• The KIPS Transactions:PartC
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• v.18C no.4
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• pp.251-254
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• 2011

In a WLAN, the data reception rate of a user station depends not only on the received signal strength (RSS) from an AP (Access Point) but also on the contention level of the AP. However, since only the RSSs measured at the physical layer have been used for a station to select an AP to associate with, the station may not satisfy the minimum quality requirements necessary for a seamless IPTV service. Thus, in this paper, we propose an AP selection method to support quality requirements of the IPTV service in a wireless LAN without modifying the IEEE 802.11 standard. A user station keeps monitoring a contention level of APs around it and a quality of an ongoing IPTV service. If the quality deteriorates below a threshold, the station reassociates with another AP having the least load so that the ongoing IPTV program is played without disruption.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.291-293
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• 2012

급격히 증가하는 모바일 디바이스에 의한 모바일 데이터 요구량을 처리하기 위해 가장많이 고려되고 있는 IEEE 802.11의 WLAN은 셀룰러보다 높은 데이터 전송속도를 제공하지만 이동성이 고려되어있지 않다. 이에 본 논문에서는 Enterprise WLAN에서 IEEE 802.21 MIH 표준에 기반하여 Media Independent Information Server (MIIS)로부터 수신된 주변 AP들의 네트워크의 정보를 바탕으로 후보 엑세스 AP 네트워크를 선정 및 WiMAX에 make-before-break 핸드오버하는 방안을 제안한다. 제안하는 방안은 실제 Enterprise WLAN와 Mobile WiMAX 환경에서 이동하는 단말의 시간에 따른 TCP throughput에 대한 성능평가를 하였다. 이를 통해 제안하는 방안의 평균TCP throughput 성능이 9.04Mbits/s으로 기존 방안의 TCP throughput 성능 6.49Mbits/s보다 약 40%향상됨을 확인하였다.

• Journal of Satellite, Information and Communications
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• v.9 no.4
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• pp.16-19
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• 2014

In this paper, the beacon signals of WiFi doppler frequency detection based WiFi-AP was designed with the subcarrier between a transmitter and a receiver of WLAN(wireless LAN). We can use such signals to identify human moving as an antenna array and tracking of RF beam. This wireless security services with the combination of WiFi doppler frequency and adaptive beacon time signal was proposed for wireless detection and motion based services.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2A
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• pp.142-152
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• 2010

When a mobile station(MS) performs a handover, in the IEEE 802.11 WLAN, MS's channel scanning for discovering new available APs is the dominating factor in handover latency, accounting 90% of overall latency. In order to reduce such a scanning latency, we focus on the method for reducing the number of channels for the MS in handover process to scan. With the help of IEEE 802.21 information server(IS), a proper order of groups of channels to be scanned is offered by the current AP depending on the information of neighbor APs in terms of the distance from serving AP, traffic load and network topology. By using this scanning order, the passive scanning of a MS in normal operation enables the MS to filter out the unavailable channels, and thus to classify the candidate channels of neighbor APs into three groups. Then, a handover-imminent MS can perform the active scanning from the most reliable group of channels. Simulation results show that the proposed scanning scheme reduce the scanning latency in comparison with the conventional scheme.

• Journal of Internet Computing and Services
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• v.10 no.1
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• pp.33-41
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• 2009

Signals transmitted from access point (AP) or stations in different wireless LANs (WLAN) interfere each other when the WLANs are closely installed. When they are configured to use the same channel, signals from an WLAN get collided with signals from other WLANs so that the delay increases to user stations and the throughput decreases. In this paper, we propose a method in which an AP in a basic service set (BSS) detects other BSSs using the same channel and switches to a different channel not being occupied by any other BSS. We can avoid using the same channel with other BSS in spacially overlapped BSS environment. The proposed scheme is simulated and its characteristics are described with the analysis of the result. The results measured in terms of throughput show that the problems in overlapped wireless LANs can be resolved with the proposed method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3A
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• pp.209-216
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• 2005

This paper generally relates to the field of wireless local area networks(WLANs), and more particularly, to AP selection and association methods for the performance of a station. In these days, IEEE 802.11 Wireless LAN network is widely deployed and used as an emerging service to connect high-speed Internet in the public wireless environment. But, if there are many users in hot spot area, they suffer a severe decrease of performance. Thus it needs an association and access control mechanism especially when it is used in the public environment. In this paper, we suggest a selection and association method using Beacon or Probe Response frames based IEEE 802.11. Station selects AP using the information of the capacity area in a Beacon or a Probe Response frame. According to the present paper, an association method for a public WLAN service, which includes a WLAN user terminal and an AP for relaying WLAN communications to and from the user terminal, includes the steps of the user terminal asking the AP's states for access to a radio channel; and the station selects and associates with the AP According to the above-described selection in a high speed wireless Internet service based on public WLAN technologies that are currently in operations. Further, it is possible to improve the efficiency of network management.

• Journal of Advanced Navigation Technology
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• v.7 no.2
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• pp.149-155
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• 2003

This paper generally relates to the field of wireless local area networks(WLANs), and more particularly, to AP selection and association methods for the performance of a station. In these days, IEEE 802.11 Wireless LAN network is widely deployed and used as an emerging service to connect high-speed Internet in the public wireless environment. But, if there are many users in hot spot area, they suffer a severe decrease of performance. Thus it needs an association and access control mechanism especially when it is used in the public environment. In this paper, we suggest a selection and association method using Beacon or Probe Response frames based IEEE 802.11. Station selects AP using the information of the capacity area in a Beacon or a Probe Response frame. According to the present paper, an association method for a public WLAN service, which includes a WLAN user terminal and an AP for relaying WLAN communications to and from the user terminal, includes the steps of the user terminal asking the AP's states for access to a radio channel; and the station selects and associates with the AP. According to the above-described selection in a high speed wireless Internet service based on public WLAN technologies that are currently in operations. Further, it is possible to improve the efficiency of network management.

• Journal of the Korea Society of Computer and Information
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• v.17 no.12
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• pp.131-136
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• 2012

In these days, with the diffusion of mobile equipments, the number of WiFi Access Point (AP) is increasing, and the growth of WiFi AP causes the throughput degradation due to interferences between APs. This recent phenomenon demands the method able to be utilized with current WiFi network to improve the throughput of Wireless LANs. This paper studied the channel assignment method and several throughput enhancement methods to optimize Radio Resource Management (RRM) for distributed infrastructure WLANs. As a result, it was able to put AP independently, improve older allocation error, and improve execution speed.

• 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.

• Journal of Communications and Networks
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• v.16 no.3
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• pp.305-310
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• 2014

Optimal position of access point (AP) is important for multi-gigabit wireless transmission in terahertz (THz) wireless local area network (WLAN)-type applications, where there exist the THz characteristic multiple clusters in channel propagation. By considering the multiple clusters in THz indoor communications, this paper investigates the optimal AP position when two APs are issued for increasing the system capacity. Numerical results reveal that the central position of each AP within each half service region, which offers the shortest cumulated path length for line-of-sight paths, is optimal to achieve the maximal system capacity.