• Journal of the Institute of Electronics and Information Engineers
• /
• v.52 no.7
• /
• pp.40-48
• /
• 2015

An optical network-on-chip(ONoC) architecture is emerging as a new paradigm for solving on-chip communication bottleneck. Recent studies on ONoC have been focusing on supporting the parallel transmission and avoiding path collisions using wavelength division multiplexing(WDM). However, since the maximum number of wavelengths, which a single waveguide can accommodate is limited by crosstalk and insertion loss. Therefore previous WDM studies based on incrementing the number of different wavelengths according to the number of nodes would be infeasible due to the implementation complexity. To solve such problems, we combined time division multiplexing(TDM) and wavelength-routed ONoC, along with an optimized channel allocation algorithm, which can minimize the number of extra wavelength channels and latency caused by combining TDM scheme.

• The Magazine of the IEIE
• /
• v.5 no.1
• /
• pp.24-30
• /
• 1978

시분할다중화방식에 따른 전 전자소자에 의한 통화로 구성과 미니컴퓨터에 의한 축적프로그램 제어방식을 채용한 전전자식 사설전화교환기 SENTINEL-500을 소개 하였다. SENTINEL-500의 표준회선용양은 480가입자회선과 시내중단회선(국선) 100회선을 수용할 수 있으며 약 1500회선까지 확장가능토록 설계되었다. SENTINEL-500은 중요한 부분을 이중화하여 고신뢰도를 갖도록 하였고 다수하이웨이의 채용과 동적 Time Slot 배정방식을 개발하여 거의 완전한 Non-Blocking switchng network를 구성 하였다. 또한 SENTINEL-500은 자체진단기능을 위시 하여 교환중단대 및 가입자를 위한 각종의service 기능을 갖고 있다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.25 no.4B
• /
• pp.743-754
• /
• 2000

In this paper, we propose wavelet transform image compression method using shuffling and bit plane correlation. Proposed method is that original image decompose into multiresolutions using biorthogonal wavelet transform with linear phase response property and decomposed subbands are classified by maximum classification gain. And classified data sets in each subband are quantized using arbitrary set optimum bit allocation method. Quantized data sets in each subband are shuffled and context based bit plane arithmetic encoded .In context based bit plane arithmetic encoding, the context for each subband is not assigned uniformly, but assigned according to maximum correlation direction. Our results are comparable, or superior for some images at low rates, to published state-of-the-art coders.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.21 no.5
• /
• pp.640-648
• /
• 2018

Time division wireless communication in tactical MANET is attractive to deliver both high data rates and long-range coverage, and to provide scheduled QoS to mission participants. This paper is about the time synchronization issue of multi-mission USV in tactical MANET. As USV communication coverage becomes longer, the synchronization error also becomes higher; therefore, which results in link disconnection, and consequent failures of reconnection because base station cannot configure necessary parameters over long-distant terminal. We propose a range adaptive time synchronization method to compensate for synchronization errors. The issue of long-range time synchronization problem was identified during maritime communication tests, and we verified the proposed method through analyses of both indoor and outdoor test results.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.42 no.6 s.336
• /
• pp.31-38
• /
• 2005

In this paper, we proposed an optical security system based on a gray-image exclusive-OR encryption using multi-phase separation and phase-wrapping method. For encryption, a gray image is sliced into binary images, which have the same pixel value, and these images are encrypted by modified XOR rules with binary random images. The XORed images and the binary images respectively combined and converted into full phase images, called an encrypted image and a key image. For decryption, when the encrypted image and key image are used as inputs on optical elements, Practically due to limited controllability of phase range in optical elements, the original gray image cannot be efficiently reconstructed by these optical elements. Therefore, by decreasing the phase ranges of the encrypted image and key image using a phase-wrapping method and separating these images into low-level phase images using multi-phase separation, the gray image can be reconstructed by optical elements which have limited control range. The decrytion process is simply implemented by interfering a multiplication result of encrypted image and key image with reference light. The validity of proposed scheme is verified and the effects, which are caused by phase limitation in decryption process, is analyzed by using computer simulations.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.10A
• /
• pp.996-1002
• /
• 2006

