GPRS
Support
node
BSC
Base
Station
ControllerPCU
BTS
Base
Transceiver
Stations
SIM
Mobile
Equipment
Internet
ISDN
PLMN
PSTN Mobile
Station
UTRANCore Network
Gateway
MSC
VLR
HLR
MSC
Mobile
Switching
Center
Gateway
GPRS
Support
node
Serving
GPRS
Support
node
UMTS
SIM
Mobile
Equipment
RNC
Radio
Network
Controller
RNC
Radio
Network
Controller
Node B
Node B
Node B
Node B
Internet
ISDN
PLMN
PSTN
User
Equipment

9. 4G : Mobile Communications

10. COMMUNICATION

11.  Movement of mobile in different regions.(near far
problem)
 Capacity of one BTS is almost full.(call
setup/disconnection)
 Umbrella approach.

12. (A) LOCATION OF A HANDOFF FUNCTION
Network-Controlled Handoff
• The network makes a handoff decision based on the measurements of the
MSs at a number of BSs.
• Used in first-generation analog systems such as AMPS (Advanced Mobile
Phone System), TACS(Total Access Communication System), and NMT
(Nordic Mobile Telephone). HO time 100-200ms
Mobile-Assisted Handoff
• The MS makes measurements and the network makes the decision.
• In circuit-switched GSM ,BSC is in charge of the radio interface management
i.e. allocation and release of radio channels and handoff management. HO
time-1s.
Mobile-Controlled Handoff
• In mobile-controlled handoff, each MS is completely in control of the handoff
process.
• This type of handoff has a short reaction time (in the order of 0.1 second).
• MS measures the signal strengths from surrounding BSs and interference
levels on all channels.
• A handoff can be initiated if the signal strength of the serving BS is lower than
that of another BS by a certain threshold.

13. (B) NETWORK ELEMENT INVOLVED
Intra-cell, Inter-cell and Inter-network.
(C) NUMBER OF ACTIVE CONNECTIONS
Hard Handover (Break “OLD” Before “NEW” Make)
• Only one connection exists in a given time point
• Used in FDMA and TDMA systems to minimize adj. channel
interference.
• Cheaper, easier to implement. Simpler hardware of MT required.
Soft Handover (Make “NEW” Before “OLD” Break)
• Several connections with the same information are maintained
simultaneously at a given time point.
• Used in UMTS to improve the signal quality.
• Uplink and downlink signals may be combined for better signal
• A mobile in UMTS may spend a large part of the connection time.
• Better connection reliability- MORE SEALMLESS HANDOVER.
• Used in CDMA technology.
• Technical Implementation expensive & complex.

14. Softer Handover
• One BTS/Node receives 2 user signals from 2 adjacent sectors it serves.
• One BTS/Node receives 2 separated signals through multi-path propagation or
reflections from buildings or natural barriers.

15. Mechanism of Hard Handover

16. Mechanism of Soft Handover

17.  Homogeneous (Horizontal) Handovers
 MT changes point of connection with same type of network
 Localized Mobility
 E.g. from a cell to another in GSM
 E.g. from an access point to another in WiFi
Reasons for handover- Worse signal quality or loss of signal, Traffic load
balancing, Cost
 Limited opportunities

18.  Heterogeneous (Vertical) Handovers
 MT changes point of connection across different
types of network .
 Global Mobility
 automatic fall over from one technology to another
in order to maintain communication.
 More opportunities
IEEE 802.21 is primarily for Vertical Handovers
….can also be used for Homogeneous
Handovers

19.  Here handover have 3 phases:
 Initiation
 Decision
 Execution
 Media independent handover (IEEE 802.21) provide
seamless mobility among different networks.
 Initiation
 Network discovery
 Network selection
 Handover negotiation
 Decision
 handover algorithm(MIHF)
 Execution
 Mobility management
 Handover management

21. executing
• Leaving one network and entering to other is finalisied . Mobility
management and handover management is key feature.
• Latencies and packet loss is checked after handover is complete.
Decision
• Decision are taken like when and where to trigger handover.
• Various parameters are kept into consideration for best network for
user.including the type of the application (e.g., conversational,
streaming), minimum bandwidth and delay required by the application,
access cost; transmit power, and the user’s preferences.
• MT are re-routed from the existing network to the new in seamless way.
• This phase also includes the authentication, authorization, and transfer
of a user’s context information.
collecting
• Information collected from diverse source like network properties,
access point, mobile devices, and user preferences.

