한국정보통신설비학회:학술대회논문집
한국정보통신설비학회 (Korea Institute of Information and Telecommunication Facilities Engineering)
- 기타
한국정보통신설비학회 2008년도 정보통신설비 학술대회
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In this paper, we propose the folded PIFA with its made an alteration to a factor of resonance for L-slot PIFA. Proposed antenna maintain diminished size patch and improve each bandwidth of GSM(0.88
$\sim$ -0.96 GHz) and W-CDMA(1.92$\sim$ 2,17 GHz) for miniaturized repeater. The non-slot step folded PIFA's structure that design of essence was general L-slot PIFA for dual-band. It has no U-slot, multi band and the another slot. The parameters of proposed antenna were optimized for dual-band and compact size by folded singleness patch. Proposed antenna by using folded singleness patch take satisfaction main point, bandwidth of GSM and W-CDMA, compact patch size($39{\times}21{\times}13mm^3$ ). The antenna was designed by FDTD simulation tool and it was made from result of simulation. Measured data shown that the proposed non-slot step folded PIFA was strong possibility. -
Future electric lights will be composed of white LEDs (Light Emitting Diodes). Indoor wireless optical communication systems utilizing white LED lights have been studying about it. Generally, plural lights are installed in room. Therefore, their optical path difference must be considered. In this paper, the influence of an optical path difference has been investigated and two approaches against this problem are introduced. One uses OOK-RZ (On-Off Keying, Return-to-Zero) coding and the other uses optical OFDM (Orthogonal Frequency Division Multiplexing). From the results of computer simulations, we have found that these approaches are feasible for the wireless optical communication systems utilizing white LED lights.
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In this paper, we study precoding techniques for co-channel interference suppression in multiuser MIMO systems. DPC is optimal techniques to achieve the system capacity of multiuser MIMO downlink channels. DPC is not proper in practical wireless systems because complexity is very high. So block diagonal precoding for multiuser MIMO downlink channel is studied. The block diagonal precoding is used to suppress co-channel interference between multiuser. Block diagonal precoding method, whose complexity is reduced by modified null space operation, change multiuser MIMO channel to multiple single-user MIMO channel. We also use V-BLAST decoder in receiver. V-BLAST decoder can achieve increased system capacity in proportion to the number of users. We show improved system performance by using computer simulation.
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A clustering scheme for ad hoc networks is aimed at managing a number of mobile devices by utilizing hierarchical structure of the networks. In order to construct and maintain an effective hierarchical structure in ad hoc networks where mobile devices may move at high mobility, the following requirements must be satisfied. The role of each mobile device for the hierarchical structure is adaptive to dynamic change of the topology of the ad hoc networks. The role of each mobile device should thus change autonomously based on the local information. The overhead for management of the hierarchical structure is small. The number of mobile devices in each cluster should thus be almost equivalent. This paper proposes an adaptive multihop clustering scheme for highly mobile ad hoc networks. The results obtained by extensive simulation experiments show that the proposed scheme does not depend on mobility and node degree of mobile devices in the ad hoc network, which satisfy the above requirements.
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In this paper, Designed Quadrature hybrid coupler apply Open-PI equivalent transmission line. Using the proposed structure we achieve significant size reduction with the same results of conventional quadrature hybrid coupler at 912MHz. The measured frequency responses agree well with simulated one.
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The CORBA that supports FPGA has not been used generally and it is difficult to implement and to develop the CORBA for FPGA. In this paper we propose the way to design FPGA to support a CORBA component. For FPGA to support the CORBA component, embedded processor provided by FPGA and PCI based CORBA is utilized. The PCI based CORBA is for improving data transfer throughput. This paper will be organized as follows. In Chapter I, existing research trend and background are presented for why we propose design of FPGA that support the CORBA component. In Chapter II, FPGA design for supporting CORBA components is proposed and described in detail. In Chapter III, simple experiment is tested to confirm the proposed FPGA design. Finally session 4 is conclusion of this paper.
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In this paper, we analyze the performance of pulse position modulation-time hopping ultra wide band (PPM-TH UWB) systems with antenna diversity technique in indoor wireless channel. A modified Saleh and Valenzuela (SV) model is adopted as a UWB indoor channel model. Perfect synchronization between a transmitter and a receiver is assumed. Therefore, coherent equal gain combining (EGC) scheme to collect the energy available in the multipath components is investigated. It is shown that the performance is improved by increasing the number of antennas at the receiver. The results of this paper can be applied to the applications of UWB.
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In this paper, study noise performance of LNA to enhance Q-factor of input circuit by patterned ground shield is inserted inductor using TSMC 0.18um. Applied LNA technology is cascode method. The input matching circuit was constituted on-chip and wirebonding inductor. Taguchi's method is used for the best suited structure of PGS. We confirmed enhancement of Q-factor by inserted PGS into inductor. The input matching circuit enhanced Q-factor by inductor with PGS improve noise figure of LNA.
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In this paper, we analyze the performance of ultra wide band (UWB) systems in indoor wireless channel in accordance with the number of pulses per bit at transmit signals and the decision types of receiver. The indoor channel is modeled as the modified Saleh and Valenzuela (SV) model which has been proposed as a UWB channel model by the IEEE group, IEEE 802.15.SG3a. Two types of UWB signals are considered One is the pulse position modulation-time hopping (PPM-TH) signal. And the other is the pulse amplitude modulation-direct sequence (PAM-DS) signal. It is assumed that the receiver is an ideal receiver which can receive all signals of the multipath.
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Many applications of sensor network require connection to the Internet. The transmission protocol of traditional sensor network was designed within the sensor network itself. However, based on 6LoWPAN which can be accessed using IPv6, direct connection is possible between the sensor network and the TCP/IP network outside. Transmission of data in applications of sensor network falls into two main categories. One is a small packet that is periodically produced such as packet related to temperature and humidity. The other is a relatively large packet that brings about network overheads such as images. We investigated the conformance test and pros and cons of application data over the transmission protocol of Zigbee and 6LoWPAN. As a result, both Zigbee and 6LoWPAN have shown low rate of loss for periodic data and have in creased reliability of data transfer. When transmitting streaming image data, both ACK, non ACK mode of Zigbee and UDP of 6LoWPAN minimized transmission time but suffered the consequences of high packet loss. Even though TCP of 6LoWPAN required a long transmission time, we were able to confirm that no loss has occurred.
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유비쿼터스도시(u-City) 에서 제공할 서비스 즉, u-City서비스를 실제로 구현하기 위해서 사용되는 기술을 u-City 기술이라고 할 수 있다 본 논문에서는 u-City서비스, u-City 기반시설 그리고 u-City 기술들 간의 관계를 명확히 설명하기 위한 도구로서 u-City 기술 참조모델을 정의하였다. 이러한 참조모델을 사용함으로써 u-City 구축자, 서비스 제공자, 운영자, 이용자 등 여러 u-City 참여자들이 공감할 수 있는 서비스-기술 연계 모델을 제시하였으며 향후 u-IT 세부 기술이 발전하고 새로운 u-City 서비스가 추가되어도 이를 원활히 수용할 수 있도록 하였다.
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This article describes power supply infrastructure construction methods which are considered from U-City infrastructure. For the eisting city and town, it is one the issue to find an economic method to construct outside infrastructure including ubiquitous service device. Because the economic construction method could minimize the construction budget which cost big portion of U-City. And the power supply infrastructure is the fundamental layer to keep network and service layer stable. This paper suggests several ways to construct methods with keeping pre-constructed underground power cable by attaching inepensive power nodal controller working in zigbee network and introduces how to monitor and mana ge the status of power supply to network and service device.
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성공적인 u-City 서비스를 제공하는데 있어 가장 중요한 역할을 수행하는 기능으로 u-City 통합운영센터가 지목되고 있다. 본 논문에서는 u-City 통합운영센터의 효율적인 운영 모델을 제안하였으며 이를 위해서 먼저 u-City 기술 참조모델을 기반으로 하는 표준화된 u-City 서비스 도입 및 운영 방안을 제시하였다. 또한 기존에 제공되고 있는 각종 도시 정보서비스를 점진적으로 u-City 서비스에서 수용하는 전략으로서 점진적 서비스 융합 방안을 제시하였다.
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In now days, Ubiquitous technology grow up, so the variety service are developed. Sensor networks purpose is collection information about environment and geographic. But sensor network has limit in power, cost and so on. There is much restriction. Some sensor networks purpose is monitoring environment. And there is some relation in sensing data. Sensor nodes sense information by periods. First sensing data correlate with next sensing data. At this point, this paper suggest power saving method. Some data are same, the other data are similar.
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u-City 도시통합운영 플랫폼은 u-City 내 교통, 건물, 시설물 등의 첨단화된 기반 시설을 전반적으로 관리하고 체계적으로 통제 가능하도록 한다. 그러나, 도시통합운영 플랫폼에 인가되는 부하는 도시 전반에 분산된 센서와 같은 정보원의 규모뿐 아니라 그 정보의 복잡성에도 의존할 수 밖에 없어, 효율적인 도시운영을 위해서는 플랫폼의 성능확보 방안이 고려되어야 한다. 일반적인 성능개선의 방법으로는 이미 발생한 부하의 효율적 처리를 통한 개선과 더불어 부하원의 근본적 통제와 같은 우회적 방법이 사용될 수 있다. 본 고에서는 네트워크 구조 개선을 통한 부하분산 방법과 더불어 플랫폼의 주 부하원인 센서 네트워크와의 연동방식 개선이라는 두 가지 측면에서 u-City 도시통합운영 플랫폼의 성능개선 방향을 고찰한다.
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제주도는 지리적 특성으로 인해 식수 및 용수를 지표수로 충당하기 어렵다. 이런 이유로 제주도에는 많은 취수장을 사용 지하수를 각종 용수로 이용하고 있다. 특히 식음수로 이용되는 지하수의 경우 수질과 유량, 탱크의 수위 등의 정보가 높은 수질과 안정적인 공급을 위해 반드시 필요하다 현재 제주도의 각 취수장에는 지하수 모니터링 시스템이 설치되어 다섯 가지 항목의 수질과 유량, 수위데이터를 수집하고 이를 바탕으로 각 취수장을 관리한다. 하지만 자연적 특성으로 인해 낙뢰가 빈번한 제주도에서 유선으로 연결된 시스템은 한 번의 낙뢰로 인해 전체 시스템이 다운될 수 있는 위험을 가지고 있다. 이런 위험을 막고자 무선 통신을 기반으로 하는 새로운 지하수 모니터링 시스템의 구축이 필요하였다. 본 논문에서는 IP-USN을 이용하여 원거리에 있는 수질, 유량 및 수위 측정 센서의 값을 무선으로 수집하고 이를 다시 중앙 모니터링 센터로 전송하는 시스템을 소개하고 시스템과 네트워크 구성 및 실제 구현에 대해 소개한다.
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최근 신도시를 중심으로 추진 중인 U-City 사업과 함께 도시시설물 관리분야에 정보기술의 활용이 활발히 이루어지고 있다. 특히 복잡, 다양해지고 있는 도시시설물의 효율적이며 지능적인 관리를 위하여 다수의 도시시설물들을 통합적으로 관리할 수 있는 통합관리 플랫폼에 대한 관심이 높아지고 있다. 따라서 본 논문에서는 기존의 개별적인 도시시설물 관리가 가지는 주요 문제점들을 살펴보고 이를 효과적으로 해결할 수 있는 도시시설물 통합관리 방안을 제시하였으며, 아울러 통합관리 플랫폼의 개념을 구조와 핵심 기능을 중심으로 설명하였다. 최신 공간정보기술과 상황인지기술을 기반으로 한 통합관리 플랫폼은 도시공간정보와 센서정보를 통합적으로 관리하고 다양한 도시 상황을 지능적으로 처리함으로써 관리 비용절감과 함께 관리자의 신속한 의사결정을 가능케 한다.
