큐잉모델과 추계적 페트리 네트를 이용한 핸드오프 호의 채널 할당방식에 대한 성능분석

노철우,국광호 新羅大學校 1995 論文集 Vol.39 No.1

A traffic model and analysis for cellular mobile system with handoff are described. Four channel assignment schems for handoff procedures are considered. In the first scheme, the base station makes no distinction between new call attempts and handoff call attempts. In the second scheme, a fixed number of channels in each cell are reserved exclusively for handoff calls. In the third scheme, queueing is allowed only to handoff calls. The last scheme combines the second and third schemes. We propose to model the channel assignment scheme by both a class of queueing model and Stochastic Petri Nets. The SPN(Stochastic Petri Net) can be solved numerically by SPNP, a software tool for the analysis so SRN(Stochastic Reward Net). Using our model, we compare above four schems and numerical results. These numericall results show blocking probabilities and throughputs.

SRN을 이용한 멀티미디어 채널의 성능분석

노철우 신라대학교 자연과학연구소 2004 自然科學論文集 Vol.13 No.-

본 논문에서는 멀티미디어 통신을 위한 멀티미디어 채널을 모델링하고 이에 대한 성능분석을 수행한다. 음성과 데이터를 포함한 멀티미디어 패킷은 한 개의 채널을 점유할 수 있으며전송될때 까지 큐에서 대기할 수 있다. 데이터패킷은 최대 k 개 만큼 큐에서 대기할 수 있으나 음성 패킷은 대기할 수 없으며 채널을 점유 못하면 서비스를 거절당한다. 데이터 패킷의경우 큐잉을 허용한다. 멀티미디어 패킷의 도착 과정에 따른 멀티미디어 채널의 사용과 채널 부족시 큐잉에 대한 성능분석을 수행한다. SRN은 추계적 페트리 네트의 확장형으로 모델에 적절한 reward를 부여함으로써 원하는 성능지표를 쉽게 계산할 수 있는 모델링 도구이다. 멀티미디어 채널을 위한 SRN 모델이 개발되었으며 음성을 위한 on-off프로세스와 데이터 패킷을 위한 MMPP 프로세스를 고려한다. 본 논문의 기여도는 멀티미디어 채널의 성능분석을 위해 필요한 마르코프 체인의 복잡한 해석적 분석대신 SRN 모델링 기법과 모델에서의 reward 개념에 의한 손쉬운 성능분석 수행 방법을 제시한데 있다. In this paper, a multimedia channel for the transmission of multmedia packets is modeled and evaluated. The multimedia packets such as voice and data enter a channel and are kept in a queue until they can be transmitted. The queue can hold a maxium of K data packets and no voice packets can enter the channel unless the channel is empty. SRN is an extension of stochastic Petri nets and provides compact modeling facilities for system analysis. To get the performance index, appropriate reward rates are assigned to its SRN. In this paper, SRN models for performance analysis of a multimedia channel are developed. Two different kinds of arrival processes, a on-off process for voice packet and a MMPP process for data packet, are taken into account in these SRN models. The key contribution of this paper constitutes the Petri nets modeling techniques instead of complicate numerical analysis of Markov chains and easy way of performance analysis for channel allocations under SRN rewards concepts.

Stochastic Reward Nets을 이용한 통신 프로토콜 검증기법에 대한 연구

노철우,박현희,윤현주 신라대학교 자연과학연구소 1999 自然科學論文集 Vol.6 No.-

In this paper, we describe validation techniques of communication protocol using Petri Nets. The Techniques which can validate protocol design specification written by SDL are constructed and protocol models are developed. Validation technique steps are as follows : SDL specifications are transformed into SRN, from which reachability graghs are obtained. By analyzing the graphs, validation properties such as reachability, boundness and liveness as well as logical errors in design are verified. SRN models for timer and retransmission, essential components of protocol are developed using SRN properties such as cardinality, multiple inhibitor arc, timed and immediate transitions.

W-CDMA 망에서의 위치 서비스 기능 및 시스템 설계

노철우,노문환,김동회,송평중 新羅大學校 2002 論文集 Vol.51 No.-

The LoCation Services (LCS) feature in W-CDMA(Wideband CDMA) network provides the mechanisms to support mobile location services for operators, subscribers and third part service providers. The existing location positioning method are classified into the cell ID based, OTDOA, and network assisted GPS. A new hybrid location positioning method which combines three of these methods are proposed. We present the LCS funcition and system design using SDL (Specification and Description Language) and SDL development tool (SDT). This design covers the LCS functional model and signalling procedure, system architecture, data structrue, and process SDL diagram.

GNU Zebra를 이용한 임베디드 리눅스 라우터 개발

노철우,방석윤 신라대학교 자연과학연구소 2003 自然科學論文集 Vol.12 No.-

In this paper, we address the development of an embedded Linux router using the GNU Zebra routing protocol under the embedded Linux development environments. The objective is to establish the development methods of embedded system based on the porting of Linux kernel. The details of Linux kernel porting, which supports for a network protocol stack, to the dedicated hardware is described. By porting, the router embedded system is developed for replacing a high cost commercial router equipment with the implemented one. After establishing a test environment of the implemented router, the routing function is verified with the routing tables and performance analysis with one of the commercial routers is presented.