USB(Universal Serial Bus) is one of the most popular communication interfaces. When USB is used in an extended range, especially configurating In-home network by connecting multiple digital devices each other, USB interface uses the bandwidth in the way of TDM (Time Division Multiplexing) so that the bottleneck of bus bandwidth can be brought. In this paper, the more effective usage of bus bandwidth to overcome this situation is introduced.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.3
• /
• pp.579-585
• /
• 2006

In this study, we analysis an optical receivers using the optical preamplifier in a spectrum-sliced WDM systems. The average numbers of photons/bit, for an $10^{-9}$ error probability, counts using the OOK and FSK transmission. As a result, the theoretical sensitivity for PIN receiver and optical preamplifier receiver are approximately $9.2\times10^4\;and\;7.2\times10^2$ in the m=20, respectively. Also, the average numbers of photons/bit, for and given error probability, theoretical receiver sensitivity for Gaussian method and k-square method are approximately $9\times10^2\;and\;2.16\times10^2$ in the m=40, respectively. And the average numbers of photons/bit, for an given error probability, theoretical receiver sensitivity, OOK and FSK transmission are approximately $1.9\times10^2\;and\;3.1\times10^2$ in the m=20, respectively.

• Journal of IKEEE
• /
• v.5 no.2 s.9
• /
• pp.201-210
• /
• 2001

Wavelength and repetition-rate tunable optical pulse-trains for ultrafast optical time- and wavelength division multiplexing are generated from a semiconductor fiber ring laser by optical injection mode-locking. The pulse trains show the pulse with of ${\sim}10$ ps and the wavelength tuning of wider than 30 nm at various repetition-rates of 10 GHz, 20 GHz, 30 GHz and 40 GHz, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.9A
• /
• pp.714-721
• /
• 2005

In this parer, we analyze the preamble model in the OFDMA/TDD(OFDM-FDMA/Time Division Duplexing). Besides, under AWGN, ITU-R M.1225 Ped-B and Veh-A channel environments, we analyze capabilities of symbol timing & carrier frequency offset and performance of cell searching capabilities applied to OFDM/TDD system through computer simulation. The performance using Detection Probability, False Alarm Probability, Missing Probability, Mean Acquisition Time and MSE(Mean Square Error) is analyzed. Especially, in the case of symbol timing offset estimation, the preamble structure and its algorithm with enhanced performance are proposed and then compared with existing ones.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2002.11b
• /
• pp.1411-1414
• /
• 2002

블루투스는 본래 이동전화 핸드셋, 헤드셋, 그리고 휴대형 컴퓨터와 같은 장치를 연결하는 케이블을 제거하기 위해 개발된 것으로 저가, 저 전력, 단거리의 무선 기술이다. 그러나 전자 제품간에 표준화된 무선 통신이 가능하게 됨으로 인하여 블루투스는 휴대전화나 PDA, 노트북 PC 와 같은 모바일 기기에 부착되어 무선 ad-hoc 네트워크를 구성할 수 있게 되었다. 블루투스는 시분할 다중화 시스템(TDM) 방식으로 최대 8 개의 블루투스 기기가 모여 하나의 채널을 공유하는 '피코넷(piconet)' 을 형성할 수 있고 여러 개의 피코넷을 연결하여 '스캐터넷(scatternet)' 이라는 더 큰 네트워크를 구성할 수 있다. 이러한 블루투스 네트워크에서 기존의 브로드캐스트 서비스는 단순한 재전송 방식으로 인해 신뢰성과 효율성에 있어서 많은 문제점을 안고 있으며 블루투스의 특징을 고려하지 못하고 있다. 따라서 본 논문에서는 블루투스 네트워크에서 브로드캐스트 패킷의 수신을 보장하면서 대역폭을 효율적으로 사용하는 브로드캐스트 패킷 전송 기법을 제시하고자 한다.