• Journal of information and communication convergence engineering
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• v.15 no.1
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• pp.37-42
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• 2017

The constrained application protocol (CoAP) can be used for remotely controlling various sensor devices in Internet of Things (IoT) networks. In CoAP, to support the handover of a mobile sensor device, service discovery and message transmission needs to be repeated, although doing so would increase the handover delay significantly. To address this limitation of CoAP, a centralized CoAP scheme has been proposed. However, it tends to result in performance degradation for an inter-domain handover case. In this letter, we propose a distributed CoAP handover scheme to support the inter-domain handover. In the proposed scheme, a distributed mobility agent (DMA) is used for managing the location of mobile sensors in a domain and performing handover control operations with its neighboring DMAs in a distributed manner. A performance comparison reveals that the proposed scheme offers a performance improvement of up to 29.5% in terms of the handover delay.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.10
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• pp.2586-2596
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• 1996

The handover area is the region where a call can be handled by the base stations in any of the adjacent cells, and handover duration time is viewed as the time an mobile station resides inthe handover area. In this paper, analytic model to estimate the distribution function(df) of the handover duration time is proposed. Based on the df of the handover duration time, the simulation and anlytic models for the First Come first Serve(FCFS) scheme are presented, and the simulation results for the Measurement Based Prioritization Scheme(MBPS) are compared with the analytic results of the FCFS handover scheme. Those results show that the MBPS scheme is seen to provide lower handover failures than FCFS queueing with slightly increasing the new call blocking probability.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.4
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• pp.216-222
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• 2013

Handover is a technical methodology to support mobility of wireless communication users, which mainly affects the capacity of wireless communication systems and the quality of service (QoS) of link level signal. However, in OFDMA-based cellular systems, there are few published technical reports investigating handovers with respect to diversity gains and resource consumption depending on what handover technique is adopted. In this paper, we propose handover schemes exploiting transmit diversity and macro-diversity in order to increase capacity of OFDMA-based wireless communication systems, and analyze their performance. In cellular environments, depending on what handover scheme is selected, average signal-to-interference-and-noise ratio is calculated first for a handover user in order to evaluate the link level QoS. Through this technical evaluation for handover schemes, we conclude what handover scheme is suitable for OFDMA-based cellular systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11B
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• pp.987-996
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• 2006

In NEMO scenarios, mobile node's variety of movements and mobile router's point of attachment changes can result in handover. This handover process needs additional time to finish due to the multiple levels of indirection involved in NEMO. And the performance issues of mobile node's handover such as handover delay and packet loss in above cases haven't been studied thoroughly. So, in this paper, we define fast handover failure cases in hierarchical mobile IPv6 network based NEMO. We briefly described NEMO architecture and handover procedures of FMIPv6 and HMIPv6. And then, we classified mobile node or mobile router's movement pattern into several scenarios. Analysis for the fast handover classified NEMO scenarios, in terms of handover latency and packet delivery cost have been performed.

• International journal of advanced smart convergence
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• v.1 no.1
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• pp.19-26
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• 2012

The deployment of mobile femtocellular networks can enhance the service quality for the users inside the vehicles. The deployment of mobile femtocells generates a lot of handover calls. Also, numbers of group handover scenarios are found in mobile femtocellular network deployment. The ability to seamlessly switch between the femtocells and the macrocell networks is a key concern for femtocell network deployment. However, until now there is no effective and complete handover scheme for the mobile femtocell network deployment. Also handover between the backhaul networks is a major concern for the mobile femtocellular network deployment. In this paper, we propose handover control between the access networks for the individual handover cases. Call flows for the handover between the backhaul networks of the macrocell-to-macrocell case are proposed in this paper. We also propose the link switching for the FSO based backhaul networks. The proposed resource allocation scheme ensures the negligible handover call dropping probability as well as higher bandwidth utilization.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.6A
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• pp.651-659
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• 2004

The Fast Handover protocol ［1］ provides seameless handover in wireless If networks by minimizing handover latency, which uses anticipation based on layer 2 (L2) trigger information. Therefore, it incurs higher signaling costs compared with the basic Mobile U protocol. Furthermore, since the L2 trigger is based on fluctuating wireless channel states, the handover anticipation may sometimes be incorrect. In the case of incorrect anticipation, unnecessary buffer space may be used for the purpose of providing a smooth handover. Therefore, it is essentical to analyze these overhead costs, in order to evaluate and compare the performance of Fast Handover with that of the basic Mobile U protocol. In this paper, we analyzed the overhead associated with Fast Handover including the signaling cost and the packet delivery cost. We formulated these costs based on a timing diagram and compared Fast Handover with basic Mobile Ipv6 in terms of their packet loss rates and buffer requirements. Also, we studied the impact of the L2 triggering time on the total overhead cost.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12A
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• pp.1200-1208
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• 2008

In TD-SCDMA systems based on TDD, when mobiles move to cell from cell, Baton Handover was used to maintain an ongoing call. But baton handover has a great demand for the equipment and system. Then both hard handover and baton handover are used alternativly in real systems. But ratio of handover success in real system is 95% which is too low to be used in systems. This paper proposes to employ Soft Handover in TD-SCDMA systems which has performed in WCDMA systems. Also we carry out the simulation, which get result of the BER performance between baton handover method and proposed handover method. The proposed method is forward to be better performance than those of the baton and hard handover.

• Journal of Korean Clinical Nursing Research
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• v.19 no.2
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• pp.181-194
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• 2013

Purpose: Examining current status of nursing intershift handover practice would provide opportunity to identify areas in need of improvement. The aim of this study was to describe nursing intershift handover practice in Korean hospitals. Methods: A cross-sectional survey using questionnaire was used to collect data. A total of 788 nurses working in general hospitals had participated. Results: More than half of the nurses participated responded that they used kardex for verbal handover (51.8%). The average time took for handover was 40.2 minutes (SD=14.7). Only 5.8% of nurses were satisfied with intershift handover practice. 72.9% of respondents did not have manuals for handover and 86% of nurses considered intershift handover manuals were necessary. Most nurses considered intershift handover pratice as an important component for patient safety (99.2%). The causes of handover error were interruption during handover, high work load, and stress/fatigue of nurses. Conclusion: The findings of this study indicated a need to develop handover practice guidelines which outline pertinent details. Intershift handover practice guidelines could provide consistency and structure to the information that is handed over.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8A
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• pp.802-812
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• 2007

A Fast handover protocols for Mobile IPv6 networks can support seamless service by reducing handover latency to mobile nodes. To gain advantage derived from the fast handover in IEEE 802.16e networks, we propose a new fast handover protocol using a multiple simultaneous binding mechanism and a handover protocol based on trigger event for IEEE 802.21 in order to integrate IEEE 802.16e handover protocol and FMIPv6 handover protocol using link layer trigger. Through the numerical analysis, we compare performance of the proposed protocol and FMIPv6 protocol.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.10B
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• pp.1175-1181
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• 2011

For vertical handover, the part for the homogeneous handover needs to be modified, which allows users to utilize the various wireless access schemes with a mobile terminal with PFMIPv6. In this paper, we considered a cross-layer design for fast vertical handover between MIH and PFMIPv6, where two MIH-layer messages are suggested to reduce handover latency and integrate between MIH and PFMIPv6 efficiently. The proposed scheme is evaluated with handover latency. The results show that the proposed handover procedure reduces handover latency compared with the existing one.