• Journal of Institute of Control, Robotics and Systems
• /
• v.13 no.12
• /
• pp.1198-1206
• /
• 2007

It is common to use PC or Digital picture frame in stand-alone fashion to view images, movies, or to listen MP3 musics which are considered as multimedia contents, However, such existing methods have weakness for expanding network requirements or augmenting extra data, in such case inevitably requiring external devices. With keeping in mind for such expansion, in this study, we have suggested a new concepts of network module which may utilize an image server for data transmission, in the proposed module, data alarm packet was defined for alerting incoming data from the image server and it became possible to synchronize between the image server and device not only in wired but also in wireless environments through UART. The method consists of a control module for an image server and a synchronization module between the server and the device. We have also tested the feasibility for future commercial usages such as advertisements through performance evaluations.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2008.11a
• /
• pp.1280-1283
• /
• 2008

The network performance of MOGs(Multiplayer Online Games) can be measured by the amount of network loads and the response times on user inputs. This paper introduces a frame locking algorithm and a game turn algorithm that have been used for game synchronization in the area of RTS(Real-time Strategy Simulation) Games, a kind of MOG; the results of performance evaluation of these two algorithms are also given. In addition, a server architecture for MOG servers in which replacing synchronization algorithms can be done easily for pursuing efficient performance evaluation, is also introduced.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.1A
• /
• pp.65-76
• /
• 2004

In this paper, a novel preamble structure, including a synchronization preamble and a cell search preamble, is proposed for OFDM-based cellular systems. An efficient algorithm for downlink synchronization and cell searching using the preamble is also proposed. The synchronization process includes the initial symbol timing estimation using continuously, or at least, periodically transmitted downlink signal, frame synchronization, the fine symbol timing estimation, and the frequency offset estimation using the synchronization preamble, and the cell identification using the cell searching preamble. Performance of each synchronization and cell searching step is analyzed and the analytic results including the overall performance of the synchronization and cell searching are verified by computer simulation. It is shown that the proposed preamble with the corresponding synchronization and cell searching algorithm can provide very robust synchronization and cell searching capability even in bad cellular environments.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.10 no.1
• /
• pp.99-108
• /
• 1999

In this paper, we propose $\pi$/4 QPSK scheme with block modulation algorithm, which can reduce preamble in order to transmit ATM cell efficiently in the uplink channel of LMDS, and also designed a new carrier recovery circuit which can improve carrier synchronization performance of block demodulation algorithm. The $\pi$/4 QPSK scheme employing the proposed block modulation algorithm achieved efficient frame transmission by making use of a few preamble when carrier synchronization, symbol timing synchronization and slot timing synchronization were performed by burst data of ATM cell in LMDS environment. For performance evaluation of the proposed method, a simulation analyzing the variation of carrier synchronization, symbol timing synchronization and slot timing synchronization using LMDS environment and burst mode condition was executed. In the simulation, the proposed method showed a good performance even though the reduced preamble as a few aspossible when carrier synchronization, symbol timing synchronization and slot timing synchronization is performed.

• Journal of the Korea Society of Computer and Information
• /
• v.22 no.9
• /
• pp.57-64
• /
• 2017

CCSDS Standard is widely used in the international space telecommunication area. But standard recommendation of CCSDS is not restrictive, so, we can select an appropriate encryption protocol among the layer. For synchronization, encryption sync is attached in the beginning of the encrypted data. In the exceptional environmental condition, although the receiver can not decrypt the normal data, the sender have no conception of that situation. In this paper, we propose a two-stage SES alarmed link encryption synchronization method having optimized threshold value necessary to decide whether the receiver has a correct decryption or not. first, through the experiment of mutual relations between error rate and encryption synchronization detection error, we can predict worst communication environment for the selected encryption synchronization pattern. second, through the experiment for finding what number of consecutive frame synchronization error is an appropriate reference value and analysis of that experiment, we suggest an optimized threshold value for resynchronization request. lastly, through the output images we can predict the probability error that should be guaranteed by channel coder.

• ETRI Journal
• /
• v.31 no.4
• /
• pp.466-468
• /
• 2009

In this letter, we propose a one-way ranging algorithm that is based on wireless synchronization with measured timestamps and clock frequency offsets. In our proposed algorithm, an active mobile node initiates a ranging procedure by transmitting a ranging frame, and the anchor nodes report their timestamps for the received ranging frame to a reference anchor node. The synchronization of a pair of nodes is provided with instantaneous time information, and the corresponding difference of distances can be calculated.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.38 no.8
• /
• pp.1-10
• /
• 2001

This paper describes new line code algorithm, called NIDI(Nibble Inversion mock Inversion) which is well suited for interconnection and transmission technology, The proposed line code which includes only one redundancy bit serves primary features of line code and synchronization patterns for byte or frame synchronization in interconnection, Also, this line code provides in-band signals and speciaI characters.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.1
• /
• pp.114-123
• /
• 2000

The flow structure around a rotating axial-fan was experimentally investigated using a phase averaging velocity field measurement technique. The fan blades were divided into 4 different phases, for which 500 velocity fields were acquired for each phase angle with a 2-frame PTV system. Velocity field measurements were also carried out at two planes parallel to the axis of rotation, with offsets toward the radial direction of the fan. For accurate synchronization of the PTV system with the phase of the axial fan, two synchronization circuits were employed with a photo-detector attached to the rotating shaft. The phase averaged velocity fields show periodic variations with respect to the blade phase. The periodic formation of vortices at the blade tip is also observed in vorticity contour plots. Locations of local maximum turbulence intensities in the axial and radial directions are found to be located in an alternating pattern. These experimental results can be used to validate numerical calculations and to understand the flow characteristics of an axial fan.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.44 no.2
• /
• pp.37-45
• /
• 2007

A lot of conventional algorithms has tried to cancel the Residual Frame Synchronization Error (RFSE), which causes the performance degradation of channel estimation when using interpolation in lattice-type pilot-aided Time Division Duplex (TDD) OFDM systems. Among them, a pre- and post-compensation method has been attractive to eliminate the effects of RFSE, providing good performance but requiring high computational complexity. In this paper we propose a new method which lowers computational costs by adjusting the starting point of TDD OFDM systems' FFT window in order to compensate for the RFSE. For the performance verification, we apply the proposed method to IEEE 802.16e standard and also estimate additionally required computational power of it compared to the pre- and post-compensation method. Simulation and implementation results show that the proposed algorithm has performance similar to the conventional method and is very efficient with low power implementation, requiring only 4.9 % of the power which the conventional method needs additionally.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.41 no.4
• /
• pp.424-432
• /
• 2016

World's leading countries are developing next generation digital broadcasting system specifications to support UHDTV (ultra-high definition television) contents and other various services. In order to maximize the transmission capacity by using the bandwidth efficiently, most broadcasting systems adopt MIMO-OFDM. In distributed-MIMO systems, multiple transmit antennas are spatially separated and therefore result in multiple timing offsets. To overcome this problem, this paper proposes a technique using a null symbol to detect each individual signal from distributed transmit antennas. By inserting null symbols before preambles, the receiver can distinguish the signals between each transmit antennas and perform frame synchronization. When the reception time difference is shorter than 500 samples, the proposed method outperforms the conventional method.