1. Prepared by: Hassan Khalil and Dr.Mohammad Hamarsheh
Speed Effect on the Performance of Vertical Handover in Wifi-3G Network
Prepared by: Hassan Khalil and Dr.Mohammad Hamarsheh

2. Outline
Research Objectives
Introduction
Problem Statement
Vertical Handover Scenarios
Experimental Results & Analysis
Results Modeling and Discussion
Conclusion & Future Work

3. Introduction Wireless Access Technologies Vertical Handover
IEEE Standard

4. Wireless Access Technologies
IEEE from the IEEE 802 Family of Standards
Known as WiFi network, it is compliant to operate in WLAN.
High bandwidth and low cost network.
Preferred technology of access in hot-spot areas.
UMTS as 3G Cellular Network
Defined by the 3rd Generation Partnership Project (3GPP)
Consists of Circuit switched and Packet switched network
Offers services such as voice, video and data.
Table 1: Characteristics of UMTS and WiFi [Kav07] [Dje11]
Wireless Technology
Coverage area
Bandwidth
Mobility
Spectrum
UMTS
10 Km
384 kb/s ~ 2 Mb/s
High
Licensed
IEEE802.11
WiFi
50 ~ 300 m
Up to 54 Mb/s
Low
Unlicensed (free)

5. Vertical Handover
Vertical handover is the process that enables the mobile node to redirect traffic flow between network interfaces based on obtained facilities from different wireless access networks.
Fig.1. Handover phases.
Fig.2. General scenario for vertical and horizontal handover

6. IEEE Standard
Media Independent Handover (MIH) is based on the IEEE Standard.
Defines extensible mechanisms for handover between implementations of IEEE802 family of standards and Cellular networks.
Bridges the gaps for integrating technology dependent networks by providing a global view of all the heterogeneous candidate networks to the mobile node.
Fig.3. Services provided in the abstraction layer of IEEE802.21

7. Problem Statement
What are the key factors that affect the QoS in the vertical handover scenarios?
How do the access network facilities and constrains affect the QoS in the vertical handover scenarios?
How to implement vertical handover scenarios that are applicable to observe the needed evaluation metrics?
To what extent the obtained results are acceptable with respect to the QoS standards?

8. Related Works
The research in [Rah13] studies the vertical handover between WiFi and WiMAX enhanced by MIH standard and proposed multi criteria decision algorithm for network selection using NS-2.
In [Mar10], the research addressed the vertical handover between WiFi and WiMAX using MIH standard implemented in NS-2. Number of mobile nodes was studied as effective factor as well as the application bitrate.
The research in [Ast13] use real testbed (ODTONE) which is an implementation of the MIH standard, to study the vertical handover between WiFi and WiMAX.
The research in [So08] proposed vertical handover decision algorithm for the integration between WiFi and CDMA networks without considering the MIH standard.

9. Related Works - continue
The research in [Mcn04] is one of the earliest studies in vertical handover focusing on handover decision policies based on RSS and cost function by exploiting the Mobile IP protocol for handover.
In [Cha11], handover mechanism between WiFi and WiMAX is proposed based on MIH standard. The impact of the Link Going Down factor on the handover latency and packet loss was studied.
The research in [Lin12] addressed the vertical handover between WiMAX and UMTS as well as WiMAX and WiFi using cross-layer scheduling scheme and QoS classes of services.

10. Vertical Handover Scenarios
Research Methodology
Simulation Stages
Evaluation Metrics

11. Research Methodology
Mobility scenarios were implemented based on the mobility direction from WiFi to UMTS.
The scenarios were implemented using NS-2 which is the most widely used simulation tool in the literature to evaluate vertical handover [Bar11].
Exploitation of the wireless modules implemented in NS-2:
IEEE module contributed by National Institute of Standards and Technology (NIST).
UMTS module contributed by EURANE.
WiFi module.

12. Fig.4. Simulation Stages, Evaluation metrics filtering and extraction.

13. Simulation Parameters
Table 2: Simulation Parameters for WiFi and UMTS [Mar10] [Vra10].

14. Evaluation Metrics
VN: Visited Network
SN: Serving Network

15. Experimental Results and Analysis
Throughput
Total packet loss
E2E Delay
Handover Latency

16. WiFi Throughput (WiFi to UMTS)
Fig.7. Average Throughput on mobile node WiFi and UMTS interfaces for application with bitrate 64kb/s.
Fig.8. Average Throughput on mobile node WiFi and UMTS interfaces for application with bitrate 3840kb/s.