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도시의 많은 시설물을 좀더 지능화된 체계로 관리하기 위한 수단으로 RFID/USN을 이용한 솔루션이 다양하게 제안되고 있다. 최근에 상하수도, 전력, 가스, 통신 관로 등 지하시설물 관리분야도 기존의 도면 관리체계에서 센서를 이용한 실시간 운영관리시스템 형태로의 진화를 시도하고 있다. USN은 일반적으로 무선전송을 기반으로 발전시킨 기술로서 이를 지하 매설물 센서네트워크에 적용할 경우 여러 가지 제약사항이 따르게 된다. 전자기파의 물리적 특성상 지하에서는 통신이 어렵기 때문에 이를 보완할 수 있는 적용기술 및 시설물 분포에 맞는 네트워크 토폴로지 또 싱크 노드의 물리적 설치공간 확보 및 구동전력 공급 등 현장에서 부딪히는 여러 가지 네트워크 구축에 관련된 현안사항에 대하여 그 해결방법에 대하여 기술하였다.
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CMOS 기반의 고주파 집적회로에서는 높은 이득과 출력을 얻기 위하여 인덕터와 같은 수동소자를 사용한다. 그러나 수동소자를 사용하게 되면 넓은 면적을 차지하기 때문에 회로의 크기를 증가시키는 단점을 갖는다. 본 논문에서는 PMOS 를 기반으로 구현한 active inductor 를 적용하여 회로의 면적을 줄일 수 있으며, 기존의 주파수 변환기와 동등한 선형 특성을 갖는 상향 주파수 변환기를 설계하였다. 인덕터를 적용한 상향 주파수 변환기의 OIP3 (
$3^{rd}$ Output Intercept Point)는 1.3 dBm 을 가지며, 제안한 상향 주파수 변환기의 OIP3 는 0.8 dBm 으로 동등한 선형 특성을 보이며, layout 상에서 회로의 면적을 40 % 이상 감소하는 특성의 선형 송신기용 주파수 변환기를 설계 분석하였다. -
A transmitter (TX) leakage cancellation scheme using a Micro Controller Unit (MCU) is introduced. This paper highlights an adaptive anti-leakage signal generation via an MCU, which plays the key role in reducing the TX leakage signal level. High transmitter-to-receiver (TX-to-RX) isolation is verified with measurement results.
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Voice over IP is a telephone service which sends and receives the voices through the Internet. Because the infrastructure of wireless and mobile communication networks such as 3G, Wi-Fi and WiMAX has expanded, the study about Mobile VoIP, which provides the voice service from wireless network, has been actively in progress. Since Rei 6 HSPA in 3GPP and Rev A lxEVDO in 3GPP2, VoIP through the data channel is more efficient than circuit switch. It is predicted that VoIP over 4G will be more effective and 4G mobile VoIP business will be vitalized in the future. In addition, there are businesses which offer VoWLAN by using software such as Skype and Fring. They provide services which cheapen the price of international calls and long distance calls. This paper will present the Korean and other countries' mobile VoIP trends, its classification along the network connection, the study on techniques, and conditions of mobile VoIP. It also will be described a view of terminal convergence and service convergence.
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Forensic Marking is the technology that enables the service providers (SP) to identify the illegal digital contents distributors by first inserting markings (data indicating the user information and playback time) in realtime into the digital contents at time of playback of digital contents, and then later by extracting inserted markings from the contents which are illegally captured from the multimedia device such as IPTV STBs and distributed over the Internet. Digital Rights Management (DRM), which is a very popular content protection technology, has the security hole that can be vulnerable because the encrypted digital contents are transformed into their original plaintext forms after the decrypting process on the STBs. Therefore Forensic Marking (FM) has now become a companion content protection solution to DRM. This article describes a new way of tracking up to 4 illegal content users in FM implementation using the blue-difference chroma component of YCbCr color space. This FM technology has many advantages like fast processing time and easy portability to STB devices compared to that of the traditional watermarking processing in the frequency domain.
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3GPP는 사용자의 다운링크 패킷 데이터 Throughput을 높이고,NodeB에 MAC계층을 위치시켜, 사용자의 스케줄링과 재전송을 담당하게 함으로써, 다운링크 패킷의 전송 지연을 감소시키는 HSDPA(High Speed Data Packet Access)기술을 Release 5에서 도입하였다. NodeB에 위치한 MAC-hs 스케줄러는 각각의 사용자에게 가용한 NodeB의 RF power와 code 자원을 제공하며, R99에서 사용했던 Power control을 이용하는 대신, AMC(Adaptive Modulation and Coding)기능을 제공하여 Radio conditions에 따라 전송되는 Data Format을 조정하여 채널환경이 좋은 사용자에게는 높은 data Throughput을 제공하며, 채널환경이 좋지 않은 사용자에게는 낮은 data throughput을 제공하고 있다. 본 고에서는 매 TTI에 스케줄링된 사용자에게 제공하고도, RF power 및 code 자원이 남아 있을 경우, 스케줄러는 남은 자원을 각각의 사용자에게 재 분배하여, 초기에 추정한 HSDPA Throughput보다 향상된 성능을 갖을 수 있음을 설명하였다.
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The multistage wavelength division multiplexed passive optical network (WDM-PON) with multiple remote nodes (RN) can accommodate widely spread subscribers efficiently and it increases the channel usage. We implemented a multistage RN using band add-drop filters and it was applied to a wavelength-locked Fabry-Petor laser diode based gigabit WDM-PON.
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Wireless Personal Area Network 기술 중 하나인 지그비는 네트워크를 구성할 때 기본적으로 모든 채널에 대해 에너지를 측정한 후 이를 바탕으로 채널을 선택하는 방법을 사용한다. 지그비가 사용하는 주파수 대역인 ISM Band는 특별한 라이센스 없이 누구나 사용할 수 있는 주파수 대역이므로 다양한 간섭 요인들이 존재하게 되며, 이 간섭 요인들 중 지그비의 통신 성능에 가장 큰 영향을 미치는 것은 무선랜으로 알려져 있다. 본 논문에서는 무선랜의 채널 사용 패턴을 사전정보로 활용하여 지그비 채널 선택 과정을 효율적으로 수행할 수 있는 알고리즘을 제안하고자 한다. 제안된 알고리즘에 의하면 지그비 채널 선택 시 일부 지그비 채널에 대해서만 측정하여도 되므로 지그비 네트워크 구성 시 채널 선택에 소요되는 시간을 단축할 수 있게 된다.
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KT starts MMS(Multimedia Messaging System) service based on wired BcN(Broadband Convergence Network) telephone on August, 2008. BcN telephones have various service functions, and MMS service has been serviced for years. However, we should check KT MMS service system. KT MMS service is based on a PS(presence server), so KT MMS system sends a MMS message to the most convenience terminal for each receiver. Most other current MMS system send MMS message to a terminal which the sender set directly. However KT MMS system decides called party terminal based on the receiver's situation.
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In this paper, the Transport Protocol Experts Group(TPEG) transmission and reception system based on Digital Radio Mondiale(DRM) is implemented for traffic information services. DRM stands for the European radio broadcasting standard to bring AM radio into digital radio, designed to work at frequencies below 30MHz. DRM can offer various data services such as text messages and a slide show service as well as audio services. In spite of low datarate, the TPEG system on DRM has an advantage that the traffic information service system for whole country can be established because DRM can offer wider service ranges than terrestrial-digital multimedia broadcasting(T-DMB) and simply archive a single frequency network.
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System을 통해 출력되는 신호를 측정할 때 정확한 측정을 방해하는 요소로 잡음이 있다. 이런 신호 측정의 방해 요소인 잡음을 제거 하는 방법 중의 하나로 Lock-in Amp(LIA)가 사용되고 있다. 본 논문에서는 잡음 신호의 제거를 위해 사용 하는 LIA를 제작 하고 특성을 파악 하였으며 RF통신을 이용하여 무선 형태로 제작 하였다. 현재 상용화된 LIA는 프로브를 통한 유선으로 측정신호의 입력을 받게 되지만 본 논문에서 제작된 LIA는 무선신호 형태로 입력 하게 된다. RF통신의 케리어 주파수는 447.9[MHz]로 Digital GMSK 변복조방식을 이용하였다. LIA의 제작은 Dual Phase Sensitive Detecter을 사용하였으며, 주요 구성 요소인 Phase Locked Loop, Phase Shifter, Phase Sensitive Detector, Low Pass Filter등의 구조와 특성을 조사하였다.
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본 논문에서는 응급상황에 직면한 사람의 위치를 빠르고 정확하게 추적 하기 위하여 광역의 위치추적 기술과 새롭게 제안하는 근거리 위치추적 기술인 능동형 위치추적기법이 융합된 신 개념의 긴급 sos 시스템을 제시하였으며 응급한 상황에 직면한 사람이 소지하는 초소형, 저전력 응급신호 발생장치(Beacon)의 동작 특성을 분석하였다. 그리고 Beacon의 동작 특성 분석을 기반으로 통신 칩의 전력 소모를 최소화 하기 위한 기술을 제안 하였다.
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Wireless sensor network (WSN) is expected to be used in many applications. However, sensor nodes still have some secure problems to use them in the real applications. They are typically deployed on open, wide, and unattended environments. An adversary using these features can easily compromise the deployed sensor nodes and use compromised sensor nodes to inject fabricated data to the sensor network (false data injection attack). The injected fabricated data drains much energy of them and causes a false alarm. To detect and drop the injected fabricated data, a filtering-based security method and adaptive methods are proposed. The number of different partitions is important to make event report since they can make a correctness event report if the representative node does not receive message authentication codes made by the different partition keys. The proposed methods cannot guarantee the detection power since they do not consider the filtering scheme. We proposed clustering method for filtering-based secure methods. Our proposed method uses fuzzy system to enhance the detection power of a cluster.
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The RFID system is very useful in various fields such as the distribution industry and the management of the material, etc. However, the RFID system suffers from various attacks since it does not have a complete authentication protocol. Therefore, this paper propose the authentication protocol that used key server to resist various attacks including DoS(Denial of Service) attack. For easy implementation, the proposed protocol also uses CRC, RN16 generation function existing in EPCglobal class 1 gen2 protocol. This paper performed security analysis to prove that the proposed protocol is resistant to various attacks. The analytical results showed that the proposed protocol offered a secure RFID system.
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통신기술과 컴퓨터기술의 발전으로 새로운 전기통신 서비스가 개발 보급되고, 그 예로 도난, 화재, 가스 유출 등 가정 안에서 일어나는 각종 위급상황을 해당관서에 자동으로 알려주는 원격 안전관리시스템의 중요성과 인력 검침에 따른 노동력 확보문제나 효율적이고 경제적인 검침에 따른 운용방안이 요구되는 시점에서 원격검침 시스템(AMRS)의 필요성이 더욱 대두되고 있다. 본 논문에서는 각각의 원격 검침 시스템의 사용된 통신 방식을 비교하고 원격 검침시스템의 국내 외 기술 개발 동향 및 앞으로의 발전방향을 모색하였다. 이에 고유가시대의 검침비용을 절감하고 고객 서비스 향상 방안에 도움이 되고자 한다.
