• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.44-48
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• 2001

In this paper we describe the design of symbol timing and carrier synchronization algorithms for burst receiver. The demodulator consists of digital down converter, matched filter and synchronization circuits. For symbol timing recovery we use modified Gardner algorithm. And we use decision directed method for carrier phase recovery. For the sake of performance analysis, we compare simulation results with the board implemented by FPGA which is APEX20KE series chip for Alter. The performance results show it works quite well up to the condition that a frequency offset equal to 0.1% of symbol rate.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.187-190
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• 1998

In this paper, a synchronization method of OFDM signals are introduced and its performance is estimated. A proposed method can perform a frame/symbol timing, carrier frequency synchronizations. Reference symbols consist of two duplicate OFDM symbols carrying signals on every sub-carriers. Performances of synchronization under 60GHz millimeter-wave indoor channels are evaluated, which were measured with frequency-sweeping method in common office buildings. A proposed method has improved performances owing to long averaging durations of synchronization metrics in frame/symbol timing, carrier frequency synchronization procedures.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3C
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• pp.189-194
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• 2007

This paper derives and computes the detection probability of timing synchronization in an orthogonal frequency division multiplexing (OFDM) system encountered with a multipath Rayleigh fading channel and imperfect noise estimation. The timing synchronization scheme using a simple repeated constant amplitude zero auto-correlation (CAZAC) training symbol and correlation techniques is adopted. With this provision, we focus on the numerical analysis for OFDM timing synchronization scheme employing a preadvancement technique to reduce the inter-symbol interference (ISI). For measuring system performance, the detection performance derived in the considered system is presented in a multipath Rayleigh fading channel.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.487-489
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• 2005

This paper proposes a symbol timing recovery method that is simple in structure and can provide high speed symbol synchronization. Transmitter and receiver are not synchronized in communication systems using digital modulation. Receiver should search the timing variation of transmitter continuously. The proposed timing recovery method searches sample position by comparing previous sample value with next sample value. This method can be applied to digital and optical transceivers with high data rate.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.451-453
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• 2005

In this paper, a preamble structure and a timing synchronization method for 802.16e based system are developed. The performances of the timing offset estimation in multipath fading channel is compared in terms of absolute mean. The simulation result shows that the proposed method has smaller mean.

• Journal of Digital Contents Society
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• v.12 no.2
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• pp.177-184
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• 2011

This study deals with Timing Synchronization of motion picture and music in film music's physical point of view. Timing Synchronization appears by using Click Track, which calculates time of picture and location of bar. We also can find Hit, the emphasis point of music, by computation Frame Per Beat and estimate the location of note per time. Hit can be placed at upbeat, but, because of music's characteristic, it is more convenient to composer when it's placed at downbeat. Therefore, this study suggests three methods to sync the music and picture. First of all, sync through time conversion, second of all, sync through tempo conversion, and lastly, there is way to sync through offset. These each methods have their pros and cons, so choice should be made based on the music's natural flow.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.41-44
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• 2000

In this paper, an improved timing synchronization method for OFDM system is proposed. In multipath fading channels, timing offset estimation algorithm based on simple correlation metric can cause inter-symbol interference (ISI). The proposed algorithm promises accurate timing offset estimation, which can be achieved by simple windowing. The estimation errors in several multipath channels are evaluated in computer simulations.

• Journal of Communications and Networks
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• v.18 no.1
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• pp.65-74
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• 2016

Ship ad-hoc network (SANET) extends the coverage of the maritime communication among ships with the reduced cost. To fulfill the growing demands of real-time services, the SANET requires an efficient clock time synchronization algorithm which has not been carefully investigated under the ad-hoc maritime environment. This is mainly because the conventional algorithms only suggest to decrease the beacon collision probability that diminishes the clock drift among the units. However, the SANET is a very large-scale network in terms of geographic scope, e.g., with 100 km coverage. The key factor to affect the synchronization performance is the signal propagation delay, which has not being carefully considered in the existing algorithms. Therefore, it requires a robust multi-hop synchronization algorithm to support the communication among hundreds of the ships under the maritime environment. The proposed algorithm has to face and overcome several challenges, i.e., physical clock, e.g., coordinated universal time (UTC)/global positioning system (GPS) unavailable due to the atrocious weather, network link stability, and large propagation delay in the SANET. In this paper, we propose a logical clock synchronization algorithm with multi-hop function for the SANET, namely multi-hop clock synchronization for SANET (MCSS). It works in an ad-hoc manner in case of no UTC/GPS being available, and the multi-hop function makes sure the link stability of the network. For the proposed MCSS, the synchronization time reference nodes (STRNs) are efficiently selected by considering the propagation delay, and the beacon collision can be decreased by the combination of adaptive timing synchronization procedure (ATSP) with the proposed STRN selection procedure. Based on the simulation results, we finalize the multi-hop frame structure of the SANET by considering the clock synchronization, where the physical layer parameters are contrived to meet the requirements of target applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8C
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• pp.697-708
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• 2010

In this paper, we compare the timing synchronization performance of the adaptive filter to that of the correlator in direct sequence spread spectrum (DS/SS) systems. The test variables used in the code synchronization are statistically analyzed for both schemes, and then the obtained results are used in calculating the detection and false alarm probabilities. Based on the derived probabilities, the synchronization performance is compared and the simulation is followed. Analysis and simulation results show that the correlator outperforms the adaptive filter under most synchronization environments.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.73-76
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• 2005

Preamble based synchronization result in performance degradation due to the high time variation in the power delay profile of the channel in fast varying channel. Since most of the timing metric that exploit the preamble is not based on theoretical back ground, it is not easy to find out the reason. In this paper, the behavior of the timing metric in the multipath fading channel is explained.