• Journal of Communications and Networks
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• v.17 no.6
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• pp.582-591
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• 2015

A massive distributed storage system is the foundation for big data operations. Access latency performance is a key metric in distributed storage systems since it greatly impacts user experience while existing codes mainly focus on improving performance such as storage overhead and repair cost. By generating parity nodes from parity nodes, in this paper we design new XOR-based erasure codes hierarchical tree structure code (HTSC) and high failure tolerant HTSC (FH HTSC) to reduce access latency in distributed storage systems. By comparing with other popular and representative codes, we show that, under the same repair cost, HTSC and FH HTSC codes can reduce access latency while maintaining favorable performance in other metrics. In particular, under the same repair cost, FH HTSC can achieve lower access latency, higher or equal failure tolerance and lower computation cost compared with the representative codes while enjoying similar storage overhead. Accordingly, FH HTSC is a superior choice for applications requiring low access latency and outstanding failure tolerance capability at the same time.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.4
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• pp.721-728
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• 1994

In this paper, we analyzed the performances of system considering diversity for FH/CPFSK system with limiter-discrimicator detection and integrate-and-dump post-detection filtering. And, we considered thermal noise and partial-band jamming noise, intersymbol interference for all eight of the possible adjacent bit data patterns, FM noise clicks for evaluation systems. In result, the performance of FH/CPFSK system with diversity under the worst-case partial band jamming noise degraded about 5dB rather than that of without diversity when we considered the thermal noise but improved about 16dB rather than of without diversity when we ignored the thermal noise.

• International Journal of Computer Science & Network Security
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• v.22 no.3
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• pp.236-244
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• 2022

Network Mobility Basic Support (NEMO BS) protocol has been accredited and approved by Internet Engineering Task Force (IETF) working group for mobility of sub-networks. Trains, aircrafts and buses are three examples of typical applications for this protocol. The NEMO BS protocol was designed to offer Internet access for a group of passengers in a roaming vehicle in an adequate fashion. Furthermore, in NEMO BS protocol, specific gateways referred to Mobile Routers (MRs) are responsible for carrying out the mobility management operations. Unfortunately, the main limitations of this basic solution are pinball suboptimal routing, excessive signaling cost, scalability, packet delivery overhead and handoff latency. In order to tackle shortcomings of triangular routing and Quality of Service (QoS) deterioration, the proposed scheme (Diff-FH NEMO) has previously evolved for end-users in moving network. In this sense, the article focuses on an exhaustive analytic evaluation at Home Agent (HA) entity of the proposed solutions. An investigation has been conducted on the signaling costs to assess the performance of the proposed scheme (Diff-FH NEMO) in comparison with the standard NEMO BS protocol and MIPv6 based Route Optimization (MIRON) scheme. The obtained results demonstrate that, the proposed scheme (Diff-FH NEMO) significantly improves the signaling cost at the HA entity in terms of the subnet residence time, number of mobile nodes, the number of DMRs, the number of LFNs and the number of CNs.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.405-408
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• 2001

In this paper, we design tracking filter that get frequency range from 30 to 88 ［MHz］ for FH/BFSK communication system. This filter use for switching componet BJT. as result, This tracking filter has a insertion loss of 0.77~1.93［dB］. And it has a cutoff characteristic 30/3［dB］ shape factor of 3.9~6.2［dB］. The tracking filter satisfy its specification

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.5
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• pp.424-433
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• 1991

In the noncoherent FH/FSK system presence of the multitione jamming and noise, in the case random and 송 structures jamming model, the performance analyzed that random and struetured jamming derived error proability. It is found that error probability and performance when error corecting code used Hamming. BCH, Convolutional code under the worst case partial band jamming interference.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.324-330
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• 2002

In this paper, we proposed a simple modification on Fiebig's REC algorithm for multiuser detection of FH/MFSK systems replacing hard limiter with soft limiter. The performance improvement of our modified REC algorithm has been confirmed with computer simulations. for the parameter of interest, the capacity could be increased about 5% or more without degrading the reliability.

• ETRI Journal
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• v.35 no.5
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• pp.748-756
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• 2013

This paper addresses the problem of online hop timing detection and frequency estimation of multiple frequency-hopping (FH) signals with antenna arrays. The problem is deemed as a dynamic one, as no information about the hop timing, pattern, or rate is known in advance, and the hop rate may change during the observation time. The technique of particle filtering is introduced to solve this dynamic problem, and real-time frequency and direction of arrival estimates of the FH signals can be obtained directly, while the hop timing is detected online according to the temporal autoregressive moving average process. The problem of network sorting is also addressed in this paper. Numerical examples are carried out to show the performance of the proposed method.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.5
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• pp.1-9
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• 1994

In this paper, we analyzed the performances for FH/CPFSK system with limiter-discriminator detection and integrate-and-dump post-detection filtering under thermal noise and partial-band jamming noise. And,we considered intersymbol interference-related SNR and differential phase parameters for all eight of the possible adjacent bit data patterns, FM noise clicks for evaluating FH/CPFSK and CPFSK Systems. In result, the optimum modulation index h was 0.7 and the optimum value of bandwidth-time product D was 1.0 Next, when we considered the thermal noise under the partial-band jamming, the thermal noise significantly influenced the error probability of system below 20dB approximately but could ignore above 20dB.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.42-51
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• 1996

Performance analysis of FH/CPFSK system with liiter-discriminator detection and integrate-dump post-detection filtering under the thermal noise and the partial-band noise jamming on the rayleigh fading channel have been analyzed. The thermal noise and partial-band noise jamming, rayleigh fading, intersymbol interference for all eight of the possible adjacent bit data patterns, and FM noise click for evaluating systems have been considered. Also optimum parameters to improve performance of FH/CPFSK system have been obtained and validities for AMPS and CDMA system of land-mobile-communication system through computer simulation have been proved.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.5 no.3
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• pp.3-13
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• 1994

In the environments with interference and Rayleigh fading the bit error probability equation of FH / MFSK signal has been derived and the error rate has been evaluated. And the results are shown in graphs and discussed. The degree of improvement of error rate performance has been found out in space diversity technique. From the results, we know that maximal ratio combining is very effective for Rayleigh fading and interference.