22. PERFORMANCE EVALUATION (TECHNOLOGY) IN
HETEROGENEOUS NETWORKS
UMTS takes average of 29.6ms to deliver one packet, WiMAX
gives 0.81ms and WiFi gives 0.23ms of latencies respectively

23. Abbreviation Ref# Some Available Handoff Mechanisms
UARTVHO 12
Use of Adaptive Resonance Theory for Vertical Handoff
Decision in heterogeneous Wireless Environment
VHDAHWN 16
A Vertical Handoff Decision Algorithm for Heterogeneous
Wireless Networks
TAHDM 11
Towards Autonomic Handover Decision Management in 4G
Networks
EDHMHN 13
Efficient decision handoff mechanism for heterogeneous
network
PEHHWN 8
Policy-Enabled Handoffs across Heterogeneous Wireless
Networks
VHDAPOP 10
Vertical Handoff Decision Algorithms for Providing Optimized
Performance in heterogeneous Wireless Networks
ADDMVHO 9
A Dynamic Decision Model for Vertical Handoffs across
Heterogeneous Wireless Networks
PERFORMANCE EVALUATION (H.O. MECHANISMS) IN
HETEROGENEOUS NETWORKS

24. REQUIREMENT OF H.O. MECHANISMS IN
HETEROGENEOUS NETWORKS
DYNAMIC REQUIREMENTS NON-DYNAMIC REQUIREMENTS
DYNAMIC REQUIREMENTS INCLUDE RSS,
VELOCITY THROUGHPUT USER
PREFERENCES AS PARAMETERS.
NON-DYNAMIC REQUIREMENTS INCLUDE NETWORK
COST, POWER CONSUMPTION, NETWORK SECURITY
AND BANDWIDTH AS PARAMETERS.
REQUIREMENTS OF HANDOVER MECHANISMS OUTLINED ARE AS BELOW,
HOWEVER, IT IS BEING STATED THE IMPORTANT PARAMETERS/METRICS AS REQUIREMENTS BUT OTHER
PARAMETERS SUCH AS NETWORK CONDITIONS, NETWORK CAPABILITY AND BIT ERROR RATE CAN ALSO
BE CONSIDERED DURING VERTICAL HANDOFF. A GOOD HANDOFF MECHANISM DECISION MODEL SHOULD
HAVE BOTH DYNAMIC AND NON-DYNAMIC METRICS. HOWEVER, IT IS IMPORTANT TO CONSIDER MAXIMUM
NUMBER OF STATIC AND DYNAMIC REQUIREMENTS DURING VHO BUT IT IS DIFFICULT TO INCLUDE ALL
THE METRICS IN IN A SINGLE DECISION MODEL DUE TO COMPLEXITY OF ALGORITHMS AND CONFLICTING
ISSUES OF MULTIPLE METRICS

25. REQUIREMENT OF H.O. MECHANISMS IN
HETEROGENEOUS NETWORKS
S.N REQUIREMENT PURPOSE IN HANDOVER MECHANISMS
1 BANDWIDTH
Higher offered bandwidth ensures lower call dropping and call blocking
probabilities; hence higher throughput.
2 H.O LATENCY
Delay in process of handover of calls between two.
It is minimized by suitable decision models by a handoff latency factor.
3
POWER
CONSUMPTION
During handoff, frequent interface activation can cause considerable battery
drainage. Power saving is important factor in h.o mechanism
4 NETWORK COST
The cost is to be minimized during VHO in wireless networks. The new call
arrival rates and handoff call arrival rates can be analyzed using cost function
5
USER
PREFERENCES
The user preferences could be preferred networks, user application
requirements (real time, non-real time), service types (Voice, data, video),
Quality of service (It is a set of technologies for managing network traffic in a
cost effective manner to enhance user experiences for wireless environments)
etc.
6
NETWORK
THROUGHPUT
It is average data rate of successful data or message delivery over
a specific communications link.It is measured in bits per second (bps).
Maximum network throughput equals the TCP window size divided by the
round-trip time of communications data packets.

26. PERFORMANCE EVALUATION
(HANDOVER MECHANISMS)
7
NETWORK
LOAD
BALANCING
To provide a high quality communication service for mobile subscribers and to
enhance a high traffic-carrying capacity when there are variations in traffic to
balance the network load & to avoid deterioration in quality of services.
8
NETWORK
SECURITY
To prevent and monitor unauthorized access, misuse, modification, and network-
accessible resources
to attain the highest levels of integrity, authentication, and confidentiality, network
security features should be embedded in the handoff policies.
9
RECEIVED
SIGNAL
STRENGTH
(RSS)
RSS is the performance of signal strength between a mobile node (MN) and access
point (AP),the wireless signal strength in each direction determines the total amount
of network bandwidth available along that connection. It depicts the power present
in a received signal.
A signal must be strong enough between base station and mobile unit to maintain
signal quality at receiver. The RSS should not be below a certain threshold in a
network during handoff. VHO includes three sequential steps as discussed earlier in
this paper, namely handoff initiation, handoff decision and handoff execution.
Handoff initiation is concerned with measurement of RSS
10 VELOCITY
Velocity of the host should also be considered during handoff decision. Because of
the overlaid architecture of heterogeneous networks, handing off to an embedded
network, having small cell area, when travelling at high speeds is discouraged since
a handoff back to the original network would occur very shortly afterwards

