• Journal of Communications and Networks
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• v.15 no.1
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• pp.15-24
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• 2013

Provisioning of quality of service (QoS) is a key issue in any multi-media system. However, in wireless systems, supporting QoS requirements of different traffic types is a more challenging problem due to the need to simultaneously minimize two performance metrics - the probability of dropping a handover call and the probability of blocking a new call. Since QoS requirements are not as stringent for non-real-time traffic, as opposed to real-time traffic, more calls can be accommodated by releasing some bandwidth from the already admitted non-real-time traffic calls. If the released bandwidth that is used to handle handover calls is larger than the released bandwidth that is used for new calls, then the resulting probability of dropping a handover call is smaller than the probability of blocking a new call. In this paper, we propose an efficient call admission control algorithm that relies on adaptive multi-level bandwidth-allocation scheme for non-realtime calls. The scheme allows reduction of the call dropping probability, along with an increase in the bandwidth utilization. The numerical results show that the proposed scheme is capable of attaining negligible handover call dropping probability without sacrificing bandwidth utilization.

• Journal of Information Processing Systems
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• v.11 no.4
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• pp.583-600
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• 2015

Generally, the wireless network provides priority to handover calls instead of new calls to maintain its quality of service (QoS). Because of this QoS provisioning, a call admission control (CAC) scheme is essential for the suitable management of limited radio resources of wireless networks to uphold different factors, such as new call blocking probability, handover call dropping probability, channel utilization, etc. Designing an optimal CAC scheme is still a challenging task due to having a number of considerable factors, such as new call blocking probability, handover call dropping probability, channel utilization, traffic rate, etc. Among existing CAC schemes such as, fixed guard band (FGB), fractional guard channel (FGC), limited fractional channel (LFC), and Uniform Fractional Channel (UFC), the LFC scheme is optimal considering the new call blocking and handover call dropping probability. However, this scheme does not consider channel utilization. In this paper, a CAC scheme, which is termed by a uniform fractional band (UFB) to overcome the limitations of existing schemes, is proposed. This scheme is oriented by priority and non-priority guard channels with a set of fractional channels instead of fractionizing the total channels like FGC and UFC schemes. These fractional channels in the UFB scheme accept new calls with a predefined uniform acceptance factor and assist the network in utilizing more channels. The mathematical models, operational benefits, and the limitations of existing CAC schemes are also discussed. Subsequently, we prepared a comparative study between the existing and proposed scheme in terms of the aforementioned QoS related factors. The numerical results we have obtained so far show that the proposed UFB scheme is an optimal CAC scheme in terms of QoS and resource utilization as compared to the existing schemes.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1463-1466
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• 2002

This paper suggests the effective channel assignment scheme for mobility prediction handover. For maintaining required quality of service (QoS) during handover, there are handover algorithms these reserve the channel where the movement is predicted. But channel assignment schemes these have been studied are not considered mobility prediction handover. This paper suggests the channel assignment scheme that considers mobility predicted handover. The suggested algorithm maintains dropping probability of handover calls, decreases blocking probability of new calls and increases channel utilization.

• Journal of Advanced Navigation Technology
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• v.21 no.4
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• pp.347-352
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• 2017

In this paper, we propose a method that reduces mobile user's handover call dropping probability by using cognitive radio technology(CR) in cellular - based wireless cognitive radio networks. The proposed method predicts a cell to visit by Ziv-Lempel algorithm, and then supports mobile user with prediction of spectrum holes based on CR technology when allocated channels are short in the cell. We make neural network predict spectrum hole resources, and make handover calls use the resources before initial calls. Simulation results show CR technology has the capability to reduce mobile user handover call dropping probability in cellular mobile communication networks.

• 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.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.4
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• pp.56-63
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• 2009

Resource reservation scheme is effective for better QoS guarantee to handover call for the next generation cellular systems where handover rate highly increases. However, resource reservation for handover call can incur negative impact on the new user admission. In this paper, we propose a random access based adaptive group-wise reservation to effectively reduce dropping rate of handover call, while protecting new local call. In the proposed scheme, target base station divides adaptively future handover users into groups based on the expected handover time, and then does group-wise reservation, where service allocation within each group is done on random access basis. Markov approach is also provided to analyze the performance of the proposed scheme. By computer simulation, it is shown that theoretical analysis on the performance is similar to the simulation results and the proposed reservation scheme outperforms the conventional scheme with respect to dropping probability of handover call.

• The Transactions of the Korea Information Processing Society
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• v.7 no.8S
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• pp.2608-2619
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• 2000

This paper proposes the Handover Scheme for the mobile and describes the result of the performance analysis. In the conventional scheme of handover request, the withdrawal of terminal may occur because handover request is performed based on fixed signal level without considering network load and terminal mobility. The proposed scheme offers the minimization of withdrawal and handover blocking probability by means of the handover request of terminal based on the network load and terminal mobility. Conventional handover scheme has the sequential procedure that network performs resource check and path rerouting on the handover by MT(Mobile Terminal). Proposed handover scheme pre-processes the resource check before the handover request by predicting the handover request timo so that handover latency can be reduced. Moreover, path optimization is executed after the completion of handover in order to reduce handover latency. The rdduction of handover latency prevents the dropping of service by minimizing backward handover blocking. In summary, we propose the prediction of handover request time and decision method based on terminal, validating the performance of proposed scheme considering various cases of simulation.

• Journal of Information Processing Systems
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• v.14 no.3
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• pp.771-789
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• 2018

In heterogeneous wireless networks supporting multi-access services, selecting the best network from among the possible heterogeneous connections and providing seamless service during handover for a higher Quality of Services (QoSs) is a big challenge. Thus, we need an intelligent vertical handover (VHO) decision using suitable network parameters. In the conventional VHOs, various network parameters (i.e., signal strength, bandwidth, dropping probability, monetary cost of service, and power consumption) have been used to measure network status and select the preferred network. Because of various parameter features defined in each wireless/mobile network, the parameter conversion between different networks is required for a handover decision. Therefore, the handover process is highly complex and the selection of parameters is always an issue. In this paper, we present how to maximize network utilization as more than one target network exists during VHO. Also, we show how network parameters can be imbedded into IEEE 802.21-based signaling procedures to provide seamless connectivity during a handover. The network simulation showed that QoS-effective target network selection could be achieved by choosing the suitable parameters from Layers 1 and 2 in each candidate network.

• ETRI Journal
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• v.29 no.1
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• pp.113-115
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• 2007

A dynamic tri-threshold call admission control scheme has been developed. This scheme supports voice, data, and multimedia services and it complies with the universal mobile telecommunications system. The performance of the proposed scheme is evaluated under varying handover rates. The QoS performance-including channel utilization, call dropping probability, and blocking probability-is investigated. The performance of the developed scheme is found to be encouraging.

• Journal of IKEEE
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• v.7 no.1 s.12
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• pp.80-87
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• 2003

This paper proposes a routing scheme for multi-hop LEO satellite networks with inter-satellite links aiming for reducing the number of link handovers while keeping the efficient use of network resource. The proposed routing scheme controls the link handovers by taking account of the deterministic LEO satellite system dynamics, geographical location of a ground terminal and statistic information of call duration. The performance of the proposed routing scheme has been evaluated and compared with previous routing schemes in terms of average number of link handovers during a call, the call blocking and dropping probability, and the network utilization.