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

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

Introduction Wireless Access Technologies Vertical Handover IEEE802.21 Standard

Wireless Access Technologies IEEE802.11 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)

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

IEEE802.21 Standard Media Independent Handover (MIH) is based on the IEEE802.21 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

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?

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.

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.

Vertical Handover Scenarios Research Methodology Simulation Stages Evaluation Metrics

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: IEEE802.21 module contributed by National Institute of Standards and Technology (NIST). UMTS module contributed by EURANE. WiFi module.

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

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

Evaluation Metrics   VN: Visited Network SN: Serving Network        

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

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.

Normalized Throughput Fig.9 Normalized Average Throughput

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

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

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

Handover Latency Fig.12. Handover Latency

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

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

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

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

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 ~ 3840 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%

Conclusion IEEE802.21 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.

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.

Main References [Kav07] Aktul Kavas. Comparative analysis of WLAN, WiMAX and UMTS technologies. In PIERS Proceedings, pages 150-- 157, Czech Republic, August 2007. [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 2011. [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. 985-997, ISSN 0140-3664. [Mar10] Hugo Marques, José Ribeiro, Paulo Marques, and Jonathan Rodriguez, “Simulation of 802.21 Handovers Using ns- 2,” Journal of Computer Systems, Networks, and Communications, vol. 2010, Article ID 794749, 2010. [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. 2010. [Mat13] http://www.mathworks.com/products/curvefitting/ Accessed on Nov. 2013 [Itu11] ITU-T Recommendation Y.1541, “Network Performance Objectives for IP-Based Services”. Dec. 2011 [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, 2013. [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. 478-482, ISSN 1434-8411.

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 802.21 in Heterogeneous 3G and Wireless Networks”, Journal of Internet Technology, vol.12 no.5, pp. 801-812, Oct. 2011. [Lin12] Chih-Peng Lin, Hsing-Lung Chen, and Jenq-Shiou Leu. 2012. A predictive handover scheme to improve service quality in the IEEE 802.21 network. Computer. Electronics. Eng. 38, 3 May 2012, 681-693.

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