27. PERFORMANCE EVALUATION
(HANDOVER MECHANISMS)
SOME HANDOVER MECHANISMS
REFERENCE # 12 14 11 13 8 10 9
S.
N REQUIREMENT
UARTV
HO
VHDAH
WN
TAHDM
EDHM
HN
PEHH
WN
VHDAPO
P
ADDMVH
O
1 BANDWIDTH Y Y Y Y Y Y Y
2 H.O LATENCY Y Y
3
POWER
CONSUMPTION
Y Y Y Y Y
4 NETWORK COST Y Y Y Y Y Y
5
USER
PREFERENCES
Y Y Y Y Y
6
NETWORK
THROUGHPUT
Y Y Y Y
7
NETWORK LOAD
BALANCING
Y Y Y Y Y
8
NETWORK
SECURITY
Y
9
RECEIVED SIGNAL
STRENGTH (RSS)
Y Y Y Y
10 VELOCITY Y Y Y

28.  The decision mechanism of VHO can become more fruitful, if the number of
parameters is more during decision making . The success of VHO
mechanism depends upon the decision model based on requirements/
metrics. An efficient decision mechanism can not only enhance the system
capacity but also improve the quality of services for a user.
 The 4G wireless networks create new handover challenges due to multiple
requirements for vertical handoff. The requirements of proposed VHO include
high bandwidth, low handoff latency, lower power consumption, minimum
network cost, balanced network load, network security, user preferences,
throughput and RSS of a switching network.
 Establishing the VHO requirements is a critical milestone in the development
of vertical handoff mechanism for 4G.
 The evaluation indicate the need to have a VHO mechanism for 4G wireless
networks that has the ability to satisfy maximum number of requirements.
 However, it is difficult to consider all the parameters during designing the
decision model for VHO but if we consider more parameters, the outcome of
the decision mechanism would definitely improve.

29. 1. McNair, J. ; Fang Zhu (2004), “Vertical handoffs in fourth-generation multinetwork environments”in IEEE pp8-15
2. Mandeep Kaur Gondara and Dr. Sanjay Kadam (2011) “ Requirements of vertical Handoff Mechanism in 4G
wireless Networks” - International Journal of Wireless & Mobile Networks (IJWMN) Vol. 3, No. 2, April 2011 pp18-
27.
3. A Handout on GSM Basics,Version 1 Revision 0, published by BRBRAITT, BSNL Jabalpur, Issued in March –
2007
4. Avi Freedman, Zion Hadad (sep 2002 ), “ Handoff Schemes Overview and Guidelines for Handoff Procedures in
802.16” , in IEEE C802.16sgm-02/24
5. S.K. Shukla, A.K. Vatsa, Pooja Dubey (2012), “Fast & Reactive Handoff Over Hetrogeneous Networks”in
IJCSMS-International Journal Of Computer Science and Management Studies, Vol-12 Issue-02 April 2012 pp7-
12
6. 4G Americas, (October 2013) “ Self Optimizing Networks-benefits of SON in LTE” pp12,13-50
7. Zahid Ghadialy (2005), “Handover principle and concepts “ from google search
8. H.J. Wang, R. H. Katz & J. Giese,(1999) “Policy-Enabled Handoffs across Heterogeneous Wireless Networks”,
In proc. of ACM WMCSA.
9. Pramod Goyal & S. K. Saxena,(2008)“A Dynamic Decision Model for Vertical Handoffsacross Heterogeneous
Wireless Networks”,677 ? 2008 WASET.ORG, World Academy of Science, Engineering and Technology,Issue
41,pp 676-682.
10.SuKyoung Lee , Kotikalapudi Sriram, Kyungsoo Kim, Yoon Hyuk Kim & Nada Golmie,January (2009)“Vertical
Handoff Decision Algorithms for Providing Optimized Performance in Heterogeneous Wireless Networks”,IEEE
transactions on Vehicular Technology.
11.Joon-Myung Kang, Hong-Taek Ju2 & James Won-Ki Hong,(2006) “Towards Autonomic Handover Decision
Management in 4G Networks”, In Proceedings of MMNS'2006,pp145-157.
12.Mrs. Chandralekha & Dr. Prafulla Kumar Behera,November (2009) “Use of Adaptive Resonance Theory for
Vertical Handoff Decision in Heterogeneous Wireless Environment”, International Journal of Recent Trends in
Engineering, Vol. 2, No. 3.
13.A. Dvir, R. Giladi, I. Kitroser & M. Segal,February (2010) “Efficient decision handoff mechanism for
heterogeneous network”, International journal of Wireless and Mobile networks,Vol. 2, No. 1.
14.E.Stevens-Navarro,Vincent W.S.Wong & Yuxia Lin,(2007) "A Vertical Handoff Decision Algorithm for
Heterogeneous Wireless Networks",In Proc. of Wireless Communications and Networking Conference, IEEE ;
doi:10.1109/WCNC. 2007.590

30. Thanks for
your time
Narendra Kumar
+91- 9450000911