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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Electronics and Telecommunications Research Institute
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Volume & Issues
Volume 24, Issue 6 - Dec 2002
Volume 24, Issue 5 - Oct 2002
Volume 24, Issue 4 - Aug 2002
Volume 24, Issue 3 - Jun 2002
Volume 24, Issue 2 - Apr 2002
Volume 24, Issue 1 - Feb 2002
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Signaling and Control Procedures Using Generalized MPLS Protocol for IP over an Optical Network
Um, Tai-Won ; Choi, Jun-Kyun ; Kim, Young-Ae ; Lee, Hyeong-Ho ; Jung, Hae-Won ; Jong, Sang-Gug ;
ETRI Journal, volume 24, issue 2, 2002, Pages 69~69
This paper reviews the existing research activities on signaling and control procedures for IP over optical networks. We focus on the IP-centric signaling and control architecture based on the generalized multi-protocol label switching (GMPLS) protocol and analyze various scenarios and technical issues for deploying the IP over an optical network. We analyze the signaling and operations and administration and maintenance requirements for integrating an IP network and an optical network in order to cope with the high bandwidth and poor resource granularity of the optical network, including the optical cross-connect system. On the basis of network architecture and a reference configuration model, we investigate the GMPLS-based control architecture and interconnection model appropriate for controlling IP bandwidth and optical lambda resources. The signaling and control procedure based on GMPLS on optical user-network interface and network-network interface are comparatively investigated to provide the optical lightpath. We also study protection and restoration procedures to protect link failure when it applies to generalized MPLS signaling.
Design of Hybrid Optical Amplifiers for High Capacity Optical Transmission
Kim, Seung-Kwan ; Chang, Sun-Hyok ; Han, Jin-Soo ; Chu, Moo-Jung ;
ETRI Journal, volume 24, issue 2, 2002, Pages 81~81
This paper describes our design of a hybrid amplifier composed of a distributed Raman amplifier and erbium-doped fiber amplifiers for C- and L-bands. We characterize the distributed Raman amplifier by numerical simulation based on the experimentally measured Raman gain coefficient of an ordinary single mode fiber transmission line. In single channel amplification, the crosstalk caused by double Rayleigh scattering was independent of signal input power and simply given as a function of the Raman gain. The double Rayleigh scattering induced power penalty was less than 0.1 dB after 1000 km if the on-off Raman gain was below 21 dB. For multiple channel amplification, using commercially available pump laser diodes and fiber components, we determined and optimized the conditions of three-wavelength Raman pumping for an amplification bandwidth of 32 nm for C-band and 34 nm for L-band. After analyzing the conventional erbium-doped fiber amplifier analysis in C-band, we estimated the performance of the hybrid amplifier for long haul optical transmission. Compared with erbium-doped fiber amplifiers, the optical signal-to-noise ratio was calculated to be higher by more than 3 dB in the optical link using the designed hybrid amplifier.
Optical BGP Routing Convergence in Lightpath Failure of Optical Internet
Jeong, Sang-Jin ; Youn, Chan-Hyun ; Kang, Min-Ho ; Min, Kyoung-Seon ; Hong, Hyun-Ha ; Kim, Hae-Geun ;
ETRI Journal, volume 24, issue 2, 2002, Pages 97~97
Optical Border Gateway Protocol (OBGP) is an extension to BGP for Optical Cross Connects (OXCs) to automatically setup multiple direct optical lightpaths between many different autonomous domains. With OBGP, the routing component of a network may be distributed to the edge of the network while the packet classification and forwarding is done in the core. However, it is necessary to analyze the stable convergence functions of OBGP in case of lightpath failures. In this paper, we first describe the architecture of the OBGP model and analyze the potential problems of OBGP, e.g., virtual BGP router convergence behavior in the presence of lightpath failure. We then propose an OBGP convergence model derived from an inter-AS (Autonomous System) relationship. The evaluation results show that the proposed model can be used for a stable OBGP routing policy and OBGP routing convergence under lightpath failures of the optical Internet.
A Novel Vertical Directional Coupler Switch with Switching Operation-Induced, Extinction Ratio-Adjusted, and Extinction Ratio-Enhanced Sections
Cho, Sung-Chan ; Hong, Hyun-Ha ; Yang, Choong-Reol ; Choi, Jee-Yon ; Kang, Min-Ho ; Hwang, Hyun-Yong ; Choi, Young-Woo ; Kim, Hae-Geun ; Jung, Byung-Min ; Kim, Boo-Gyoun ;
ETRI Journal, volume 24, issue 2, 2002, Pages 109~109
We propose a novel very short (<
) vertical directional coupler switch with high extinction ratios larger than 30 dB. The device consists of a switching operation induced section (SOIS), an extinction ratio adjusted section (ERAS), and an extinction ratio enhanced section (ERES). These are achieved by changing the refractive index of one core. The switching operation is induced by changing the refractive index of one core in the SOIS. The improvement of extinction ratios larger than 30 dB for both the cross and bar states is made by controlling the asymmetry of the refractive indices of both cores in the ERES. Through the ERAS, different extinction ratios between the cross and bar states at the end of the SOIS are changed to the same value. For this reason, the optimum asymmetry of the refractive indices of the cores for the maximum extinction ratios and the lengths of ERES are the same for cross and bar states. Design guidelines for high extinction ratios with large tolerances are presented.
