• 한국정보통신학회논문지
• /
• 제1권1호
• /
• pp.47-54
• /
• 1997

본 논문에서는 셀룰러 이동 통신에서 사용되는 채널할당에 관한 알고리즘을 제안한다. 제안된 알고리즘은 기지국과 이동국사이의 거리에 따라 채널을 할당하고, 할당된 채널은 거리를 기준으로 하여 전력제어를 실시하는 알고리즘을 제안한다. 이 방법은 희망파와 간섭파의 전력비(carrier to interference ratio : CIR)가 일정한. 레벌을 만족한다면 어떤 채널도 사용할 수 있다. 제안된 알고리즘은 동일 채널에 대한 주파수 재사용거리를 감소시킬 수 있기 때문에 주파수 효율을 증대시킬 수 있고, 기존의 고정할당법과 비교할 때 2배 이상의 주파수효율을 얻을 수 있었다.

• Asia pacific journal of information systems
• /
• 제3권1호
• /
• pp.31-53
• /
• 1993

Computer Aided Software Engineering(CASE) tools are suggested as an automated method for the efficient development of softwares. This study are intended to measure the use level of CASE tools and to provide the meaningful information on the whole software development environment supported by CASE tools. Therefore, the results of a survey on CASE environment in Korea are empirically reported and analyzed. The use of CASE tools is measured; purposes purchasing CASE tools and achievement levels are investigated. Implications from the comparative analysis of the utilization of software engineering methodologies between the CASE user group and the non-user group are described. A proposition is suggested to check the request frequency for program change. Further studies on the reverse engineering, program reuse and the use of CASE tools under distributed processing systems such as client-server environments are suggested.

• 전자공학회논문지C
• /
• 제34C권8호
• /
• pp.22-38
• /
• 1997

This paper proposes a new VLSI architecture for morphological filters and presents its chip design and implementation. The proposed architecture can significantly reduce hardware costs compared with existing architecture by using a feedback loop path to reuse partial results and a decoder/encoder pair to detect maximum/minimum values. In addition, the proposed architecture requires one common architecture for both diltion and erosion and fewer number of operations. Moreover, it can be easily extended for larger size morphologica operations. We developed VHDL (VHSIC hardware description language) models, performed logic synthesis using the SYNOPSYS CAD tool. We used the SOG (sea-of-gate) cell library and implemented the actual chip. The total number of gates is only 2,667 and the clock frequency is 30 MHz that meets real-time image processing requirements.

• 한국정보통신설비학회:학술대회논문집
• /
• 한국정보통신설비학회 2006년도 하계학술대회
• /
• pp.43-46
• /
• 2006

IEEE 802.16 WirelessMAN aiming to broadband wireless access (BWA) is evolving to 4G mobile communication system through the standardization of IEEE 802.16e supporting mobility on existing fixed WirelessMAN system. It is necessary for hand-over to provide seamless data service while MS (Mobile Station) moves to another BS (Base Station). Because the performance of handover affects packet loss or delay of any communications, it must consider low latency handover mechanism in packet based network. In this paper, we describes handover scheme of IEEE 802.16e with the cell edge interference problem and shows the way to solve the problem in frequency reuse one deployment. Our scheme reduces the handover latency and packet loss probability.

• 대한전기학회논문지:시스템및제어부문D
• /
• 제49권8호
• /
• pp.481-490
• /
• 2000

This paper analyzes interference power, Erlang capacity, the number of handoff occurrences, and call blocking probability with respect to the cell radius, the soft handoff region, and the mobile's velocity in a CDMA hierarchical cellular system. The microcell cellular system has the higher Erlang capacity than the macrocell cellular system. However, the microcell cellular system, which has a high system capacity through frequency reuse has the call blocking probability higher than macrocell cellular system. Also the interference power and the call blocking probability are decreased with the operation of soft handoff. Therefore, this paper presents the optimization of soft handoff region so as to maximize system's Erlang capacity with the low the call blocking probability according to mobile's velocity in the CDMA hierarchial cellular system.

