• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2001년도 추계종합학술대회
• /
• pp.113-116
• /
• 2001

본 논문에서는 WDM 단일흡 방송망에서 멀티캐스트 스케줄링 알고리즘을 제안하였다. 기존의 멀티캐스트 스케줄링 알고리즘의 주요 연구내용은 멀티캐스트 그룹에 속하는 수신노드가 수신준비가 끝난 후 데이터 메시지를 수신하기까지 기다리는 지연시간을 최소화 할 수 있도록 서브그룹을 나누는 연구가 대부분이다. 이들 서브그룹을 나누기 위한 방법들은 송신노드에서 사용하는 데이터 채널에 수신기를 튜닝하여 가장 지연시간이 작도록 그룹화 시키는 알고리즘이다. 그러나 수신기의 이전 튜닝상태를 고려하면 보다 최적화된 멀티캐스트 스케줄링이 가능할 것이다. 따라서 본 논문에서는 수신노드의 수신기의 현재 상태를 수집하여 멀티캐스트 메시지의 전송 시간이 최소가 되도록 멀티캐스트 그룹을 서브그룹화 하는 방안을 제안하였다. 제안된 방법은 가변송수신기를 사용하는 WDM 단일홉 방송망에서 동작되며 고정된 제어채널을 통해 수신노드의 상태를 수집할 수 있도록 구성하였다. 또한 제안된 방법은 컴퓨터 시뮬레이션을 통하여 성능을 분석하고 기존의 멀티캐스트 스케줄링 알고리즘과 비교하였다.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
• /
• pp.141-144
• /
• 2006

The deviations in the injection orbital parameters, resulting from launcher dispersions, need to be estimated and used for autonomous satellite operations. For the proposed small satellite mission of the university there will be two GPS receivers onboard the satellite to provide the instantaneous orbital state to the onboard data handling system. In order to meet the power requirements, the satellite will be sun-tracking whenever there is no imaging operation. For imaging activities, the satellite will be maneuvered to nadir-pointing mode. Due to such different modes of orientation the geometry for the GPS receivers will not be favorable at all times and there will be instances of poor geometry resulting in no output from the GPS receivers. Onboard the satellite, the orbital information should be continuously available for autonomous switching on/off of various subsystems. The paper presents the strategies to make use of small arcs of data from GPS receivers to compute the mean orbital parameters and use the updated orbital parameters to calculate the position and velocity whenever the same is not available from GPS receiver. Thus the navigation message from the GPS receiver, namely the position vector in Earth-Centered-Earth-Fixed (ECEF) frame, is used as measurements. As for estimation, two techniques - (1) batch least squares method, and (2) Kalman Filter method are used for orbit estimation (in real time). The performance of the onboard orbit estimation has been assessed based on hardware based multi-channel GPS Signal simulator. The results indicate good converge even with short arcs of data as the GPS navigation data are generally very accurate and the data rate is also fast (typically 1Hz).

• 정보처리학회논문지C
• /
• 제9C권6호
• /
• pp.919-926
• /
• 2002

본 논문에서는 WDM 단일홉 Broadcast-and-select망에서 멀티캐스트 서비스를 지원하기 위한 스케줄링 알고리즘을 제안하였다. 기존의 멀티캐스트 스케줄링 알고리즘들은 고정된 송신기와 튜닝이 가능한 수신기에 대하여 멀티캐스트 서비스의 지연시간을 줄이기 위해 멀티캐스트 그룹을 어떻게 적절한 서브그룹으로 나눌 것인가에 대한 것이었다. 이러한 알고리즘들은 송신측의 파장으로 튜닝되어 바로 수신할 준비가 되어 있는 노드들에 대하여 이루어졌기 때문에 수신측의 상태정보를 이용할 수 없었으며, 모든 수신노드의 튜닝지연으로 인해 전체적인 지연시간이 길어지게 되었다. 따라서 본 논문에서는 튜닝이 가능한 송신기와 수신기의 상태정보, 그리고 메시지 전송시간과 튜닝지연시간을 이용하여 서브그룹을 나누는 H_EAR과 PGM 두 알고리즘을 제안하고, 컴퓨터 시뮬레이션을 통해 제안된 알고리즘의 성능이 기존의 멀티캐스트 스케줄링 알고리즘에 비하여 지연시간과 서브 그룹수의 측면에서 우수함을 보였다.

• Journal of electromagnetic engineering and science
• /
• 제6권2호
• /
• pp.83-91
• /
• 2006

In this paper, we develop space-time(ST) Rake receivers for Time Division Synchronous Code Division Multiple Access(TD-SCDMA) base stations(BS). The beamforming of BS transforms the uplink MIMO channel space into many sub-sectors' channels to be nearly orthogonal, thus, well established 1-D Rake technology can be used to TD-SCDMA base station to construct ST Rake, which simplified the system's implementation as well as enlarged users' capacity by the beamforming. The construction and capacity of MIMO sub-sectors by multi-beamforming have been presented. The proposed ST Rake algorithm include the multi-beamforming algorithm for MIMO sub-sectors and classical 1-D Rake algorithm. The calculating formulas for interference plus noise ratio(SINR) and bit error rate(BER) have been derived. Simulations verify that the proposed ST Rake receiver for BS is effective, and the BS systems can get higher system capacity and can be of better performance than presented TD-SCDMA systems.