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In 1989, Kocher et al. introduced Differential Power Attack on block ciphers. This attack allows to extract secret key used in cryptographic computations even if these are executed inside tamper-resistant devices such as smart card. Since 1989, many papers were published to improve resistance of DPA. At FSE 2003 and 2004, Akkar and Goubin presented several masking methods to protect iterated block ciphers such as DES against Differential Power Attack. The idea is to randomize the first few and last few rounds(3
$\sim$ 4 round) of the cipher with independent random masks at each round and thereby disabling power attacks on subsequent inner rounds. This paper show how to combine truncated differential cryptanalysis applied to the first few rounds of the cipher with power attacks to extract the secret key from intermediate unmasked values. -
Generally, sensor nodes can be easily compromised and seized by an adversary because sensor nodes are hostile environments after dissemination. An adversary may be various security attacks into the networks using compromised node. False data injection attack using compromised node, it may not only cause false alarms, but also the depletion of the severe amount of energy waste. Dynamic en-route scheme for Filtering False Data Injection (DEF) can detect and drop such forged report during the forwarding process. In this scheme, each forwarding nodes verify reports using a regular probability. In this paper, we propose verification probability adjustment scheme of forwarding nodes though a fuzzy rule-base system for the Dynamic en-route filtering scheme for Filtering False Data Injection in sensor networks. Verification probability determination of forwarding nodes use false traffic rate and distance form source to base station.
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Recently, Lu and Cao proposed a password-authenticated key exchange protocol in the three party setting, and the authors claimed that their protocol works within three rounds. In this paper, we analyze the protocol and show the protocol cannot work within three rounds. We also find two security flaws in the protocol. The protocol is vulnerable to an undetectable password guessing attack and an off-line password guessing attack.
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In 2006, ITU-R estimated the spectrum requirements for IMT-Advanced including IMT-2000 and its enhancements. And WRC-07 indentified four new spectrum bands for IMT system. Based on these results, there are many activities which are related with IMT system and its spectrum inside and outside of the country. This paper covers the next generation mobile telecommunication spectrum issues and outlook for the future of it.
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긴급 SOS 시스템을 구축하기 위하여 빠르고 정확한 위치추적 기술의 개발이 필요하다. 본 논문에서는 긴급한 상황에 처한 사람의 위치를 빠르고 정확하게 추적하기 위하여 핸드폰기지국 망을 이용한 광역위치추적 기술과 근거리 위치추적 기술로 제안된 능동형 위치추적 기술이 융합된 신개념의 긴급 SOS 시스템을 제안하고, 근거리 위치추적 기술인 능동형 위치추적 기술에 Zigbee 통신 방식을 적용하여 링크 버짓과 채널 모델을 이용한 근거리 위치추적 성능을 분석 하였다.
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There are many application areas of sensor networks, such as surveillance, hospital monitoring, and home network. These are dependent on the secure operation of networks, and will have serious outcome if the networks is injured. An adversary can inject false data into the network through the compromising node. Ye et al. proposed a statistical en-route filtering scheme (SEF) to detect such false data during forwarding process. In this scheme, it is important that the choice of the threshold value since it trades off security and overhead. This paper presents an adaptive threshold value determining method in the SEF using fuzzy logic. The fuzzy logic determines a security distance value by considering the situation of the network. The Sensor network is divided into several areas by the security distance value, it can each area to uses the different threshold value. The fuzzy based threshold value can reduce the energy consumption in transmitting.
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Recently, location based service(LBS) expended based on personal specialized service, however since commercialized GPS based emergency rescue service comes with shadow zone for GPS signal such as inside building, the accuracy and reliability are not guaranteed. Therefore to improve such problem, we propose an active location detecting algorithm using RFID-TAG and Yagiantenna. To track the location of RFID-TAG where signal is generated, location tracking device in which Yagi-Antenna is installed moves around. Since directed wave and reflected wave co-exist during signal reception, final signal generated location is searched by setting up multiple of locations where signal can be generated on the map and moving location tracking device along minimum length of path. The algorithm proposed in this paper was verified of its technical validity through simulator.
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In order to estimate cell images, high-performance electron microscopes are used nowadays. In this paper, we propose a new simple, fast and efficient method for real-time automatic focusing in electron microscopes. The proposed algorithm is based on the prediction-error variance, and demonstrates its feasibility by using extensive experiments. This method is fast, easy to implement, accurate, and not demanding on computation time.
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This paper shows the formulation of fast moving least square reproducing kernel method (FMLSRKM) which is a kind of meshfree methods. FMLSRKM has some advantages compared to conventional numerical techniques such as finite element method. For simple analysis on a rectangular waveguide, point collocation scheme is introduced and applied.
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In this paper a detail study of existing steganographic methods are presented. An example is given of LSB substitution with uncompressed domain i.e., BMP image. In case of compressed domain JPEG image steganography is presented. Almost all popular steganographic algorithms, such as JPEG JSteg, F3, F4 and Selective Block Steganography (SBS) are described. The applications of steganographic methods are also presented briefly.
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In most sensor networks, nodes can be easily compromised by adversaries due to hostile environments. Adversaries may use compromised nodes to inject false reports into the sensor networks. Such false report attacks will cause false alarms that can waste real-world response effort, and draining the finite amount of energy resource in the battery-powered network. A dynamic enroute scheme proposed by Yu and Guan can detect and drop such false reports during the forwarding phase. In this scheme, choosing a threshold value is very important, as it trades off between security power and energy consumption. In this paper, we propose a threshold determining method which uses the fuzzy rule-based system. The base station periodically determines a threshold value though the fuzzy rule-based system. The number of cluster nodes, the value of the key dissemination limit, and the remaining energy of nodes are used to determine the threshold value.
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In this paper a new steganographic method is presented with minimum distortion. This paper focused on DCT rounding error and optimized that in a very easy way, resulting stego image has less distortion than other existing methods. The proposed method compared with F5 steganography algorithm, and the proposed method achieved better performance. This paper considered the DCT rounding error for lower distortion with possibly higher embedding capacity.
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This article presents a methodology for the monitoring of air pollution. All over the world, the interest in the environment has been continuously increasing. Unfortunately, much of this interest is due to emerging problems, such as the greenhouse effect and climate change. For this reason, research into carbon dioxide, which causes the greenhouse effect, is progressing rapidly. This article presents a method of measuring the level of carbon dioxide and other substances in the air through the utilization of mobile-networking base stations and measured data. First of all, sensors are attached at the appropriate position of the mobile-networking base stations. These sensors will measure the air quality in their respective positions, and send sensor data to an urban management center via network gateways and data-collecting systems. The measured data can be used for various purposes. In general, it can be used to measure the air quality, which can then be used as a basis for urban planning. The method described herein utilizes airpollution sensors that are attached to the base stations in different locations and at varying heights. The data obtained hereby will be applicable in many fields. At this time this is simply a methodology, however we hope that it will lead to a practical application.
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현재 무선 환경에서 이동성을 제공하려는 노력은 다양한 계층의 프로토콜에서 활발히 진행이 되고 있으며 이중에서도 IP 서브넷이 변경 되어도 이동성이 제공 가능한 IP 이동성 기술이 다양한 계층의 이동성 프로토콜 중에서도 가장 활발히 연구가 이루어지고 있다. IP 이동성 기술은 Mobile IP(MIP)가 나온 이후에 핸드오버 지연을 개선한 Hierarchical MIP 및 Fast MIP 등 다양한 타입으로 확장되어 연구가 진행 중에 있다. 그러나 MIP의 경우는 단말에 MIP Client 스택이 탑재 되어야 하고 단말의 전력 소모 및 HO 지연 크다는 단점 등으로 인하여 기술이 활성화되는데 한계성을 지녀 왔다. 따라서 최근에는 이를 개선한 Proxy MIP 관련 연구들이 활발히 이루어지고 있으며 또한 IP 계층 이동성 기술만으로는 성능 개선에 한계가 있다고 보고 다양한 계층의 이동성 기술과 연동을 하려는 시도도 동시에 이루어지고 있다. 따라서 본 논문에서는 타 계층에서 제공되는 MIH 프로토콜 기능을 활용하여 802.11 WLANs 환경에 Proxy MIPv4를 적용하여 이동성을 제공 시 발생하는 핸드오버 지연 요소를 최소화 하였다. 제안된 메커니즘은 MIH가 제공하는 Event, Command, Information 서비스를 활용하여 단말이 새로운 Target 망에 접속하기 이전에 인증 Key 교환 기법을 통해 핸드오버 시 발생하는 인증 지연을 최소화하였으며 추가적으로 Inter-AP간 Tunneling 및 Forwarding 기법을 적용하여 핸드오버 시 발생되는 Packet 손실을 최소화 하는 성능 향상 방안을 제안하였다.
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RF power amplifier requires linearization in order to reduce adjacent channel interference. And most of the existing linearization algorithms assume that a PA has memory-less nonlinearity. But for the wider bandwidth signal, the memory effect of PA cannot be ignored. This paper investigates digital pre-distortion by use of a memory polynomial model which compensates for amplifier nonlinearity and memory effect. The look-up table based implementation scheme is used to reduce the computational complexity of the pre-distortion block. The linearization performance is demonstrated on wideband CDMA signal and class AB high power amplifier.
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현재 WLAN, WiBro, HSDPA 등의 다양한 형태의 망 환경들이 존재함에 따라 이러한 다양한 형태의 망간 연동을 통한 시너지 효과를 활용하여 사용자에게 높은 질의 서비스를 제공하려는 수많은 시도들이 이루어지고 있으며 우선적으로 단말이 이종망간에 이동을 하더라도 서비스 연속성을 제공하여 주는 이동성 제공 기술에 관한 연구들이 활발히 진행 중에 있다. 그러나 이미 상용 서비스를 제공 중인 이종 망간(i.e., WiBro 와 HSDPA)에 서비스 연속성을 제공하는 데 있어서는 접속 망 자체의 기본적인 기술적 특성 (i.e., 전송 속도, Coverage, QoS)이외에도 이미 망을 Deployment하여 서비스를 제공 중인 사업자의 현실적인 문제 (i.e., 접속 망 기능 변경의 어려움 및 비용) 등 다양한 변수들도 존재하며 이러한 망의 다양성을 충족시키면서 망간 서비스 연속성을 제공하기 위해서는 하나의 독자적인 이동성 기술로는 한계를 가지게 된다. 따라서 본 논문에서는 이미 망이 Deployment되어 상용 서비스 중인 Wi-Bro와 HSDPA망간에 서비스 연속성을 제공하기 위해서 발생할 수 있는 현실적인 문제점들을 제시하고 이를 고려한 효율적인 이동성 프로토콜을 제안한다. 본 논문에서는 Client Mobile IPv4(CMIPv4)와 Proxy Mobile IPv4 (PMIPV4)의 기술적인 장점을 취하고, 이미 Deployment되어 서비스를 제공 중인 망의 상황에 따라 유동적으로 CMIPv4와 PMIPv4 기술을 동시에 혼재하여 적용가능 한 Hybrid Mobile IP의 이동성 기술 방안을 제안하였다.
