• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.35S no.1
• /
• pp.39-51
• /
• 1998

In this paper, we propose signaling procedures amon network elements for a connection rerouting method which can reduce inter-switch handoff processing delay reduces the delay in the connection re-routing by reserving VPI/VCIs for possible inter-switch handoff calls in advance. Additionally, we mathematically analyze the signaling procedures and then suggest solutions to the relations with cluser size, network topoloty, handoff-request rete and handoff delay. With simulation, the solutions are validated. From numerical examples, we concluded taht handoff delay, one of the handoff QoSs, can be satisfied by adjusting the cluster size and network topology according to the handoff -request rate of service area. With our proposed signaling and analytic methods, we concluded that the connection rerouting method using cluster-sectoring effectively reduces the delay of inter-switch handoff processing than dynamic connection rerouting method. Our solutions are useful in guaranteeing the requested handoff delay (especially, inter-switch handoff delay) when the connection rerouting method is applied to ATM-based wireless/wired integrated network.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.4
• /
• pp.748-760
• /
• 1997

The handoff failure probability has to be enhanced efficiently to enhance the performance of PCS system. In this paper a new scheme called velocity adaptive handoff algorithm for reducing handoff failure probability and maintaining the carried traffic constantly in PCS systems, by assigning low handoff threshold value for high mobility calls, and assigning high handoff threshold value for low mobility calls, is presented. The performance of evaluation of this new scheme is carried out in terms of tranffic characteristics. Also velocity estimation algorithm for this new scheme is presented. According to the result, the handoff failure probability of velocity adaptive handoff algorithm is enhanced about 60%.

• Child Health Nursing Research
• /
• v.21 no.3
• /
• pp.204-215
• /
• 2015

Purpose: This descriptive research was conducted to identify educational needs in pediatric nursing handoff training to improve students' handoff skills. Methods: Data were collected using a survey with 188 senior nursing students and 48 pediatric nursing professors and clinical nurses. The survey included items on general information as well as experiences in handoff training, necessity, training content, and items for a handoff training program in pediatric nursing. Results: Of the nursing students, 30.5% reported receiving handoff training during their clinical hours. After their handoff training, the students' confidence index was only 3.78 out of 10. Significantly, 98.3% of the respondents said that pediatric handoff training is necessary. In addition, participants reported that simulation practice (26.5%) is an appropriate educational method, and the time required for handoff training should be 8.16 hrs. Admission process was placed first as the most critical circumstance for handoff (56.8%). High demands were observed for the necessity of training content for patients with respiratory problems. Conclusion: The results of this study show the various educational needs for developing a patient safety pediatric handoff training program to promote nursing students' skills in handoff.

• International Journal of Contents
• /
• v.1 no.1
• /
• pp.45-49
• /
• 2005

If the service provider provides mobile service with mobile switching centers that use different handoff message format, the soft-handoff between mobile switching centers is not available and the hard-handoff scheme is used instead. When this occurs, calls are often disconnected or there is an interruption of service. This can be very annoying to a mobile user. We propose the handoff subsystem of the ATM switch which provides the soft-handoff between wireless cells under the control of different MSCs. The proposed handoff subsystem transforms the handoff message format of the source MSC to that of the destination MSC. It also provides efficient routing scheme that distributes handoff packets to balance the traffic load.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.12A
• /
• pp.991-1001
• /
• 2003

CCFH(Candidatecasting Fast Handoff) algorithm excels the performance of existing fast handoff schemes using multicasting in terms of handoff latency and B/W efficiency. The scheme uses L2 information(BSSID) at Wireless LAN and starts multicasting before L2 handoff. So it can reduce L3 handoff latency. At this article, we would show that Candidatecasting Fast Handoff Scheme is clearly new scheme using L2 information and has the good performance.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.8
• /
• pp.1659-1667
• /
• 1997

In DS-CDMA cellular systems, using the same frequency channel at the adjacent cells simultaneously makes soft handoff possible. In soft handoff, mobiles use multiple radio resources for the space diversity of signal in the overlapped region. The previous traffic models of hard handoff are not applicable to the system with soft handoff due to switching radio channels in that region. The handoff rate can be calculated by the mobility of mobiles, which is a function of the size and shape of a cell, and the speed and density of the mobiles. In this paper, we propose an analytical traffic model to study the soft handoff rate. We assume that the system uses a two-way handoff scheme for practical purposes, which connects only two cells to a mobile during soft handoff. We performed a computer simulation to confirm the accuracy of the proposed soft handoff model. The simulation results show good agreement with the analytical model.