• 방송공학회논문지
• /
• 제7권1호
• /
• pp.10-20
• /
• 2002

지상파 DTV 방송 구역내의 음영지역을 보완하기 위하여 KBS 기술연구소에서는 DTV 중계기와 동일채널 중계기술을 연구하고 있다. 특히. 동일채널 중계기법은 주파수 자원을 재사용하여 서비스 범위를 확장할 수 있으나 ATSC DTV 시스템에 적용하기 위해서는 많은 제약이 따른다. 본 논문에서는 동일 채널 중계방식 중 단순 중계방식과 재생 중계방식을 실제 필드테스트를 통해서 비교하고. DTV 방송 시스템을 위한 동일 채널 중계기의 설치 조건과 활용 가능성에 대해서 분석한다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2000년도 ITC-CSCC -1
• /
• pp.339-342
• /
• 2000

This paper presented a FPGA design of SEED, which is the Korea standard 128-bit block cipher. In this work, SEED was designed technology- independently for other applications such as ASIC or core-based designs. Hence in case of changing the target of design, it is not necessary to modify design or need only minor modification to reuse the design. Since SEED algorithm requires a lot of hardware resources, each unit was designed only once and used sequentially. So, the number of gates was minimized and SEED algorithm was fitted in FPGA without additional components. It was confirmed that the rate of resource usage is about 80% in ALTERA 10KE and the SEED design operates in a clock frequency of 131.57 MHz and an encryption rate of 29 Mbps.

• 한국정보통신학회논문지
• /
• 제5권2호
• /
• pp.263-268
• /
• 2001

본 논문은 근거리에서의 차량간 통신에 밀리미터나 광전파를 분석하는데 효과적인 Ray Tracing방법을 도입하여 오율특성을 분석하였다. 분석환경으로는 간섭신호에 강한 장점을 지니며 산소흡수에 의한 감쇠가 크며 주파수 재사용효율이 좋은 60㎓ 대역에서의 비트오율을 분석하였다. 전파모델로 지면반사파, 콘크리트벽에 의한 반사와 옆 도로를 달리는 차량에 의한 반사를 고려한 Two-Ray 라이시안 채널에서의 다중접속자에 의한 DS/CDMA 시스템의 비트오율특성을 분석하여 검토하였다. 성능 개선 기법으로는 MRC 다이버시티를 채용하였다.

• International journal of advanced smart convergence
• /
• 제10권3호
• /
• pp.81-88
• /
• 2021

This paper proposes two types of subharmonic RF receiver front-end (called LMV) where, in a single stage, quadrature voltage-controlled oscillator (QVCO) is stacked on top of a low noise amplifier. Since the QVCO itself plays the role of the single-balanced subharmonic mixer with the dc current reuse technique by stacking, the proposed topology can remove the RF mixer component in the RF front-end and thus reduce the chip size and the power consumption. Another advantage of the proposed topologies is that many challenges of the direct conversion receiver can be easily evaded with the subharmonic mixing in the QVCO itself. The intermediate frequency signal can be directly extracted at the center taps of the two inductors of the QVCO. Using a 65 nm complementary metal oxide semiconductor (CMOS) technology, the proposed subharmonic RF front-ends are designed. Oscillating at around 2.4 GHz band, the proposed subharmonic LMVs are compared in terms of phase noise, voltage conversion gain and double sideband noise figure. The subharmonic LMVs consume about 330 ㎼ dc power from a 1-V supply.

• ETRI Journal
• /
• 제44권6호
• /
• pp.955-965
• /
• 2022

A low Earth orbit (LEO) satellite constellation could be used to provide network coverage for the entire globe. This study considers multi-beam frequency reuse in LEO satellite systems. In such a system, the channel is time-varying due to the fast movement of the satellite. This study proposes an efficient power and bandwidth allocation method that employs two linear machine learning algorithms and take channel conditions and traffic demand (TD) as input. With the aid of a simple linear system, the proposed scheme allows for the optimum allocation of resources under dynamic channel and TD conditions. Additionally, efficient projection schemes are added to the proposed method so that the provided capacity is best approximated to TD when TD exceeds the maximum allowable system capacity. The simulation results show that the proposed method outperforms existing methods.