• 전자공학회논문지
• /
• 제49권9호
• /
• pp.43-48
• /
• 2012

본 논문에서는 다중 접합 기반 수신기 (MPDR)의 영상 제거 성능을 향상시키는 반복적인 단일주파수 CW 신호 기반 I/Q 신호 재생 알고리즘을 제안한다. 이 논문에서는 MPDR 수신기의 I/Q 신호 재생이 직접변환수신기의 I/Q 부정합 보상임을 보인다. 분석을 바탕으로 I/Q 재생의 정확도를 영상 제거비로써 평가한다. 제안한 방법은 기존의 I/Q 신호 재생 방법에 비해서 20dB 이상 영상 제거비를 향상시킨다. 모의실험 결과는 제안한 방법을 이용한 MPDR 수신기의 영상 제거비가 70dB 이상임을 보이고, 비트오율 성능은 페이딩 채널 환경에서 조차도 일반적인 동기 수신기의 성능과 거의 같음을 보인다.

• ETRI Journal
• /
• 제36권2호
• /
• pp.188-196
• /
• 2014

This paper describes a simple delay diversity technique for terrestrial digital multimedia broadcasting (T-DMB) and digital audio broadcasting in a single-frequency network (SFN). For the diversity technique, a delay diversity scheme is adopted. In the delay diversity scheme, a non-delayed signal is transmitted in the first antenna, and delayed versions of the signal are transmitted in each additional antenna. For an SFN environment with multiple transmitters, delay diversity can be executed by controlling the emission times of the transmitters. This SFN delay diversity scheme does not require any hardware changes in either the transmitter or receiver, and perfect backward compatibility can be acquired. To evaluate the performance improvement, laboratory tests are executed with various types of commercial T-DMB receivers as well as a measurement receiver. The improvement in the bit error rate performance is evaluated using a measurement receiver, and an improvement of the threshold of visibility value is evaluated for commercial receivers. Test results show that the T-DMB system can obtain diversity gain using the described technique.

• 센서학회지
• /
• 제28권6호
• /
• pp.385-389
• /
• 2019

As we become an aging society, the number of dementia patients increases every year (an estimated 10% of the elderly, equating to 1.27 million in 30 years). In addition, 17,000 cases of missing people with disabilities and dementia are reported annually, indicating that more than one person per hour goes missing. More than 50% of those who are lost suffer injuries (some of which are fatal) within 24 hours after going missing. This is why measures are urgently required to ensure safety of the elderly. The core function of the disappearances prevention system proposed by this research group is to identify and respond early to deviations of dementia patients from their homes or facilities by identifying the location of the occurrence of disappearance, so that real-time notifications occur when a they leave the protected area. In addition, multiple receivers and public transportation integrated terminals share information when a patient leaves and uses public transportation to ensure their safe return. Most existing beacon-based positioning service models have fixed signal transmitters and are serviced in the form of transport receivers, but the proposed service model has users wearing the BLE beacon and receivers fixed.

• 전기학회논문지
• /
• 제63권9호
• /
• pp.1259-1265
• /
• 2014

In this paper, the real-time attitude determination based Matlab using low-cost receivers was designed and evaluated. The GNSS attitude determination system was implemented to operation in real-time by TimerCallback in MATLAB. The TTM(Transmission Time Misalignment) of U-blox receiver was confirmed through zero baseline tests and this problem was revised. The computed attitude by the high-cost NovAtel receiver was compared to the computed attitude by the low-cost U-blox receiver. As a result of this, the performance of attitude determination systems by low-cost receiver was confirmed. To determine baseline, LAMBDA and BC-LAMBDA for integer ambiguities search methods were used. To confirm suitable integer ambiguity search method in real-time attitude determination algorithm, determined baselines by two methods were compared, and it was confirmed that BC-LAMBDA is more suitable. As a result of this, the operation of real-time attitude determination system was confirmed using 3 low-cost receivers.

• 한국안전학회지
• /
• 제29권5호
• /
• pp.54-59
• /
• 2014

The record type receivers that are operated in large industrial sites have strength in preventing fire. However, because of its long circuit lines and multiple detectors, the receivers are vulnerable to lightning, noise, and breakdown of equipments, resulting in malfunction. In case of malfunctioning of detection circuits of main protection areas, such as electrical room and server room, potential release of gaseous extinguisher agents may lead to property and life damage. In this paper, we present the results on the characteristics of the transponder that initiates the solenoid valves, with respect to various electromagnetic and lightning inflow conditions. Based on the measured data, we analyzed the systematic problems of the transponder. In order to prevent receiver malfunctions, a sequential circuit was configured with two additional transponders and a timer. The circuit was tested with a simulator with preference and delay circuit algorithms.

• 한국통신학회논문지
• /
• 제30권9C호
• /
• pp.899-906
• /
• 2005

이 논문에서는 충격성 잡음 감쇄 채널에서 가장 비슷함을 바탕으로 최적 갈퀴수신기를 이끌어 내고, 얼개가 간단한 준최적 갈퀴수신기를 얻는다. 잡음이 충격성이면 충격성 환경을 고려한 갈퀴수신기가 정규 잡음에 최적화된 갈퀴수실기보다 성능이 좋다는 것을 모의실험으로 보인다. 또한, 갈퀴수신기의 가락 수가 늘어날수록, 충격성 환경에 알맞게 만든 갈퀴수신기는 성능이 나아지지만, 정규 잡음에 최적화된 갈퀴수신기는 충격성 환경에서 성능이 떨어짐을 보인다.