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급격한 이동통신 기술의 발전에 힘입어 음영지역 해소 및 고속 데이터 처리를 위해 댁내 기지국에 대한 개발 및 연구가 진행 중이다. 댁내 기지국은 크게 음영지역 해소를 위한 Open 방식의 기지국과 고속 데이터 처리를 위해 특정 가입자만 사용할 수 있는 Close 방식이 있다. 상기 방식들은 망의 특성에 맞게 이를 제공하는 망 사업자에 의해 선택 된다. 댁내 기지국을 관리하기 위해서는 많은 시간과 인력자원이 소요되므로 자동으로 설정 및 최적화시키는 기능이 요구 시 되고 있으며, 이를 3GPP에서 SON (Self Organizing Optimizing Networks) 이라 일컫고 연구진행 중이다. 본 논문은 댁내 기지국 관리를 위해 셀의 기본 인자인 PCI(Physical Layer Identity) 할당 방안과 댁내 기지국간 간섭을 최소화 시키기 위한 Adaptive Coverage 방안을 제시한다. 또한 계층적 셀 구성(Hierarchical Cell Structure)에 따른 이동성 제공 방안을 제시한다.
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There are several kinds of service standards for 3G(
$3^{rd}$ -Generation) wireless communication as WCDMA, CDMA2000 and WiBro(Wireless Broadband Internet). Especially WiBro Wave2 system is a marked currnt issue. In this paper, we describe on the cell plan tool to desgin WiBro Wave2 network. For this, we treat from basic theory to practical substance to produce new(or modified) path loss prediction model for 2.3GHz. And we explain the method how to implement new technology MIMO(Multiple Input Multiple Output) deployed in Wave2 system. Also we emphasize on the importance of LOS(Line Of Sight) analysis in WiBro network design. -
Femtocells are cellular access points that connect to a mobile operator's network using residential DSL or cable broadband connections. They have been developed to work with a range of different cellular standards including CDMA, GSM and UMTS. Like legacy base station, the frequency accuracy and phase alignment is necessary for ensuring the quality of service (QoS) for applications such as voice, real-time video, wireless hand-off, and data over a converged access medium at the femtocell. But, the GPS has some problem to be used at the femtocell, because it is difficult to set-up, depends on the satellite condition, and very expensive. So, some techniques are discussed to alternate with the legacy GPS system. NTP, PTP, Synchronous Ethernet use the ethernet to synchronize distributed clocks in packet networks. AGPS support reliable position information than the legacy GPS in poor signal conditions. But, These method also have some problems. So, hybrid timing method like A-GPS+PTP and TV+GPS was developed to make up the weak point of GPS. This paper introduces the each method and compare each other and y propose much better solution for timing synchronization at the Femtocell
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Exchange System for mobile communication operator is very important for providing continuous services to customers. However traditional solution is too expensive for choosing in the real environment. In this paper, we suggest cost-effective auto backup monitoring solution, which is robust for system failure. And this suggested solution will also can be adopted to the
$4^{th}$ generation of IP core network. -
This paper presents a new dynamically adaptable polling scheme for efficient support of real-time traffic over an IEEE 802.11 wireless LAN network. The poll scheduling plays an important role in IEEE 802.11 PCF. However, the current version of the polling list management scheme proposed in the IEEE802.11 standard is inefficient when a variable number of mobile stations have variable packets to transmit. If Point Coordinator has an exact information on the station status, it is possible to efficiently perform polling. In this thesis, we suggest an adaptable polling scheme to meet requirements of the stations. In our scheme, each station transmits packets including a piggyback information to inform that it wants to receive a poll in the next polling duration. Simulation results indicate that our scheme may reduces the packet discard ratio and real-time packet transfer delay.
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In this paper, we analyze the performance of RAKE receiver for impulse radio-ultra wide band (IR-UWB) systems in indoor multipath radio channel. Pulse position modulation-time hopping (PPM-TH) signal is considered. And we also consider three types of RAKE receivers, which are ideal RAKE, selective RAKE, and partial RAKE receivers. The indoor channel is modeled as the modified Saleh and Valenzuela (SV) model which has been proposed as a UWB channel model by the IEEE group, IEEE 802.15.SG3a.
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The Digital Radio Mondiale (DRM) system is a digital broadcasting standard designed for use in the LF, MF and HF bands of the broadcasting bands below 30 MHz. The system provides both superior audio quality and improved user services / operability compared with existing AM transmissions. In this paper, we propose a variable point Prime Factor FFT design method for Digital Radio Mondiale (DRM) system. Proposed method processes a various size IFFT/FFT of Robustness Mode on DRM standard efficiently by composing Radix-Prime Factor FFT Processing Unit of form similar to Radix-4 by insertion of a variable Prime Factor Twiddle Factor and Garbage data. So, we improved limitation that cannot process 112/176/256/288 FFT of each mode of DRM system with a existent Radix Processor and increase memory size and memory access time for IFFT/FFT processing by software processing in case of implementation with a existent high speed DSP.
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Recently, landslides frequently occur on natural slope and/or man-made cut slope during periods of intense rainfall. With a rapidly increasing population on or near steep terrain, landslides have become one of the most significant natural hazards. Thus, it is necessary to protect people from landslides and to minimize the damage of houses, roads and other facilities. To accomplish this goal, many landslide monitoring systems have been developed throughout the world. In this paper, a simple landslide detection system that enables people to escape the endangered area is introduced. The system is focused on the debris flows which happen frequently during periods of intense rainfall. The system is based on the wireless sensor network (WSN) that is composed of wireless sensor nodes, gateway, and remote server system. Wireless sensor nodes and gateway are deployed by commercially available Microstrain G-Link products. Five wireless sensor nodes and one gateway are installed at the test slope for detecting ground movement. The acceleration and inclination data of test slope can be obtained, which provides a potential to detect landslide. In addition, thresholds to determine whether the test slope is stable or not are suggested by a series of numerical simulations, using geotechnical analysis software package. It is obtained that the alarm should be issued if the x-direction displacement of sensor node is greater than 20mili-meters and the inclination of sensor node is greater than 3 degrees. It is expected that the landslide detection method using wireless senor network can provide early warning where landslides are prone to occur.
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최근 유가의 상승은 공간이동의 비용을 매우 크게하여 경제성장을 약화시키고 있다. 이러한 시기에 본 논문은 시간적/공간적 제약을 극복하고 효율적으로 작업할 수 있는 서비스 모델을 제안한다. 인터넷 및 IT인프라의 발전은 사람들이 시간과 공간의 제약없이 언제, 어디에서나 누구와도 작업할 수 있도록 가능하게 할 것이다. 정해진 시간이 아니라 자기가 일하고 싶은 시간에 가상의 일터에서 가상의 조직을 이용하여 전 세계 어디에 있는 누구와도 같이 일을 할 수 있는 공간이 만들어지는 것이다. 이렇게 일하는 방식을 u-Work이라하며 u-Work서비스가 가능하게 해 준다. 본 논문은 u-Work의 유형을 재택근무, 이동원격근무, u-Work센터근무로 분류하고, 공공기관 u-Work서비스 모델을 제안하고자 한다. 또한, 제안한 공공기관 u-Work서비스 모델의 구축방안을 시설인프라 측면, IT인프라 측면, 운용인프라 측면으로 나누어 기술한다. 구축된 u-Work서비스는 전 세계의 전문인력을 활용할 수도 있으며, 사회적 약자의 생산활동 참여 기회를 높이는 등 유연한 노동시장을 만들어 줄 것이다.
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This article describes a LED illumination infrastructure for ubiquitous society based on the Visible Light Communication technology. The VLC is one of the advanced communication system using "Visible Light". The VLC system has a lot of advantageous features and can be used in various places for the next future generation. So, we analyzed ubiquitous service model based on the VLC system and some applications. And we renewed discussion about LED illumination infrastructure for u-Society.
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Starting from 2005, as the new city paradigm, the term 'u-City' was created in Korea. U-City service, as defined in "u-City law", is a service that connects and intermediates among government, traffic, welfare, environment, disaster mitigation, etc., and their data based on ubiquitous city technology and infrastructure. According to the survey executed by local governments, the improvements in the standard of living of citizens have in turn increased the needs for anti-mitigation services. Such trend is bolstered with the recent disasters such as the conflagration of Korean Soong-rae Gate and the devastating earthquake of Sichuan province. This article describes a concept of the u-City disaster prevention service and looks into the activities and planning of u-City disaster prevention service of local governments. This paper also briefly looks into the law and policies to derive the needs of u-City disaster prevention service as well as the current technologies and u-City disaster prevention services of local governments. Ultimately, this paper offers the strategic direction of developing u-Disaster Prevention City.
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This article describes developments in fiber to the home (FTTH), and introduces the technical reviews for the various types to realize FTTH. Also, we have presented the results of each EPON, GPON and WDM-PON standardization by each IEEE, ITU-T and TTA. Finally, based on the above results, we proposed the trend of FTTH service deployment strategies.
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DWDM(dense wavelength division multiplexing)-PON technology is applied to subscriber network as the same as E-PON or G-PON. And its network components consist of OLT, ONU and RN. Legacy DWDM technologies have been applied on the long-haul part of optical network due to its excessive high cost. But many researchers have successfully devised a few methods which can considerably reduce the cost of equipment. Nowadays DWDM-PON equipment's has arrived to a level having a competitive price in comparison to E-PON or G-PON on condition of giving equal bandwidth. Recently a major domestic ISP has deployed DWDM-PON equipments in one apartment complex area in the purpose of satisfying ever-increasing bandwidth demand. The ISP increased data transmission capacity from 1 G to 16G without any additional fiber deployment. In this paper we introduce roughly three technologies of implementing DWDM-PON's optic module and related optic devices. And we also describe pre-test of vendor's DWDM-PON equipment and discuss the result. Lastly we propose some of network configurations which adopt DWDM-PON technology. By adopting DWDM-PON technology ISP can greatly save the cost of deploying broadband subscriber network.
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We propose a PON repeater system which transports multiple PON channels at the same time over the physical limit of the standard E-PON reach. To increase the physical reach up to 60km, we used the O-E-O (optic-electric-optic) signal regeneration on an active remote terminal which is placed between a central office and passive remote nodes. Also, by incorporating the well-established WDM technology to aggregate multiple E-PON channels, we successfully increased the split ratio (the number of subscribers per fiber core) to over 256.
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최근 통신시스템과 핸드폰, PDA등의 통신기기들의 발전에 따라 사용자들은 높은 데이터 전송률과 고속의 통신서비스를 요구하고 있다. 이러한 상황에서 유 무선 통합 시스템인 Radio-over-Fiber(RoF) 시스템은 그 대안으로 대두되고 있다. 본 논문에서는 광전자소자를 선 왜곡 방식에 적용하여 광 송신기의 선형성을 향상시키는 방법을 제안하였다. 선 왜곡 방식은 두 개의 루프로 구성되어 있으며, 광 부품인 레이저 다이오드와 포토 다이오드 그리고 RF 부품인 위상변위기, 감쇄기, RF 결합/분배기, RF 증폭기를 사용하였다. 메인 루프에서 주 레이저 다이오드의 비선형성에 의해 발생된 왜곡신호성분은 보조 루프에서 부 레이저 다이오드를 이용하여 추출된 선 왜곡신호에 의해서 제거된다. 제안된 선형화 기법을 적용하여 2.4 GHz에서 선형화 기법을 적용하기 전보다 3차 상호변조 왜곡성분이 약 30dB 향상된 결과를 얻었다.
