• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.3
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• pp.3-9
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• 2017

Recently, in 3rd Generation Partnership Project(3GPP), there is a study of the Long Term Evolution(LTE) based vehicle communication which has been actively conducted to provide a transport efficiency, telematics and infortainment. Because the vehicle communication is closely related to the safety, it requires a reliable communication. Because vehicle speed is very fast, unlike the movement of the user, radio channel is rapidly changed and generate a number of problems such as transmission quality degradation. Therefore, we have to continuously updates the channel estimates. There are five types of conventional channel estimation scheme. Least Square(LS) is obtained by pilot symbol which is known to transmitter and receiver. Decision Directed Channel Estimation(DDCE) scheme uses the data signal for channel estimation. Constructed Data Pilot(CDP) scheme uses the correlation characteristic between adjacent two data symbols. Spectral Temporal Averaging(STA) scheme uses the frequency-time domain average of the channel. Smoothing scheme reduces the peak error value of data decision. In this paper, we propose the novel channel estimation scheme in LTE based Vehicle-to-Vehicle(V2V) environment. In our Hybrid Reliable Channel Estimation(HRCE) scheme, DDCE and Smoothing schemes are combined and finally the Linear Minimum Mean Square Error(LMMSE) scheme is applied to minimize the channel estimation error. Therefore it is possible to detect the reliable data. In simulation results, overall performance can be improved in terms of Normalized Mean Square Error(NMSE) and Bit Error Rate(BER).

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.34 no.4
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• pp.98-109
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• 2016

The purpose of this study is to identify characteristics of spatial structure of Jiangnan water town in China which has been developed along the water channel. Spatial structural characteristics of the water town, Wuzhen and Nanxun in Zhejiang Province are as follows. First, location of town, spatial framework, lot division, and architectural style get determined by the water channel. The water channel is constructed in cross shape, T-shape, or in combination. Secondly, public space of water town is established along main water channel. Visually and functionally alternating private buildings are established on the water channel side and they are creating unique landscape of Jiangnan water town in overall harmony. Thirdly, residential area is established on the east-west water channel side with southward sunny-faced arrangement and waterside residence is in introvert spatial structure with courtyard but the exterior space is connected with water channel intimately. Fourthly, various spatial components along the water channel enrich the sense of place in water town. The components are corridor with roof, tea house, waterside steps, waterside theater and watergate etc. Uniqueness of place is becoming the core competence in modern townscape. In this aspect, Jiangnan water town with historical and cultural accumulation is suggesting a significant implication. Major implications are as follows. First, promotion of proximity to the water is the basic value that the spatial plan of waterfront needs to pursue. Secondly, mixed use is essential for effective land use and revitalization of waterfront. Thirdly, waterfront plan based on the local uniqueness as the place asset is being required.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12A
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• pp.933-940
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• 2009

This paper proposes a robust detection scheme for quasi-orthogonal space-time block code over time-selective fading channels. The proposed detector performs interference cancellation and decision feedback equalization to remove the inter-antenna interference and inter-symbol interference when the channel varies from symbol to symbol. Cholesky factorization is used on the channel Gram matrix after performing interference cancellation to obtain feed forward equalizer and feedback equalizer. It is shown by simulations that the proposed detection scheme outperforms the conventional detection schemes and the exiting detection schemes to time-selectivity.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.10
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• pp.2493-2508
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• 2012

The performance of a MIMO system with adaptive modulation (AM) and space-time coding over Ricean fading channels for perfect and imperfect channel state information (CSI) is presented. The fading gain value is partitioned into a number of regions by which the modulation is adapted according to the region the fading gain falls in. Under a target bit error rate (BER) constraint, the switching thresholds for AM are given. Based on these results, we derive the calculation formulae of the theoretical spectrum efficiency (SE) and average BER. As a result, closed-form SE expression and accurate BER expression are respectively obtained. Besides, using the approximation of complementary error function, a tightly closed-form approximation of average BER is also derived to simplify the calculation of accurate theoretical BER. Computer simulation shows that the theoretical SE and BER are in good agreement with the corresponding simulation, and the approximate BER is also close to the accurate one. The results show that the AM scheme in Ricean fading channel provides better SE than that in Rayleigh fading channel due to the direct-path propagation, and has performance degradation in SE and BER for imperfect CSI.

