• 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 Communications and Networks
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• v.6 no.3
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• pp.245-257
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• 2004

Driven by the growing number of the mobile subscribers, efficient channel resource management plays a key role for provisioning multimedia service in the next generation personal communication systems. To reuse limited channel resources, diminishing the coverage areas of cells seems to be the ultimate solution. Thus, however, causes more handover events. To provide seamless connection environment for mobile terminals and applications, this article presents a novel handover scheme called the intelligent channel reservation (ICR) scheme, which exploits the location prediction technologies to accurately reserve channel resources for handover connections. Considering the fact that each mobile terminal has its individual mobility characteristic, the ICR scheme utilizes a channel reserving notification procedure (CRNP) to collect adequate parameters for predicting the future location of individual mobile terminals. These parameters will be utilized by the handover prediction function to estimate the expected handover blocking rate and the expected number of idle channels. Based on the handover prediction estimations, a cost function for calculating the damages from blocking the handover connections and idling channel resources, and a corresponding algorithm for minimizing the cost function are proposed. In addition, a guard channel decision maker (GCDM) determines the appropriate number of guard channels. The experimental results show that the ICR scheme does reduce the handover-blocking rate while keeping the number of idle channels small.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.11
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• pp.3680-3693
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• 2022

The handover procedure of IEEE 802.11 wireless local area networks (WLANs) introduces significant delay, which can degrade the quality of service (QoS) especially for delay-sensitive applications. Although studies have been conducted to support handover in SDN-based WLAN, there is no research to reduce the channel scanning procedure that takes up the most delay time in the handover process. The channel scanning procedure is essential to determine the appropriate access point (AP). To mitigate this problem, this paper proposes a SWITCH: SDN-WLAN integrated handover scheme for QoS-Guaranteed mobile service. In SWITCH, each AP periodically broadcasts beacon frames through different channels in a predetermined order that includes the operating channel information of the AP. This allows mobile stations (MSs) to receive the beacon frames of nearby APs, and therefore they can determine the appropriate APs for handover without the channel scanning procedure. By reporting the information of the newly moved AP to the SDN controller, a flow rule is installed in advance to provide fast handover, and packet loss is reduced by buffering data destined for MS. In addition, the proposed scheme can adaptively operate SWITCH to consider the user location and QoS requirement of flow to save radio resource overhead. Performance evaluation results demonstrate that SWITCH can reduce the handover delays, flow table utilization ratio and radio resource overhead while improving the network throughput.

• ETRI Journal
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• v.32 no.5
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• pp.823-826
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• 2010

This letter proposes a handover ranging power adjustment scheme to improve handover performance. Incorrect ranging power can degrade handover performance due to the increased handover latency; therefore, the proposed scheme exploits the uplink channel information to adjust the uplink handover ranging power. Simulation results demonstrate that the proposed scheme reduces call outage probability by 33% compared to that of the conventional scheme. It also improves the number of users who satisfy the system requirements for handover interruption time.

• Journal of applied mathematics & informatics
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• v.33 no.1_2
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• pp.211-217
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• 2015

A dynamic spectrum access scheme with channel partitioning for secondary handover calls in cognitive radio networks is proposed to reduce forced termination probability due to spectrum handover failure. A continuous-time Markov chain method for evaluating its performance such as blocking probability, forced termination probability, and throughput is presented. Numerical and simulation results are provided to demonstrate the effectiveness of the proposed scheme with channel partitioning.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.13-16
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• 2000

This paper introduces a more effective usage of the limited OVSF cod in compressed mode which is used during inter-frequency/inter-system handover in UTRA(Universal mobile telecommunications system) Terrestrial Radio Access). The usager is to use dynamic common channel which is shared by several users during the compressed mode.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.11 s.353
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• pp.44-53
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• 2006

In this paper, we propose a new Active Channel Scanning scheme by scanning active channels employed by neighbor APs' with the handover counts and non overlap channel information for fast handover. Under the proposed scheme, the mobile which has finished handover to connect a new APsends the neighbor AP's channel information learned by itself during handover to the new AP. And then, the new AP relays the neighbor channel information to the old AP. It decides a priority by handover counts and non overlap channel information for building a Neighbor Channel Table(NCT), and also sends the table information to its associated mobile nodes, periodically. As a result each mobile can scan only active neighbor APs' channels when performs handover based on the referring to NCT information. Using NS-2 Simulator, we applied to supposed ACS that the result of simulation decides to sort by handover counts and non overlap channel information. we evaluate our proposed ACS scheme based on NCT along with the full scanning scheme and the selective scanning scheme. From simulation results, we show that the proposed scheme is advantageous over the other two schemes in terms of the number of scanning channels and the scanning latency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.12C
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• pp.1273-1279
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• 2006

In this paper, we address the design of adaptive handover schemes based on the signal strength measurement for cellular communications systems. Conventional handover algorithms, which are based only on the downlink measurement, cannot guarantee the required uplink quality because uplink channel can differ greatly from downlink channel quality. Therefore, we proposes a new suboptimal adaptive handover algorithm that considers both the uplink and downlink channel quality in order to achieve the best cell selection gains when there is a wide difference between the uplink and downlink signal quality. Simulation results show that the proposed scheme achieves better performance compared to conventional handover schemes.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.2
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• pp.60-66
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• 2008

In this paper, a new subcarrier-based handover scheme which exploits different channel gains of subcarriers in downlink OFDMA cellular systems. In this handover scheme, mobile users can obtain diversity gain by subcarrier selection. Feedback for unselected subcarriers reduces interference. The capacity enhancement by the handover scheme is originated from the following two characteristics of OFDMA systems. One is that interference per subcarrier is proportional to the traffic load. The other is that every subcarrier has different channel gain ?? 새 the Rayleigh fading channel. Therefore, selecting subcarriers with stronger channel gains results in diversity gain. Simulation results confirm that the proposed handover scheme improves the capacity of the OFDMA systems by reducing 24 percentage of the outage probability.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.595-598
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• 2014

In order to provide the Mobile Stations operating in IEEE 802.11 Wireless LAN network with seamless handover, a comprehensive study on the functions of handover considering various networking environments and characteristics of Mobile Stations is required. Note that the channel scan process finding a new AP takes the major portion of handover time, and this is the most significant issue with seamless handover for real-time multimedia service in WLAN environment. In this paper the functions required to provide seamless handover in IEEE 802.11 WLAN network are identified, and a new scanning technique is proposed with which the Mobile Stations can selectively scan the channels to reduce the channel scan time in various network environments. Here each Mobile Station awares of the channels the neighbor APs are using by scanning them in advance according to the proposed technique. Afterwards, when handover is actually required, the optimal AP is decided quickly by scanning only the predetemined group of channels and order of scan without unnecessary scan of all the channels. In addition, proposes to enter the Scan Trigger Value and Handover Threshold Value in mobile phones in order to prevent the phenomenon can not handover.