• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.4
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• pp.295-301
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• 2011

A triple-band transceiver module for 2.3/2.5/3.5 GHz mobile WiMAX, IEEE 802.16e, applications is introduced. The suggested transceiver module consists of RFIC, reconfigurable/multi-resonance MIMO antenna, embedded PCB, mobile WiMAX base band, memory and channel selection front-end module. The RFIC is fabricated in $0.13{\mu}m$ RF CMOS process and has 3.5 dB noise figure(NF) of receiver and 1 dBm maximum power of transmitter with 68-pin QFN package, $8{\times}8\;mm^2$ area. The area reduction of transceiver module is achieved by using embedded PCB which decreases area by 9% of the area of transceiver module with normal PCB. The developed triple-band mobile WiMAX transceiver module is tested by performing radio conformance test(RCT) and measuring carrier to interference plus noise ratio (CINR) and received signal strength indication (RSSI) in each 2.3/2.5/3.5 GHz frequency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.5
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• pp.1125-1132
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• 2010

WiBro(Wireless Broadband Internet) is the standard of high-speed portable internet based on OFDMA/TDD (Orthogonal frequency division multiple access / Time division duplexing) techniques, and the subset of consolidated version of IEEE802.16e Wireless MAN standard. In this paper, we propose performance improvements of WiBro system using the 64QAM SOFM(Self-Organizing Feature Maps)prefiltering. Proposed method used the prefiltering SOFM neural network blind equalization in the Broadband 64 QAM WiBro system receiver. The prefiltering SOFM neural network constellates 64QAM that is transmitter data shape and the blind equalization removes ICI(Inter Carrier Interference). To verificate the proposed method usability, the MSE and the BER are simulated. The simulation results shown that is improved the performances of the proposed WiBro system using the 64QAM SOFM Prefiltering than the existing WiBro system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8A
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• pp.815-820
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• 2008

Carrier frequency offset (CFO) is one of the most important problems in an orthogonal frequency division multiplexing (OFDM) system, which seriously degrades the performance of the systems due to its time-variant behavior. In this paper, the performance of a pilot-assisted fine CFO estimator in OFDM-based mobile WiMAX systems is analyzed. Analytical closed-form expression of the mean square error (MSE) of the post-FFT based CFO synchronization scheme is reported for time-variant fading channels. Taking into account the frame structure of the IEEE802.16e standard, simulation results are used to verify the theoretical analysis developed in this paper.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.2
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• pp.23-32
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• 2010

WiBro(Wireless Broadband), the service based on IEEE 802.16e(mobile WiMAX) standard, is a wireless broadband Internet technology being developed by the domestic telecommunication industry. In this paper, we analyze security vulnerabilities of WiBro focusing on initial authentication phase and propose a specification-based intrusion detection system that can detect those vulnerabilities. We first derive a specification from the normally operational process of the initial authentication based on PKMv2 EAP-AKA and formalize the derived specification as a state transition diagram. Proposed system executes the intrusion detection based on those specification and state transition diagram. In this paper, to verify the detection capability of proposed system, we construct a test bed network and execute scenario-based test.

• Journal of Advanced Navigation Technology
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• v.18 no.1
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• pp.84-89
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• 2014

Worldwide Interoperability for Microwave Access (WiMAX) is an efficient technology for 20th century communication system. The technology provides broadband speed without the need for cables and is based on the IEEE 802.16 standard(also called Wireless MAN). Mobile WiMAX is defined as IEEE802.16e which is advanced and efficient technology for mobile telecommunication rather than GSM, CDMA technology. In this work link budget calculation for WiMAX have been done. Cell range have been calculated over digital modulations and they are BPSK, QPSK and QAM. Here different types of models like Cost 231 model have been used for different types of areas like open, rural and urban areas and Erceg-Greenstein model for sub-urban areas. Effect of various parameters like frequency, base station antenna height, transmission power and SNR over cell range have been studied. Analysis have done for both uplink and downlink.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.2
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• pp.160-168
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• 2013

In tactical environment, tactical wireless networks are generally comprised of Tactical MANETs(T-MANETs) or Tactical WMNs(T-WMNs). The most important services in tactical network are voice and low rate data such as command control and situation awareness. These data should be forwarded via multi-hop in tactical wireless networks. Urgent and mission-critical data should be protected in this environment, so QoS(Quality of Service) must be guaranteed for specific type of traffic for satisfying the requirement of a user. In IEEE 802.11s, TDMA-based MAC protocol, MCCA(MCF Controlled Channel Access), has a function of resource reservation. But 802.11s protocol can not guarantee the end-to-end QoS, because it only supports reservation with neighbors. In this paper, we propose the routing protocol, R-HWMP(Reservation-based HWMP) which has the resource reservation to support the end-to-end QoS. The proposed protocol can reserve the channel slots and find optimal path in T-WMNs. We analyzed the performance of the proposed protocol and showed that end-to-end QoS is guaranteed using NS-2 simulation.

