• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.5 s.347
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• pp.59-67
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• 2006

We demonstrate bidirectional long-reach 35-channel dense wavelength division multiplexing-passive optical network(DWDM-PON) based on wavelength-locked Fabry-Perot laser diodes (F-P LDs). The mode control of F-P LD enhances output power at decreased the required injection power. We show packet-loss-free transmission in all 70 channels at 125 Mb/s per channel line rate through 70 km of single mode fiber without optical amplifier The DWDM-PON can consolidate a metro network into an access network by bypassing the central offices within its reach. The proposed DWDM-PON can accommodate about 80 subscribers with an EDFA-based broadband light source. Further expansion up to 100 subscribers is possible with a semiconductor-based BLS.

• The KIPS Transactions:PartC
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• v.14C no.4
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• pp.349-358
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• 2007

Ethernet Passive Optical Network(EPON), which is one of PON technologies for realizing FTTx(Fiber-To-The-Curb/Home/Office), can cost-effectively construct optical access networks. In addition, EPON can provide high transmission rate up to 10Gbps and it is compatible with existing customer devices equipped with Ethernet card. To effectively control frame transmission from ONUs to OLT EPON can use Multi-Point Control Protocol(MPCP) with additional control functions in addition to Media Access Control(MAC) protocol function. For EPON, many researches on intra- and inter-ONU scheduling algorithms have been performed. Among the inter-ONU scheduling algorithms, IPS(Interleaved Polling with Stop) based on polling scheme is efficient because OLT assigns available time portion to each ONU given the request information from all ONUs. Since the IPS needs an idle time period on uplink between two consecutive frame transmission periods, it wastes time without frame transmissions. In this paper, we propose a dynamic bandwidth allocation algorithm to increase the channel utilization on uplink and evaluate its performance using simulations. The simulation results show that the proposed Two-phase Cycle Danamic Bandwidth Allocation(TCDBA) algorithm improves the throughput about 15%, compared with the IPS and Fast Gate Dynamic Bandwidth Allocation(FGDBA). Also, the average transmission time of the proposed algorithm is lower than those of other schemes.

• Journal of Internet Computing and Services
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• v.8 no.4
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• pp.41-49
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• 2007

Ethernet passive optical network(EPON) is the next-generation technology for supporting services of high-quality at low-cost. In the EPON, all optical network units(ONUs) have to share a limited uplink channel for upstream data. In order to satisfy bandwidth demands of users on high-capacity local access networks(LANs), the optical line terminal(OLT) efficiently divides and allocates time slots of uplink channel to all ONUs. We discuss previous schemes for dynamic bandwidth allocation(DBA), such as interleaved polling with adaptive cycle time(IPACT) and sliding cycle time(SLICT). In this paper, dynamic right sizing of maximum-windows(DRSM), as a novel bandwidth allocation service, is proposed for more effective and efficient time slot allocation of the uplink channel. DRSM which is based on past information of bandwidth allocated by OLT calculates maximum available bandwidth and dynamically alters the maximum window size for the next ONU. This scheme does not only exert every effort to meet bandwidth demands of ONUs with the possible scope, it also seeks fairness of bandwidth allocation among ONUs.

• Electronics and Telecommunications Trends
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• v.27 no.2
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• pp.89-98
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• 2012

광통신 기술의 발달과 인터넷 서비스 수요의 급격한 증가로 2000년대 초반부터 광가입자망 연구 및 상용화가 이루어졌다. 최근에는 스마트폰 등 모바일 단말의 확산과 IPTV의 수요 증대에 따른 폭발적 트래픽 증가에 대처하기 위하여 친환경, 에너지 절감형 차세대 초고속 대용량 광가입자망 기술에 대한 요구가 증대되고 있다. 차세대 광가입자망은 국내뿐 아니라 국외에서도 다양한 프로젝트를 통해 전송 거리, 분기 수 및 전송 용량을 늘리는 방향으로 연구개발이 진행되고 있으며 기존의 TDM, WDM(Wavelength Division Multiplexing) 기술뿐만 아니라 무선 통신에서 사용되던 OFDM(Orthogonal Frequency-Division Multiplexing) 등의 신호변조 기법들을 광가입망 기술에 접목하려는 시도들이 진행되고 있다. 이와 같은 광가입자망 기술들은 ITU-T, IEEE, IEC뿐만 아니라 FSAN(Full Service Access Network), BBF(Broadband Forum), MSF(Multi-service Forum) 등의 표준화 단체에서 활발히 국제표준화가 진행 중이다. 본고에서는 현재 진행되고 있는 차세대 광가입자망 기술에 대한 국내 외 기술개발 현황 및 표준화 현황을 살펴보고자 한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.10B
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• pp.1216-1221
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• 2011

We propose a multiplexed fiber Bragg grating (FBG) sensor network for vessel monitoring to measure the variation of strain and temperature by environmental perturbation based on code division multiple access (CDMA). The center wavelength of FBG was linearly changed by environmental perturbation such as strain and temperature variation so that we could be monitoring the state of sensors. A RSOA was used as optical broadband source and which was modulated by using pseudo random binary sequence (PRBS) signal. The correlation peak of reflected signal from sensor networks was measured. In this paper, we used the sliding correlation techniques for high speed response and dynamic rage of sensors.

