• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.10
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• pp.1950-1956
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• 2007

IEEE 802.16e has many points to be improved. Among them, fast handover is essential when user moves in high speed. In this paper we proposed a fast handover scheme using handover candidate BS set. This scheme is based on IEEE 802.16e, however according to the performance evaluation results through simulation; our proposed scheme shows more than 30% of handover delay reduction and at least 5% of handover drop probability improvement.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8A
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• pp.802-812
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• 2007

A Fast handover protocols for Mobile IPv6 networks can support seamless service by reducing handover latency to mobile nodes. To gain advantage derived from the fast handover in IEEE 802.16e networks, we propose a new fast handover protocol using a multiple simultaneous binding mechanism and a handover protocol based on trigger event for IEEE 802.21 in order to integrate IEEE 802.16e handover protocol and FMIPv6 handover protocol using link layer trigger. Through the numerical analysis, we compare performance of the proposed protocol and FMIPv6 protocol.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.311-316
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• 2005

The power saving mechanism of IEEE 802.16e operates in two modes; awake mode and sleep mode. While the user terminal transmits and receives packets in awake mode, it sleeps for a given interval to save the power consumption in sleep mode. The IEEE 802.16e specifies that the user terminal increases the sleep interval exponentially unless it has to wake up. In this paper, we analyze the performance of IEEE 802.16e power saving mechanism by considering down link traffic conditions. With the extensive simulations, we observe the trade-off between the power saving performance and the average packet delay. In addition, we observe that various performance parameters of IEEE 802.16e power saving mechanism are affected by the traffic patterns.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12A
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• pp.959-965
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• 2011

As the usage of mobile stations increases thanks to various services, power saving mechanisms of mobile station operated by battery power have been gained much attention. This paper presents a power saving mechanism(PSM) of IEEE 802.16m, called Mobile WiMAX, for 4G mobile technology. This paper first presents different points of the PSM of IEEE 802.16m from IEEE 802.16e, which is a basis of IEEE 802.16m. This paper proposes a dynamic sleep cycle adjustment algorithm for improving the performance of IEEE 802.16m PSM by considering the arrival pattern of incoming packets from base station. Performance of the algorithm is analyzed in terms of energy consumption as well as waiting time of packets.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11A
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• pp.1113-1119
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• 2007

In this paper, first, we proposed various possible candidate schemes for determining initial sleep window size and varying sleep window size in sleep mode for power saving class I of IEEE 802.16e. Then, we analyzed and compared the power saving performances of those schemes. The schemes used for the comparisons are EICV of IEEE 802.16e, and other comparable schemes such as EIED, EILD, LIED and LILD. Experimental results show that LILD and EIED outperform other comparable schemes. Especially, EIED shows the better performances for the case of high traffic intensity environments, while LILD does for the low traffic intensity case.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.872-875
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• 2005

Portable Internet extended from wireless LAN has a large cell size, similar to a wireless mobile communication, and can provides the seamless service which offers middle-low speed mobility. IEEE 802.16e, the international standard of Portable Internet, uses PKMv2(Privacy Key Management) protocol for authorization and key exchange between a MSS(Mobile Subscriber Station) and a BS(Base Station). This paper first reviews and studies overall security architecture of TTA HPi standard and IEEE 802.16e which supports mobility based on WMAN(Wireless Metropolitan Area Network) standard(IEEE 802.16)

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.24-34
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• 2010

본 고에서는 IEEE 802.16m 표준 및 기술 동향에 대해서 개관한다. 현재 상용화된 IEEE 802.16e 시스템에서 진화된 IEEE 802.16m 시스템은 IMT-2000을 대체할 차세대 이동 통신 시스템을 목표로 한다. 이런 요구 사항을 만족시키기 위해 우선 IEEE 802.16m 시스템은 IEEE 802.16e 시스템과의 호환성이 유지되어야 하며, 차세대 통신 시스템 표준으로 추진 중인 IMT-Advanced 시스템의 성능 요구사항을 만족시켜야 한다. 이와 같은 목표 달성을 위해 물리 계층 및 MAC 계층에서 다양한 기술들이 고려되었고, 본 고에서 전반적인 기술들에 대해서 간략히 살펴보도록 한다. 더불어, ITU-R에 제출한 IMT-Advanced 제안서의 결과를 토대로 IEEE 802.16m 시스템의 성능을 살펴보도록 한다.