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KT는 기업대상 전국대표번호서비스(예: 1588, 1577 등)와 기업이 보유하고 운용중인 콜센타 서비스를 통합한 새로운 부가서비스를 기업고객에게 제공하여 기업 콜센타의 인바운드 및 아웃바운드 호처리를 효율화하고, 고객사에게 일원화된 고객 접점 센터 구축을 통한 One-Contact, One-Stop서비스 구현 가능하게 함은 물론 기업고객측 회선, 장비 등에 대한 투자 및 운용비용을 절감할 수 있게 하고 있다. 이를 위해 KT에서는 기업 콜센타 구축시 다양한 구축환경(예: 고객사 CTI 미들웨어)과 고객사가 보유한 멀티사이트 콜센타에 적합하도록 지능망 개선 및 효율적인 시스템간 접속환경 제공으로 변화하는 기업 콜센타 고객의 니즈에 맞는 유연하고 강력한 서비스를 제공하고 있다. 본 논문에서는 기업형 콜센타 솔루션에 관한 통신사업자별 제공 기술 및 현황, KT에서 제공중인 콜센타 제공 구조에서의 지능망 제공 요소와 고객사 콜센타와의 망간 시스템 연동관계를 분석하고, KT에서 콜센타 부가서비스기반 호 제어하에서 제공하고 있는 기업의 콜센타 유형별 구축방안을 실제 적용 사례를 기반으로 제시하고 이에 따른 최적의 콜센타 구축방안을 제시한다.
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The standardization for Seamless IP Mobility between heterogeneous networks is being progressed according to each specific purpose of the organizations such as ITU-T (International Telecommunications Union - Telecommunication), 3GPP(3rd Generation Partnership Project), IETF(Internet Engineering Task Force), and IEEE(Institute of Electrical and Electronics Engineers). [1] Specially VCC (Voice Call Continuity) for seamless voice continuity between heterogeneous networks using IMS (IP Multimedia Subsystem) of the next generation platform is being introduced into a few companies, and also MIH (Media Independent Handover) and MIP (Mobile IP) for IP mobility between heterogeneous networks are being customized by their internal situation. This article describes the idea to support IP Mobility between heterogeneous networks in the network which IMS platform is deployed and only supports the mobility for the voice by the type of AS (Application Server).
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We study signal characteristics of the injection-locked Fabry-Perot laser diodes(FP-LDs) for the development of a costeffective WDM-PON solution. The output power and system performance of WDM-PON using injection locked FP-LD are depend on optical characteristics of injection source. The effect of optical power and polarization state of the injection source experimentally investigated. We also measured BER characteristics of the directly modulated FPLD and its power penalty at the BER of
$10^{-9}$ . -
유비쿼터스 도시의 개념이 등장하면서 도시관리에 대한 중요성이 점차 부각되어가고 있다. 특히 지하시설물에 대한 안전한 관리는 안전한 도시를 표방하는 유시티 에서는 없어서는 안될 중요한 공공서비스라 할 수 있다. 최근 이러한 도시의 지하시설물의 안전한 관리를 위한 체계적인 관리 방안에 대한 연구가 국토해양부를 중심으로 활발히 이루어지고 있다. 지하시설물의 특성상 안전하고 체계적인 관리를 위해서는 무엇보다 지하시설물에 대한 정확한 위치좌표를 알아야 하고 지하시설물에 일어나는 변화에 대한 정보를 수집하기 위해 센서적용기술을 필요로 한다. 본 논문에서는 유비쿼터스 도시 내 지하시설물 구축과정에서의 절대위치확보 방안과 각 지하매설물별 특성을 고려한 센서적용방안에 대한 내용을 기술하였다.
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사용자의 각 개인별 관심 및 환경에 따라 적절한 정보를 다양한 입출력 방식으로 제공하고, 가정내의 모든 장소에서 네트워크 접속이 가능한 사용자 중심의 지능형 홈 네트워크 환경의 새로운 요구가 대두 되고 있다. 또한 집안의 온도, 가스, 화재, 도어, 적외선 센서들로부터 수집된 정보를 요약, 분석, 처리 가공하여 문자 및 그래픽 등으로 보고 받는 사용자 중심의 서비스 제공이 요구 된다. 이에 본 논문은 전력선 통신 (Power Line Communication, PLC)을 이용한 흠 네트워크 시스템을 구축하여 가정내의 온도, 화재, 침입방지 등의 보안 문제뿐만 아니라 정보가전기기들이 네트워크로 상호 연결되어 기기, 시간, 장소에 구애 받지 않는 다양한 서비스의 제공이 가능하며, 중앙의 홈 서버를 통해 집안 전체의 관리가 가능한 안전하고 스마트한 자동화 서비스를 제공하는 환경을 구축한다.
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This paper describes some field multiplication algorithm over GF(
$2^m$ ) on 8-bit processor. Through performance comparisons among algorithm, we show that our proposal is faster than existing algorithms. The proposed algorithm save 26.38% of running time compared with naive comb multiplication algorithm which is a kind of lookup-table (LUT) based algorithm. With the proposed algorithm, a scalar multiplication over GF($2^{163}$ ) can be computed within 1.04 secs on 8-bit MICAz sensor mote. -
This paper shows an implementation of WLAN-based Audio/Video(A/V) system for multimedia home networks. Proposed WLAN-based A/V system can transmit multimedia data of high quality. The entire system consists of a 16-bit RISC controller, a program ROM, a SRAM, timers, an interrupt controller, a DART, GPIOs, an I2C and the OFDM modem supporting for the IEEE 802.11g standard. The simple MAC functions are implemented by firmware on an embedded 16-bit RISC controller. The OFDM modem supports a complete set of data rates up to 54Mbps. Proposed the system is implemented by an Altera FPGA EP1S60F1020C6 device, a 10-bit 2-ch DAC, a 10-bit 2-ch ADC and RF/IF chips.
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Recently, the development of u-City and u-City services have been actively pursued by individual local government bodies in South Korea. This study focuses on the development of u-Health service, one of the services of u-City, by studying u-Health services in development (domestic and foreign) and by analyzing and proposing the communication infrastructure required to provide such services. Mainly, this study will focus on analyzing the current trend in personal mobile device based u-Health services domestically and internationally, and propose a new type of u-Health service, u-Diet service. The study will introduce the architecture, service scenario, technologies, characteristics, and the business model for the u-Diet service. It is expected that this study will provide the guideline for developing new u-Health services.
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Convergence services are very important to mobile operators in next generation mobile networks. However, mobile operators cannot deal with all convergence services because there are numerous convergence services. Thus, they should select and develop main technologies to provide convergence services which are areas to grow our business. In this paper, we introduce basic technologies to provide convergence services and then present some evaluation models to select an important area and technology.
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In the block cipher, DPA-resistant masking methods make an appropriation of extremely high cost for the non-linear part. Block ciphers like AES and ARIA use the inversion operation as this non-linear part. This make various countermeasures be proposed for reducing the cost of masking inversion. In this paper, we propose the efficient masking inverter by rearranging the masking inversion operation over the composite field and finding duplicated multiplications.
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The primitive of Identity-Based Broadcast Encryption allows a sender to distribute session keys or messages for a dynamically changing set of receivers using the receiver's identity as a public key. We already know that the trade-off exists the efficiency between the public parameter size and the ciphertext size. So, if the ciphertext size is O(1), then the public parameter size may be O(n). Some of IBBE scheme take the public parameters as input in decryption phase. Thus, a decryption device (or client) has to store the public parameters or receive it. This means that a decryption device (or client) has to have the proper size storage. Recently, delerabl
$\square$ e proposed an IBBE which have the O(1) size ciphertexts and the O(n) size public parameters. In this paper, we present an IBBE scheme. In our construction the ciphertext size and the public parameter size are sub-linear in the total number of receivers, and the private key size is constant. -
IP-based mobile communication system is one of the key research items in the mobile networks for a long time. But, due to some technical issues and no need of markets, it is still not full-fledged. Recently, CDMA and WCDMA service providers want to introduce IP-based network connectivity. Even though their efforts, the main network intra-structure depends on ATM or HDLC technology. This article describes a good example of commercialization of IP-based mobile communication systems. Our research is not experimental system but a in-service system - replacing the existing equipments with new IP-based systems. In this paper, we introduce IP related technologies used in our research such as IP-based ATCA(Advanced Telecommunications Computing Architecture) platform, HA(High Availability) redundancy, IP multicast, network redundancy techniques, multi-link bundling and IP header compression. These are already well-known to internet domain. We mix them with mobile communication systems concretely.
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와이브로(WiBro), 3G 무선인터넷(HSDPA), 3G LTE 등과 같은 와이어리스 브로드밴드(Wireless Broand) 기술이 점차 성숙됨에 따라 이들 망을 활용한 다양한 무선인터넷 서비스를 제공하려는 사업자들이 증가하고 있다. 기존의 WLAN, 2G/3G 회선망에서의 제한된 이동성 및 네트워크 전송 속도를 개선한 와이어리스 브로드밴드 서비스 시장은 국내에서도 2006년부터 WiBro 및 HSDPA가 사용됨에 따라 사업자간의 경쟁도 본격화되고 있다. 이러한 환경 속에서 사업자들은 신속하고 편리한 서비스 개통과 스마트폰, USB모뎀, 노트북, UMPC, PMP등 다양한 단말들의 펌웨어 업그레이드, A/S 처리 방안에 대해 고심을 하고 있으며, 이들 문제점은 막대한 비용과 고객 민원을 야기시키는 요인이기도 하다. 따라서 경제적인 관리비용으로 동적인 서비스/펌웨어 업그레이드 및 A/S에 대한 고객 만족도를 높이기 위한 단말 원격 관리 필요성이 절실히 요구된다. WiBro 단말의 안전하고 효율적으로 관리하기 위해서는 단말과 기지국사이의 무선구간에 대한 보안(security)을 강화시켜 줄 수 있으면서 이동성(mobility)을 고려한 OMA DM프로토콜을 이용하는 것이 적합하다. 또한, WiBro에서 가입자 인증을 채택하고 있는 UICC의 관리를 위해서 3GPP에서 정의하는 SMS/MMS기반의 또는 BIP(Bear Independent Protocol)기반의 OTA기술을 병행하여 사용하여야 한다. 본 논문에서는 Wi-MAX단말 관리를 위한 OTA Provisioning 규격으로 OMA DM과 TR069이 WiMAX 단말을 위하여 어떻게 적용하도록 규정하고 있는지를 살펴본다. 특히, WiBro 가입자 인증뿐만 아니라 폰북, DRM, 금융서비스 등 다양한 부가 서비스를 위하여 사용되는 UICC의 원격관리를 위한 관리 요소들을 정의, 설계하고 이를 바탕으로 구현된 KTUICC OTA Provisioning시스템을 소개한다.
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현재 통신 시장의 상황은 유무선 통신서비스 시장의 포화, 이동통신 시장의 기존 유선전화 규모 초과, 그리고 유선통신의 서비스 사업자의 영역 확대 도모 등을 특징으로 한다. 유무선 통합 (Fixed Mobile Convergence, FMC) 서비스는 유선통신 사업자를 중심으로 한 비즈니스 모델로 사용자에게 유무선 통신망 종류에 상관없이 일관되고 끊김없는 서비스를 제공하는 것을 목표로 한다. 이동통신망까지 확대하여 고객 기반을 유지하고자 하는 유선사업자들은 FMC 서비스 중 하나의 방안으로 IMS (IP Multimedia Subsystems) 기반의 VCC(Voice Call Continuity) 기능에 주목하고 있다. VCC AS(Application Server)는 이종망 (WiFi-CDMA)간 Seamless 핸드오버기능을 수행하므로, WiFi 와 CDMA를 지원할 수 있는 듀얼단말을 이용하여 사용자가 WiFi 서비스 지역과 CDMA 서비스 지역간 이동시에도 Seamless 한 음성서비스를 제공한다. 이에 본 논문은 IMS/VCC 기반으로 음성 seamless 핸드오버 적용 사례(시범서비스)를 중심으로 유무선 통신사업자 상호 Win-Win을 추구할 수 있는 LG데이콤 특화 VCC 모델을 제시한다. 그리고 LG데이콤이 추구하는 차세대 서비스인 사용자 context 기반의 개인화된 서비스 제공을 위한 IMS 기반 통합 프로파일/인증/과금 연구 동향에 대해 간략히 소개한다.
