• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39A no.12
• /
• pp.718-728
• /
• 2014

The multi-band wireless local area network (WLAN) using 60 GHz band and the lower band (typically 2.4 GHz/5 GHz band) can support the very high data rate in short-distance communication using 60 GHz band and the long-distance communication using the lower band. For heightening the efficiency of multi-band WLAN, an band selection scheme is a necessity. In this paper, we propose an effective frequency band selection scheme for multi-band WLANs. By using computer simulation with NS-3, we show the performance of the proposed schemes when the stations suffer from the human blockage and the log-normal shadowing.

• Journal of Advanced Navigation Technology
• /
• v.10 no.1
• /
• pp.13-19
• /
• 2006

In this paper, Gaussian impulse generator for DS-UWB was proposed and fabricated so that the frequency band allocated to WLAN, around 5 GHz, was suppressed in accordance with the regulation of radiation spectrum limitation defined by FCC. In order to transform an unipolar rectangular signal to a Gaussian impulse, the proposed impulse generator consists of two stage impulse generation parts; the first stage using dual SRD and the second stage using gain switching of semiconductor laser diode. The result shows a gaussian impulse as narrow as 180 psec in width. In addition, high order derivative Gaussian filter with a structure of 4 stage ring resonators was designed and fabricated so that DS-UWB impulse generator could reduce the frequency spectrum of WLAN by 25 dB compared to the spectral power of th adjacent UWB band.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.15 no.3
• /
• pp.551-560
• /
• 2011

Recently, There has been increasing concern about WLAN-based indoor positioning system. Most of the existing WLAN-based positioning systems use a fingerprinting method as a main approach. In the fingerprinting approach, the accuracy of the location of a mobile objects is proportional to the number of reference points. However, depending on the increasing number of reference points in the training phase, it requires more time and effort to create fingerprint database. To solve these problems, we propose the new indoor positioning algorithm that calculate the distance between a mobile objects and an AP using the information of surrounding environment WLAN based APs and applied the particle filter to the proposed algorithm in order to improve the accuracy of the estimated location in this paper. To implement this algorithm, at first environmental information database such as wall, iron door, glass door, partition etc. existing in the periphery of the AP should be established. The positioning use attenuation model and path loss model. Our experimental results with proposed algorithm are verified that the positioning accuracy was low but solved the problems with fingerprinting, compared with other positioning algorithms.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2018.10a
• /
• pp.517-521
• /
• 2018

In this paper, we designed a microstrip antenna for LTE / WLAN for wireless mobile communication high - speed communication network. The substrate of the proposed antenna is FR-4 (er = 4.3), the size is $20[mm]{\times}40[mm]$ and can be used in the frequency band of 2.77 [GHz] and 5 [GHz] Respectively. The simulation was performed using CST Microwave Studio 2014. The simulation result shows that the gain is 2.034 [dBi] at 2.77 [GHz] and 4.95 [dBi] at 5 [GHz]. The S-parameter was also found to be less than -10 [dB] (WSWR 2: 1) in the desired frequency band. The frequency bands of LTE and WLAN are widely used around the world, and the usage of the frequency is also increasing. For this reason, the dual-band antenna of LTE / WLAN is designed to help many users in a good way to use both technologies.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.6
• /
• pp.116-126
• /
• 2008

This paper describes the Dual-band WLAN transmitter with 2.4[GHz], 5[GHz]. Dual-band WLAN transmitter was designed at 2.4[GHz] and 5[GHz]. The Dual-band WLAN transmitter has a amplifier which operate at 2.4[GHz] and 5[GHz] frequency and two VCO(Voltage Controlled Oscillator) or VCO has a wide scope of frequency. these problem cause a size and a power consumption, The Dual-band WLAN transmitter module was proposed to solve these. the transmitter was designed to get output signals of IEEE 802.11a's 5.8[GHz] band signal using frequency multiplication way or to act a amplifier about the 2.4[GHz] band signal of IEEE 802.11b/g, according to inputed frequency and bias voltage that a eve using single transmission block. The output spectrum get the improved specification of ACPR of 4[dB], 6[dB], 16[dB] at +11[MHz], +20[MHz], +30[MHz] offset of center frequency compared to no linearization, was satisfied to transmit spectrum mask of IEEE 802.11a wireless Lan.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.11
• /
• pp.2656-2664
• /
• 2015

IoT management hub has to request the WLAN AP list of the accessible areas in a place that is installed, or choose a specific WLAN AP you want to connect in order to be connected to the Internet. the specific method also is required to input the password when the security key was set. As that way, IoT management hub needs both the display device and the input device to see the list of WLAN AP and to input the security key. If the IoT management hub is consist of them, It is difficult to achieve the objective of the miniaturization and cost reduction. In this paper, we propose a method to connect to a WLAN AP network using a smart-phone without the display device and the input device.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.12 no.12
• /
• pp.2195-2200
• /
• 2008

The use of WLAN technology specially 802.11 b and g has seen huge subscriber growth in a relatively short time period due to low cost and ease of installation of WLAN hardware. These technologies provide multiple data rates ranging from 1 to 54 Mbps depending on modulation used in physical layer. This paper presents the performance of 802.11b and g under different data rates in mobile IPv4 environment. OPNET is used in the study as the network simulator. The performance metrics used in this wort is data traffic received by a WLAN station roaming amongst Access Point(AP) of different ESSs. It is found that much data packets are lost during handover between mobile agents. The traffic received by the roaming station varies based on the data rates provided by two different WLAN technologies.

• 한국ITS학회:학술대회논문집
• /
• v.2006 no.10
• /
• pp.108-112
• /
• 2006

• Information and Communications Magazine
• /
• v.31 no.5
• /
• pp.73-79
• /
• 2014

IEEE 802.11 Wireless Local Area Network (WLAN)을 위한 전력 절약 방식에 관한 연구는 오랫동안 연구 되었음에도 불구하고 계속 발전하고 있다. 본 고는 최근 진행된 IEEE 802.11WLAN을 위한 전력절약방식에 관해 알아보고 향후 진행될 관련 연구 방향에 대해서 논의해 본다.

• Review of KIISC
• /
• v.15 no.5
• /
• pp.83-89
• /
• 2005

네트워크 컨버전스 및 사용자 이동성의 중시로 무선랜 기반에서 음성 서비스를 이용하고자 하는 VoWLAN 서비스에 대한 관심이 고조되고 있다. 그러나 무선랜 보안 표준기술을 그대로 적용하고자 할 때는 AP 간을 이동할 때와 서브넷 간을 이동할 때 로밍에 대한 문제가 발생한다. 이에 본 논문에서는 VoWLAN 서비스를 구현할 때 로밍과 보안 기능을 동시에 제공하기 위한 설계방법을 제안한다.