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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of Advanced Navigation Technology
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Journal DOI :
The Korea Navigation Institute
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Volume & Issues
Volume 7, Issue 2 - Dec 2003
Volume 7, Issue 1 - Jun 2003
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Output Power Improvement of Push-Push FET DRO with an Additional DR
Kim, Ihn S. ; Jo, Chisung ; Han, Yongin ;
The Journal of Advanced Navigation Technology, volume 7, issue 1, 2003, Pages 1~5
In this paper, the output power level and phase noise property of nine conventional push-push FET DROs (Dielectric Resonator Oscillator) have been experimentally investigated by adding one more identical DR at the drain port. The nine oscillators designed to generate 20 GHz from 10 GHz fundamental frequency, have been tested for each of three different power combiners at the output port. It has been observed that the output power level of the push-push FET DROs can be improved by placing the DR while maintaining their phase noise characteristics were approximately the same as before adding the DR.
Design and Performance Analysis of Non-coherent Code Tracking Loops for HSDPA MODEM
Yang, Yeon-Sil ; Park, Hyung-Rae ;
The Journal of Advanced Navigation Technology, volume 7, issue 1, 2003, Pages 6~13
In this paper, a non-coherent code tracking loop is designed for 3GPP HSDPA MODEM and its performance is analyzed in terms of steady-state jitter variance and transient response characteristics. Analytical closed-form formula for steady-state jitter variance is first derived for AWGN environments as a function of pulse-shaping filter, timing offset, signal-to-interference ratio, and loop bandwidth. Also obtained is the transient response characteristic of a tracking loop. Finally, the performance of the designed tracking loop is confirmed by computer simulations.
Wideband Optical Phase Conjugator using HNL-DSF in WDM Systems with Path-Averaged Intensity Approximation Mid-Span Spectral Inversion
Lee, Seong-Real ; Lee, Yun-Hyun ;
The Journal of Advanced Navigation Technology, volume 7, issue 1, 2003, Pages 14~21
We investigated the optimum pump light power compensating distorted WDM signal due to both chromatic dispersion and self phase modulation (SPM). The considered system is
Gbps intensity modulation direct detection (IM/DD) WDM transmission system with path-averaged intensity approximation (PAIA) mid-span spectral inversion (MSSI) as compensation method. This system have highly nonlinear dispersion shifted fiber (HNL-DSF) as nonlinear medium of optical phase conjugator (OPC) in the mid-way of total transmission line. We confirmed that HNL-DSF is an useful nonlinear medium in OPC for wideband WDM transmission, and the excellent compensation is obtained when the pump light power of HNL-DSF OPC was selected to equalize the conjugated light power into the second half fiber section with the input WDM signal light power depending on total transmission length. By this approach, it is verified the possibility to realize a long-haul high capacities WDM system by using PAIA MSSI compensation method, which have HNL-DSF OPC with optimal pump light power depending on transmission length.
The Analysis on the Effects of Interference between HAPS and NGSO System in the Service Link
Yang, Eui-Jang ; Kim, Kyu-Hwan ; Ham, Hyung-Il ; Kang, Yung-Heung ;
The Journal of Advanced Navigation Technology, volume 7, issue 1, 2003, Pages 22~29
In this paper, we analyze the interference effects between NGSO(Non-Geostationary Orbit) and HAPS(High Altitude Platform System) by dividing into two cases. The one is interference effects of HAPS into NGSO, the another is the interference effects of NGSO into HAPS. At the result, we canknow the interference effect into NGSO mobile station is the highest when position of NGSO is
. In this case, we can also know the interference effects from both HAPS and NGSO exceed interference criteria when the number of users are more than 20. And, in the case of the interference effect into HAPS mobile station, we can know it is the highest when elevation angle of NGSO is
, and the interference effects from both NGSO and HAPS exceed interference criteria when the number of users is more then 10. Moreover, the interference effect is the minimum, when elevation angle of NGSO is
, at this time, in case that the number of users of NGSO equal to the number of user of HAPS, the interference effects exceed interference criteria when the number of users is 190.
Performance Analysis of Multi-Carrier CDMA Systems under Indoor Wireless Environment with Impulsive Noise
Lee, Young-Choon ; Park, Ki-Sik ; Cho, Sung-Joon ;
The Journal of Advanced Navigation Technology, volume 7, issue 1, 2003, Pages 30~37
In this paper, we have analyzed the BER (Bit Error Rate) performance of MC-CDMA systems under indoor wireless environment with class A impulsive noise suggested by Middleton. For the performance evaluation, we considered from strong to weak impulsive noise characteristics. And we have evaluated the degree of performance improvement by using turbo code as a compensation technique to impulsive noise. From the result of analysis, it is found powerful performance improvement scheme must be adopted in the system under impulsive noise environment, and when turbo code scheme is adopted, system BER performance is improved by the
. As the impulsive noise characteristics approaches AWGN characteristics, the degree of performance improvement by adopting turbo code become larger.
