Intro | Member | Publication | Project | Seminar | Board
Introduction | Research Area

  Current Research Area

  The NDS Lab is currently focusing on two areas of research: Networking and Distributed systems. In the networking area, wireless sensor networks, mobile communications, and fixed/wireless network convergence are main issues of research. We are interested in investigating various issues raised in the development of so-called mobile Internet, which utilizes mobile devices and embedded devices for end users. They may include new ideas introduced in mobile communications, wireless sensor networks, networks convergence and Next Generation Internet. In the distributed systems area, we are mainly concerned with developing effective algorithms to provide a secure, friendly and reliable computing environment

   Networking Area

  • Wireless Sensor Networks
  • Mobile Communications
  • Wired/Wireless Network Convergence
  • Address Architecture in Next Generation Internet/Multi-Homing
  • Mobility Management for Heterogeneous Access Networks
  • QoS Control & Management
  • Network Performance Evaluation

       Distributed Systems Area

  • Reliable Multicast Protocol
  • Distributed Computing Environment

  •   Research Equipments


      Sun Workstation, Personal Computers, Intel PC servers, Intel PC Linux servers, Laptop PCs(IBM, Compaq, Sony), PDAs(Compaq), Cisco router 3640, ATM Switch/Hub, WLAN access points & NICs, Micazs


      AirMagnet Trio(Laptop/PDA), Chariot, OSF DCE 1.1, SIMSCRIPT II.5, SLAM II, Entera, Visual Studio 98, Visio Technial 5.0, VisiBroker, Windows NT Workstation, Windows 2000 server

      Past Research & Achievements

       QoS Routing

      Due to various demands for requirements such as bandwidth, delay and so on, the routing methods that be able to guarantee QoS requirements are required, which is called QoS routing. The basic function of QoS routing is to find a network path that satisfies the given constraints. There are many issues in finding a QoS path: multiple constraints, finding multiple path, the combination of QoS architectures(DiffServ/IntServ) and so on. Moreover, it is very diffcult to solve because keeping the former routing protocol with less modifications, the QoS routing methods must be applied. Many solutions about QoS routing have been proposed in the networking research area. So, we have dealt with the combination of QoS architectures and find the network path(s) that guarantee QoS requirements among a lot of problems in QoS routing.

       Multimedia Communication Architecture

      Current the Internet are not well suited to the heterogeneous environments inherent to real-time multimedia applications. Existing network architecture are unable to satisfy the requirements of users, causing many users to be cut off from the Internet real-time multimedia infrastructure. So we has been studying new internet real-time multimedia communication architecture.

       QoS Control & Management

      The QoS control & management technology provides the functions such as path and forwarding schedule methods for traffic. To appropriately assign QoS resource , it is important to study about the mechanism which calculates and provides the required resources based on the network state and application requests. QoS control & management is different from the former that, because there are lots of information to collect and different admission control policy is applied according to each QoS requirement. So we has been studying the adaptive control and management methods to provide the efficiency and scalability in larger network environment.

       Mobile Communications

      Mobile communication systems, or just mobile systems are communication systems with many access points, or base stations. Mobile users can move around with his mobile phone and communicate through the nearest base station that supports its nearby geographical area. Beginning of first generation, many architectures have been proposed, implemented and put to pratical use. In the next section, the short history of mobile communication is introduced.

      First generation (1G) is analog systems with basic speech service. For examples, there are NMT (Scandinavia and Finland), TACS (Great Britain), and AMPS (North America). In second generation(2G), Digital systems with higher capacity, better speech quality, and simple data services. For examples, there are GSM (Global), D-AMPS (America), PDC (Japan), and IS-95 (USA and Korea). In evolved second generation (2.5G), improved data services (packet data and higher bitrates) are applied. There are GPRS (packet data in GSM) and EDGE (higher bitrates within GSM). Third generation (3G), further improved data services (higher bitrates, streaming services e.g. video) are considered( WCDMA). Now, Fourth generation (4G) is coming. In fourth generation even higher bitrates, ad-hoc systems, multi-hop (peer-to-peer) and so on will be considered.

      Currently mobile communication is between 3G and 4G. In the 3GPP(The 3rd generation partnership project), the technical spec. for mobile communication of 3rd generation is almost done. And some products that provide the fuctions in 3rd spec. is coming out. But the 3GPP spec. describe the entire architecture and left the details to service providers. The issues mainly discussed in mobile communication are the LMS(Location Management System), to configure cells, to use channels efficiently and so on. So we have studied about the efficient LMS and how to use channels adaptively.

       Network Performance Evaluation

      So many equipments and applications are coming out at the high speed. One of the major issues in the Internet is the performance evaluation for network system usability. To improve network system quality of service, system administrators should evaluate how their systems are working, and should operate their systems to perform users' requests and optimize performance. Several ways to measure and evaluate network performance have been developed so far. We have studied new performance evaluation methods for network system usability.

       Reliable Multicast Protocol

      Most protocols (such as the ISO Transport Protocols or TCP or UDP) only provide a unicast transmission service. Nodes of the network already have the ability to send to one other node at a time. All transmission with a unicast service is inherently point-to-point. If a node wants to send the same information to N destinations using a unicast transport service, it must perform a replicated unicast, and send N copies of the data to each destination. A better way to transmit data from one source to many destinations is to provide a multicast transport service. With a multicast transport service, a single node can send data to many destinations by making just a single call on the transport service. We have been studied how to construct the efficient and reliable multicast trees , how to apply QoS-enabled multicast for such as real-time service, conferencing and so on.

       Distributed Computing Environment

      Distributed computing is one research topic which solves a large problem by distributing small parts of the problem to many computers to solve and then combining the solutions into a solution for the problem. Distributed computing have been designed to use the computers of hundreds of thousands of volunteers all over the world, via IP-enabled network. The reason is to look for extra-terrestrial radio signals, to look for prime numbers so large that they have more than ten million digits, and to find more effective drugs to fight the AIDS virus. We have been studying how to distribute the load to hundreds of computers efficiently, how to apply clustering to distributed computing methods and so on.

       Software Defined Radio

      SDR is an enabling technology applicable across a wide range of areas within the wireless industry that provides efficient and comparatively inexpensive solutions to several constraints posed in current systems. For example, SDR-enabled user devices and network equipment can be dynamically programmed in software to reconfigure their characteristics for better performance, richer feature sets, advanced new services that provide choices to the end-user and new revenue streams for the service provider. SDR enhances and extends the capabilities of current and proposed wireless standards and serves as an enabler of choice as well for Internet concepts & business models in the wireless industry. We have studied SDR and implemented SDR-enabled applications.

    Networking & Distributed Systems Laboratory
    Room 341, PIRL, POSTECH, Hyoja-Dong, Pohang, KOREA, 790-784
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