• Title, Summary, Keyword: communications

Search Result 30,763, Processing Time 0.124 seconds

Demonstration of Time- and Wavelength-Division Multiplexed Passive Optical Network Based on VCSEL Array

  • Mun, Sil-Gu;Lee, Eun-Gu;Lee, Jie Hyun;Park, Heuk;Kang, Sae-Kyoung;Lee, Han Hyub;Kim, Kwangok;Doo, Kyeong-Hwan;Lee, Hyunjae;Chung, Hwan Seok;Lee, Jong Hyun;Lee, Sangsoo;Lee, Jyung Chan
    • ETRI Journal
    • /
    • v.38 no.1
    • /
    • pp.9-17
    • /
    • 2016
  • We demonstrate a time- and wavelength-division multiplexed passive optical network system employing a vertical-cavity surface-emitting laser array-based optical line terminal transceiver and a tunable bidirectional optical subassembly-based optical network terminal transceiver. A packet error-free operation is achieved after a 40 km single-mode fiber bidirectional transmission. We also discuss an arrayed waveguide grating, a photo detector array based on complementary metal-oxide-semiconductor photonics technologies, and low-cost key devices for deployment in access networks.

Millimeter-wave Technologies for ITS Wireless Communications

  • Fujise, Masayuki
    • Information and Communications Magazine
    • /
    • v.19 no.9
    • /
    • pp.31-42
    • /
    • 2002
  • CRL (Communications Research Laboratory, Independent Administrative Institution, Japan) is developing ITS wireless communication technologies in millimeter-wave frequency region. Technologies are categorized for inter-vehicle communications (IVC) and road-vehicle communications (RVC). In this paper, system concepts and the experimental facilities are introduced. The experimental facility for inter-vehicle communications is gotten ready in 60 GHz frequency region and the experimental system for road-vehicle communications is based on RoF (Radio on Fiber) technology in 36-37GHz frequency region.

Pre-select Diversity with the Aid of Downlink Beamforming in Indoor MC-CDMA System

  • Pham, Van-Su;Le, Minh-Tuan;Linh Mai;Yim, Mun-Hyuk;Yoon, Gi-Wan;Kim, Dong-Hyun
    • Journal of information and communication convergence engineering
    • /
    • v.2 no.2
    • /
    • pp.71-75
    • /
    • 2004
  • In non-selective frequency environment, it is difficult to take the advantage of path diversity. In the literature, some methods have been proposed to solve the issue. This paper presents a new method to obtain the resolvable path in Indoor Multi-carrier Code Division Multiple Access (MC-CDMA) system by using downlink beam forming. With the aid of downlink beamforming, the most reliable path is found and chosen for the communication link. The new approach is evaluated in term of bit error rate (BER) and power consumption. The simulation results show that the new approach can get better BER performance. However, the cost of BER improvement is a small degradation in power reservation.

Blind Source Separation of Instantaneous Mixture of Delayed Sources Using High-Order Taylor Approximation

  • Zhao, Wei;Yuan, Zhigang;Shen, Yuehong;Cao, Yufan;Wei, Yimin;Xu, Pengcheng;Jian, Wei
    • ETRI Journal
    • /
    • v.37 no.4
    • /
    • pp.727-735
    • /
    • 2015
  • This paper deals with the problem of blind source separation (BSS), where observed signals are a mixture of delayed sources. In reference to a previous work, when the delay time is small such that the first-order Taylor approximation holds, delayed observations are transformed into an instantaneous mixture of original sources and their derivatives, for which an extended second-order blind identification (SOBI) approach is used to recover sources. Inspired by the results of this previous work, we propose to generalize its first-order Taylor approximation to suit higher-order approximations in the case of a large delay time based on a similar version of its extended SOBI. Compared to SOBI and its extended version for a first-order Taylor approximation, our method is more efficient in terms of separation quality when the delay time is large. Simulation results verify the performance of our approach under different time delays and signal-to-noise ratio conditions, respectively.

Development of the Test and Mnitor System for Satellite Communications Payload and Network

  • Kong, Nam-Soo
    • 제어로봇시스템학회:학술대회논문집
    • /
    • /
    • pp.34-37
    • /
    • 1994
  • A satellite communications monitoring and control system(SCMCS) has been developed at ETRI to provide the capabilities of in-orbit test (IOT) for communications payload and communications system monitoring(CSM) for the satellite communications services. The paper discusses the system level design of SCMCS and its tasks.

  • PDF

IDNet: Beyond All-IP Network

  • Jung, Heeyoung;Lim, Wan-Seon;Hong, Jungha;Hur, Cinyoung;Lee, Joo-Chul;You, Taewan;Eun, Jeesook;Kwak, Byeongok;Kim, Jeonghwan;Jeon, Hae Sook;Kim, Tae Hwan;Chun, Woojik
    • ETRI Journal
    • /
    • v.37 no.5
    • /
    • pp.833-844
    • /
    • 2015
  • Recently, new network systems have begun to emerge (for instance, 5G, IoT, and ICN) that require capabilities beyond that provided by existing IP networking. To fulfill the requirements, some new networking technologies are being proposed. The promising approach of the new networking technology is to try to overcome the architectural limitations of IP networking by adopting an identifier (ID)-based networking concept in which communication objects are identified independently from a specific location and mechanism. However, we note that existing ID-based networking proposals only partially meet the requirements of emerging and future networks. This paper proposes a new ID-based networking architecture and mechanisms, named IDNet, to meet all of the requirements of emerging and future networks. IDNet is designed with four major functional blocks-routing, forwarding, mapping system, and application interface. For the proof of concept, we develop numeric models for IDNet and implement a prototype of IDNet.

Optical Camera Communications: Future Approach of Visible Light Communication

  • Le, Nam-Tuan;Nguyen, Trang;Jang, Yeong Min
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.40 no.2
    • /
    • pp.380-384
    • /
    • 2015
  • As an extension of Visible Light Communication, Optical Camera Communications (OCC) will be a promising service for smart devices. Especially in line of sight marketing service and indoor localization application, by using camera which exists in smart devices, small amount of data (url link) can be broadcasted or find direction from the illumination system. This paper introduces the operation of wireless communications technology that transmits optical information from optical light source to camera, called Optical Camera Communications.

Context-aware Multimedia Framework based on Software Agent Platforms

  • Hendry;Seongjoon Pak;Yumi Sohn;Kim, Munchurl
    • Proceedings of the Korean Information Science Society Conference
    • /
    • /
    • pp.253-255
    • /
    • 2003
  • We address an integrated multimedia framework based on a software agent platform for context-aware multimedia computing. We adopt the FIPA (Foundation for Intelligent Physical Agents) platform which provides agent communications and management mechanisms. In order to express context information, we use MPEG-21 metadata for describing user characteristics and usage environment. We encapsulate such context information as a FIPA message to be delivered between agents. Based on context information, appropriate multimedia content delivery becomes possible. We present our system implementation with a use case scenario and show that our proposed framework is effective for context-aware multimedia computing so that personalization of multimedia consumption can be possible.

  • PDF