• Information and Communications Magazine
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• v.24 no.11
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• pp.5-13
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• 2007

광대역 무선 접속 표준을 관장하는 IEEE 802.16 워킹 그룹은 IEEE 802.16 표준을 2004년에 발표하였으며 이 IEEE 802.16 표준안에는 현재 WiMAX(Worldwide Interoperability for Microwave Access)라 불리는 고정 및 저속 이동 접속에 대한 광대역 무선 통신 지원 기술이 포함되어 있다. 특히 여러 기술 중 보안 관점에서 IEEE 802.16 표준은 MAC 계층 안에 PKM(Privacy Key Management)라고 불리는 Security Sub-layer를 가지고 있다. PKM은 PKMv1과 PKMv2로 구분되며, 먼저 PKMv1은 기본적인 인증 및 기밀성 기능을 제공하고 IEEE 802.16 표준에 기본적으로 적용되어있다. 하지만, IEEE 802.16 표준 이후 많은 연구들이 PKMv1의 보안성에 대하여 의문을 제기하였고 이에 따라 IEEE 802.16 표준안의 확장 개선안으로서 완전한 이동성을 바탕으로 하는 2005년 발표된 IEEE 802.16e 표준안에서는 향상된 보안 기능을 제공하는 PKMv2를 제공하며 기존 표준안의 부족한 점을 보완하기 위하여 시도하였다. 이러한 PKMv2는 EAP(Extensible Authentication Protocol) 인증, AES(Advanced Encryption Standard) 기반 기밀성 제공 알고리즘, CMAC/HMAC(Cipher/Hashed Message Authentication Code)을 사용한 메시지 인증 기능 제공 등 보다 다양한 보안 기능을 제공하였다. 그러나 IEEE 802.16e 표준안의 보안 기능은 SS(Subscriber Station)과 BS(Base Station)간의 통신구간 보안에 초점을 맞추어서 네트워크 도메인간의 보안 문제나 핸드오버시 보안과 같은 네트워크 구조적 보안 취약성을 여전히 가지고 있다. 하지만 표준안에서 정의하고 있는 SS와 BS 구간 보안 역시 완전한 솔루션을 제시하고 있지는 않다. 본 논문에서는 이러한 취약성을 고찰하고 그에 따른 대응방안을 제시하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11C
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• pp.1023-1029
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• 2006

In this Paper, we present a novel authentication and key exchange(AKE) protocol for inter-NSP(provider) roaming in IEEE 802.16e networks. The proposed protocol allows performing both user and device authentication jointly by using two different authentication credentials and Provides user anonymity and session key establishment. Also, this protocol requires only two round number message exchange between foreign network and home network.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.5
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• pp.47-53
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• 2007

The purpose of IEEE 802.16j is to extend coverage and to enhance throughput by using relay station additionally to conventional IEEE 802.16e . The cellular system experiences performance degradation at the cell edge due to pathloss, shadow and multipath fading. We can get advantage of spatial diversity gain by using relays more than two cooperatively in the IEEE 802.16j system. Cooperative relaying using space-time code provides better performance under multipath fading and has more robustness against the shadow fading than single relaying. In this paper, we investigate the performance of IEEE 802.16j using cooperative relaying by link level simulation. We also show that the cooperative relaying system achieves better performance than the conventional single relaying system. We apply realistic shadow model considering correlations between shadow fadings of different relaying paths. It is shown that the performance of the system depends highly on the spatial location of relay stations.