• The KIPS Transactions:PartC
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• v.16C no.2
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• pp.257-266
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• 2009

Now a days, as increased the use of mobile units like a laptop computer and PDA, the demand for high speed internet service is increasing. On the other hand, PKMv2 which is provided from IEEE 802.16e cannot support fully on the security of high speed internet service. This paper proposes light-weight mutual authentication protocol which solved security problem of PKMv2 related to integrity of mobile node for transmission of safe high speed data of mobile node operating in mobile WiMAX environment. Proposed mutual authentication protocol increases the efficiency as the user in network can move in network safely without additional procedure of authentication between subscriber and base station after user's initial authentication. Also, the proposed mutual authentication protocol is safe from the security attack (the man-in-the-middle attack and reply attack) between subscriber and base station by generating a key adopt to PRF() function using random number and secret value in order to secure certification.

• The Journal of the Korea Contents Association
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• v.11 no.1
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• pp.34-41
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• 2011

At present wireless internet access service is available through the 3G network, mobile WiMAX and WiFi anytime and anywhere. In this environment where there are various networks, users should be able to select specific networks depending on different situations. And it is necessary to provide mobility support between homogeneous and between heterogenous networks. Given this situation, the many proposals have been presented to link 3G, which has the largest service area among various networks, with mobile WiMAX(IEEE 802.16e), or with WiFi(IEEE 802.11). But, recently, with the increasing volume of wireless internet use and wireless internet data, due to the advents of net-book, e-book and smart phone, the service area of WiFi and mobile WiMAX has rapidly expanded. Especially, the availability of real-time application such as internet phone has led to the relative shrinking of the proportion of 3G mobile communication network giving conventional voice service, and enlargement of those of wireless internet access networks like WiFi and mobile WiMAX. This paper suggests a handover scheme based on PMIPv6, whitch support mobility between WiFi and mobile WiMAX, and minimizes handover delay. In this scheme, the mobile node has a dual stack structure composed of two interfaces-WiFi and mobile WiMAX. Since WiFi dose not support mobility, it is suggested that the mobile node have the capacity to deal with handover signaling between gateway in case of handover between homogeneous networks. This handover scheme, suggested comparing with current handovers between homogeneous networks, has proved, in its analytic evaluation, to be able to reduce handover, transmission, and signaling overhead.

• The KIPS Transactions:PartC
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• v.18C no.4
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• pp.265-278
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• 2011

The objective of this paper is to analyze and characterize end-to-end packet statistics after modeling and simulation of WiFi (IEEE 802.11g) and WiMAX (IEEE 802.16e) of a virtual wireless network using OPNET Modeler Wireless Suite. Wireless internal and external network simulators such as Remcom's Wireless InSite Real Time (RT) module, WinProp: W-LAN/Fixed WiMAX/Mobile WiMAX, and SMI system, are designed to consider data transfer rate based on wireless propagation signal strength. However, we approached our research in a different perspective without support for characteristic of these wireless network simulators. That is, we will discuss the purpose of a visual analysis for these packets, how to receive each point packets (e.g., wireless user, base station or access point, and http server) through end-to-end virtual network modeling based on integrated wired and wireless network without wireless propagation signal strength. Measuring packet statistics is important in QoS metric analysis among wireless network performance metrics. Clear packet statistics is an especially essential metric in guaranteeing QoS for WiMAX users. We have found some interesting results through modeling and simulation for virtual wireless network using OPNET Modeler Wireless Suite. We are also able to analyze multi-view efficiency through experiment/observation result.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.633-635
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• 2012

최근 이동통신 시스템 및 통신기술의 발달로 인해 동일 장소에서 동일 시간에 다양한 접속 네트워크에 접근이 가능하다. 또한 스마트폰과 같은 다양한 네트워크에 접속 할 수 있는 멀티인터페이스를 장착한 장치들이 등장하고 있다. 하지만 기존 네트워크 프로토콜은 단일인터페이스를 가정하고 구현되어 있다. 따라서 멀티인터페이스 환경에서 응용 서비스 요구에 맞는 네트워크 인터페이스를 선택할 수 있는 기능이 없다. 따라서 본 논문에서는 응용서비스가 요구하는 네트워크 품질에 맞는 최선의 네트워크를 선택할 수 있는 멀티인터페이스 기반 QoS 방법을 제안한다.