• IEMEK Journal of Embedded Systems and Applications
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• v.4 no.1
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• pp.16-22
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• 2009

This paper aims at designing an impulse-radio ultra-wideband (IR-UWB) transceiver, especially targeting the IEEE 802.15.4a indoor ranging and communication systems. We first investigate the IEEE 802.15.4a IR-UWB signals and suggest the full-digital transceiver architecture accordingly. Since the wireless systems equipped with the impulse signal have the property of low-duty cycle, i.e., discontinuity in time, while the conventional systems takes the continuous signals, it is required to reconfigure the system design, including link budget. Following brief introduction to our IEEE 802.15.4a IR-UWB system hardware, we finally examine the ranging performance in indoor environments to verify our system design.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1485-1488
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• 2008

Lawful Interception (LI) 이란 합법적인 형태의 도청을 말하며, 전통적인 Wired tapping 뿐만 아니라, 최근의 복잡해진 인터넷 및 통신환경의 여러 형태의 데이터들에 대한 감청이 포함 될 수 있다. 미국과 유럽 중심으로 개발 된 감청 표준들은 3 세대 통신망 위주의 감청을 위한 표준들이 대부분이며, 802.16e 기술중의 하나인 모바일 WiMax 를 위한 합법적 감청 표준 개발은 진행 중에 있는 실정이다. 특히, Wibro 와 같이 모바일 유닛(MU)이 Radio Access Contro (RAS)와 Access Control Router (ACR)를 자유롭게 이동하는 상황에서 패킷들에 대한 지속적인 추적은 합법적 감청 분야의 중요한 이슈 중의 하나이다. 따라서, 본 논문에서는 국내의 802.16e/WiBro 네트워크 사용자의 증가 및 그에 따른 보안위협 발생의 가능성 증가에 따라 합법적인 감청을 위한 효과적인 아키텍처를 제안하고자 한다. 본 논문에서 제안하는 아키텍처는 802.16e/WiBro 망내의 합법적 감청을 위하여 네트워크상에서의 효과적인 감청 관련 정보 교환을 위한 기본적인 메커니즘을 포함하고 있다.

• Information and Communications Magazine
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• v.25 no.3
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• pp.60-63
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• 2008

WiBro 기술이 IEEE 802.16e 표준으로 채택되기까지의 과정은 크게, 국내표준이 우선되던 단계(2002. 11$\sim$2004. 6.)와 IEEE 802.16을 중심으로 국제표준에 힘쓰던 단계(2004. 7.$\sim$2005. 12.)으로 나누어서 볼 수 있다. 첫 번째 단계는 정부에 의한 비활성화된 2.3-2.4 GHz WLL용 주파수 대역의 회수 및 활용을 위한 WiBro 개념의 도입부터, ETRI를 중심으로 한 연구개발 프로젝트의 추진, TTA 내의 PG302 프로젝트그룹의 결성 및 적극적 국내표준화 활동을 통한 표준초안의 개발까지의 과정에 해당된다. 이 과정에서 개념의 창출부터, 요구사항의 정의, 방식의 선정, 규격 초안의 개발까지의 과정을 독자적으로 수행하였으며, 독자 기술에 의한 국내 기술의 개발 및 표준화를 바탕으로 국제표준화를 추진하기 위한 꿈과 도전의 시기였다고 할 수 있다. 두 번째 단계는 규모의 경제의 실현 및 국제표준의 중요성에 대한 인식에 따른 IEEE 802.16e를 중심으로 한 국제표준화의 추진을 통한 표준 IPR의 확보 및 시험 규격 등 제반 규격의 정비 등 세계 최초 상용화를 위한 표준선도의 시기였다고 할 수 있다. 나름 아쉬움이 없는 것은 아니나, 우리 힘으로 여러 난관들을 극복하고 상용화 및 IMT-2000 국제표준채택을 통한 세계화의 실현 등을 위한 성숙의 시기였다고 할수 있다. 이제 4세대 이동통신 표준화에서도 대한민국이 주도적인 역할을 수행해야 할 때이다. 좀 더 우리의 역량을 결집하고 발휘할 수 있도록 지혜를 발휘하여야 한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.5
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• pp.39-48
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• 2016

One of the major trends of automotive networking architecture is the introduction of automotive Ethernet. Ethernet is already used in single automotive applications (e.g. to connect high-data-rate sources as video cameras), it is expected that the ongoing standardization at IEEE (IEEE802.3bw - 100BASE-T1, respectively IEEE P802.3bp - 1000BASE-T1) will lead to a much broader adoption in future. Those applications will not be limited to simple point-to-point connections, but may affect Electric/Electronic(EE) Architectures as a whole. It is agreed that IP based traffic via Ethernet could be secured by application of well-established IP security protocols (e.g., IPSec, TLS) combined with additional components like, e.g., automotive firewall or IDS. In the case of safety and real-time related applications on resource constraint devices, the IP based communication is not the favorite option to be used with complicated and performance demanding TLS or IPSec. Those applications will be foreseeable incorporate Layer-2 based communication protocols as, e.g., currently standardized at IEEE[13]. The present paper reflects the state-of-the-art communication concepts with respect to security and identifies architectural challenges and potential solutions for future Ethernet Switch-based EE-Architectures. It also gives an overview and provide insights into the ongoing security relevant standardization activities concerning automotive Ethernet. Furthermore, the properties of non-automotive Ethernet security mechanisms as, e.g., IEEE 802.1AE aka. MACsec or 802.1X Port-based Network Access Control, will be evaluated and the applicability for automotive applications will be assessed.

