• Electronics and Telecommunications Trends
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• v.10 no.1 s.35
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• pp.113-122
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• 1995

현재 발표된 공간 광스위치 구조들은 전자 스위치 및 전자 통신 분야에서 많이 이용된 Clos, Benes, Banyan, omega, shuffle network 등을 directional coupler switch, TIR(total internal reflection) switch, cross X switch 등 여러가지 단위 광스위치를 이용하여 고안한 것으로 서로 다른 장단점을 갖고 있다. 따라서 4 X 4나 8 X 8, 또는 그 이상의 확장된 광스위치를 제작하기 위해서는 이러한 기존 구조에 대한 조사 및 분석이 선행되어야 한다. 본 논문은 현재 개발되어 발표된 광스위치의 구조들을 조사하여 특성을 비교하였다.

• Journal of KIISE:Information Networking
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• v.29 no.6
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• pp.696-705
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• 2002

This paper presents a new copy network for multicast ATM switches. Many studies have been carried out up to date since the proposition of Lee's copy network. However, the overflows and cell conflicts within the switch have still been raised a problem in argument. In order to reduce those problems, we proposed a 3-dimensional multicast switching architecture which has shared buffers in this paper. The proposed architecture can reduce the overflows and cell conflicts through multiple paths and output ports even in the high load environments. Also, we proposed a cell splitting algorithm which handles the cell in the case of large fan-out, and a copy network to increase throughput by expanding the Lee's Broadcast Banyan Network(BBN). Cell copy uses the Boolean interval splitting algorithm and the multicast pattern of the cells according to the self-routing characteristics of the network. In the proposed copy network, we improve the problems such as overflow, cell splitting of large fanout, cell conflicts, etc., which were still existed in the Lee's network. The results of performance evaluation by computer simulation show that the proposed scheme has better throughput, cell loss rate and cell delay than the conventional method.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.3
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• pp.255-263
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• 2000

A multistage interconnection network is a suitable class of interconnection architecture for constructing large-scale multicomputers. Broadcast and multicast communication are fundamental in supporting collective communication operations such as reduction and barrier synchronization. In this paper, we propose a new multicast technique in wormhole-switched bidirectional multistage banyan networks for constructing large-scale multicomputers. To efficiently support broadcast and multicast with simple additional hardware without deadlock, we propose a two-phase multicast algorithm which takes only two transmissions to perform a broadcast and a multicast to an arbitrary number of desired destinations. We encode a header as a cube and adopt the most upper input link first scheme with periodic priority rotation as arbitration mechanism on contented output links. We coalesce the desired destination addresses into multiple number of cubes. And then, we evaluate the performance of the proposed algorithm by simulation. The proposed two-phase multicast algorithm makes a significant improvement in terms of latency. It is noticeable that the two-phase algorithm keeps broadcast latency as efficient as the multicast latency of fanout 2^m where m is the minimum integer satisfying $2^m{\geq} {\sqrt{N}}$ ( N is a network size).

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.1
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• pp.1-8
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• 1997

A wide class of networking application services, such as video teleconferencing, VOD, LAN bridging, and distributed data processing require multipoint communications. The essential component inteh network to achieve this is a multicast packet switch which is capable of packet replication and switching. In this paper, we propose an efficient mukticast addressing scheme using the smallest number of routing bits which is deterministic lower bound. The new scheme performs all point-to-multipoint connection in radix-2 tree ATM switch like banyan network. Also, we provide a simple radix-2 switch block diagram for achieving our algorithm. And we investigate several addressing schemes for implementing multicasting in radix-r tree ATM switch and evaluate several performance factors, such as complexity of the additional header bits, requirement of the internal speedup and complexity of the major hardware.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.3
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• pp.256-263
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• 2002