• Proceedings of the Korea Society for Simulation Conference
• /
• 2003.11a
• /
• pp.139-144
• /
• 2003

Mobile Node has to maintain communication as they move form place to place, so it doesn't guarantee Quality of Service(QoS). Fast Handoff is important to provide multimedia and real-time applications services in mobile, and it is closely related to handoff delay. Therefore, handoff delay problem is actively studied to quarantee QoS as a main issue in mobile IP research area. Next generation Mobile IPv6 resolve this problem somewhat, triangle problem for first packet and handoff delay still remain. In this paper, we suggest SNMP Information-based routing that adds keyword management method to Information-based routing in active network in order to resolve such a problem, and then suggest QoS controlled handoff based on SNMP Information-Based routing. After modeling of suggested method and existing handoff method, simulations are carried out with NS-2 for performance evaluation. The results of simulations show the some improvement on handoff delay, and therefore on QoS improvement.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.7A
• /
• pp.987-995
• /
• 1999

The handoff is a distinctive characteristic of the mobile networks. In the CDMA systems, if base stations support multiple Frequency Assignment (FA), they provide both soft handoff and hard handoff. Under the CDMA environments, the soft handoff guarantees the favorable service quality and the continuity of call connection without interruption, and increases the service capacity of the base stations. This paper proposes call connection control schemes with handoff queue for supporting efficient handoff processing. The proposed schemes are divided into two categories: single handoff queue scheme and multiple handoff queue scheme. We analyze the performance of the proposed call connection control schemes using numerical analysis. From the analysis results, we can say that it is more desirable to avoid hard handoff as long as handoff queues are used. When a single handoff queue used, adaptive scheme that properly mixes avoidable and avoidable hard handoff method under the given traffic condition is more desirable. In case that multiple handoff queues are used, the suitable trade-off needs to be developed between handoff blocking probability and hard handoff probability to guarantee a given blocking probability threshold.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.44 no.5
• /
• pp.16-24
• /
• 2007

Wireless mesh network extends the limited coverage of conventional wireless service from one-hop access point to wider area. It is recognized as an important issue to provide seamless handoff in the wide coverage of wireless mesh network. A long handoff delay may cause high packet loss and disconnection of service, degrading the network performance. The handoff delay is mainly introduced from the channel scanning process obtaining information to make handoff decision and the unnecessary handoffs due to inaccurate handoff decision. In this paper, we propose the handoff algorithm based on one-way trip time (OTT) to expedite the handoff procedure. As compared to the handoff algorithm based on the receiving signal power, the proposed algorithm takes advantage of OTT to obtain the necessary handoff information in a relatively shorter time and reduce the unnecessary handoffs. The performance of proposed algorithm is evaluated through the simulations. It is verified that the proposed handoff algorithm can effectively enhance the handoff accuracy, and therefore reduce the handoff delay and unnecessary handoffs.

• ETRI Journal
• /
• v.28 no.5
• /
• pp.676-679
• /
• 2006

In this letter, we propose an adaptive hard handoff algorithm with a dynamic hysteresis value based on the received signal strength from the serving base station, for mobile cellular communication systems. A discrete-time method is presented to evaluate handoff algorithms analytically. Performance is evaluated in terms of the average number of handoffs, the probability of link degradation, and the average handoff delay. Numerical results and simulations demonstrate that the proposed algorithm outperforms the handoff algorithm with fixed hysteresis values and the handoff algorithm using both threshold and hysteresis.