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Many different types of network equipments are deployed in a large-scale IP network. In this operating environment, network service providers suffer from difficulty in controlling various equipments simultaneously in case network faults happen in their overall or regional network due to physical link failure or abnormal traffic. This paper presents a policy-based methodology to control many different types of network equipments at the same time in abnormal cases. The key idea is that NMS(Network Management System) keeps vendor-neutral control policies in normal times and that when an abnormal case occurs in network, NMS transforms the selected policy into vendor-specific control commands and enforces them to various equipments simultaneously.
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홈 네트워크내에서 Always-on 기기 특성으로 인하여 불필요한 에너지를 소비하는 경우가 전체 소모전력량의 60%이상을 차지한다. 그러므로 이러한 에너지 소비를 줄일 수 있는 방안에 대한 연구의 필요성이 점차 증대되고 있으며, 본고에서 연구한 Ethement 기반의 트래픽량에 의한 대기모드 전환 알고리즘은 에너지 절감에 매우 유용한 연구기술이라 할 수 있다. 이에, 본고에서는 idle time때의 네트워크 에너지 소비를 절감하기 위한 대기전력 지원형 Green Ethernet Gateway시스템설계 및 구현방안과 시스템 대기모드상태를 최대한 연장하여 energy efficient효과를 향상시키기 위한 Proxying 기반 control policy를 제안한다. 일반적으로 홈네트워크의 네트워크 연결은 ethemet을 중심으로 이루어지며, 대부분 게이트웨이를 기반으로 그 연결이 구성된다. 그러나 홈네트워크의 일반적인 동작시간이 8시간 내외인데도 불구하고, 네트워크 연결을 위해서 full Power 상태를 유지해야하는 기존의 energy unaware기반의 게이트웨이 구조로는 에너지측면에서 막대한 에너지 낭비를 초래한다. 이에 본고에서는 게이트웨이에서의 에너지 절감을 위한 트래픽량 기반의 대기모드 지원형 시스템을 구현하고 실제 홈네트워크 적용을 통한 에너지 절약효과를 실험한다. 또한 활성모드, 대기모드간 전환을 효과적으로 하기 위한 layer 2,3 Packe기반의 지능형 Proxying 알고리즘을 이용한 control policy를 제안한다.
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IEEE 802.11e standardized the EDCA mechanism to support the priority based QoS. And the virtual collision handler schedules the transmission time of each MAC frame using the internal back-off window according to the access category(AC). This can provides the differentiated QoS to real-time services at the medium traffic load condition. However, the transmission delay of MAC frame for real-time services may be increased as the traffic load of best effort service increases. It becomes more critical when the real-time service uses a compressed mode video codec such as moving picture experts group(MPEG) 4 codec. That is because each frame has the different importance. That is, the I-frame has more information as compared with the P- and the B-frame. In this paper, we proposed a buffer management algorithm based on the frame importance and the delay bound. The proposed algorithm is consisted of the traffic regulator based on the dual token bucket algorithm and the active queue management algorithm. The traffic regulator reduces the transmission rate of lower AC until that the virtual collision handler can transmit an I-frame. And the active queue management discards frame based on the importance of each frame and the delay bound of head of line(HoL) frame when the channel resource is insufficient.
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Cognitive Radio (CR) technology is proposed for using the unused spectrum band efficiently because of the spectrum scarcity problems. Spectrum sensing is one of the most challenging issues in cognitive radio system. In this paper, we focus on the signal detection of WiBro system band. As most of the modulated signals can be treated as cyclostationary random process, we can detect the signal of the OFDM signals in WiBro system. OFDM symbols using WiBro system have several pilot subcarriers and periodic pilots have cyclostationary characteristic. To improve of the detection performance, we get diversity gain using multiple antennas.
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Multiple antenna technology, such as multiple input multiple output (MIMO), beamforming is one of the most promising technology for broadband wireless communication. In OFDM environment, we found that as the number of paths is increased, smart antenna system cannot fully exploit beamforming gain. In this paper, we propose a beamforming scheme and analyze the performance of the proposed beamforming scheme in WiBro smart antenna system. WiBro is an OFDMA-based multiple access service for wireless broadband multimedia environment. The proposed beamforming technique for WiBro smart antenna system can effectively improve the performance of the systems in multipath fading environment.
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OFDM (Orthogonal Frequency Division Multiplexing) modulation using the orthogonal subcarriers reduces the delay spread by increasing robustness to multipath fading and can use overlapped bandwidth due to orthogonality on frequency domain. Thus data rate and spectral efficiency are increased. Because of these reason, OFDM is used for high speed data transmission for multimedia transmission as HSDPA, WiBro, WLAN. However OFDM also has drawbacks that have the high PAPR (Peak to Average Power Ratio). This high PAPR takes place because of parallel processing a number of data at once using a FFT processor. By high PAPR, amplifier doesn't act in dynamic range, so that BER performance is worse. In this paper, we reduce the PAPR using SLM(Selective Mapping). SLM doesn't effect on BER performance, but should transmit the side information for demodulation [2]. Also PAPR is higher as the number of FFT processor is larger. Thus SLM has high complexity. In this paper, we analyze the performance of SLM using scaling for no side information.
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Recently WiBro network is installed for high speed wireless internet service by telecommunication service provider, however WiBro service is not provided in the region of mountain or difficult region to install network infra. Fixed repeater is used to resolve those shadow area problem in current WiBro network. This paper study introducing Ad-hoc based multi-hop relay instead of using fixed repeater in order to resolve those shadow area problem. Cost down of fixed repeater and active network expansion is possible to resolve shadow area problem by introducing multi-hop relay technology.
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Cyclic prefix (CP) is one of the most important technique to OFDM system and is reducing inter-symbol interference (ISI) effects in high speed wireless mobile communication system. At the time varying channel condition, however, fixed CP length is not only increasing power consumption but also reducing data transmission rate. So in this paper, we propose the system that has adaptive CP length for high speed data transmission system. We don't control CP length of every symbol but adjust symbol interval depending on channel condition to CP reconstruction.
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In this paper, the high efficiency and linearity Doherty power amplifier using DGS and adaptive bias technique has been designed and realized for 2.3GHz WiBro applications. The Doherty amplifier has been implemented us-ing silicon MRF 281 LDMOS FET. The RF performances of the Doherty power amplifier (a combination of a class AB carrier amplifier and a bias-tuned class C peaking amplifier) have been compared with those of a class AB amplifier alone, and conventional Doherty amplifier. The Maximum PAE of designed Doherty power amplifier with DGS and adaptive bias technique has been 36.6% at 34.01dBm output power. The proposed Doherty power amplifier showed an improvement 1dB at output power and 7.6% PAE than a class AB amplifier alone.
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In this paper, we introduce a platform of advanced multiple antenna system based on orthogonal frequency-division multiplexing (OFDM). The advanced multiple antennas have beamforming gain using array antenna. In array antenna systems, received signal has phase delay caused distance of each antennas, therefore it should compensate with optimum weight vector which calculated by Lagrange algorithm. To implement the presented above procedures using Digital Signal Processor (DSP), we should fixed-point design. The performance of implemented platform is verified through MATLAB
$^{(R)}$ simulations with various signal environments. -
This paper presents the design and analysis of 2.45GHz Low-IF Mixer using CMOS 0.18um. The Mixer is implemented by using the Gilbert-type configuration, current bleeding technique, and the resonating technique for the tail capacitance. And the design of this Double Balance Mixer is based on its lineaity since it is important in the interference cancellation system. The low flicker noise mixer is implemented by incorporating a double balanced Gilber-type configuration, the RF leakage-less current bleeding technique, and Cp resonating technique. The proposed mixer has a simulated conversion gain of 16dB a simulated IIP3 of -3.3dBm and P1dB is -19dBm. A simulated noise figure of 6.9dB at l0MHz and a flicker corner frequency of 510kHz while consuming only 10.65mW od DC power. The layout of Mixer for one-chip design in a 0.18-um TSMC process has 0.474mm
$\times$ 0.39 mm size. -
This paper presents the program to analyze an antenna for using the Moment Method. The program contains three different functional steps. In the first stage, the pre-processor is based on the Delaunay Triangulation Algorithm. The next stage, the main-processor, can be considered the core process of the program, which solutions are obtaining the linear matrix for using the Moment Method. The final stages, the name of the post-processor, analyze radiation patterns, which results are same with the S-parameters. The results demonstrate satisfactory agreement with the results for using other numerical packages and measurement data. We can confirm that the results of this program compare with the results of common program to analyze for an antenna.
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A new type of cross-coupled planar microwave filter using coupled microstrip square open-loop resonators diplexer pro-posed. A method for the rigorous calculation of the coupling coefficients of basic four pole electric and magnetic coupling structures encountered. Simple empirical models are derived for estimation of the coupling coefficients. Experiments are performed to verify the theory. And a method for diplexer matching is conjugate matching that has characteristic better than open matching method.
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In this paper, performance of a double binary turbo coded ultra wide band (UWB) system is analyzed and simulated in an indoor wireless channel. Binary pulse position modulation-time hopping (BPPM-TH) signals are considered. The indoor wireless channel is modeled as a modified Saleh and Valenzuela (SV) channel. The performance is evaluated in terms of bit error probability (BER). From the simulation results, it is seen that double binary turbo coding offers considerable coding gain with reasonable encoding complexity. It is also demonstrated that the performance of the UWB system can be substantially improved by increasing the number of iterations.
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In this paper, a novel compact broadband dual frequency microstrip antenna is presented. The meander type patch has been designed to have dual resonant frequencies, and the ground with slot was employed to expand the bandwidth in WCDMA band. The simulated results were obtained using HFSS, and the measurement on the proposed antenna was conducted in an anechoic chamber equipped with a network analyzer and a far field measurement system. As a result, measured maximum gain of antenna is 2.07
$\sim$ 2.87 dBi in the GSM band and 3.91$\sim$ 5.61 dBi in the WCDMA band. -
In this paper, we present and analyze a robust frequency offset estimation scheme for orthogonal frequency division multiplexing (OFDM) systems over radio communication channels. When there exists frequency offset, the loss of orthogonality occurs and the interference problem among several subcarriers in OFDM signals is introduced. The guard interval of OFDM signals is employed for estimating the frequency offset. Furthermore, in order to enhance the frequency offset estimation performance, a ternary sequence is utilized. A frequency offset is estimated based on the synchronized correlator output. The proposed frequency offset estimation scheme can be applied to track the carrier frequency offset of OFDM systems.
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In this papers, a PLDRO(Phase Locked Dielectric Resonator Oscillator) is designed and implemented at the oscillator in which fundamental frequency is 18.3 GHz. The proposed PLDRO so as to improve the PLDRO of the general structure is designed to the goal of the minimize of the size and the performance improvement. Three VCO(Voltage controlled Oscillator) and the power combiner improved the output power. A VCDRO(Voltage Controlled Dielectric Resonator Oscillator) is manufactured using a varactor diode to tune oscillating frequency electrically, and its phase is locked to reference frequency by SPD(Sampling Phase Detector). This product is fabricated on Teflon substrate with dielectric constant 2.2 and device is ATF -13786 of Ka-band using. This PLDRO generates an output power of 5.67 dBm at 18.3 GHz and has the characteristics of a phase noise of -80.10 dBc/Hz at 1 kHz offset frequency from carrier, the second harmonic suppression of -33 dBc. The proposed PLDRO can be used in Ka-band satellite applications
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It is decidedly important to ensure QoS(Quality of Service) in order to make it possible a variety of multi-media services and realtime contents services in Wireless networks. One of methods to offer these services is the advanced prediction of Handoff through terminal's directional. In this paper, it is applied that the AP weight for the ground information of peripheral cell and the weight value of history table for the cell frequently visited. Also, it is expected that will be guarant QoS of substantial data in the case of Handoff through exact directional prediction of the next cell by using Kalman Filter algorithm applied GPS coordinates value.
