• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.42 no.5 s.335
• /
• pp.23-28
• /
• 2005

Recently, new concept, NP(Network Processor) was emerged into communication systems to cope with the various service requirements from Internet users. NP is an unique promising technique to capable of implementing of the packet processing in wire-speed and providing the flexibility for supporting the newly network services, having satisfied with implementation using hardware and software respectively in past, This paper deals with the implementation techniques and evaluation results of the line card capable to do packet forwarding function with packet processing power of wire-speed and applicable to various physical interfaces. There are several interfaces of POS, Gigabit ethernet and EPON in E-OLT(EPON Optical Line Terminal) system of PATH(Photonic Access To Home) network. Therefore, the E-OLT's packet forwarding engine have to support various subscriber's interface in wire speed. Our system is implemented the subscriber's card in daughter board and the setup procedure is done by system firmware based on the module's identifier acquired from installed physical board.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.8
• /
• pp.1549-1560
• /
• 2009

In the TDMA PON system, the DBA is essential for ONUs to send data efficiently to the upstream. In this paper, we implement a DBA processor for the G-PON OLT with downstream and upstream rate, 2.5 and 1.25 Gbps, respectively, The processor collects bandwidth request messages from ONUs at every cycle time and allocates properly bandwidth to each Alloc-ID with considering priority and fairness for traffics. In the proposed DBA algorithm, one cycle time consists of multiple G-PON frames ($m{\times}125{\mu}s$) for high link efficiency. In particular, the link efficiency is higher because the algorithm adopts a method that an additional overhead is eliminated when an allocated bandwidth is laid between two G-PON frames for an ONU. This enables that the processor flexibly allocates the bandwidth from zero to the maximum link capacity for an ONU. The proposed DBA processor is implemented with the FPGA and shows bandwidth allocating processes for ONUs with logic analyzer.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39A no.6
• /
• pp.357-364
• /
• 2014

In this paper deals with PON Remote monitoring solution using Reflecting Filter. The current FTTH-PON can not be monitored in real time that Optical cable fault and Quality degradation of Splitter. To solve this problem, Monitoring can make Feeder Network and Splitter that Reflecting filter development using the basic structure of Fiber Bragg grating. Reflecting Filter is Quality Monitoring System shall provide tools for user to view and analyze degradation of cables and splitter in particular predict any gradual component degradation(Optical cable bending, splice, connector, etc) before it becomes service impacting. The Reflecting Filter solution is splitter down and confirm the fault location of optical cable and it will send central control station can be monitored system an alarm to the OLT. In other words, wavelength side branches Mating existing communication affairs (Coupler) using the core of one optical wavelength for live monitoring two wavelengths and sends the subscriber side modem and aggregation switch device remotely using a reflective optical line filter monitoring the study of the system. this study can development of Reflecting filter improve the average processing time of Optical cable fault and efficient Maintenance of the network.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.8C
• /
• pp.803-811
• /
• 2002

Asynchronous Transfer Mode-Passive Optical Network(ATM-PON) Technology is one of the best solutions for implementation of broadband access network. In this paper, we propose a new Dynamic Bandwidth Allocation (DBA) algorithm for ATM-PON systems. The DBA is a key technique for data traffic management. DBA has been studied widely to allow ATM-PON to transport data traffic cost-effectively and efficiently, and currently a hot standardization issue in Full Service Access Network(FSAN) and ITU-T. The proposed DBA algorithm efficiently manages the user traffics according to their service categories. Performance of the proposed algorithm, in aspect of Cell Transfer Delay(CTD) and Cell Delay Variation(CDV), is evaluated using computer simulation.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.40 no.7
• /
• pp.261-272
• /
• 2003

An Ethernet PON(Passive Optical Network) is an economical and efficient access network that has received significant research attention in recent years. A MAC(Media Access Control) protocol of PON , the next generation access network, is based on TDMA(Time Division Multiple Access) basically and can classify this protocol into a fixed length slot assignment method suitable for leased line supporting QoS(Quality of Service) and a variable length slot assignment method suitable for LAN/MAN with the best effort. For analyzing the performance of these protocols, we design an Ethernet PON model using OPNET tool. To establish the maximum efficiency of a network, we verify a MAC protocol and determine the optimal number of ONUs(Optical Network Unit) that can be accepted by one OLT(Optical Line Terminal) and propose the suitable buffer size of ONU based on analyzing the end-to-end Ethernet delay, queuing delay, throughput, and utilization.