Optical Multistage Interconnection Networks(OMINs) comprising photonic switches have been studied extensively as important interconnecting building blocks for communication networks and parallel computing systems. A basic element of photonic switching networks is a 2$\times$2 directional coupler with two inputs and two outputs. This paper is concerned with the diagnosis of cross-talk-faults in OMINs. As the size of today's network becomes very large, the conventional diagnosis methods based on tests and simulation have become inefficient, or even more, impractical. In this paper, we propose a simple and easily implementable algorithm for detection and isolation of the single crosstalk-fault in OMINs. Specifically, we develope an algorithm fur the isolation of the source fault in switching elements whenever the single crosstalk-fault is detected in OMINS. The proposed algorithm is illustrated by an example of 16$\times$16 banyan network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.56-63
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• 2000

In this paper, we design new high performance ATM switch architectures based on a Generalized Shuffle network(GSN). The GSN is a distributed network topology with the number of nodes in O(N). To improve the throughput of the switch, a layering strategy called Weaved GSN(WGSN). WGSN has an additional connection links between switching elements which locate in the same position of adjacent GSNs. The analysis and simulation are performed under uniform and full load conditions, and the results show that the proposed switch has better throughput and cell loss performance when compared with other banyan-based switch architectures known so far.

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.167-174
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• 1999

In this paper, we propose the adaptive separated-queueing ATM switching model for the effective processing of the various types of multimedia traffic by virtue of ATM switching network with multiple outlets which is the essential part of B-ISDN. This proposed model employs the dynamically separated buffering mechanism in the processing of two classes of cell, realtime service traffic and non-realtime service traffic, at the output buffer to enhance the overall QoS(Quality of Service). The adopted ATM switch architecture has Batcher-banyan based network, but it uses different topologies and control techniques 6to resolve the cell contention. For the performance evaluation of our proposed method, we have done both analytical modeling and simulation. The both results show that our proposed queueing strategy is quite appropriate to the ATM switch with multiple outlets and can quarantee the QoS requirements of the incoming multimedia traffic.

• Journal of KIISE:Information Networking
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• v.30 no.1
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• pp.134-142
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• 2003

We present an ATM switch architectures based on the multistage interconnection network(MIN) for the efficient multicast traffic control. Many of these applications require multicast connections as well as point-to-point connections. Muiticast connection in which the same message is delivered from a source to arbitrary number of destinations is fundamental in the areas such as teleconferencing, VOD(video on demand), distributed data processing, etc. In designing the multicast ATM switches to support those services, we should consider the fairness(impartiality) and priority control, in addition to the overflow problem, cell processing with large number of copies, and the blocking problem. In particular, the fairness problem which is to distribute the incoming cells to input ports smoothly is occurred when a cell with the large copy number enters upper input port. In this case, the upper input port sends before the lower input port because of the calculating method of running sum, and therefore cell arrived into lower input port Is delayed to next cycle to be sent and transmission delay time becomes longer. In this paper, we propose the cell splitting and group splitting algorithm, and also the fairness scheme on the basis of the nonblocking characteristics for issuing appropriate copy number depending on the number of Input cell in demand. We evaluate the performance of the proposed schemes in terms of the throughput, cell loss rate and cell delay.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9A
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• pp.1276-1284
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• 1999

We have evaluated the BER's and CLP's of Wireless ATM (WATM) cells employing the concatenated FEC code with pilot symbols for fading compensation through the simulation in indoor wireless channel modeled as a Rayleigh and a Rician fading channel, respectively. The results of the performance evaluation are compared with those obtained by employing the convolutional code in the same condition. In Rayleigh fading channel, considering the maximum tolerance BER ( $10^-3$) as a criterion of the voice service, it is blown that the performance improvement of about 4 dB is obtained in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols rather than the convolutional code with pilot symbols.When the values of K parameter which means the ratio of the direct signal to scattered signal power in Rician fading channel are 6 and 10, it is shown that the performance improvement of about 4 dB and 2 dB is obtained, respectively, in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols considering the maximum tolerance BER of the voice service. Also in Rician fading channel of K=6 and K= 10, considering CLP = $10^-3$ as a criterion, it is observed that the performance improvement of about 3.5 dB and1.5 dB is obtained, respectively, in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols.