• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.10
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• pp.33-51
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• 1997

On ATM-based wired/wireless integrated network, we apply the connection re-routing method[1] which reduced the inter-cluster handoff delay by reserving VPI/VCLs for possible inter-cluster handoff calls in advance. Additionally, we propose wired resource reservation methods, which are ausiliary method and split method, for handoff QoS guarantee of various expected services. The characteristics of these methods reserve wired connection resources based on the information on the possible inter-cluster handoff calls. With mathematical analysis, we also propose each algorithm and cost function for deciding an optimal amount in reserving resources. With numberical examples, we can see that the auxiliary method effectively reduces the cost in all cases(.alpha.>.betha., .alpha.=.betha., and .alpha.<.betha.). The split method has a little cost-reduction effects, when handoffs call does not have priority over new calls (that is, .alpha..leq..betha.) and the total capacity is relatively large. In other cases, the split method, however, has effective cost-reduction effects. The numerical resutls show that these reservation methods ca flexibly cope with the time-variant environment and meet the QoS requriements on the inter-cluster handoff calls.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.7
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• pp.24-31
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• 2009

Resource reservation scheme is an effective method to guarantee QoS for handoff calls in the next generation multimedia mobile communication systems, but it causes negative impacts on blocking probability of new calls. In this paper, to optimize the tradeoff between dropping probability of handoff calls and blocking probability of new calls, relay station based handoff prioritization control algorithm is proposed. In this algorithm, the relay station participates in handoff procedure and enables mobile stations to have guaranteed prompt service after handoff by providing highly efficient data transmission. In this paper, Markov chain models of the proposed handoff prioritization schemes are developed, and dropping probability of handoff packets and blocking probability of new packets are derived. By numerical analysis, the proposed algorithm has been proved to outperform conventional handoff prioritization schemes in terms of dropping probability of handoff packets and blocking Probability of new packets.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.8
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• pp.1-9
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• 1997

Soft handoff provided in CDMA cellular system has much advantage such as better service quality, interference control and low call dropping probability. In this paepr, we propose an optimum resource reservationscheme for handoff calls in the CDMA cellular system to increase the soft handoff probability in handoff. In the proposed scheme, resources of each frquency channel are reserved for handoff according to the number of its neighbot cells serving the same frequency channel. A performance analysis shows that the soft handoff probability of the proposed scheme is higher than that of conventional scheme disregarding the condition of frquency assignment of neighbot cells, and that ever frequency channel served by neighbor cells should reserve more than one traffic channel for handoff to get good performance.

• Journal of Advanced Navigation Technology
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• v.19 no.4
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• pp.318-322
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• 2015

In wireless communication networks, most of the prediction techniques are used for predicting the amount of resource required by user's calls for improving their demanding quality of service. However, we propose a channel allocation scheme based on predicting the resources of white spectrum holes for improving the QoS of rental user's spectrum handoff calls for cognitive radio networks in this paper. This method is supported by Wiener predictor to predict the amount of white spectrum holes of license user's free spectrum resources. We classify rental user's calls into initial calls and spectrum handoff calls, and some portion of predicted spectrum-hole resources is reserved for spectrum handoff calls' priority allocation. Simulations show that the performance of the proposed scheme outperforms in spectrum handoff call's dropping rate than an existing method without spectrum hole prediction(11% average improvement in 50% reservation).

• Journal of Advanced Navigation Technology
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• v.13 no.2
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• pp.208-213
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• 2009

This paper presents an adaptive call admission control(CAC) algorithm based on a target handoff call dropping probability in mobile wireless environments. This method uses a neural network for predicting and reserving the bandwidth demands for handoff calls and new calls. The amount of bandwidth to be reserved is adaptively adjusted by a target value of handoff call dropping probability(CDP). That is, if the handoff CDP exceeds the a target CDP value, the bandwidth to be reserved should be increased to reduce the handoff dropping probability below a target value. The proposed method is intended to prevent from increasing handoff call dropping probability when bandwidth to be reserved is not enough for handoff calls due to an uncertain prediction. Our simulations compare the handoff CDP in proposed CAC with that of an existing CAC. Results show that the proposed method sustains handoff call dropping probability below our target value.

• Journal of the Korean Operations Research and Management Science Society
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• v.36 no.3
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• pp.45-59
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• 2011

OFDMA systems have been expected to be widely used to provide multimedia services over wireless channels. To evaluate performance of the OFDMA system, power should be considered as system resource as well as subcarriers. This study propose a queueing traffic model incorporating two kinds of resources (power and subcarriers), and an extended model giving a priority to handoff calls over new calls. Some extensive experiments are conducted to illustrate the usefulness of the proposed traffic model.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.85-94
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• 2005

In this thesis, we propose a Speed Accommodation Priority Algorithm Scheme(SPAS) and Traffic Control Model Scheme (TCMS) to satisfy a desired handoff dropping probability and to reduce the blocking probability of new calls using mobility characteristics and handoff rate in mobile communication networks. The guard channels below threshold can guarantee the Quality of Service(QoS) in terms of the request handoff dropping probability and the guard channels above the threshold can be used to handle high priority new calls and high priority handoff calls. When the ratio of the handoff call arrival rate is less then the ratio of the new call arrival rate, the proposed method can guarantee the new call better than the previous guard channel scheme.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.2
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• pp.24-31
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• 2000

The channel allocation strategy is very important in wireless multimedia networks since the mobility of users needs to be considered in addition to diversity of QoS requirements of multimedia traffic. A existing strategy to decrease the probability of handoff failure is guard channel method, which reserves channels at each base station for handoff calls. In this paper, we propose an efficient channel allocation strategy based on the prioritization of handoff calls used in the guard channel method. In the Proposed strategy guard channels are shared between non-real time and real time handoff calls. To decrease the probability of handoff failure, (when resources become scarce), the Call Admission Control takes some resources away from the active calls. The simulation results demonstrate that the Proposed strategy Provides higher channel utilization and lower probability of handoff failure than those of existing strategies.

• The Journal of the Korea Contents Association
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• v.2 no.1
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• pp.104-112
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• 2002

Dynamic Handoff Control Scheme (DHCS), which is propose d in this paper, suggests the method to request handoff at the optimal time. To accomplish this, DHCS measures the speed of the mobile station and sets the pilot strength for handoff request. When the pilot strength of the current base station is bigg or than the pilot strength for handoff request, which means the pilot strength of the current base station is big enough so the possibility of the call to be disconnected is low, DHCS doesn't request for the handoff even though the pilot strength of the adjacent base station is bigger than the pilot strength of the curent base station. DHCS guarantees the QoS (Quality of Service) by processing the handoff calls prior to new calls at the base station and providing continuous service for the mobile station by setting the priorities for the calls according to the queue waiting time transmitted from the mobile stations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.316-323
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• 2002

In this paper, we analyze the call control scheme that is using buffer at new call and handoff call for non-uniform traffic load distribution, the multiple cell environments and the multiple types of services such as voice and data service. Considering the facts, the call admission control method using the effective bandwidth concept is employed in this paper, The bandwidth for a new call and a handoff call is allocated by the number of mobile station and dynamically assigned by taking account of the blocking rate of new calls and the dropping rate of handoff calls. The call control procedure is experimented through a simulation study by dynamically the bandwidth to new and handoff calls based on the blocking rate and the dropping rate. The results show our call control scheme can get a good quality of service for mobile users.