17. Normalized Throughput
Fig.9 Normalized Average Throughput

18. Fig5.Packet Loss Ratio on WiFi network
Total Received Packet
Fig5.Packet Loss Ratio on WiFi network
Fig.6.Total Packets Received on UMTS interface for two applications with bitrate 64kb/s and 3840 kb/s

19. Total Packet Loss Ratio
Fig.10. Packet Loss Ratio on WiFi network
Fig.11. Packet Loss Ratio on UMTS network

20. Fig.13. Average End to End Delay in WiFi network
E2E Delay
Fig.13. Average End to End Delay in WiFi network
Fig.14. Average End to End Delay in UMTS network

21. Handover Latency
Fig.12. Handover Latency

22. Power Signal on Wifi Interface
Fig.15. Power RSS measured on the mobile node WiFi interface while it is leaving WiFi network

23. Results Modeling and Discussion
Curve Fitting
Summary for metrics behaviors
Results compared to ITU-T
Results compared to Related Works

24. Fig.16. Curve Fitting for WiFi Throughput
Fig.16. Curve Fitting for WiFi Throughput
Coefficients for 64 kb/s:

25. Summary for Metrics’ Behaviors
Table 3: Summary of the evaluation metrics behavior and the obtained results’ values

26. Results compared to ITU-T
Table 4: Obtained results compared to ITU-T recommendations for voice and video [Mar10][Itu11].
Evaluation Metric
Application
Acceptable values recommended by ITU-T
Obtained Results
E2E one way Delay
Voice
150 ~ 200 ms
46 ~ 50 ms delay in WiFi for bitrates 64 ~ kb/s in both scenarios.
54 ms delay in UMTS for bitrates 64 ~ 384 kb/s in both scenarios.
1 s delay in UMTS for bitrates > 384 kb/s.
11 ms latency when handover to WiFi .
144 ~ 168 ms latency when handover to UMTS.
Video
< 280 ms
Total Packet Loss Ratio
 Voice
< 2%
0.4% packet loss for bitrates < 384 kb/s when handover to UMTS.
No packet loss for bitrate < 384 kb/s when handover to WiFi.
Packet loss > 10% for bitrates > 384 kb/s in both directions.
  Video
< 1%

27. Conclusion
IEEE highly enhance vertical handover between WiFi and UMTS by achieving service continuity.
Applications with bitrate less than the UMTS bandwidth achieve QoS requirements.
The obtained results show that considering mobile node speed and applications bitrate in addition to RSS as multi criteria for vertical handover decision algorithms will enhance the performance in the vertical handover scenarios.

28. Future Work and Recommendations
Implementing multi criteria decision algorithm in addition to the RSS based by considering the mobile node speed and applications bitrate.
Trying to implement the proposed scenarios using ODTONE may lead to more realistic observations.
Optimizing the parameters and coefficients of the fitting equations may achieve more general models.
Adding more WiFi access points and consider the number of mobile handovers and its necessity with respect to the mobile node speed and network bandwidth.

29. Main References
[Kav07] Aktul Kavas. Comparative analysis of WLAN, WiMAX and UMTS technologies. In PIERS Proceedings, pages , Czech Republic, August [Dje11] A. Djemai, M. Hadjila, M. Feham, “Performance Analysis of the Interconnection between WiMAX and UMTS Using MIH Services in MIPv6 “, IJCSNS International Journal of Computer Science and Network Security, VOL.11 No.8, August [Bar11] Johann Márquez-Barja, Carlos T. Calafate, Juan-Carlos Cano, Pietro Manzoni, An overview of vertical handover techniques: Algorithms, protocols and tools, Computer Communications, Volume 34, Issue 8, 1 June 2011, PP , ISSN [Mar10] Hugo Marques, José Ribeiro, Paulo Marques, and Jonathan Rodriguez, “Simulation of Handovers Using ns- 2,” Journal of Computer Systems, Networks, and Communications, vol. 2010, Article ID , [Vra10] M. Vranjes, T. Svedek, and S. Imac-Drlje, “The Use of NS-2 Simulator in Studying UMTS Performances”, International Journal of Electrical and Computer Engineering Systems, Vol. 1, No. 2, Dec [Mat13] Accessed on Nov [Itu11] ITU-T Recommendation Y.1541, “Network Performance Objectives for IP-Based Services”. Dec [Rah13] A. Rahil, N. Mbarek, O. Togni, Smart Network Selection and Packet Loss Improvement during Handover in Heterogeneous Environment, in Proc. of ICNS 2013, Lisbon, march 2013 [Ast13] J. Astorga, M. Aguado, N. Toledo, and M. Higuero, “A high performance link layer mobility management strategy for professional private broadband networks,” Journal of Network and Computer Applications, vol. 36, no. 4, pp. 1152– 1163, [So08] Jae-Woo So, Vertical handoff in integrated CDMA and WLAN systems, AEU - International Journal of Electronics and Communications, Volume 62, Issue 6, 2 June 2008, PP , ISSN

30. Main References - Continue
[Mcn04] McNair, J.; Fang Zhu, "Vertical handoffs in fourth-generation multinetwork environments," Wireless Communications, IEEE, vol.11, no.3, pp.8, 15, June 2004.
[Cha11] L.H. Chang, H.C. Chu, T.H. Lee, J.J Liaw and C.C. Wang, “A Handover Mechanism Using IEEE in Heterogeneous 3G and Wireless Networks”, Journal of Internet Technology, vol.12 no.5, pp , Oct
[Lin12] Chih-Peng Lin, Hsing-Lung Chen, and Jenq-Shiou Leu A predictive handover scheme to improve service quality in the IEEE network. Computer. Electronics. Eng. 38, 3 May 2012,

31. Thank You