• Journal of Communications and Networks
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• v.4 no.2
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• pp.128-135
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• 2002

We propose a new space priority mechanism, and analyze its performance in a single Constant Bit Rate (CBR) server. The arrival process is derived from the superposition of two types of traffics, each in turn results from the superposition of homogeneous ON-OFF sources that can be approximated by means of a two-state Markov Modulated Poisson Process (MMPP). The buffer mechanism enables the Asynchronous Transfer Mode (ATM) layer to adapt the quality of the cell transfer to the Quality of Service (QoS) requirements and to improve the utilization of network resources. This is achieved by "Selective-Delaying and Pushing-ln"(SDPI) cells according to the class they belong to. The scheme is applicable to schedule delay-tolerant non-real time traffic and delay-sensitive real time traffic. Analytical expressions for various performance parameters and numerical results are obtained. Simulation results in term of cell loss probability conform with our numerical analysis.

• The Transactions of the Korea Information Processing Society
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• v.3 no.4
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• pp.697-708
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• 1996

In this paper, we study reactive congestion control with priority in ATM network. The priority schemes for buffer access, partial buffer sharing have been investigated in order to improve the utilization of ATM network resources the network and to satisfy the most demanding traffic class. We consider in this paper a discrete-time queueing model for partial buffer sharing with two Markov modulated Poisson inputs. This model can be used to analyze the the effects of the partial buffer sharing priority scheme on system performance for realistic cases of bursty services. Explicit formulae are derived for the number of cells in the system and the loss probabilities for the traffic. Congestion may still occur because of unpredictable statistical fluctuation of traffic sources even when preventive control is performed in the network. In this Paper, we study reactive congestion control, in which each source changes its cell emitting rate a daptively to the traffic load at the switching node. Our intention is that,by incorporating such a congcstion control method in ATM network,more efficient congsestion control is established. We develope an analytical model,and carry out an approximateanalysis of reactive congestion con-trol with priority.Numerical results show that several orders of magnitude improvement in the loss probability can be achieved for the high priority class with little impact on the low priority class performance.And the results show that the reactive congestion control with priority are very effective in avoiding congestion and in achieving the statistical gain.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.4
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• pp.14-19
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• 2005

In general, cell transmission delay is more sensitive for real time video service rather than cell losses in a wireless ATM network. Existing handoff schemes, which are emphasizing the prevention of cell losses, have limitations in cell transmission delay to satisfy QoS. In this paper, we propose a scheme to minimize transmission delay generated during the handoff and to maintain the sequence of cells. Transmission delay can be reduced by transmitting ATM cells with low CLP(i.e., CLP=0) prior to others and by discarding cells with high CLP(i.e., CLP= 1). The simulation results show that the proposed scheme is suitable for delay sensitive real time VBR service as well as fast handoff by giving high CLP to less meaningful MPEG frames.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.9
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• pp.1209-1218
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• 1995

In this paper, we develope an ATM switch simulator in order to evaluate the HAN/B-ISDN ATM switch currently being developed by ETRI. It models the basic cell switching functions of the target ATM switch with priority control and multicasting features and it also supports such various traffic models as random or bursty traffic, balanced or unbalanced traffic, multicast traffic models. Using this simulator, we can evaluate the performances of the ATM switch in terms of various performance indices, i.e. cell delay, cell loss probability, etc., and this simulator can be utilized in the system parameter tunings such as the common buffer size and address buffer size.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.8
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• pp.1928-1936
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• 1996

In this paper, we propose an adaptive bandwidth allocation algorithm for the transmission of VBR video through ATM Networks. In order to evaluate the required bandwidth for the VBR video, the characteristics of the compressed VBR video generated by the two-layered coder are analyzed with variations in the number of GOP(N), quantizer scale(q), and the number of low-frequency DCT coefficients(.betha.). The two-layer coder which is used to separate from the number of DCT coefficients is designed to transmit the VBR video efficiently. The compressed data generated by the two-layer coder are splitted into the high priority and low priority cells. If congestion is occurred in ATM networks, the minimum image quality is maintained by the high priority cells. The required bandwidth for VBR video is estimated with a prediction algorithm using the scene anframe correlations as well as the statistical properties of the VBR video sources. Strong correlation among the adjacent slices in a frame represents by the scene correlation andstrong correlation among the frames is represented by the frame correlation. The performance of the bandwidth allocation scheme proposed is evaluated in terms of the bandwith utilization, cell loss rate, and SNR with variations in q, n, .betha.. Simulation rewsults shown that the proposed scheme is superior to the conventional methods.

• The KIPS Transactions:PartC
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• v.9C no.2
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• pp.277-282
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• 2002

In general, requirements for QoS are different according to the type of services in wire-line and wireless ATM networks, and real-time video service is more sensitive to cell transmission delay than to cell loss. Existing handoff schemes emphasizing prevention of cell loss had limitations in cell transmission delay to satisfy QoS. In this paper, a novel scheme to transmit ATM cells with low CLP(when CLP = 0) prior to others and discarding cells with high CLP(when CLF = 1) in ATM cell header among cells to be forwarded to new base station during handoffs in real-time VBR service is proposed. The proposed scheme is proven to be suitable for the satisfaction of QoS of real-time VBR service and appropriate for fast handoffs by giving high CLP value to less meaningful MPEG frames through simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8A
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• pp.1195-1207
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• 1999

Wireless channel has high error rate and limited bandwidth. In order to guarantee the quality of service for multimedia through wireless channel, wireless ATM network requires the cell structure with error control schemes and an efficient medium access control protocol. In this paprt, an efficient medium access control protocol, which is considered of cell structure and the QOS, is proposed for wireless ATM networks. Many kinds of ATM cell structures are analyzed in terms of cell error rate and cell loss rate to choose the proper cell structures for this proposed MAC protocol. And a bandwidth allocation algorithm is also designed to satisfy the priority of services. The performance of proposed MAC protocol are evaluated in terms of channel utilization, call blocking and packet discard probability accotding to different kinds of cell structure through simulation.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.131-134
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• 2000

Only MAC protocol can satisfy the service quality of the request of bandwidth, delay time, and cell loss at the same time and it is because MAC protocol provides mobile terminal an environment to use channel evenly and effectively This Paper has been adapted Mobile ATM Standardization of ETSI in maximum and used not only for practicing in-band signal to a priority order but also to the next reserved slot assignment of the dynamic frame. Also, by accepting VBR traffic more adaptively, the effectiveness of transmission channel has been maximized as well, and these are compared with the old way of it and analyzed to confirm the effectiveness.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1847-1850
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• 2002

In this paper, MPLS Router module supporting Differentiated Service(Diffserv) for quality of Service (QoS) and High-speed switching is proposed and implemented. And we compare and analyze the proposed architecture with the conventional one in terms of CLR (Cell Loss Rate) and average delay. Switch is an extended system of Queue of each VOQ and PHB in the manner of Input Queuing for QoS. Algorithm, Priority-iSLIP is used for its scheduling algorithm. The proposed architecture is modeled in C++ and verified.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7C
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• pp.664-669
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• 2002

In this paper, we propose the fuzzy control algorithm for effective buffer control to connected traffic in ATM networks. The proposed Fuzzy control algorithm has two priorities and uses Fuzzy sets to search for dynamic thresholds. In this words, the difuzzification value controls the threshold in the buffer to according to traffic priority (low or high) using fuzzy set theory for traffic connected after reasoning. Performance analysis result: it was confirmed that with the proposed scheme, performance improves at cell loss rate, when compared with the existing PBS scheme.