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This article describes an interference reduction scheme for Mobile WiMAX in an indoor environment. The feasibility of user deployed femtocells in the same frequency channel as an existing macro cell network is investigated. One of the important requirements for co-channel operation of femtocells such as auto-configuration and self optimization are discussed. In femtocell deployments, leakage of the pilot signal to the outside of a house can result of the higher number of mobility events caused by passing user of macrocell. This interference effect can be minimized by reducing the pilot power using proper scheme. This paper introduces existing auto-configuration method of power control and proposed interference reduction scheme using power control for Mobile WiMAX in an indoor environment.
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This paper describes the design of single body type repeater antenna for isolation enhancement between donor and receptor antennas. The antenna system consists of cavity, triangular patch antenna and cavity reflector. The antenna satisfies return-loss and isolation specifications in the desired band while the broadside gain is a little bit short from the spec.
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This article describes a design and implementation of low power consumption wireless sensor network platform for intelligent motorway monitoring. There are many dangerous situations on motorway, foggy weathers, rapidly changes of temperature, etc. We designed a system for monitoring motorway environment for report dangerous situation. We introduce this system and its lowpower consumption characteristics which important to battery based system.
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In this paper, we discuss the recent trends on the passive UHF RFID tag chip design techniques and several important system parameters. We also summarize link budget studies on both conventional and modem UHF RFID communications. The paper highlights the reverse link limited case, which has known to be the minor concern if reader continuous wave (CW) can reach the tag in sufficient level. This makes sense when the tag sensitivity is rather high (over 10-12
${\mu}W$ ); however, since the tag chip fabrication technologies have been developed by time, the tag chip threshold levels are now less-dominant in determining link margin. If the tag limitation can be alleviated, the forward link limited case can be resolved; thus, we rather focus on the path-loss problem. Since the path-losses are still exist in both forward and reverse links, and it can be doubled while CW travels the reader-tag-reader path because forward link and reverse link are on the same distance. Consider if reader receiver sensitivity is very high in the worst case. In this case, weaken tag response (i.e., backscatters) cannot reach the level that reader receiver can process tag data; bit-error rate can be higher. Overall, backscatter levels should be high enough so that reader receiver can correctly function. After discussing link budget, we carried out practical measurements on fading effects between two circularly polarized UHF RFID antennas in a small scale area. -
In this paper, we introduce the positioning methods using the grid sensor network. The basic operational principle of grid sensor network can be the wireless communication using the sensor node attached on the objects. Sink node receives the environmental information (e.g., temperature, humidity and so on), and transmits the information to the core database. Since the grid sensor network basically uses wireless communication, it is necessary to observe the place where grid sensor nodes to be installed. In this sense, we carried out the practical measurement on the wireless propagation in an applicable field. In addition, link budget study and SNR estimation works were done in accordance with the results from the measurement.
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오늘날 비즈니스의 글로벌화, 사업장의 분산화는 필연적으로 영상회의의 활성화를 가져왔으나, 기 구축된 SD(Standard Definition)급 화질의 영상회의는 실감성 및 장시간 사용시 피로감 등에 따른 이용율 저조로 기대 만큼의 성화를 이루지 못하였다. 또한 기존 영상회의 시스템에서의 dec는 보조적 채널, 시스템 조작과 운영의 복잡성, 낮은 해상도로 인한 표정 및 눈짓 등의 요소 포착이 어려운 한계를 극복하지 못하였고, 기업들은 기업 내부 및 국내외 타기업들과의 협업을 위해 막대한 비용과 시간이 요구되고 있는 실정이다. KT는 기존 영상회의 문제 극복을 위해 서울<->대전 연구소간 전용선 연결, 비용 및 여러 site 확장을 위한 VPN으로의 전환 방안등 최상의 영상회의 구축을 위한 검토를 통해 Full HD실감 화질의 영상회의를 구축하였으며, 향후에는 Full HD 데이터 압축 기술 향상 및 데이터 전송 방안에 대한 더 많은 연구가 필요하다고 판단된다. 본 고에서는 KT에서 구축한 영상회의 사례를 중심으로 기본적인 기술과 구조, 국내외 시장의 현황 및 활용 방안에 대해 논하였다.
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통신기기실은 겨울철에도 냉방이 이루어질 만큼 열이 많이 발생하는 공간으로, 다수의 특수형 공조기가 설치되어 운용되고 있는데, 여기서 발생된 열은 열교환을 통하여 실외 기에서 그냥 외부로 버려지고 있다. 이 열은 겨울철에 사무실 난방과 온수공급에 필요한 적당한 온도와 풍부한 열량을 가지고 있어 그동안 활용 방법을 많이 모색해 왔으나, 시도되었던 제품이나 방법은 현실성이 떨어지거나 제품화 되지 못하고 있는 실정이었다. 이에, KT인프라연구소에서는 현실성 있는 제안으로 실외기로 가는 고온 고압의 냉매를 인접 사무실로 자동 전환시켜 난방을 가능케 하는 Package Type의 응축열 난방기를 개발하였는데, 본 논문에서는 이에 대한 개발과정과 Spec을 소개하고, 철저한 성능검증과 에너지 절감 효과 분석 결과를 제시하여 사업 적용에 필요한 기초자료로 활용 할 수 있도록 하였다. 개발된 응축열 난방기는 에너지를 대폭 절감할 수 있을 뿐 아니라 지구 온난화의 주범인
$CO_2$ 를 감축시킬 수 있어 대외 이미지 개선에도 크게 기여할 것이라고 생각된다. -
본 논문에서는 Spurious NAK Suppression알고리즘을 통하여 RLP의 성능향상에 대한 기법을 제안한다. 일반적으로, Hybrid ARQ기법에서는 MAC과 Physical Layer에서의 Retransmission 및 Error Correction으로 무선환경에서의 Error를 줄이고 latency를 보장하고 있다. 그러나 Hybrid ARQ에서의 Multiple SAW나 Selective-ARQ에 의해서 인접한 Packet들 간의 out-of-sequence문제가 발생할 수 밖에 없으며, upper layer인 RLP(혹은 RLC)에서는 이를 re-sequencing하여야 하는 부담감이 생기게 된다. 본 논문에서는 RLP receiver에서의 re-sequencing방법에 있어서, 효율적으로 RLP-NAK의 전송시점을 결정하는 NAK suppression 방법을 제안하고 있으며, 실험을 통하여 높은 성능향상을 보임을 확인할 수 있다.
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과거 CDMA 시스템에서 이동단말과 PSTN 및 PSDN간의 통신이 가능하게 하기 위해서는 망간의 정합기능을 수행하는 연동장치(IWF Inter-Working Function)가 필요로 되는데, 이때 이동단말과 BSC/MSC간의 무선 데이터를 IWF로 HDLC 프레임 형태로 구동하고 반대로 IWF로부터 수신된 데이터 프레임을 이동 단말측으로 전달하기 위하여 HDLC frame driver의 역할이 필요하다. 또한 교환기와 IWF간의 데이터 통신은 Frame-relay 프로토콜을 이용하며 정합기능을 수행해 주어야 한다. 본 논문에서 구현된 기능은 과거 CDMA 의 MSC 내에 구현된 본 기능이 HDLC 정합, Frame-Relay 정합, IPC, Datapath 등의 기능들로 구분되어 분리되어 있는 구조를 통합하여 하나의 기능 Board로 통합하였고 이러한 기능을 MG(Media Gateway) System에 기반하여 구현하여 적용하였다.
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Last year UMTS (UMTS: Universal Mobile Telecommunication System) 3G service started and these days 3 its service subscribers sharply increased. Now totally we have been increasing 13 million subscribers, every month 0.8 million people join 3G Service. MSC (Mobile Switching Center) is most important equipment in 3G system, so we call it 'core' network. Higher capacity MSC required to accommodating 1 million subscribers. It is very important whether MSC can accommodate maximum subscriber or not. So systematic analysis, reliable test results are required. This article presents WCDMA MSC performance evaluation case. This would be some direction for designing and developing some communication equipment. This Case Study demonstrates our MSC system performance.
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Vehicular Ad hoc Networks have attracted extensive attentions in recent years for their promises in improving safety and enabling other value-added services. Security and privacy are two integrated issues in the deployment of vehicular networks. Privacy-preserving authentication is a key technique in addressing these two issues. We propose a hash chain based authentication protocol that preserves the user privacy. We show that the our scheme can efficiently authenticate users. Name of Our protocol is
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전기전자 장치 내부의 PCB에 존재하는 전력공급/접지판은 RF 공진잡음을 발생시켜 디지틀 신호 품질 저하 및 불요방사의 문제를 일으킨다. 본 논문에서는, 전력공급/접지판의 RF 잡음을 제거하기 위한 방법으로 Mush-room EBG 구조를 사용할 때 이 구조가 가지는 전자기 및 전기적 특성을 모드해석법과 회로이론의 하이브리드화를 통해 예측을 수행한다. 예측을 통해 잡음을 억제할 수 있는 유용한 정보를 얻는다.
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본 논문에서는 원전 증기발생기세관 진단을 위한 와전류탐상의 전자기 수치해석을 수행하였다. 전자기적 특성을 해석하기 위하여 맥스웰 방정식을 이용하여 지배방정식을 유도하였고, 3차원 전자기 유한요소 프로그램인 OPERA 3D를 이용하여 전자기 수치 해석을 수행하였다. 신호해석을 위해 사용된 프로브의 종류는 배열와전류프로브이며, FBH 결함의 신호를 해석하였다. 결함의 깊이는 세관 두께의 40[%], 60[%] 및 100[%]로 하였다. 시험주파수는 100[kHz], 300[kHz], 400[kHz]를 사용하였고, 각각의 결함 및 시험주파수에 대한 결과를 비교 분석하였다. 본 논문의 결과는 앞으로 배열와전류프로브를 이용하여 원전 증기발생기세관 진단을 할 경우 신호 해석에 도움이 될 것으로 사료된다.
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Due to the rapid development of telecommunication industry, most telecom operators are investing to upgrade their access networks by using optical cables instead of copper cables. Building new telecom ducts for optical cable installation requires so huge capital expenses that most telecom operators need to remove unused copper cables in order to secure enough space to in-stall optical cables. In this paper, we will present a alternative method to extract copper from removed copper cables.
