• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.4 no.1 s.6
• /
• pp.63-71
• /
• 2005

This paper proposes the channel estimation method robust to severe frequency selective fading channels in O%M system using wide bandwidth for the high data rate transmission. DDCE, which uses data between the high correlated symbols, is usually used for channel estimation in the slow fading channels. DDCE can get high gains in the non-selective channels. As the bandwidth of system gets wider, it becomes more severe frequency selective fading environments so that the reliability of data becomes lower and error flow is occurred. FE method, this paper proposed, uses the relation between sub-carriers of OFDM in frequency selective fading channels so FE method gets some gains by adapting the power value at a target frequency to the mean value of channel estimated values of adjacent sub-carriers. Because FE uses only preamble unlike DDCE using data, it is independent of data rate related to the reliability of data and the number of multipath. Consequently, FE can obtain considerable gains in the wideband systems where the errorflow of DDCE is occurred, and FE is applicable to frequency selective fading environments.

• Water for future
• /
• v.25 no.1
• /
• pp.101-110
• /
• 1992

In this paper for simulating spatially and temporally varied moving storm in a watershed a distributed model was developed. The model is conducted by two major flow simulations which overland flow simulation and channel network flow simulation. Two dimensional continuity equation and momentum equation of kinematic approximation are used in the overland flow simulation. On the other hand, in the channel networks simulation two types of governing equations which are one dimensional continuity and momentum equations between two adjacent sections in a channel, and continuity and energy equations at a channel junction are applied. The finite element formulations were used in the overland flow simulation and the implicit finite difference formulations were used in the channel network simulation. The finite element formulations for the overland flow are analyzed by the Gauss elimination method and the finite difference formulations for the channel network flow are analyzed by the double sweep method having advantages of computational speed and reduced computer storages. Several recurrent coefficient equations for channel network simulation are suggested in the paper.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.9C
• /
• pp.887-895
• /
• 2009

This paper proposes a cooperative power allocation with the use of partial channel information (e.g., the average signal-to-noise ratio (SNR) and transmit correlation) in multi-cell dual-hop multi-input single-output (MISO) relay systems. In a dual-hop MISO relay channel, it is desirable to allocate the transmit power between dual-hop links to maximize the end-to-end capacity. We consider the maximization of the end-to-end capacity of a dual-hop MISO relay channel under sum-power constraint. The proposed scheme adaptively allocates the transmit power considering the average channel gain of the target relay and the transmit correlation of the desired and inter-relay interference channel from adjacent relays. It is shown by means of upper-bound analysis that the end-to-end capacity can be maximized by making the angle difference of the principal eigenvectors of the desired and inter-relay interference channel orthogonal in highly-correlated channel environments. Finally, the performance of the proposed scheme is verified by computer simulation.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39C no.9
• /
• pp.757-766
• /
• 2014

To compensate signal loss due to the channel blockage in satellite communication link, we propose a cooperative communication scheme for OTM(On-The-Move) terminal in next generation satellite communication systems. The proposed scheme configures cooperation subnet with adjacent OTM terminal with the help of ground communication equipment. Shared data is spread by orthogonal spreading code, then the spread sequences are transmitted simultaneously. The receiver combines the power of received signals by EGC(Equal gain combining). The OTM terminal blockage channel is modeled by 2-state Markov chain. We evaluate the bit error rate according to the blockage channel of the channel state for the performance analysis of the proposed scheme. As a result, the proposed scheme shows better BER performance than traditional scheme with the help of subset members. In particular, the proposed scheme shows superior performance as the channel block probability is higher. However, as the number of subset members is increasing, there is a constraint because of the higher multiple access interference.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.5C
• /
• pp.351-360
• /
• 2008