Survivability in the Optical Internet Using the Optical Burst Switch
Oh, Seung-Hun ; Kim, Young-Han ; Yoo, Myung-Sik ; Hong, Hyun-Ha ;
ETRI Journal, volume 24, issue 2, 2002, Pages 117~117
Due to its salient features, the optical burst switch is becoming a key technology for the optical Internet. Within this technology, the survivability issue in the optical Internet has to be addressed because a simple failure causes severe damage to the huge amount of data carried in optical fiber. In this paper, we introduce a restoration procedure that can provide good survivability in the optical burst switch (OBS)-based optical Internet. OBS restoration can survive various types of network failure while maintaining good network performance. We propose novel restoration mechanisms, namely, "temporary Label Switched Path (LSP)" and "bossy LSP," to enhance restoration time and network utilization. The simulation results verify that the proposed OBS restoration achieves good network performance and provides good network connectivity as well.
An Optimization Approach to Routing and Wavelength Assignment in WDM All-Optical Mesh Networks without Wavelength Conversion
Lee, Kyung-Sik ; Kang, Kug-Chang ; Lee, Tae-Han ; Park, Sung-Soo ;
ETRI Journal, volume 24, issue 2, 2002, Pages 131~131
This paper considers a routing and wavelength assignment problem (RWAP) for the implementation of efficient Wavelength Division Multiplexing all-optical mesh networks without wavelength conversion. For a given physical network and required connections, the solution to the RWAP consists in how to select a suitable path and wavelength among the many possible choices for each connection so that no two paths using the same wavelength pass through the same link, while minimizing the number of required wavelengths. We introduce an integer programming formulation of the RWAP, which has an exponential number of variables, and propose an algorithm to solve it based on the column generation technique. The proposed algorithm can yield high quality solutions and tight lower bounds at the same time. Though the proposed algorithm cannot guarantee optimal solutions, computational results show that the algorithm yields provably good solutions within a reasonable time.
Design and Performance Analysis of a Contention-Based Reservation Protocol for a Local Area Optical Internet
Choi, Jin-Seek ; Lee, Jang-Won ; Kang, Min-Ho ;
ETRI Journal, volume 24, issue 2, 2002, Pages 142~142
In this paper, we propose and analyze a new multiple access protocol for a local area optical Internet based on a wavelength division multiplexing technique which uses a passive star coupler. The proposed contention-based reservation protocol can support variable-length as well as fixed-length messages for transporting Internet packets with one reservation of a minislot at the beginning of a packet transmission. The minislot is used to reserve the data channel on the basis of the slotted ALOHA protocol and the control node ensures subsequent message transmission on the same wavelength. Thus, all messages need not be broken down to many fixed-length packets, and consecutive messages are transmitted through the same wavelength. Moreover, the proposed protocol reduces the collision probability of minislots and improves wavelength utilization. We determine the maximum throughput and verify the results with simulation.
Dimensioning a Retro-Directive Array for Communications via a Stratospheric Platform
Thornton, John ;
ETRI Journal, volume 24, issue 2, 2002, Pages 153~153
High Altitude Platforms-craft maintaining stations in the stratosphere at altitudes of around 20 km-have been proposed as a means of supporting wireless telecommunications. They could exploit the best aspects of both terrestrial and satellite systems and support efficient frequency re-use plans. For solar powered platforms the power available for the downlink amplifiers may be minimal, particularly at night and/or higher latitudes. This paper discusses a novel type of link based on a modulated retro-directive transponder carried by the HAP. Relying chiefly on the ground station infrastructure, this would substantially reduce power consumption on the platform. We investigate the efficiency of the transponder aperture as a function of its area by developing general models for losses in the transmission lines which interconnect antenna pairs in the retro-directive array.
A VLSI Architecture for Novel Decision Feedback Differential Phase Detection with an Accumulator
Kim, Chang-Kon ; Chong, Jong-Wha ;
ETRI Journal, volume 24, issue 2, 2002, Pages 161~161
This paper proposes a novel decision feedback differential phase detection (DF-DPD) for M-ary DPSK. A conventional differential phase detection method for M-ary Differential Phase Shift Keying (DPSK) can simplify the receiver architecture. However, it possesses a poorer bit error rate (BER) performance than coherent detection because of the prior noisy phase sample. Multiple-symbol differential detection methods, such as maximum likelihood differential phase detection, Viterbi-DPD, and DF-DPD using L-1 previous detected symbols, have attempted to improve BER performance. As the detection length, L, increases, the BER performance of the DF-DPD improves but the complexity of the architecture increases dramatically. This paper proposes a simplified DF-DPD architecture replacing the conventional delay and additional architecture with an accumulator. The proposed architecture also improves BER performance by minimizing the current differential phase noise through the accumulation of previous differential phase noise samples. The simulation results show that the BER performance of the proposed architecture approaches that of a coherent detection with differential decoding.
Optimal Time Slot Assignment Algorithm for Combined Unicast and Multicast Packets
Lee, Heyung-Sub ; Joo, Un-Gi ; Lee, Hyeong-Ho ; Kim, Whan-Woo ;
ETRI Journal, volume 24, issue 2, 2002, Pages 172~172
This paper considers a packet-scheduling algorithm for a given combined traffic of unicast and multicast data packets and proposes a hybrid router with several dedicated buses for multicast traffic. Our objective is to develop a scheduling algorithm that minimizes schedule length for the given traffic in the hybrid router. We derive a lower bound and develop an optimal solution algorithm for the hybrid router.
Human Head Size and SAR Characteristics for Handset Exposure
Lee, Ae-Kyoung ; Choi, Hyung-Do ; Lee, Hyung-Soo ; Pack, Jeong-Ki ;
ETRI Journal, volume 24, issue 2, 2002, Pages 176~176
Using scaled models for an anatomical head model and a simple head model, we investigated the effects of head size on specific absorption rate characteristics for two mobile phones operating at 835 MHz and 1765 MHz. Our results showed that a larger head produced a higher localized SAR at 835 MHz. However, at 1765 MHz, the differences among the head models were insignificant since the superficial absorption was dominant over the effects of head shape and size. A larger head produced a lower whole-head averaged SAR at both frequencies.