• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.38B no.8
• /
• pp.623-631
• /
• 2013

Wireless LAN (WLAN) interface is one of the major sources drastically depleting the battery power of mobile devices such as smartphones and tablets. Most commercial mobile devices employ a power saving technique putting their WLAN interface into a sleep state when there is no network traffic, and thereby, save the battery power. However, since an access point (AP) just transmits the packet(s) received from a server to the corresponding mobile device immediately, it may cause a problem that the mobile device constantly remains in an awake state so that its battery power is rapidly drained. In this paper, we point out this problem and propose a new scheme that can save the mobile device's battery power with an adaptive packet scheduling at the AP side. From the experimental results based on a testbed, we found that the proposed scheme outperforms existing schemes over 50% in terms of power saving.

• Journal of the Korea Society of Computer and Information
• /
• v.15 no.11
• /
• pp.117-124
• /
• 2010

Appling centralized network management architecture SNMP(Simple Network Management Protocol) to wireless networks causes the network overhead, NAT(Network Address Translation) problem on AP, and performance degradation of mobile nodes. In this paper, we propose an integrated management scheme for wired and wireless networks using mobile agents in order to solve above problems. In our proposed scheme, SNMP is applied to manage wired networks and MAs of SNMP are implemented in APs or wireless nodes to manage wireless networks. In addition, we propose a method to reduce the redundant OID information within SNMP response messages. Through the analysis, we show that our proposal resolves the given problems and reduces the processing delay of the wireless nodes.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.8
• /
• pp.3654-3659
• /
• 2011

The MAC protocol of HiperLAN/2 is based on TDMA/TDD. The radio channels are assigned by AP(Access Point) that is centrally operated. Mobile terminal that data transmission is necessary to uplink requests radio resource to AP through RCH channels. The changing number of RCHs in each MAC frame is important because too many RCHs may result in a waste of radio resources and too few RCHs may result in many access collisions and prolong time that connect to AP. Therefore, number of RCH should be allocated properly according to traffic. From these viewpoints, this paper proposes an advanced scheme that dynamically changed the number of RCH which is based on the number of success and collision of RR message in previous MAC frame. To prove efficiency of proposed scheme, lots of simulations are conducted and analyzed.

• 한국정보통신설비학회:학술대회논문집
• /
• 2007.08a
• /
• pp.159-162
• /
• 2007

최근 IPv6 기반 WiBro 망에서 다수의 사용자가 동종망간 혹은 이기종망간 인터넷 연결을 유지하면서 그룹으로 이동하는 상황에서의 핸드오버 처리 폭증 및 핸드오버 지연 시간 문제를 효율적으로 해결할수 있는 기술 및 시스템이 요구되어 지고 있다. 본 이동 AP는 IPv6 기반 WiBro 망에서 다양한 광대역무선망 접속 및 다양한 하향 단말 접속이 가능한 하드웨어 기반에 네트워크 이동성 기술를 구현하여 IPv6 기반 WiBro 네트워크 실, 내외 환경에서 이동성을 지원하지 않는 다수의 단말들이 네트워크 이동시 각 단말들의 이동성 처리가 수행됨을 확인하였으며 관련 서비스 연속성이 유지됨을 시험을 통해 확인 할 수 있었다.

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

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.4
• /
• pp.463-469
• /
• 2014

We propose an interworking architecture between a smart TV and a smart phone. This architecture provides control mechanism for the newly adopted App on Smart-TV with smart phone. The general method connecting between a smart phone and a mobile AP is very carefully complex and troublesome procedure. The mobile AP transfers data from a smart phone to a smart TV after getting the connection. Connecting procedure between a smart phone and a mobile AP is therefore necessary operation. We worked out the new procedure and control method that acquires some information from Near Field Communication or Quick Reference codes for connecting between a smart TV and a smart phone. Our proposed architecture was confirmed practical possibility as user-oriented automatic connection and simple manipulation for control a kiosk or various display equipment.

• Proceedings of the Korean Information Science Society Conference
• /
• 1999.10c
• /
• pp.673-675
• /
• 1999

본 논문은 기존의 유선환경에서의 서비스 환경을 이동 환경에서도 지원하기 위한 분산 구조를 다루고 있다. 이를 위하여 이동 단말기를 논리적으로 대신하는 이동 AP의 위치를 추적하는 추적 AP를 두어 기존의 응용 환경에서 수행되던 응용 프로그램들을 무선이동 환경에서도 수용할 수 있도록 하였다. 이동 단말기의 위치 변경에 따른 이동 AP, 추적 AP 사이에서 발생되는 핸드오프처리 알고리즘이 소개되었으며, 이 알고리즘은 패킷 손실이나 순서의 변경과 같은 흐름제어 기능을 포함하고 있다. 또한 무선 환경에서 발생 가능한 핸드오프와 소프트 핸드오프를 함께 고려하였다. 시뮬레이션의 결과는 핸드오프 과정에서의 추가 지연 시간에 대한 내용을 다루고 있다.

• Journal of Digital Convergence
• /
• v.10 no.4
• /
• pp.257-263
• /
• 2012

Smart phones become popular all over the world recently. At the same time, demand of various additional services, such as SNS by utilizing low-cost reliable Wi-Fi network and position information, is expected to keep growing. In this paper, Implementation of SNS based on an Open Wi-Fi & Position Information was proposed. This service is achieved by constructing an Open Wi-Fi network based on a built AP access information database. And in order to provide durable connection in mobile environment, RSS detect AP switching module and mobile IP are utilized in the proposed service. Furthermore, with the utilization of GPS information of AP, AP providers could delivery various information such as advertisements, promotion events. In addition, it is possible for AP users to communicate with each other, thus a position information based SNS was also proposed in this paper.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2011.10a
• /
• pp.261-264
• /
• 2011

Corded telephone to the phone using a wireless phone as the trend to switch, free Wi-Fi-enabled mobile phones, netbooks, and mobile devices, are spreading rapidly. But wireless Internet phone calls using your existing Internet network to deliver Internet services because it has a vulnerability that will occur. Government agencies are using Voice over Internet Protocol(VoIP) calls from the current wired and wireless connection and usage is increasing. In this paper, we have discovered that the vulnerability of wireless internet Wi-Fi AP and the FMC administrative agencies, such as VoIP on your wireless device to study the vulnerability. Wi-Fi AP and the FMC is to analyze the vulnerability. VoIP call interception, attack, attack on the base of the experiment is the analysis. Security-enhanced VoIP call for a Wi-Fi AP and the FMC's defense against man-in-the-middle attacks and is the study of security measures.

• Journal of the Korea Society of Computer and Information
• /
• v.20 no.2
• /
• pp.89-97
• /
• 2015

In this paper, we propose a handoff method supporting LBS (Location Based Services) Information in mobile clouding environment. In mobile clouding computing, handoff delay and re-authentication is occurred. A mobile node needs re-authentication procedure from cloud server whenever it arrives new AP. But Using of location information of node enables to reduce delay time due to re-authentication. To reduce re-authentication delay time, proposed method stores location information of APs on WiFi based location server to complement. GPS-based technology which can't receive satellite signal in indoor and then node collects location information of AP at handoff time. And also enables to process LBS without increasing handoff delay by splitting the process of handoff from process of requesting location information. For analysis of proposed method, We analyze handoff delay and location information process time and have compared previous handoff method in cloud environment. We confirmed that proposed method shows lower delay time without increasing LBS process time than previous method because node receives location information from location information server when handoff is occurred.