In cellular mobile radio systems with frequency reuse, the interference signals degrade the channel estimation and signal detection performance due to the low signal-to-interference ratio near coverage boundaries. When the preamble pilot sequences from different cells are orthogonal or located in disjointed positions, they can be used for multi-cell channel estimation and interference cancellation. In time-varying channels caused by Doppler spread, data pilot symbols are needed for channel estimations. However, data pilot symbols are usually located in identical positions for the overhead reduction, which degrades the channel estimation performance. In this paper, we demonstrate a significant amount of performance improvement is achieved by multiplying different pseudonoise(PN) sequences to the data pilot symbols from adjacent interference cells. In particular, for detection scheme using maximal ratio combining(MRC) and inter-cell spatial demultiplexing(ISD), quantitative performance gain of spectral efficiency for different values of Doppler frequency and interference power is presented.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.1
• /
• pp.32-41
• /
• 2014

Currently, the three major Korean mobile operators hold a total of 390MHz of bandwidth, but at the current data traffic increase of almost 6 times per year, more frequency bandwidth should be secured in order to meet the exploding data traffic in the future. It is believed that 2.1GHz frequency band is suitable for mobile communication in the light of frequency characteristics and continuity of the band. In this paper, we perform compliance analysis with the international radio regulation for coexistence with the adjacent region in order to use 2.1GHz band for LTE-Advanced. In addition, we verify that 2.1GHz band can coexist with the adjacent band by conducting an interference evaluation.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.5
• /
• pp.1762-1773
• /
• 2014

In this paper, a distributed image coding scheme for multi-view video through an efficient generation of side information is proposed. A distributed video coding technique corrects the errors in the side information, which is generated with the original image, by using the channel coding technique at the decoder. Therefore, the more correct the generated side information is, the better the performance of distributed video coding. The proposed technique is to apply the distributed video coding schemes to the image coding for multi-view video. It generates side information by selectively and efficiently using both 3-dimensional warping based on the depth map with spatially adjacent frames and motion-compensated temporal interpolation with temporally adjacent frames. In this scheme the difference between the adjacent frames, the sizes of the motion vectors for the adjacent blocks, and the edge information are used as the selection criteria. From the experiments, it was observed that the quality of the side information generated by the proposed technique was improved by the average peak signal-to-noise ratio of 0.97dB than the one by motion-compensated temporal interpolation or 3-dimensional warping. The result from analyzing the rate-distortion curves revealed that the proposed scheme could reduce the bit-rate by 8.01% on average at the same peak signal-to-noise ratio value, compared to previous work.

• Journal of the Korean Professional Engineers Association
• /
• v.34 no.4
• /
• pp.30-35
• /
• 2001

The 8-VSB modulation technology developed by ATSC was adapted for national terrestrial DTV broadcasting. It uses same bandwidth of 6㎒ as the one of NTSC TV broadcasting. The simulcast on the both of analog and digital is mandated for some period, some shortage within the limited frequency resource . ATSC transmission technology is excellent in long distance broadcasting, but it is even poorer than other transmission technology In mobile receiving. The design of transmission system in the ATSC broadcasting is food enough with the provision of wide area service without Interference from adjacent channel. To provide adequate DTV service within the broadcasting area, transmission technology is an important factor

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.1372-1375
• /
• 1996

In this paper, we developed and ERMS, which monitors radiation continuously in the vicinity of the nuclear power plant not only to intend health and security of the adjacent residents but also to prevent environmental pollution. Especially, applying digital DCU and SCA which are easy to control and accurate, we obtained good results.

• Proceedings of the IEEK Conference
• /
• 1999.06a
• /
• pp.187-190
• /
• 1999

In order to predict the effect of power amplifier non-linearity for digital modulated signal, this paper analyses the adjacent channel power ratio(ACPR) with the various AM-to-PM distortion levels. As the phase distortion increases from 0$^{\circ}$ to 12$^{\circ}$ at 1㏈compression point by 2.4$^{\circ}$ step, the input power level which satisfies the required ACPR decreases from 3.5㏈ to 6.5㏈ less than the 1㏈ compression input power.