• Journal of the Korea Society for Simulation
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• v.15 no.3
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• pp.87-91
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• 2006

With the growth of the internet, the number of wireless internet users has increased continuously up to date. However, mobile communications could not support high speed transmission rate with cheap communication fee and wireless LAN has problems in providing terminal mobility and wide area connectivity, respectively. So the WMAN standard has been newly designed to make up for these limits. The initial 802.16 specification effectively offers a solution for providing fixed users with high speed wireless communication but it does not offer terminal mobility. So the 802.16d and 802.16e have been developed as the next generation solution that can support various PHY layer (SC, SCa, OFDM, OFDMA) and offer the terminal mobility. In this paper, we propose an effective uplink scheduling algorithm for VoIP with using UGS, and we show that our proposed algorithm is superior in view of average delay and management of uplink bandwidth to conventional rtPS algorithm and the scheme in reference, with using NS-2 network simulator.

• The KIPS Transactions:PartC
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• v.16C no.5
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• pp.661-668
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• 2009

The Extended real-time Polling Service (ErtPS) is proposed tosupport QoS of VoIP service with silence suppression which generates variable size data packets in IEEE 802.16e systems. If the silence is suppressed, VoIP should support Comfort Noise Generation (CNG) which generates comfort noise for receiver's auditory sense to notify the status of connection to the user. CNG mode in silent-period generates a data with lower bit rate at long packet transmission intervals in comparison with talk-spurt. Therefore, if the ErtPS, which is designed to support service flows that generate data packets on a periodic basis, is applied to silent-period, resources of the uplink are used inefficiently. In this paper, we proposed the Improved ErtPS algorithm for efficient resource utilization of the silent-period in VoIP traffic supporting CNG. In the proposed algorithm, the base station allocates bandwidth depending on the status of voice at the appropriate interval by havingthe user inform the changes of voice status. The Improved ErtPS utilizes the Cannel Quality Information Channel (CQICH) which is an uplink subchannel for delivering quality information of channel to the base station on a periodic basis in 802.16e systems. We evaluated the performance of proposed algorithm using OPNET simulator. We validated that proposed algorithm improves the bandwidth utilization of the uplink and packet transmission latency

• ETRI Journal
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• v.32 no.5
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• pp.823-826
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• 2010

This letter proposes a handover ranging power adjustment scheme to improve handover performance. Incorrect ranging power can degrade handover performance due to the increased handover latency; therefore, the proposed scheme exploits the uplink channel information to adjust the uplink handover ranging power. Simulation results demonstrate that the proposed scheme reduces call outage probability by 33% compared to that of the conventional scheme. It also improves the number of users who satisfy the system requirements for handover interruption time.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.490-490
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• 2006

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.326-326
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• 2006

• Journal of Communications and Networks
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• v.10 no.4
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• pp.412-421
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• 2008

We observe simultaneous transmission of relay stations (RSs) allowed in current IEEE 802.16j draft standard for multi-hop relay networks may involve severe interference among the RSs, hence leading to throughput degradation. Allowing only 1/3 of the RSs to simultaneously transmit instead of 1/2 RSs as in the current draft standard reduces the interference but results in reduced throughput. To remedy this problem, we devise schemes to incorporate network coding at link-layer level (decode-and-forward) into the simultaneous transmission of RSs. Data movement is rearranged to maximize coding gain. Formula is derived to dictate exact movement of packets traveling between base station (BS) and mobile stations (MSs) via intermediate RSs. The frame structure in the current IEEE 802.16j draft standard does not allow broadcast needed for network coding. We devise a new frame structure which supports the broadcast. A new R-MAP (pointers to the burst data) is introduced to implement the broadcast. Since our new frame structure is used only for BS to RS or RS to RS communication, our schemes retain backward compatibility with legacy MSs based on IEEE 802.16e standard. Simulation based on simple configuration of RSs shows considerable improvement in terms of system throughput and round trip delay. For a 4-hop relay network with 1 BS and 4 RSs with symmetric traffic in uplink (UL) and downlink (DL), throughput is improved by 49% in DL and by 84% in UL traffic compared with IEEE 802.16j draft standard under the assumption that omni-directional antennae are used in BS and RSs.