• Journal of KIISE:Information Networking
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• v.29 no.2
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• pp.129-140
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• 2002

In this paper, we consider the problem of packet transmission in a wavelength division multiplexed(WDM) optical network. Our network model assumes that receivers are fixed-tuned and transmitters are tunable such that optical lasers assigned to transmitters have limited access to the network bandwidth: hence each node must be equipped with multiple optical lasers and/or multiple optical filters in order to maintain a single-hop network. We first analyze scheduling all-to-all packet transmissions and present optimum scheduling for all-to-all packet transmissions. We then extend the analysis to the case of arbitrary traffic demands. We show that the scheduling with arbitrary traffic demand is NP-hard. A heuristic algorithm based on list scheduling is presented. The upper bound so obtained is compared with the lower bound and provides performance guarantees with arbitrary demands. The result are applicable to arbitrary tuning delay, arbitrary number of wavelength channels and optical lasers of arbitrary tuning ranges.

• International Journal of Computer Science & Network Security
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• v.23 no.8
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• pp.204-209
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• 2023

Dynamic Bandwidth Allocation (DBA) methods in telecommunication network & systems have emerged with mechanisms for sharing limited resources in a rapidly growing number of users in today's access networks. Since the DBA research trends are incredibly fast-changing literature where almost every day new areas and terms continue to emerge. Co - citation analysis offers a significant support to researchers to distinguish intellectual bases and potentially leading edges of a specific field. We present the visualization based analysis for DBA algorithms in telecommunication field using mainstream co-citation analysis tool-CiteSpace and web of science (WoS) analysis. Research records for the period of decade (2009-2018) for this analysis are sought from WoS. The visualization results identify the most influential DBA algorithms research studies, journals, major countries, institutions, and researchers, and indicate the intellectual bases and focus entirely on DBA algorithms in the literature, offering guidance to interested researchers on more study of DBA algorithms.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.1
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• pp.53-59
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• 2000

We propose a modified nonlinear fiber optic interferometer which can serve to generate binary optical pulse sequences for CDMA networks, and to decode them. In one arm cross-phase modulation between a CW signal and a counter- or copropagating high-power pulse takes place in sequences of segment connected via VDM couplers. Preliminary experimental results on code generation as well as autocorrelation and crosscorrelation are presented, using Sagnac interferometer. As we expected, the experimental results show that the outputs of the interferometer device are not summed simply on the basis of power, but the sin-squared version of it. Arbitrary codes can in principle be implemented.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.154-157
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• 1999

Photonic Slot Routing(PSR) is a promising approach to solve the fundamental scalability problem of all-optical packet switched WDM networks. In photonic slot routing, packets destined for the same subnetwork are aggregated to form a photonic slot which is jointly routed as a single unit of information through the network. The relative location of the nodes from bridge may cause to fairness problem in the unidirectional WDM ring network based on PSR. As photonic slots from different subnetworks can originate contentions at the bridge, packets may be dropped and retransmitted. Thus we evaluated the performance of PSR based WDM ring network in the point of fairness for each node and slot contentions at the bridge. Simulation results show that the PSR based WDM ring requires a slot access mechanism to guarantee the transmission fairness and efficient switch architecture to resolve slot contention at the bridge.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.9
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• pp.31-40
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• 1997

This paper presents a hybrid WDM/TDM channel acess protocol for high speed WDM networks based on passive double star topology. In the proposed scheme, all nodes in a network are splitted into groups forming passive double star topology and each node has a tunable transmitter and a fixed receiver. WDM channels are allocated to the groups, which are used as home channels to transmit or receive packets. TDM frames of the WDM channel are composed of the same number of slots as that of groups, and all nodes in a group transmit packets simultaneously at each slot. The proposed scheme reduces the system complexity and the number of the required WDM channels. It was proved that the proposed protocol is less sensitive to the propagation delay and maintaining its superior transmission performance by employing the efficient transmission schedule based on passive double star topology.