• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.64-66
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• 2002

공간-시간 부호(Space-Time Code)는 다중 안테나 시스템에서 기존의 기술에 비해서 부가적인 대역폭이 필요 없이 부호화 이득을 얻을 수 있다. 지금까지 공간-시간 부호(Space-Time Code)는 다이버시티 이득의 관점에서는 신호행렬들의 차가 완전-계수(Full-Rank)를 가져야 하고, 코딩 이득의 관점에서는 신호행렬들의 차의 determinant 값이 최소값을 가져야 한다. 본 논문에서는 공간-시간 블록 부호 디자인(Space-Time Block Code) 관점에서 직교-디자인(Orthogonal-design) 즉, 최소거리가 5이면서 완전-계수(Full-Rank)인 디자인을 비교대상으로 완전-계수(Full-Rank)가 아니면서 최소거리가 5와7인두 부호에 관하여 연구되어졌다.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.93-96
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• 2003

In this paper, multiple trellis code is combined with differential unitary space-time modulation (DUSTM). After the set partitioning of unitary space-time constellation for multiple trellis code is described, several code constructed are provided. BER results are presented.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.83-86
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• 1999

In this paper, a serially concatenated space-time code (SCSTC) with bandwidth efficiency and high data rate is studied. The suggested SCSTC is composed of space-time code, the convolutional code and Interleaver. The SCSTC has a very high BER performance than the conventional space-time code. The BER performance of the suggested SCSTC can be proven by using computer simulation through the iterative decoding method. The first decoder uses Symbol-MAP algorithm and the second decoder uses Bit-MAP algorithm for decoding tile information bits. The simulation results show the performance of the suggested SCSTC is better than the conventional Space-Time Code.

• Journal of Korea Multimedia Society
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• v.9 no.6
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• pp.728-734
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• 2006

Carrier interferometry code is considered as a promising scheme that provides significant performance improvement via frequency diversity effect. Space-time coding is commonly employed to achieve a performance gain through space diversity. The combination of these techniques and forward error correction coding will lead to enhanced system capacity and performance. This paper presents a low-density parity check (LDPC) coded space-time orthogonal frequency division multiplexing (OFDM) transmission scheme with carrier interferometry code for high-capacity and high-performance mobile multimedia communications. Computer simulations demonstrate that the proposed mobile multimedia transmission system offers a considerable performance improvement of approximately 9dB in terms of Eb/No in the Rayleigh fading channel with relatively low delay spread, in comparison with space-time OFDM. Performance gains are further increased, comparing with traditional OFDM systems.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.11
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• pp.1144-1149
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• 2009

This paper deals with the time synchronization problem over SpaceWire links. SpaceWire is a standard for high-speed links and networks between spacecraft components, which was invented for better, cheaper, faster on-board data handling in spacecraft. The standard defines Time-Code for time distribution over SpaceWire network. When a Time-Code is transmitted, transmission delay and jitter is unavoidable. In this paper, a mechanism to remove Time-Code transmission delay and jitter over SpaceWire links is proposed and implemented with FPGA for validation. The proposed mechanism achieves high resolution clock synchronization over SpaceWire links, complies with the standard and can be easily adopted over SpaceWire network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.4A
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• pp.519-527
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• 2000

This paper suggests and analyzes the Serially Concatenated Space-Time Code(SCSTC) with the possibility of a efficient high-speed transmission in a band limited channel. The suggested code has a structure that uses the interleaver to connect the space-time code as an inner code and the convolutional code as a outer code serially. This code keeps the advantage of high-speed transmission and also has the high BER performance. The performance of the suggested system is compared with the conventional bandwidth efficient trellis coded modulation, such as a Serially Concatenated Trellis Coded Modulation (SCTCM) and a Turbo-Trellis Coded Modulation(Turbo-TCM). The results show that the suggested system has a 2.8dB and 3dB better BER performance than SCTCM and Turbo-TCM respectively in case of the transmission rate 2b/s/Hz in fading channel.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.4
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• pp.724-730
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• 2017

SpaceWire invented for spacecrafts has Time-Code defined for time synchronization over SpaceWire network. A Time-Code suffers transmission delay of 14[bit-period] and jitter up to 10[bit-period] whenever it passes through a SpaceWire link, which is the primary cause of time synchronization error. This work presents a simple method to improve the time synchronization which uses two extended Time-Codes. Nodes on a SpaceWire network can find how much delay and jitter a received Time-Code has suffered while it passes through the network, and they can correct time synchronization error with this information. The proposed method was validated in a simulation environment developed based on OMNeT++. The simulation result showed that time synchronization error less than a few bit-periods can be achieved. The proposed method is cost effective and suitable for small-scale SpaceWire network systems.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.277-280
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• 2003

In this paper, we analyze the performance of transmitter and receiver of W-CDMA system using the channel coding and space time code in downlink over ITU-R realistic channel model. We can improve the reliability of communications and increase the data rate by channel coding, and we can get a diversity gain by using the space time code over fading channels. We also apply the RAKE receiver to improve tile performance in multi-Path fading channel environment.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11b
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• pp.1575-1578
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• 2002

본 논문에서는 공간-시간 블록 부호디자인(Space-Time Block Code) 관점에서 직교-디자인(Orthogonal-design) 즉, 최소거리가 5이면서 완전-계수(Full-Rank)인 디자인을 비교대상으로 완전-계수(Full-Rank)가 아니면서 최소거리가 5와7인 두 부호에 관하여 연구되어졌다.

• IEMEK Journal of Embedded Systems and Applications
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• v.13 no.4
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• pp.187-194
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• 2018

The operating system for IoT should have a small memory footprint and provide low power state, real-time, multitasking, various network protocols, and security. Although the Zephyr kernel, an operating system for IoT, released by the Linux Foundation in February 2016, has these features but errors generated by the user code can generate fatal problems in the system because the Zephyr kernel adopts a single-space method that both the user code and kernel code execute in the same space. In this research, we propose a space separation method, which separates kernel space and user space, to solve this problem. The space separation that we propose consists of three modifications in Zephyr kernel. The first is the code separation that kernel code and user code execute in each space while using different stacks. The second is the kernel space protection that generates an exception by using the MPU (Memory Protection Unit) when the user code accesses the kernel space. The third is the SVC based system call that executes the system call using the SVC instruction that generates the exception. In this research, we implemented the space separation in Zephyr v1.8.0 and evaluated safety through abnormal execution of the user code. As the result, the kernel was not crashed by the errors generated by the user code and was normally executed.