Detection and Estimation of a Faults on Coaxial Cable with TFDR Algorithm
Song, Eun-Seok ; Shin, Yong-June ; Choe, Tok-Son ; Yook, Jong-Gwan ; Park, Jin-Bae ; Powers, Edward J. ;
The Journal of Advanced Navigation Technology, volume 7, issue 1, 2003, Pages 38~50
In this paper, a new high resolution reflectometry scheme, time-frequency domain reflectometry (TFDR), is proposed to detect and locate fault in wiring. Traditional reflectometry methods have been achieved in either the time domain or frequency domain only. However, time-frequency domain reflectometry utilizes time and frequency information of a transient signal to detect and locate the fault. The time-frequency domain reflectometry approach described in this paper is characterized by time-frequency reference signal design and post-processing of the reference and reflected signals to detect and locate the fault. Design of the reference signal in time-frequency domain reflectometry is based on the determination of the frequency bandwidth of the physical properties of cable under test. The detection and estimation of the fault on the time-frequency domain reflectometry relies on the time-frequency domain reflectometry is compared with commercial time domain reflectomtery (TDR) instrument. In these experiments provided in this paper, TFDR locates the fault with smaller error than TDR. Knowledge of time and frequency localized information for the reference and reflected signal gained via time-frequency analysis, allows one to detect the fault and estimate the location accurately.
Capacity Evaluation of Multi-Carrier CDMA System in Correlated MIMO Fading Channel
Roh, Jae Sung ; Cho, Sung Joon ; Kim, Choon Gil ;
The Journal of Advanced Navigation Technology, volume 7, issue 1, 2003, Pages 51~58
Generally, multi-path is viewed as an undesirable feature of wireless communications. Therefore, diversity reception and adaptive array schemes are proposed to mitigate its effects. Recently, to increase the spectrum efficiency and the link reliability, multiple-input multiple-output (MIMO) scheme is devised to exploit multi-path in a scattering wireless channel. In this paper, we have evaluated the channel capacity of MIMO Multi-Carrier CDMA system in path correlation fading channel. And, the channel capacity of MIMO system is compared with single-input single-output (SISO) system. From the results, the MIMO multi-carrier CDMA system with path correlation yields better performance with respect to channel capacity than a SISO system.
The Channel Scheduler based on Water-filling Algorithm for Best Effort Forward Link Traffics in AMC/TDM/CDM System
Ma, Dongl-Chul ; Ki, Young-Min ; Kim, Dong-Ku ;
The Journal of Advanced Navigation Technology, volume 7, issue 1, 2003, Pages 59~71
The channel scheduler is suggested the radio resource management method in order to provide service with guaranteeing fairness and throughput to the users who use limited wireless channel. Proportional fairness scheduling algorithm is the channel scheduler used in the AMC(Adaptive Modulation and Coding)/TDM system, and this algorithm increases the throughput considering the user's time fairness. In this paper is suggested the channel scheduler combining CDM scheme available in AMC/TDM/CDM system. Unlike the system which only uses TDM which provide the only one user at the same slot, this scheduler can service a lot of users since this uses the CDM scheme with multi-cord channel. At every moment, allocation of transmission power to multi-channel users is problematic because of CDM scheme. In this paper, we propose a water-filling scheduling algorithm to solve the problem. Water-filling fairness(WF2) scheduling algorithm watches the average channel environment. So, this modified method guarantees fairness for each user in terms of power and service time.
A New Linearly Constrained Beamforming Scheme with Incoherent Environment
Kim, Young-Soo ;
The Journal of Advanced Navigation Technology, volume 7, issue 1, 2003, Pages 71~81
A new beamforming technique is presented for effectively nulling out multiple incoherent interferences incident on an equispaced linear array. The basic idea of the proposed beamformer is based on the matrix property mapping which is basically concerned with the task of recovering a signal from a noise and interference contaminated measurement made on that signal. Computer simulations are shown to illustrate the superior performance achieved with the proposed beamformer relative to that of the conventional LCMV beamformer.
Conceptual Design of Ground Control System for Stratospheric Platform for Telecommunications Application
Kang, Jay ;
The Journal of Advanced Navigation Technology, volume 7, issue 1, 2003, Pages 82~90
Recently, a new concept of telecommunication system, utilizing stratospheric platforms such as airships or airplanes, has been proposed. This system aims to provide broadband multimedia services, i.e. high-rate multimedia service, high-rate internet service, and leased line service. In this study, operation concept of the system is defined and by allocating required functions on the system and its subsystems, conceptual design of the ground control system for the stratospheric platforms is established and proposed.