• Journal of Korean Foot and Ankle Society
• /
• v.10 no.2
• /
• pp.133-139
• /
• 2006

Purpose: To evaluate the results of mosaicplasty and microfracture after surgical treatments for symptomatic osteochondral lesion of talus (OLT) by second-look arthroscopy. Materials and Methods: 7 cases of mosaicplasty and 7 cases of microfracture were reviewed who undertook second-look arthroscopy at 6 months or one year after undertaking mosaicplasty or microfracture for OLT between December 2004 and October 2005. The mean age at first operation was 43.6 years (Range, 20-59) (Mosaicplasty; 43.9 years, Microfracture; 43.4 years). The mean size of cartilage defect was $15.0{\times}7.7\;mm$ in mosaicplasty and $7.1{\times}6.6\;mm$ in microfracture. Clinical outcomes were evaluated by Freiburg ankle score. Cartilage healing state was evaluated by Insall's classification for chondromalasia during second-look arthroscopy. Results: By the Freiburg ankle score, 9 ankles (6 in mosaicplasty, 3 in microfracture) had excellent and 5 (1 in mosaicplasty, 4 in microfracture) had good results at the times of second-look arthroscopy. By Insall's classification, consistency of the osteochondral grafts and congruity between grafts and native cartilage (Grade I) were shown in 9 (6 ankles in mosaicplasty, 3 ankles in microfracture), a fissuring (Grade II) in one ankle of mosaicplasty, a fasciculation (Grade III) in one ankle of microfracture, and partial exposure of subchondral bone (Grade IV) in 3 ankles of microfractures. Conclusion: Mosaicplasty was more excellent in consistency and hardness of cartilage than microfracture. In some cases of microfracture, cartilage healing was incomplete at 6 months postoperatively, so second-look arthroscopy is necessary to identify. If incomplete cartilage healing was shown, additional procedure such as microfracture or mosaicplasty was needed.

• Journal of Broadcast Engineering
• /
• v.10 no.2
• /
• pp.182-189
• /
• 2005

In this paper, an asymmetric WDM-EPON transmission scheme is proposed to be used in a high speed access network system, which is required to implement the convergence of broadcast and communication. WDM is used for downstream transmission from OLT to access nodes, satisfying wide bandwidth requirement for broadcasting and various multimedia services. And an EPON scheme, which is cheaper than WDM, is applied to upstream transmission where less bandwidth is required. A transmission test in physical layer was performed successfully and the results are provided. If ONUs are to be used in a home gateway, its protocol should be appropriate to its traffic pattern. Voice is sensitive to a time delay while data is not. A new dynamic bandwidth assignment protocol for PON system, which can cope with various types of data in access network is proposed and its performance is analysed. A maximum cycle time is specified to achieve the QoS of signals sensitive to time delay. And a minimum window is specified to prevent the downstream control signals from uprising. It is shown by simulation that the proposed EPON protocol can provide a better performance than previous ones.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.3A
• /
• pp.223-232
• /
• 2004

In this paper we propose the hierarchical-based dynamic bandwidth allocation algorithm for multi-class services in Ethernet-PON. The proposed algorithm consists of the high level scheduler in OLT and the low level scheduler in ONU. The hierarchical architecture is able to provide scalability and resource efficiency in Ethernet-PON which has the distributed nature of the scheduling domain, with queues and the scheduler located at a large distance from each other. We also propose three dynamic bandwidth allocation algorithms for the low level scheduler: Proportional Allocation algorithm, Maximum Request First Allocation (MRFA) algorithm and High Priority First Allocation (HPFA) algorithm. We implement the Ethernet-PON standardized in the IEEE 802,3ah using OPNET. We also evaluate and analyze the performance for the proposed algorithms in terms of channel utilization, queuing delay and the amount of remainder.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.9B
• /
• pp.777-784
• /
• 2006

In this paper, we propose the PON-based access network based on conventional TDM-PON architecture, which utilizes WDM wavelength channel and bandwidth dynamically. It is also described a dynamic MAC protocol in order to increase the number of subscribers and efficiency of resource utilization. Of particular importance in the proposed approach for MAC protocol is that the wavelength channel and time slot for up/downlink is dynamically allocated according to the required QoS level and the amount of data in data transmission, through the dedicated control channel between OLT and ONU. We evaluate the performance of average packet end-to-end delay in a statistical analysis and numerical analysis. In addition, through simulations with various traffic models, we verified the superior performance of the proposed approach by comparing with the results of other E-PONs.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.1B
• /
• pp.1-10
• /
• 2003

An EPON which is going on standardization in IEEE 802.3ah, is tree topology consists of a OLT and multiple ONU using passive optical components, so this network is susceptible to variable security threats - eavesdropping, masquerading, denial of service and so on. In this paper, we design a security protocol supporting authentication and confidentiality services in MAC layer in order to prevent these security threats and to guarantee secure data exchange The designed security protocol introduce public-key based authentication and key management protocols for efficient key management, and choose Rijndael algorithm, which is recent standard of AES, to provide the confidentiality of EPON Proposed authentication and key management protocols perform authentication and public-key exchange at a time, and are secure protocols using derived common cipher key by exchanging public random number To implement the designed security protocol, we propose the procedures of authentication and public-key exchange, session key update, key recovery. This proposed protocol is verified using unknown session key, forward secrecy, unknown key-share, key-compromise impersonation.