• Current Optics and Photonics
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• v.7 no.4
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• pp.345-353
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• 2023

We propose a turbulence-tolerant Manchester on-off keying (M-OOK) transmission for free-space optical (FSO) communication. At the transmitter end, a M-OOK signal featuring a spectrum with low-frequency components absent is modulated and transmitted into a turbulent channel. At the receiver end, a low-pass filter (LPF) -based adaptive-threshold decision (ATD) with LPF-extracted channel-state information (CSI) and a high-pass filter (HPF)-based fixed-threshold decision (FTD) are employed to compensate for the effects of turbulence, owing to the low-frequency spectral characteristics of the turbulent channel. The performance of LPF-based ATD and HPF-based FTD are evaluated for various cutoff frequencies for the LPF and HPF. Besides, the proposed M-OOK transmission is compared to conventional non-return-to-zero OOK (NRZ-OOK) for different data rates. The proposed technique is verified in simulation. The simulation results show that the proposed M-OOK detection with optimized cutoff frequencies of LPF and HPF has better bit-error-rate (BER) performance compared to NRZ-OOK, and it is close to the theoretical ATD with the knowledge of precise CSI under various degrees of turbulence effects.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.8
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• pp.72-81
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• 2004

A Wind tunnel test for a high speed ground vehicle was conducted to investigate the aerodynamic interactions between the vehicle and a solid channel. The free stream velocity was 30m/see and Reynolds number per unit length was $3.1{\times}10^5/m$. Experimental devices such as a variable channel ground and guide way were used for the test. As the vehicle was close to the channel ground and guide way, lift was significantly increased, drag was slightly decreased and pitching moments were restricted to augment static stability. Using smoke-wire, flow visualization was made to confirm these results by comparing the channel and non-channel flow characteristics of the vehicle. Under the influence of the channel ground and guide way, the flow beneath the vehicle was not discharged outside wing end plates, which was the major reason of the increase in lift of the vehicle.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.12
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• pp.1005-1012
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• 2020

Avionics systems that use the PCI-Express bus unfortunately cannot use at least one I/O device if the bus fails, because the I/O device is connected to CPU through only one PCI-Express channel. This paper presents a fault-tolerant architecture of the PCI-Express bus for avionics systems, which tolerates one channel failure with help of the other redundant channel that has not been failed. In this architecture, each redundant PCI-Express channel connects a corresponding port of CPU to each switch logic of channels to provide each I/O device through a switched fault-tolerant channel. This paper includes the results of experimentation to show that the architecture detects the faulty condition in real time and switches the channel to the other redundant channel which has not been failed, when the architecture meets a failure.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.89-92
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• 2003

A geometrically uniform code in AWGN channel has strong symmetry properties such as a) the distance profiles form codewords On C to all other codewords are all the same, and b) all Voronoi regions of codewords in C have the same shape. Such properties make the word error probability of geometrically uniform codes be transparent to the transmitted codeword. In this paper, we extend the geometrically uniform codes in AWGN channel to the geometrical uniform codes in fading channel with multiple transmit antennas.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.117-120
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• 2001

In this paper, we propose a robust trellis coded modulation for a correlated Rayleigh fading channel. This method use only one transmit antenna, which can achieve superior performance compared to Space-Time Trellis Coded Modulation (STTC) over a wide channel correlation range among transmit antennas. The code is designed to have the largest Euclidean distance between faded signals at the receiver. Computer simulations are performed to evaluate the frame error rate (FER) performance and to compare the proposed code with the conventional one.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.85-88
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• 2005

Space-time code is a good solution to get transmit diversity. During the last years a number of space-time block codes have been proposed for use in multiple transmit antenna systems. This code, however, was presented only for the special case of the certain numbers of transmit antennas and the certain modulation schemes. and designed under the assumption that the transmitter has no knowledge about the channel. In this work, on the other hand, we consider the case when the transmitter has partial, but not perfect knowledge about the channel. This system can have full diversity for arbitrary number of the transmit antennas with a little bits of feedback.