• Journal of the Korean Society for Precision Engineering
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• v.26 no.10
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• pp.40-46
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• 2009

Recently CAN (Controller Area Network) is widely used as an in-vehicle networking protocol for intelligent vehicle. The identifier field (ID) of CAN is used not only to differentiate the messages but also to give different priorities to access the bus. This paper presents a dynamic 10 allocation algorithm in order to enhance the real-time quality-of-service (QoS) performance. When the network traffic is increased, this algorithm can allocate a network resource to lower priority message without degradation of the real-time QoS performance of higher priority message. In order to demonstrate the algorithm's feasibility, message transmission delays have been measured with and without the algorithm on an experimental network test bed.

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.1
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• pp.85-92
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• 2000

Channel management is critical in designing a cellular mobile system that offers high capacity and high quality. In this paper, an integrated channel management scheme is proposed, which consists of a dynamic channel allocation scheme and an admission control scheme. The dynamic channel allocation scheme allocates a call request the channel which minimizes the impact on its interfering cell, and consists of two types of channel allocation strategies : nominal channel allocation strategy and non-nominal channel allocation strategy. The admission control scheme named the variable cutoff priority scheme reserves some frequency channels for handoff cells in each cell the number of which varies according to the blocking probability of handoff class in that cell. Computationl tests are performed to evaluate the performance of the proposed scheme in terms of overall blocking probability, defined by the weighted value of the blocking probabilities of new calls and handoff calls. The results show that the proposed scheme yields better performance than other compared schemes.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.61-64
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• 2003

GPRS is designed for transmitting packet data and supposed to take its radio resource form the pool of channels unused by GSM voice services. In this paper, The GPRS and GSM circuit switched services share the same radio resource. Whenever a channel is not used by circuit switched services, it may be utilized by GPRS. In this paper, the main aim is performance and comparison resource management policies with channel de-allocation in GPRS network. Three resource management policies is voice priority, R-reservation, dynamic reservation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.9
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• pp.39-48
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• 2008

Recently, many multimedia services have emerged in Internet such as real-time and non- real time services. However, in this Internet environment, we have some limitations to satisfy each service feature. To guarantee the service features in Measurement-Based Admission Control(MBAC) based system on the flow-aware network, there is the method applying Dynamic Priority Scheduling(DPS) algorithm that gives a higher priority to an earlier incoming flow in all of the link bandwidth. This paper classifies all flows under several groups according to flow characteristics on per-flow MBAC algorithm based system. In each flow group, DPS algorithm is applied. This paper proposes two methods that are a DPS based bandwidth borrowing method and a bandwidth dynamic allocation method. The former is that if low priority class has available bandwidths, the flow of high priority class borrows the bandwidth of low priority class when high priority flow has insufficient bandwidth to connect a flow call. The later is that the each group has a minimum bandwidth and is allocated the bandwidth dynamically according to the excess rate for available bandwidth. We compare and analyze the characteristics of the two proposed methods through the simulation experiments. As the results of the experiment, the proposed methods are more effective than existing DPS based method on the packet loss and delay characteristics. Consequently the proposed two methods are very useful in various multimedia network environments.

• Journal of Computing Science and Engineering
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• v.9 no.2
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• pp.51-72
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• 2015

Time predictability is crucial in hard real-time and safety-critical systems. Cache memories, while useful for improving the average-case memory performance, are not time predictable, especially when they are shared in multicore processors. To achieve time predictability while minimizing the impact on performance, this paper explores several time-predictable scratch-pad memory (SPM) based architectures for multicore processors. To support these architectures, we propose the dynamic memory objects allocation based partition, the static allocation based partition, and the static allocation based priority L2 SPM strategy to retain the characteristic of time predictability while attempting to maximize the performance and energy efficiency. The SPM based multicore architectural design and the related allocation methods thus form a comprehensive solution to hard real-time multicore based computing. Our experimental results indicate the strengths and weaknesses of each proposed architecture and the allocation method, which offers interesting on-chip memory design options to enable multicore platforms for hard real-time systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.7
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• pp.1256-1271
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• 1994