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최근 국내에서는 가입자 댁내까지 광케이블망이 인입되는 FTTH구축이 일반화 되고 있으며, 초고속 인터넷 서비스를 기반으로 통방융합 서비스중의 하나인 IPTV 서비스도 다양한 컨텐츠의 확보로 점차 가입자 수요가 증가되고 있다. 또한 VoIP도 통신사업자를 중심으로 일반전화 시장을 점진적으로 잠식하고 있는 추세이고, 향후 수년 내에 걸쳐 모든 가입자 댁내까지 광케이블망 구축이 완료되어 All IP화가 이루어질 전망이다. 2007년부터 전국적으로 일반주택 및 다세대주택을 대상으로 FTTH구축이 진행되고 있으며, 광간선망에서 분리되어 광배선망 분기지점에 설치되는 광접속합체 및 전주 광분기함에 설치되는 스플리터에 대한 다양한 망구성 방법 등 현재 적용되고 있는 다양한 FTTH 구축방법에 대해서 논하였다. FTTH 가입자 개통 방법에 있어서도 광옥외선을 이용하여 가입자 댁내까지 인입되는 방법 및 현장에서 직접 커백터 조립이 가능한 현장조립형 광커백터에 대한 품질확인 방법에 대해 설명 하고자 한다.
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기존 지능망 서비스들이 포화 상태에 이르게 됨에 따라 수익이 나는 새로운 서비스를 개발하는 것이 점점 더 어려워지고 있다. 요즈음 전통적인 전화망과 인터넷의 결합이 새로운 경향으로 나타나고 있다. PC와 같은 인터넷 단말은 전화망의 전통적인 단말보다 저장 장치 및 유저 인터페이스 면에서 더욱 더 강력한 능력을 가지고 있다. IT 개발자들은 전화 분야의 전문 지식을 갖고 있지 않아도 Parlay API를 사용하면 새로운 통신 서비스를 쉽게 만들수 있다. HTTP 상의 SOAP을 사용하여 쉽게 두 컴퓨터 노드간의 통신이 가능하게 할 수 있더라도 일반적인 개발자는 현란한 XML 포맷 때문에 SOAP 메시지를 처리하는데 어려움을 느낀다. REST 기반 API는 이러한 것의 좋은 대체재가 될 수 있는데, 추가적인 프로토콜 층이 없이 HTTP 층만 있기 때문이다. 본 논문에서는 통화 및 메시징 서비스를 만들기 위한 REST 기반의 Open APl 를 소개한다. 제안되는 API는 클릭투콜, 미니 컨퍼런스, 통화 녹음, 주문형 오디오 재생, 단문 메시징 및 음성 메시징 기능을 제공한다. 제안되는 API 특징은 전화망과 인터넷의 컨버전스의 강력함을 보여준다.
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There are a few core technologies to enable high-performance
$4^{th}$ generation (4G) broadband wireless communication system. A multiple input multiple output (MIMO) provides high-rate transmission through expended channels by multiple array antennas in both sender and receiver side. Also orthogonal frequency division multiplexing (OFDM) is well-known as the most appropriate technique for high data rate transmission such as Mobile WiMAX and WLAN. Efficient decrease of inter-carrier interference (ISI) and inter-carrier interference (ICI) are the reasons for why OFDM is suitable for high-performance transmission, 4G mobile communication. In this paper, we mainly focus on two of objects, combination between MIMO and OFDM, and OFDM channel simulator using Ray-tracing algorithm. The results of this paper can be used implementation of a Wireless Software Platform for 4G Mobile Communication Systems. -
Image Hash specifies as a descriptor that can be used to measure similarity in images. Among all image Hash methods, histogram based image Hash has robustness to common noise-like operation and various geometric except histogram _equalization. In this_paper an improved histogram based Image Hash that is using "Imadjust" filter I together is proposed. This paper has achieved a satisfactory performance level on histogram equalization as well as geometric deformation.
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Recently mobile devices can transmit mass data contained multi-media contents. According these flow, a demand for fast data transmission is being risen, so we acutely require remarkable technology that overcome mobile communication's poor environment and rise data transmission volume. Because it can be satisfied these needs, the OFDM(Orthogonal Frequency Division Multiplexing) that rise data transmission volume using efficient frequency, and MIMO(Multiple Input Multiple Output) that rise transmission confidence and data transmission volume using numbers of antenna is attended. Before design of MIMO-OFDM System we want to make an analysis for theory of its systems, and we want to design MIMO-OFDM simulator for verify an ability of modulation, data volume and numbers of antenna.
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인프라시설은 한번 설치하면 오랜 기간동안 사용해야 하는 시설로서 설치단계에서부터 가치에 기반하여 최적으로 구축하는 것이 무엇보다도 중요하다. 지금까지 설치된 인프라시설은 초기 투자비용만 고려되었을 뿐, 생애주기비용(LCC)과 성능이 고려되지 않아 효율적인 유지관리와 제대로된 자산관리를 하지 못하고 있는 것이 현실이다. 하지만, 앞으로의 시설 구축 개념은 최저 비용 개념에서 최고 가치 개념으로 변해가고 있으며, 정부에서도 100억원 이상의 건설공사에 LCC 및 VE 검토를 의무화 하고 있는 상황으로, 인프라시설 구축 시에도 VE 대안평가가 필요하다는 의견이 많이 대두되고 있다. 따라서, 본 논문에서는 인프라시설 중 하나인 통신전주를 대상으로 VE 대안평가를 실시하여 향후 설치될 통신 전주에 대한 의사결정 가이드라인을 제시하고, 이를 체계적으로 지원할 수 있는 인프라시설 VE 평가시스템에 대한 내용도 함께 소개하여 인프라시설에 적용 가능한 VE 대안평가 기법의 초석을 마련하고자 한다.
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불포화 폴리에스테르 수지를 결합재로 사용하여 제작되는 폴리머 콘크리트 맨홀은 조기 고강도 발현, 접착성. 수밀성, 내동결융해성, 내약품성, 내마모성, 전기절연성이 우수하여 프리캐스트로 제작되는 많은 통신용 맨홀에 적용되고 있다. 폴리머 콘크리트의 결합재로 사용되는 불포화 폴리에스테르 수지는 열경화성수지로써, 자체 발열에 의해 거푸집을 탈형할 정도의 초기 경화 반응이 나타나지만, 구조물로서 요구되는 소요 강도를 발휘하기 위해서는 적정 온도에 의한 추가 양생이 반드시 필요하다. 이에 본 논문에서는 폴리머 콘크리트의 휨 강도 시험용 공시체를 사용하여, 다양한 양생 온도 조건 및 양생기간에 따른 휨 강도를 측정하였으며, 이를 가열 촉진 양생에 의한 휨 강도와 비교하여 콘크리트가 소요 강도를 발휘하는데 요구되는 적정 온도와 기간을 도출하였다. 이를 통해 폴리머 큰크리트 맨홀의 품질 확보를 위한 생산 관리와 제품 검사를 체계적이고 효율적으로 수행할 수 있도록 하였다.
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In these days, compressed file is useful in internet environment and has many advantages. So a lot of data hiding algorithms works on JPEG compressed file. Of course they know basic rules of transformation and quantization and they utilize those rules to implement their programming. But most of them evaluate the affection of data hiding after data modification. We propose how to predict the affection of data modification in course of data hiding process. Through some kind of experiments, several valuable facts are revealed which used in data hiding in compressed domain such as JPEG. These facts will improve existing data hiding algorithms (F3, F4 and F5 which including Matrix Encoding)[1],[5],[6].
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Secure broadcasting is requirement for payment of TV systems, government or company. Hierarchical key management for access control provides efficient key management in those environment. Also, time-bound hierarchical key management technique generates different keys in each time period. In 2004, Tzeng proposed a time-bound cryptgraphic key assignment scheme for access control in a hierarchy and in 2008, Bertino et al proposed an efficient time-bound hierarchical key management scheme for secure broadcasting. Tzeng's scheme and Bertino et al's scheme are organized in different environment and primitive. In this paper, we analysis above two time-bound hierarchical key management scheme.
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In this paper we propose a lock-in detection method for portable sensor systems and demonstrate with the portable detection module that has high sensitivity and robustness against the noise. The simple portable sensor module is manufactured using MCU(Micro Contorl Unit), OPAMP, MOSFET and a pair of infrared sensor. Manufactured sensor module is testified in the noisy environment caused by an external light and an white noise source. Without any type of band pass filters, we recover a signal of 33
$mV_{p-p}$ in 80$mV_{p-p}$ white noise and get the DR(Dynamic Reserve) of 14 dB. -
In this paper, we construct an efficient fuzzy identity-based encryption scheme in the random oracle model. The fuzzy identity-based encryption is an extension of identity-based encryption schemes where a user's public key is represented as his identity. Our construction requires constant number of bilinear map operations for decryption and the size of private key is small compared with the previous fuzzy identity-based encryption of Sahai-Waters. We also presents that our fuzzy identity-based encryption can be converted to attribute-based encryption schemes.
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와전류탐상(ECT) Transmit-Receive 프로브를 이용한 ECT 방법은 센서코일의 유도기전력의 변화를 관찰하여 피검사체의 결함이나 특성의 변화를 탐지해내는 방법이다. ECT T/R 프로브는 여러 개의 Pancake 코일로 구성되어있고, 각각의 코일은 Transmit 코일과 Receive 코일로 나뉜다. 본 논문은 실제 TH 프로브 제작에 앞서 동일한 특성을 갖는 와전류센서를 설계 및 제작하여 그 특성을 파악하였다. 와전류센서에 인가되는 시험주파수와 Lift-off의 변화에 대한 특성을 파악하고 와전류센서의 임피던스값을 산출하여 정규화 임피던스도를 그려 와전류센서의 특성을 살펴보았다.
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The modulation quality of the I/Q modulator in a wireless transmitter usually affects system performance and it mostly depends on both a nonlinearity and a distortion, from the third order intermodulation(
$IM_3$ ) signal and the error components such as an input amplitude error and a local phase error, respectively. This paper focused on how much the Single Sideband Ratio(SSR), which indicates the signal distortion, changes according to the variation of the error components. Consequently, since a desired signal, side band signal at the I/Q modulator output are also represented with those power series coefficients and the error components, the effects of the error components on SSR to meet the EVM specification of the WPAN can be clearly analyzed. -
While going through economic development for several decades, Korea has become an industrialized country, and the development of industrial technology accelerated the advent of the information opportunity era. The recent information oriented society has brought forth the development of new information communication technology that enables anybody to obtain information easily and simply, and recently power line communication technology is being developed that allows the use of the existing power line net-works as they are. Each advanced country that faced up to a riffle effect of power line communication technology that enables us to obtain information easily anywhere at anytime is engaged in fierce competition to be a leader in this technology and to preoccupy the standardization of power line communication technology. At this point, this study is to help Korea take the lead in information communication technology by proposing a direction for the standardization that Korean power line communication technology needs to head for by identifying the trend of the worldwide of power line communication technology.
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본 논문은 이더넷이 비동기식으로 전송됨으로 인해, 동일한 전송속도를 가진 장비라 할지라도 링크가 제공하는 명목상의 최대속도로 전송될 경우, 상호 접속한 장비간의 전송클럭 차이로 인해 프레임의 손실이 발생한다. 본 논문에서는 PHY에서 복원된 수신 클럭과 송신 클럭의 차이를 비교하고 동시에 프레임버퍼에 쌓인 큐를 참조하여 프레임 손실이 방생할 수 있는 임계치를 넘어설 경우, 전송프레임의 프리엠블 길이를 조정함으로써 이더넷 장비에서 전송클럭의 차이로 인한 프레임손실을 줄일 수 있음을 확인하였다.
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In this paper, we propose a real time video codec adapter for enabling video communications with terminals having a codec which is different from each other. When multimedia services are playing with an office service phone such as a video phone or software phone which has video capability, each terminal is not being considered to have optimized video or voice codec. So when a video phone with only one type of video codec is used in the video streaming service which requires another type of codec, the streaming service is not successful without codec transformation. The real time codec adapter in this paper provides a real time code transformation which enables communication services such as video conferencing between terminals which have different codec.