패킷교환을 위한 링크계층의 구현에 관한 연구

盧哲愚 新羅大學校 1992 論文集 Vol.34 No.1

A function of the link layer is implemented by utilizing the MK5025 chip which is used for data link layer device of the PHM block in the TDK-?? Packet switching system. A specification of both descriptor ring to transfer packet frame and CSR register to issue packet primitive is described and coded. The MK5025 phase diagram and link state diagram, apply for the LAPB mode. And the state of link layer is handled through MK5025 service privitives. The link layer procedures such as init, setup, sending, receiving and reset are coded in C language by the use of primitives. It is expected to apply easily for the interfacing with O.S and implimentation of link layer by the use of intelligent chip like MK5025 for tne other packet systems.

국제 통신 표준 언어를 이용한 통신 프로토콜 설계 및 검증 방법론 연구

노철우 한국컴퓨터교육학회 2002 컴퓨터교육학회 논문지 Vol.5 No.4

본 논문에서는 통신 프로토콜 개발 시 사용되는 PDU, SDU, SAP, 서비스 프리미티브를 어떻게 정의하고 사용하는지에 대한 명확한 설계 개념과 검증 방법을 ITU에서 통신 규격 및 설계 언어로 권고하고 있는 SDL과 국제 통신 표준 언어인 ASN.1, MSC, TTCN을 사용하여 정립한다. 통신 프로토콜의 예로 잘 알려진 Inres 프로토콜을 확장하여 SDL로 설계하며, SDL의 설계 규격에 비트 스트링 전송을 위한 ASN.1 메시지의 삽입, 규격에 대한 설계 검증을 위한 MSC의 생성, 검증으로부터 TTCN을 이용한 시험 케이스의 생성 및 적합성 시험 등 프로토콜 개발 순기 전반에 걸친 개발 방법론을 정립한다. In this paper, We set up the development methodology of communication protocols as well as the concrete design concept concerning for how to define and use the PDU, SDU, SAP, and service primitives using SDL, which is recommended by ITU-T, and other international standard languages such as ASN.1, MSC, and TTCN. This methodology covers the SDL design of extended Inres protocol, a well known protocol example, insertion of ASN.1 message for transportation of bit string, generation of MSC for validation of design specification, generation of test cases using TTCN from validation, and performance of conformance test.

마르코프 reward 모델을 이용한 통신망의 성능 및 신뢰도 분석 기법

노철우,김경민 신라대학교 자연과학연구소 1998 自然科學論文集 Vol.5 No.-

This paper describes techniques to analyze network reliability and performance using Markov Reward Models(MRM). MRM is obtained by associating reward rates with Markov chain's states. This process facilitates combined evaluation of performance and reliability. Stochastic Reward Net(SRN) is a formalism for a high level specification of MRM. Modeling techniques to construct SRN network reliability models with comparing GSPN models are given. It is shown that reward-based models could lead to more concise model specification and solution of a variety of new measures. With respect to the solution of performance and reliability models, we propose two practical approaches: hierarchichal and phase type expansion modeling and show how reliability/availability measures can be obtained via performance analysis using special reward rates assignment. Two software packages, SPNP and SHARPE, that allow the specification and solution of MRMs are used.

WBI 교수모형을 이용한 페트리 네트 학습의 설계 및 구현

김경민,노철우 신라대학교 교육과학연구소 1999 교육과학연구 Vol.- No.4

균일 마이크로 스트립 선로에서 디지털 펄스 신호의 시간영역 전송 특성 해석

김기래,노철우 신라대학교 자연과학연구소 1999 自然科學論文集 Vol.7 No.-

Recently the necessity of MMIC is increasing because clock frequency goes up by digital data transmission of Gbps class being demanded and the density of circuits gets high for the purpose of lightening and miniaturizing system, owing to the development of ultra high speed. In this paper, the distortion of square pulse and Gaussian pulse caused by dispersion as it propagates along a uniform microstrip line is investigated. A model dispersion of the phase constant proposed by Kirchning-Jansen is used to meet the frequency, accuracy, and microstrip parametric requirements. Numerical integration technique which has high accuracy and is easily simulated, is used to obtain the time domain response of pulse signals. The dispersion of pulse signals is analyzed regarding to the relative permittivity, substrate height, strip width of the microstrip line and pulse width of signal pulse. The simulation results show that small relative permittivity and small w/h ratio are advantageous for the dispersion of the pulse signals, and that pulse signals bandwidth cause smaller dispersion. The results of this paper are compatible to the trade-off determination of relative permittivity, substrate height, strip width and pulse width of signal pulse when a design of MIC and MMIC is necessary.