In this paper a GFC protocol based on HMR(High-speed Multimedia Ring) with a dynamic quota allocation is proposed and the performance of proposed protocol is evaluated by simulation. The HMR a medium access protocol proposed for Gbit ATM-LAN, can be applied to the GFC protocol without any modification because it uses only 4 bits for medium access of several topologies such as bus, ring and stared-bus, and priority control for satisfaction of different QoS(Quality of Service) requirements. The quota allocation method of HMR called static quota allocation has a problem of excessive access delay for the traffic with high burstness. In this paper a dynamic quota allocation method which allocates quota to the nodes according to the queue length is proposed and the performance of HMR with dynamic quota allocation is evaluated by seven simulation scenarios of CCITT. The HMR with proposed method shows better shows better access delay characteristics than the HMR with static quota allocation. Also the simulation results show that access delay performance of HMR is better than that of ATMR proposed by Japan and is similar to that of DQDB proposed by Australia.

• ETRI Journal
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• v.26 no.4
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• pp.321-331
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• 2004

In this paper, we propose a new dynamic bandwidth allocation (DBA) algorithm for multimedia services over Ethernet PONs (passive optical networks). The proposed algorithm is composed of a low-level scheduler in the optical network unit (ONU) and a high-level scheduler in the optical line terminal (OLT). The hierarchical DBA algorithm can provide expansibility and efficient resource allocation in an Ethernet PON system in which the packet scheduler is separated from the queues. In the proposed DBA algorithm, the OLT allocates bandwidth to the ONUs in proportion to the weight associated with their class and queue length, while the ONU preferentially allocates its bandwidth to queues with a static priority order. The proposed algorithm provides an efficient resource utilization by reducing the unused remaining bandwidth caused by the variable length of the packets. We also define the service classes and present control message formats conforming to the multi-point control protocol (MPCP) over an Ethernet PON. In order to evaluate the performance, we designed an Ethernet PON system on the basis of IEEE 802.3ah "Ethernet in the first mile" (EFM) using OPNET and carried out simulations. The results are analyzed in terms of the channel utilization, queuing delay, and ratio of the unused remaining bandwidth.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.246-251
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• 2013

In this paper, it is proposed a bandwidth allocation Scheme based on Bankruptcy theory in Distributed Mobile Multimedia Network. The proposed scheme is guaranteed a minimum allocation. So, the minimum quality of each service are guaranteed. Therefore efficient and fairness network can be configured. The performance evaluation results indicate that the proposed scheme has good performance than other existing schemes by the fairness index and the Erlang blocking formular calculation. The minimum bandwidth of the proposed scheme can be applied to other techniques of a priority based bandwidth allocation scheme and dynamic bandwidth allocation scheme.

• 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.94-103
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• 2006

Ethernet passive optical network (EPON) has drawn many attention as a promising access network technology for FTTH because it can provide a high bandwidth with a low cost. Since the uplink bandwidth in the EPON system is shared by many users, it is necessary for an EPON system to have an efficient bandwidth allocation mechanism. To support QoS in EPON, the previous bandwidth allocation schemes employ strict priority queueing (SPQ). Since SPQ gives unlimited priority to higher service class, the QoS of lower service classes gets worse. In this paper, we propose Class Gated DBA (Dynamic Bandwidth Allocation) algorithm in which the bandwidth is requested / granted in a service class basis. To avoid the monopoly in bandwidth usage by higher classes the maximum bandwidth that is allocate to each service class is limited (fairness between services classes). In addition, to avoid the monopoly in bandwidth usage by some particular users, each ONU runs fairness bandwidth allocation algorithm within each service classes. Through computer simulations, it is verified that the proposed algorithm achieves a good level of QoS, and at the same time maintains a good level of fairness between both service classes and users.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11B
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• pp.891-899
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• 2004

Ethernet passive optical network (EPON) has drawn many attention as a promising access network technology because it can provide a high bandwidth with a low cost. Since the uplink in the EPON system is shared by many users, it is necessary for an EPON system to have an efficient bandwidth allocation mechanism. In addition, as the users demand more QoS-oriented applications, it is necessary for an EPON system to have an efficient mechanism supporting QoS. In this paper, we propose a variable window dynamic bandwidth allocation (DBA) algorithm for the EPON system. Unlike the previously proposed DBA algorithms, the variable window algorithm guarantees the QoS for the highest priority class, and at the same time provides more enhanced QoS for the lower priority classes by dynamically allocating bandwidth if necessary. It is verified through the simulations that the variable window algorithm can provide more enhanced QoS performance than other DBA algorithms.